935270020151 - NXP - Datasheet.Directory

SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Rev. 02 — 14 March 2003 Product data

1. Description

The SC16C2550 is a 2 channel Universal Asynchronous Receiver and Transmitter

(UART) used for serial data communications. Its principal function is to convert

parallel data into serial data and vice versa. The UART can handle serial data rates

up to 5 Mbits/s.

The SC16C2550 is pin compatible with the ST16C2550. It will power-up to be

functionally equivalent to the 16C2450. The SC16C2550 provides enhanced UART

functions with 16-byte FIFOs, modem control interface, DMA mode data transfer. The

DMA mode data transfer is controlled by the FIFO trigger levels and the TXRDY and

RXRDY signals. On-board status registers provide the user with error indications and

operational status. System interrupts and modem control features may be tailored by

software to meet speciﬁc user requirements. An internal loop-back capability allows

on-board diagnostics. Independent programmable baud rate generators are provided

to select transmit and receive baud rates.

The SC16C2550 operates at 5 V, 3.3 V and 2.5 V and the Industrial temperature

range, and is available in plastic PLCC44, LQFP48 and DIP40 packages.

2. Features

■2 channel UART

■5 V, 3.3 V and 2.5 V operation

■Industrial temperature range

■Pin and functionally compatible to 16C2450 and software compatible with

INS8250, SC16C550

■Up to 5 Mbits/s data rate at 5 V and 3.3 V, and 3 Mbits/s at 2.5 V

■16 byte transmit FIFO to reduce the bandwidth requirement of the external CPU

■16 byte receive FIFO with error ﬂags to reduce the bandwidth requirement of the

external CPU

■Independent transmit and receive UART control

■Four selectable Receive FIFO interrupt trigger levels

■Automatic software/hardware ﬂow control

■Programmable Xon/Xoff characters

■Software selectable Baud Rate Generator

■Sleep mode

■Standard asynchronous error and framing bits (Start, Stop, and Parity Overrun

Break)

■Transmit, Receive, Line Status, and Data Set interrupts independently controlled

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 2 of 47

■Fully programmable character formatting:

◆5-, 6-, 7-, or 8-bit characters

◆Even-, Odd-, or No-Parity formats

◆1-, 11⁄2-, or 2-stop bit

◆Baud generation (DC to 1.5 Mbit/s)

■False start-bit detection

■Complete status reporting capabilities

■3-State output TTL drive capabilities for bi-directional data bus and control bus

■Line Break generation and detection

■Internal diagnostic capabilities:

◆Loop-back controls for communications link fault isolation

■Prioritized interrupt system controls

■Modem control functions (CTS, RTS, DSR, DTR, RI, DCD).

3. Ordering information

Table 1: Ordering information

Type number Package

Name Description Version

SC16C2550IN40 DIP40 plastic dual in-line package; 40 leads (600 mil) SOT129-1

SC16C2550IA44 PLCC44 plastic leaded chip carrier; 44 leads SOT187-2

SC16C2550IB48 LQFP48 plastic low proﬁle quad ﬂat package; 48 leads; body 7 ×7×1.4 mm SOT313-2

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 3 of 47

4. Block diagram

Fig 1. SC16C2550 block diagram.

TRANSMIT

FIFO

RECEIVE

SHIFT

RECEIVE

FIFO

INTERCONNECT BUS LINES

AND

CONTROL SIGNALS

SC16C2550

TRANSMIT

SHIFT

MODEM

CONTROL

LOGIC

DTRA, DTRB

RTSA, RTSB

OP2A, OP2B

CLOCK AND

BAUD RATE

GENERATOR

CTSA, CTSB

RIA, RIB

CDA, CDB

DSRA, DSRB

XTAL2XTAL1

DATA BUS

AND

CONTROL LOGIC

D0–D7

IOR

IOW

RESET

A0–A2

CSA

CSB

SELECT

LOGIC

INTA, INTB

TXRDYA, TXRD YB

RXRDYA, RXRDYB

INTERRUPT

CONTROL

LOGIC

002aaa119

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 4 of 47

5. Pinning information

5.1 Pinning

Fig 2. DIP40 pin conﬁguration.

SC16C2550IN40

002aaa105

RXB

RXA

TXA

TXB

OP2B

CSA

CSB

XTAL1

XTAL2

IOW

CDB

GND

VCC

RIA

CDA

DSRA

CTSA

RESET

DTRB

DTRA

RTSA

OP2A

INTA

INTB

CTSB

RTSB

RIB

DSRB

IOR

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 5 of 47

Fig 3. PLCC44 pin conﬁguration.

SC16C2550IA44

002aaa103

TXRDYA

VCC

RIA

CDA

DSRA

CTSA

XTAL1

XTAL2

IOW

CDB

GND

RXRDYB

IOR

DSRB

RIB

RTSB

CTSB

RXB

RXA

TXRDYB

TXA

TXB

OP2B

CSA

CSB

RESET

DTRB

DTRA

RTSA

OP2A

RXRDYA

INTA

INTB

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 6 of 47

5.2 Pin description

Fig 4. LQFP48 pin conﬁguration.

SC16C2550IB48

002aaa104

TXRDYA

VCC

RIA

CDA

DSRA

CTSA

N.C.

XTAL1

XTAL2

IOW

CDB

GND

RXRDYB

IOR

DSRB

RIB

RTSB

CTSB

N.C.

RXB

RXA

TXRDYB

TXA

TXB

OP2B

CSA

CSB

N.C.

RESET

DTRB

DTRA

RTSA

OP2A

RXRDYA

INTA

INTB

N.C.

Table 2: Pin description

Symbol Pin Type Description

DIP40 PLCC44 LQFP48

A0 28 31 28 I Address 0 select bit. Internal register address selection.

A1 27 30 27 I Address 1 select bit. Internal register address selection.

A2 26 29 26 I Address 2 select bit. Internal register address selection.

CSA, CSB 14, 15 16, 17 10, 11 I Chip Select A, B (Active-LOW). This function is associated with individual

channels, A through B. These pins enable data transfers between the user

CPU and the SC16C2550 for the channel(s) addressed. Individual UART

sections (A, B) are addressed by providing a logic 0 on the respective CSA,

CSB pin.

D0-D7 1-8 2-9 44-48,

1-3 I/O Data bus (bi-directional). These pins are the 8-bit, 3-State data bus for

transferring information to or from the controlling CPU. D0 is the least

signiﬁcant bit and the ﬁrst data bit in a transmit or receive serial data

stream.

GND 20 22 17 I Signal and power ground.

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 7 of 47

INTA,

INTB 30, 29 33, 32 30, 29 O Interrupt A, B (3-State). This function is associated with individual channel

interrupts, INTA, INTB. INTA, INTB are enabled when MCR bit 3 is set to a

logic 1, interrupts are enabled in the interrupt enable register (IER), and is

active when an interrupt condition exists. Interrupt conditions include:

receiver errors, available receiver buffer data, transmit buffer empty, or

when a modem status ﬂag is detected.

IOR 21 24 19 I Read strobe (Active-LOW strobe). A logic 0 transition on this pin will load

the contents of an internal register deﬁned by address bits A0-A2 onto the

SC16C2550 data bus (D0-D7) for access by external CPU.

IOW182015IWrite strobe (Active-LOW strobe). A logic 0 transition on this pin will

transfer the contents of the data bus (D0-D7) from the external CPU to an

internal register that is deﬁned by address bits A0-A2.

OP2A,

OP2B 31, 13 35, 15 32, 9 O Output 2 (user-deﬁned). This function is associated with individual

channels, A through B. The state at these pin(s) are deﬁned by the user

and through MCR register bit 3. INTA, INTB are set to the active mode and

OP2 to logic 0 when MCR[3] is set to a logic 1. INTA, INTB are set to the

3-State mode and OP2 to a logic 1 when MCR[3] is set to a logic 0. See

bit 3, Modem Control Register (MCR[3]). Since these bits control both the

INTA, INTB operation and OP2 outputs, only one function should be used

at one time, INT or OP2.

RESET 35 39 36 I Reset (Active-HIGH). A logic 1 on this pin will reset the internal registers

and all the outputs. The UART transmitter output and the receiver input will

be disabled during reset time. (See Section 7.11 “SC16C2550 external

reset condition” for initialization details.)

RXRDYA,

RXRDYB - 34, 23 31, 18 O Receive Ready A, B (Active-LOW). This function is associated with

PLCC44 and LQFP48 packages only. This function provides the

RX FIFO/RHR status for individual receive channels (A-B). RXRDYn is

primarily intended for monitoring DMA mode 1 transfers for the receive data

FIFOs. A logic 0 indicates there is a receive data to read/upload, i.e.,

receive ready status with one or more RX characters available in the

FIFO/RHR. This pin is a logic 1 when the FIFO/RHR is empty or when the

programmed trigger level has not been reached. This signal can also be

used for single mode transfers (DMA mode 0).

TXRDYA,

TXRDYB - 1, 12 43, 6 O Transmit Ready A, B (Active-LOW). This function is associated with

PLCC44 and LQFP48 packages only. These outputs provide the

TX FIFO/THR status for individual transmit channels (A-B). TXRDYn is

primarily intended for monitoring DMA mode 1 transfers for the transmit

data FIFOs. An individual channel’s TXRDYA, TXRDYB buffer ready status

is indicated by logic 0, i.e., at lease one location is empty and available in

the FIFO or THR. This pin goes to a logic 1 (DMA mode 1) when there are

no more empty locations in the FIFO or THR. This signal can also be used

for single mode transfers (DMA mode 0).

VCC 40 44 42 I Power supply input.

XTAL1 16 18 13 I Crystal or external clock input. Functions as a crystal input or as an

external clock input. A crystal can be connected between this pin and

XTAL2 to form an internal oscillator circuit. This conﬁguration requires an

external 1 MΩ resistor between the XTAL1 and XTAL2 pins. Alternatively,

an external clock can be connected to this pin to provide custom data rates.

(See Section 6.8 “Programmable baud rate generator”.) See Figure 5.

Table 2: Pin description

…continued

Symbol Pin Type Description

DIP40 PLCC44 LQFP48

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 8 of 47

XTAL2 17 19 14 O Output of the crystal oscillator or buffered clock. (See also XTAL1.)

Crystal oscillator output or buffered clock output. Should be left open if an

external clock is connected to XTAL1. For extended frequency operation,

this pin should be tied to VCC via a 2 kΩ resistor.

CDA,

CDB 38, 19 42, 21 40, 16 I Carrier Detect (Active-LOW). These inputs are associated with individual

UART channels A through B. A logic 0 on this pin indicates that a carrier

has been detected by the modem for that channel.

CTSA,

CTSB 36, 25 40, 28 38, 23 I Clear to Send (Active-LOW). These inputs are associated with individual

UART channels, A through B. A logic 0 on the CTS pin indicates the

modem or data set is ready to accept transmit data from the SC16C2550.

Status can be tested by reading MSR[4]. This pin has no effect on the

UART’s transmit or receive operation.

DSRA,

DSRB 37, 22 41, 25 39, 20 I Data Set Ready (Active-LOW). These inputs are associated with

individual UART channels, A through B. A logic 0 on this pin indicates the

modem or data set is powered-on and is ready for data exchange with the

UART. This pin has no effect on the UART’s transmit or receive operation.

DTRA,

DTRB 33, 34 37, 38 34, 35 O Data Terminal REady (Active-LOW). These outputs are associated with

individual UART channels, A through B. A logic 0 on this pin indicates that

the SC16C2550 is powered-on and ready. This pin can be controlled via

the modem control register. Writing a logic 1 to MCR[0] will set the DTR

output to logic 0, enabling the modem. This pin will be a logic 1 after writing

a logic 0 to MCR[0], or after a reset. This pin has no effect on the UART’s

transmit or receive operation.

RIA, RIB 39, 23 43, 26 41, 21 I Ring Indicator (Active-LOW). These inputs are associated with individual

UART channels, A through B. A logic 0 on this pin indicates the modem has

received a ringing signal from the telephone line. A logic 1 transition on this

input pin will generate an interrupt.

RTSA,

RTSB 32, 24 36, 27 33, 22 O Request to Send (Active-LOW). These outputs are associated with

individual UART channels, A through B. A logic 0 on the RTS pin indicates

the transmitter has data ready and waiting to send. Writing a logic 1 in the

modem control register MCR[1] will set this pin to a logic 0, indicating data

is available. After a reset this pin will be set to a logic 1. This pin has no

effect on the UART’s transmit or receive operation.

RXA, RXB 10, 9 11, 10 5, 4 I Receive data A, B. These inputs are associated with individual serial

channel data to the SC16C2550 receive input circuits, A-B. The RX signal

will be a logic 1 during reset, idle (no data), or when the transmitter is

disabled. During the local loop-back mode, the RX input pin is disabled and

TX data is connected to the UART RX input, internally.

TXA, TXB 11, 12 13, 14 7, 8 O Transmit data A, B. These outputs are associated with individual serial

transmit channel data from the SC16C2550. The TX signal will be a logic 1

during reset, idle (no data), or when the transmitter is disabled. During the

local loop-back mode, the TX output pin is disabled and TX data is

internally connected to the UART RX input.

Table 2: Pin description

…continued

Symbol Pin Type Description

DIP40 PLCC44 LQFP48

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 9 of 47

6. Functional description

The SC16C2550 provides serial asynchronous receive data synchronization,

parallel-to-serial and serial-to-parallel data conversions for both the transmitter and

receiver sections. These functions are necessary for converting the serial data

stream into parallel data that is required with digital data systems. Synchronization for

the serial data stream is accomplished by adding start and stop bits to the transmit

data to form a data character (character orientated protocol). Data integrity is insured

by attaching a parity bit to the data character. The parity bit is checked by the receiver

for any transmission bit errors. The electronic circuitry to provide all these functions is

fairly complex, especially when manufactured on a single integrated silicon chip. The

SC16C2550 represents such an integration with greatly enhanced features. The

SC16C2550 is fabricated with an advanced CMOS process.

The SC16C2550 is an upward solution that provides a dual UART capability with

16 bytes of transmit and receive FIFO memory, instead of none in the 16C2450. The

SC16C2550 is designed to work with high speed modems and shared network

environments that require fast data processing time. Increased performance is

realized in the SC16C2550 by the transmit and receive FIFOs. This allows the

external processor to handle more networking tasks within a given time. For example,

the ST16C2450 without a receive FIFO, will require unloading of the RHR in

93 microseconds (this example uses a character length of 11 bits, including start/stop

bits at 115.2 kbits/s). This means the external CPU will have to service the receive

FIFO less than every 100 microseconds. However, with the 16 byte FIFO in the

SC16C2550, the data buffer will not require unloading/loading for 1.53 ms. This

increases the service interval, giving the external CPU additional time for other

applications and reducing the overall UART interrupt servicing time. In addition, the

four selectable receive FIFO trigger interrupt levels is uniquely provided for maximum

data throughput performance especially when operating in a multi-channel

environment. The FIFO memory greatly reduces the bandwidth requirement of the

external controlling CPU, increases performance, and reduces power consumption.

The SC16C2550 is capable of operation up to 5 Mbits/s with a 80 MHz clock. With a

crystal or external clock input of 7.3728 MHz, the user can select data rates up to

460.8 kbits/s.

The rich feature set of the SC16C2550 is available through internal registers.

Selectable receive FIFO trigger levels, selectable TX and RX baud rates, and modem

interface controls are all standard features. Following a power-on reset or an external

reset, the SC16C2550 is software compatible with the previous generation,

ST16C2450.

6.1 UART A-B functions

The UART provides the user with the capability to bi-directionally transfer information

between an external CPU, the SC16C2550 package, and an external serial device. A

logic 0 on chip select pins CSA and/or CSB allows the user to conﬁgure, send data,

and/or receive data via UART channels A-B. Individual channel select functions are

shown in Table 3.

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 10 of 47

6.2 Internal registers

The SC16C2550 provides two sets of internal registers (A and B) consisting of

12 registers each for monitoring and controlling the functions of each channel of the

UART. These registers are shown in Table 4. The UART registers function as data

holding registers (THR/RHR), interrupt status and control registers (IER/ISR), a FIFO

control register (FCR), line status and control registers (LCR/LSR), modem status

and control registers (MCR/MSR), programmable data rate (clock) control registers

(DLL/DLM), and a user accessible scratchpad register (SPR).

[1] These registers are accessible only when LCR[7] is a logic 0.

[2] These registers are accessible only when LCR[7] is a logic 1.

[3] Enhanced Feature Register, Xon1, 2 and Xoff1, 2 are accessible only when the LCR is set to

‘BF(HEX)’.

Table 3: Serial port selection

Chip Select Function

CSA-CSB = 1 none

CSA = 0 UART channel A

CSB = 0 UART channel B

Table 4: Internal registers decoding

A2 A1 A0 READ mode WRITE mode

General register set (THR/RHR, IER/ISR, MCR/MSR, FCR, LSR, SPR)[1]

0 0 0 Receive Holding Register Transmit Holding Register

0 0 1 Interrupt Enable Register

0 1 0 Interrupt Status Register FIFO Control Register

0 1 1 Line Control Register

1 0 0 Modem Control Register

1 0 1 Line Status Register n/a

1 1 0 Modem Status Register n/a

1 1 1 Scratchpad Register Scratchpad Register

Baud rate register set (DLL/DLM)[2]

0 0 0 LSB of Divisor Latch LSB of Divisor Latch

0 0 1 MSB of Divisor Latch MSB of Divisor Latch

Enhanced register set (EFR, Xon/off 1-2)[3]

0 1 0 Enhanced Feature Register Enhanced Feature Register

1 0 0 Xon1 word Xon1 word

1 0 1 Xon2 word Xon2 word

1 1 0 Xoff1 word Xoff1 word

1 1 1 Xoff2 word Xoff2 word

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 11 of 47

6.3 FIFO operation

The 16 byte transmit and receive data FIFOs are enabled by the FIFO Control

not the transmit trigger level. The receiver FIFO section includes a time-out function

to ensure data is delivered to the external CPU. An interrupt is generated whenever

the Receive Holding Register (RHR) has not been read following the loading of a

character or the receive trigger level has not been reached.

6.4 Hardware ﬂow control

When automatic hardware ﬂow control is enabled, the SC16C2550 monitors the CTS

pin for a remote buffer overﬂow indication and controls the RTS pin for local buffer

overﬂows. Automatic hardware ﬂow control is selected by setting EFR[6] (RTS) and

EFR[7] (CTS) to a logic 1. If CTS transitions from a logic 0 to a logic 1 indicating a

ﬂow control request, ISR[5] will be set to a logic 1 (if enabled via IER[6,7]), and the

SC16C2550 will suspend TX transmissions as soon as the stop bit of the character in

process is shifted out. Transmission is resumed after the CTS input returns to a

logic 0, indicating more data may be sent.

With the Auto RTS function enabled, an interrupt is generated when the receive FIFO

reaches the programmed trigger level. The RTS pin will not be forced to a logic 1

(RTS off), until the receive FIFO reaches the next trigger level. However, the RTS pin

will return to a logic 0 after the data buffer (FIFO) is unloaded to the next trigger level

below the programmed trigger. However, under the above described conditions, the

SC16C2550 will continue to accept data until the receive FIFO is full.

6.5 Software ﬂow control

When software ﬂow control is enabled, the SC16C2550 compares one or two

sequential receive data characters with the programmed Xon/Xoff or Xoff1,2

character value(s). If received character(s) match the programmed values, the

SC16C2550 will halt transmission (TX) as soon as the current character(s) has

completed transmission. When a match occurs, the receive ready (if enabled via Xoff

IER[5]) ﬂags will be set and the interrupt output pin (if receive interrupt is enabled) will

be activated. Following a suspension due to a match of the Xoff characters’ values,

the SC16C2550 will monitor the receive data stream for a match to the Xon1,2

character value(s). If a match is found, the SC16C2550 will resume operation and

clear the ﬂags (ISR[4]).

Reset initially sets the contents of the Xon/Xoff 8-bit ﬂow control registers to a logic 0.

Following reset, the user can write any Xon/Xoff value desired for software ﬂow

control. Different conditions can be set to detect Xon/Xoff characters and

suspend/resume transmissions. When double 8-bit Xon/Xoff characters are selected,

Table 5: Flow control mechanism

Selected trigger level

(characters) INT pin activation Negate RTS or

send Xoff Assert RTS or

send Xon

1141

4484

8 8 12 8

14 14 14 10

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 12 of 47

the SC16C2550 compares two consecutive receive characters with two software ﬂow

control 8-bit values (Xon1, Xon2, Xoff1, Xoff2) and controls TX transmissions

accordingly. Under the above described ﬂow control mechanisms, ﬂow control

characters are not placed (stacked) in the user accessible RX data buffer or FIFO.

In the event that the receive buffer is overﬁlling and ﬂow control needs to be executed,

the SC16C2550 automatically sends an Xoff message (when enabled) via the serial

TX output to the remote modem. The SC16C2550 sends the Xoff1,2 characters as

soon as received data passes the programmed trigger level. To clear this condition,

the SC16C2550 will transmit the programmed Xon1,2 characters as soon as receive

data drops below the programmed trigger level.

6.6 Special feature software ﬂow control

A special feature is provided to detect an 8-bit character when EFR[5] is set. When

8-bit character is detected, it will be placed on the user-accessible data stack along

with normal incoming RX data. This condition is selected in conjunction with

EFR[0-3]. Note that software ﬂow control should be turned off when using this special

mode by setting EFR[0-3] to a logic 0.

The SC16C2550 compares each incoming receive character with Xoff2 data. If a

match exists, the received data will be transferred to the FIFO, and ISR[4] will be set

to indicate detection of a special character. Although the Internal Register Table

(Table 7) shows each X-Register with eight bits of character information, the actual

number of bits is dependent on the programmed word length. Line Control Register

bits LCR[0-1] deﬁne the number of character bits, i.e., either 5 bits, 6 bits, 7 bits or

8 bits. The word length selected by LCR[0-1] also determine the number of bits that

will be used for the special character comparison. Bit 0 in the X-registers corresponds

with the LSB bit for the receive character.

6.7 Hardware/software and time-out interrupts

The interrupts are enabled by IER[0-3]. Care must be taken when handling these

interrupts. Following a reset, if Interrupt Enable Register (IER) bit 1 = 1, the

SC16C2550 will issue a Transmit Holding Register interrupt. This interrupt must be

serviced prior to continuing operations. The LSR register provides the current

singular highest priority interrupt only. It could be noted that CTS and RTS interrupts

have lowest interrupt priority. A condition can exist where a higher priority interrupt

may mask the lower priority CTS/RTS interrupt(s). Only after servicing the higher

pending interrupt will the lower priority CTS/RTS interrupt(s) be reﬂected in the status

result in data errors.

When two interrupt conditions have the same priority, it is important to service these

interrupts correctly. Receive Data Ready and Receive Time Out have the same

interrupt priority (when enabled by IER[3]). The receiver issues an interrupt after the

number of characters have reached the programmed trigger level. In this case, the

SC16C2550 FIFO may hold more characters than the programmed trigger level.

Following the removal of a data byte, the user should re-check LSR[0] for additional

characters. A Receive Time Out will not occur if the receive FIFO is empty. The

time-out counter is reset at the center of each stop bit received or each time the

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 13 of 47

receive holding register (RHR) is read. The actual time-out value is 4 character time,

including data information length, start bit, parity bit, and the size of stop bit, i.e., 1×,

1.5×, or 2× bit times.

6.8 Programmable baud rate generator

The SC16C2550 supports high speed modem technologies that have increased input

data rates by employing data compression schemes. For example, a 33.6 kbit/s

modem that employs data compression may require a 115.2 kbit/s input data rate.

A 128.0 kbit/s ISDN modem that supports data compression may need an input

data rate of 460.8 kbit/s. The SC16C2550 can support a standard data rate of

921.6 kbit/s.

A single baud rate generator is provided for the transmitter and receiver, allowing

independent TX/RX channel control. The programmable Baud Rate Generator is

capable of operating with a frequency of up to 80 MHz. To obtain maximum data rate,

it is necessary to use full rail swing on the clock input. The SC16C2550 can be

conﬁgured for internal or external clock operation. For internal clock oscillator

operation, an industry standard microprocessor crystal is connected externally

between the XTAL1 and XTAL2 pins. Alternatively, an external clock can be

connected to the XTAL1 pin to clock the internal baud rate generator for standard or

custom rates (see Table 6).

The generator divides the input 16× clock by any divisor from 1 to 216 −1. The

SC16C2550 divides the basic external clock by 16. The basic 16× clock provides

table rates to support standard and custom applications using the same system

design. The rate table is conﬁgured via the DLL and DLM internal register functions.

Customized Baud Rates can be achieved by selecting the proper divisor values for

the MSB and LSB sections of baud rate generator.

Programming the Baud Rate Generator Registers DLM (MSB) and DLL (LSB)

provides a user capability for selecting the desired ﬁnal baud rate. The example in

Table 6 shows the selectable baud rate table available when using a 1.8432 MHz

external clock input.

Fig 5. Crystal oscillator connection.

002aaa169

1.8432 MHz

68 pF C2

68 pF

XTAL1

XTAL2

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 14 of 47

6.9 DMA operation

The SC16C2550 FIFO trigger level provides additional ﬂexibility to the user for block

mode operation. LSR[5,6] provide an indication when the transmitter is empty or has

an empty location(s). The user can optionally operate the transmit and receive FIFOs

in the DMA mode (FCR[3]). When the transmit and receive FIFOs are enabled and

the DMA mode is de-activated (DMA Mode 0), the SC16C2550 activates the interrupt

output pin for each data transmit or receive operation. When DMA mode is activated

(DMA Mode 1), the user takes the advantage of block mode operation by loading or

unloading the FIFO in a block sequence determined by the receive trigger level and

the transmit FIFO. In this mode, the SC16C2550 sets the TXRDY (or RXRDY) output

pin when characters in the transmit FIFO is below 16, or the characters in the receive

FIFOs are above the receive trigger level.

6.10 Loop-back mode

The internal loop-back capability allows on-board diagnostics. In the loop-back mode,

the normal modem interface pins are disconnected and reconﬁgured for loop-back

internally (see Figure 6). MCR[0-3] register bits are used for controlling loop-back

diagnostic testing. In the loop-back mode, the transmitter output (TX) and the receiver

input (RX) are disconnected from their associated interface pins, and instead are

connected together internally. The CTS, DSR, CD, and RI are disconnected from

their normal modem control inputs pins, and instead are connected internally to RTS,

DTR, MCR[3] (OP2) and MCR[2] (OP1). Loop-back test data is entered into the

transmit holding register via the user data bus interface, D0-D7. The transmit UART

serializes the data and passes the serial data to the receive UART via the internal

loop-back connection. The receive UART converts the serial data back into parallel

Table 6: Baud rate generator programming table using a 1.8432 MHz clock

Output

baud rate Output

16 ×clock divisor

(decimal)

Output

16 ×clock divisor

(HEX)

DLM

program value

(HEX)

DLL

program value

(HEX)

50 2304 900 09 00

75 1536 600 06 00

110 1047 417 04 17

150 768 300 03 00

300 384 180 01 80

600 192 C0 00 C0

1200 96 60 00 60

2400 48 30 00 30

3600 32 20 00 20

4800 24 18 00 18

7200 16 10 00 10

9600 12 0C 00 0C

19.2 k 6 06 00 06

38.4 k 3 03 00 03

57.6 k 2 02 00 02

115.2 k 1 01 00 01

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 15 of 47

data that is then made available at the user data interface D0-D7. The user optionally

compares the received data to the initial transmitted data for verifying error-free

operation of the UART TX/RX circuits.

In this mode, the receiver and transmitter interrupts are fully operational. The Modem

Control Interrupts are also operational.

Fig 6. Internal loop-back mode diagram.

TRANSMIT

FIFO

TXA, TXB

RECEIVE

SHIFT

RECEIVE

FIFO

INTERCONNECT BUS LINES

AND

CONTROL SIGNALS

SC16C2550

TRANSMIT

SHIFT

MODEM

CONTROL

LOGIC

CLOCK AND

BAUD RATE

GENERATOR

XTAL2XTAL1

DATA BUS

AND

CONTROL LOGIC

D0–D7

IOR

IOW

RESET

A0–A2

CSA, CSB REGISTER

SELECT

LOGIC

INTA, INTB

TXRDYA, TXRD YB

RXRDYA, RXRDYB

INTERRUPT

CONTROL

LOGIC

002aaa120

MCR[4] = 1

CTSA, CTSB

RTSA, RTSB

DSRA, DSRB

DTRA, DTRB

RIA, RIB

(OP1A, OP1B)

CDA, CDB

(OP2A, OP2B)

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 16 of 47

7. Register descriptions

Table 7 details the assigned bit functions for the SC16C2550 internal registers. The

assigned bit functions are more fully deﬁned in Section 7.1 through Section 7.11.

[1] The value shown in represents the register’s initialized HEX value; X = n/a.

[2] Accessible only when LCR[7] is logic 0.

[3] Baud rate registers accessible only when LCR[7] is logic 1.

[4] Enhanced Feature Register, Xon-1,2 and Xoff-1,2 are accessible only when LCR is set to ‘BFHex’.

Table 7: SC16C2550 internal registers

Shaded bits are only accessible when EFR[4] is set.

A2 A1 A0 Register Default[1] Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

General Register Set[2]

0 0 0 RHR XX bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

0 0 0 THR XX bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

0 0 1 IER 00 CTS

interrupt RTS

interrupt Xoff

interrupt Sleep

mode modem

status

interrupt

receive

line

status

interrupt

transmit

holding

interrupt

receive

holding

0 1 0 FCR 00 RCVR

trigger

(MSB)

RCVR

trigger

(LSB)

reserved

0reserved

0DMA

mode

select

XMIT

FIFO

reset

RCVR

FIFO

reset

FIFOs

enable

0 1 0 ISR 01 FIFOs

enabled FIFOs

enabled INT

priority

bit 4

INT

priority

bit 3

INT

priority

bit 2

INT

priority

bit 1

INT

priority

bit 0

INT

status

0 1 1 LCR 00 divisor

latch

enable

set break set parity even

parity parity

enable stop bits word

length

bit 1

word

length

bit 0

1 0 0 MCR 00 0 IR

enable 0 loop back OP2/INT

enable (OP1) RTS DTR

1 0 1 LSR 60 FIFO

data

error

THR and

TSR

empty

THR

empty break

interrupt framing

error parity

error overrun

error receive

data

ready

1 1 0 MSR X0 CD RI DSR CTS ∆CD ∆RI ∆DSR ∆CTS

1 1 1 SPR FF bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

Special Register Set[3]

0 0 0 DLL XX bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

0 0 1 DLM XX bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8

Enhanced Register Set[4]

0 1 0 EFR 00 Auto

CTS Auto

RTS Special

char.

select

Enable

IER[4-7],

ISR[4,5],

FCR[4,5],

MCR[5-7]

Cont-3

Tx, Rx

Control

Cont-2

Tx, Rx

Control

Cont-1

Tx, Rx

Control

Cont-0

Tx, Rx

Control

1 0 0 Xon-1 00 bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

1 0 1 Xon-2 00 bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8

1 1 0 Xoff-1 00 bit 7 bit 6 bit 5 bit 4 bit 3 bit 2 bit 1 bit 0

1 1 1 Xoff-2 00 bit 15 bit 14 bit 13 bit 12 bit 11 bit 10 bit 9 bit 8

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 17 of 47

7.1 Transmit (THR) and Receive (RHR) Holding Registers

The serial transmitter section consists of an 8-bit Transmit Hold Register (THR) and

Transmit Shift Register (TSR). The status of the THR is provided in the Line Status

the TSR and UART via the THR, providing that the THR is empty. The THR empty

ﬂag in the LSR register will be set to a logic 1 when the transmitter is empty or when

data is transferred to the TSR. Note that a write operation can be performed when the

THR empty ﬂag is set (logic 0 = at least one byte in FIFO/THR, logic 1 = FIFO/THR

empty).

The serial receive section also contains an 8-bit Receive Holding Register (RHR) and

a Receive Serial Shift Register (RSR). Receive data is removed from the SC16C2550

and receive FIFO by reading the RHR register. The receive section provides a

mechanism to prevent false starts. On the falling edge of a start or false start bit, an

internal receiver counter starts counting clocks at the 16× clock rate. After 7-1⁄2

clocks, the start bit time should be shifted to the center of the start bit. At this time the

start bit is sampled, and if it is still a logic 0 it is validated. Evaluating the start bit in

this manner prevents the receiver from assembling a false character. Receiver status

codes will be posted in the LSR.

7.2 Interrupt Enable Register (IER)

The Interrupt Enable Register (IER) masks the interrupts from receiver ready,

transmitter empty, line status and modem status registers. These interrupts would

normally be seen on the INTA, INTB output pins.

Table 8: Interrupt Enable Register bits description

Bit Symbol Description

7 IER[7] CTS interrupt.

Logic 0 = Disable the CTS interrupt (normal default condition).

Logic 1 = Enable the CTS interrupt. The SC16C2550 issues an

interrupt when the CTS pin transitions from a logic 0 to a logic 1.

6 IER[6] RTS interrupt.

Logic 0 = Disable the RTS interrupt (normal default condition).

Logic 1 = Enable the RTS interrupt. The SC16C2550 issues an

interrupt when the RTS pin transitions from a logic 0 to a logic 1.

5 IER[5] Xoff interrupt.

Logic 0 = Disable the software ﬂow control, receiveXoff interrupt

(normal default condition).

Logic 1 = Enable the software ﬂow control, receive Xoff interrupt.

4 IER[4] Sleep mode.

Logic 0 = Disable sleep mode (normal default condition).

Logic 1 = Enable sleep mode.

3 IER[3] Modem Status Interrupt. This interrupt will be issued whenever

there is a modem status change as reﬂected in MSR[0-3].

Logic 0 = Disable the modem status register interrupt (normal

default condition).

Logic 1 = Enable the modem status register interrupt.

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 18 of 47

7.2.1 IER versus Transmit/Receive FIFO interrupt mode operation

When the receive FIFO (FCR[0] = logic 1), and receive interrupts (IER[0] = logic 1)

are enabled, the receive interrupts and register status will reﬂect the following:

•The receive RXRDY interrupt (Level 2 ISR interrupt) is issued to the external CPU

when the receive FIFO has reached the programmed trigger level. It will be cleared

when the receive FIFO drops below the programmed trigger level.

•Receive FIFO status will also be reﬂected in the user accessible ISR register when

the receive FIFO trigger level is reached. Both the ISR register receive status bit

and the interrupt will be cleared when the FIFO drops below the trigger level.

•The receive data ready bit (LSR[0]) is set as soon as a character is transferred

from the shift register (RSR) to the receive FIFO. It is reset when the FIFO is

empty.

•When the Transmit FIFO and interrupts are enabled, an interrupt is generated

when the transmit FIFO is empty due to the unloading of the data by the TSR and

UART for transmission via the transmission media. The interrupt is cleared either

by reading the ISR register, or by loading the THR with new data characters.

2 IER[2] Receive Line Status interrupt. This interrupt will be issued

whenever a receive data error condition exists as reﬂected in

LSR[1-4].

Logic 0 = Disable the receiver line status interrupt (normal

default condition).

Logic 1 = Enable the receiver line status interrupt.

1 IER[1] Transmit Holding Register interrupt. In the 16C450 mode, this

interrupt will be issued whenever the THR is empty, and is

associated with LSR[5]. In the FIFO modes, this interrupt will be

issued whenever the FIFO is empty.

Logic 0 = Disable the Transmit Holding Register Empty (TXRDY)

interrupt (normal default condition).

Logic 1 = Enable the TXRDY (ISR level 3) interrupt.

0 IER[0] Receive Holding Register. In the 16C450 mode, this interrupt will

be issued when the RHR has data, or is cleared when the RHR is

empty. In the FIFO mode, this interrupt will be issued when the

FIFO has reached the programmed trigger level or is cleared when

the FIFO drops below the trigger level.

Logic 0 = Disable the receiver ready (ISR level 2, RXRDY)

interrupt (normal default condition).

Logic 1 = Enable the RXRDY (ISR level 2) interrupt.

Table 8: Interrupt Enable Register bits description

…continued

Bit Symbol Description

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 19 of 47

7.2.2 IER versus Receive/Transmit FIFO polled mode operation

When FCR[0] = logic 1, resetting IER[0-3] enables the SC16C2550 in the FIFO

polled mode of operation. In this mode, interrupts are not generated and the user

must poll the LSR register for TX and/or RX data status. Since the receiver and

transmitter have separate bits in the LSR either or both can be used in the polled

mode by selecting respective transmit or receive control bit(s).

•LSR[0] will be a logic 1 as long as there is one byte in the receive FIFO.

•LSR[1-4] will provide the type of receive errors, or a receive break, if encountered.

•LSR[5] will indicate when the transmit FIFO is empty.

•LSR[6] will indicate when both the transmit FIFO and transmit shift register are

empty.

•LSR[7] will show if any FIFO data errors occurred.

7.3 FIFO Control Register (FCR)

This register is used to enable the FIFOs, clear the FIFOs, set the receive FIFO

trigger levels, and select the DMA mode.

7.3.1 DMA mode

Mode 0 (FCR bit 3 = 0): Set and enable the interrupt for each single transmit or

receive operation, and is similar to the 16C450 mode. Transmit Ready (TXRDY) on

PLCC44 and LQFP48 packages will go to a logic 0 whenever the FIFO (THR, if FIFO

is not enabled) is empty. Receive Ready (RXRDY) on PLCC44 and LQFP48

packages will go to a logic 0 whenever the Receive Holding Register (RHR) is loaded

with a character.

Mode 1 (FCR bit 3 = 1): Set and enable the interrupt in a block mode operation. The

transmit interrupt is set when the transmit FIFO is empty. TXRDY on PLCC and

LQFP48 packages remains a logic 0 as long as one empty FIFO location is available.

The receive interrupt is set when the receive FIFO ﬁlls to the programmed trigger

level. However, the FIFO continues to ﬁll regardless of the programmed level until the

FIFO is full. RXRDY on PLCC44 and LQFP48 packages transitions LOW when the

FIFO reaches the trigger level, and transitions HIGH when the FIFO empties.

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 20 of 47

7.3.2 FIFO mode

Table 9: FIFO Control Register bits description

Bit Symbol Description

7-6 FCR[7]

(MSB),

FCR[6]

(LSB)

RCVR trigger. These bits are used to set the trigger level for the

receive FIFO interrupt.

Logic 0 (or cleared) = normal default condition.

Logic 1 = RX trigger level.

An interrupt is generated when the number of characters in the

FIFO equals the programmed trigger level. However, the FIFO will

continue to be loaded until it is full. Refer to Table 10.

5-4 FCR[5-4] Not used; initialized to logic 0.

3 FCR[3] DMA mode select.

Logic 0 = Set DMA mode ‘0’

Logic 1 = Set DMA mode ‘1’

Transmit operation in mode ‘0’: When the SC16C2550 is in the

16C450 mode (FIFOs disabled; FCR[0] = logic 0) or in the FIFO

mode (FIFOs enabled; FCR[0] = logic 1; FCR[3] = logic 0), and

when there are no characters in the transmit FIFO or transmit

holding register, the TXRDY pin in PLCC44 or LQFP48 packages

will be a logic 0. Once active, the TXRDY pin will go to a logic 1

after the ﬁrst character is loaded into the transmit holding register.

Receive operation in mode ‘0’: When the SC16C2550 is in

mode ‘0’ (FCR[0] = logic 0), or in the FIFO mode (FCR[3] = logic 0)

and there is at lease one character in the receive FIFO, the

RXRDY pin will be a logic 0. Once active, the RXRDY pin on

PLCC44 and LQFP48 packages will go to a logic 1 when there are

no more characters in the receiver.

Transmit operation in mode ‘1’: When the SC16C2550 is in

FIFO mode (FCR[0] = logic 1; FCR[3] = logic 1), the TXRDY pin on

PLCC44 and LQFP48 packages will be a logic 1 when the transmit

FIFO is completely full. It will be a logic 0 if one or more FIFO

locations are empty.

Receive operation in mode ‘1’: When the SC16C2550 is in FIFO

mode (FCR[0] = logic 1; FCR[3] = logic 1) and the trigger level has

been reached, or a Receive Time-Out has occurred, the RXRDY

pin on PLCC44 and LQFP48 packages will go to a logic 0. Once

activated, it will go to a logic 1 after there are no more characters in

the FIFO.

2 FCR[2] XMIT FIFO reset.

Logic 0 = Transmit FIFO not reset (normal default condition).

Logic 1 = Clears the contents of the transmit FIFO and resets

the FIFO counter logic (the transmit shift register is not cleared

or altered). This bit will return to a logic 0 after clearing the FIFO.

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 21 of 47

7.4 Interrupt Status Register (ISR)

The SC16C2550 provides four levels of prioritized interrupts to minimize external

software interaction. The Interrupt Status Register (ISR) provides the user with four

interrupt status bits. Performing a read cycle on the ISR will provide the user with the

highest pending interrupt level to be serviced. No other interrupts are acknowledged

until the pending interrupt is serviced. A lower level interrupt may be seen after

servicing the higher level interrupt and re-reading the interrupt status bits. Table 11

“Interrupt source” shows the data values (bits 0-3) for the four prioritized interrupt

levels and the interrupt sources associated with each of these interrupt levels.

1 FCR[1] RCVR FIFO reset.

Logic 0 = Receive FIFO not reset (normal default condition).

Logic 1 = Clears the contents of the receive FIFO and resets the

FIFO counter logic (the receive shift register is not cleared or

altered). This bit will return to a logic 0 after clearing the FIFO.

0 FCR[0] FIFOs enabled.

Logic 0 = Disable the transmit and receive FIFO (normal default

condition).

Logic 1 = Enable the transmit and receive FIFO. This bit must

be a ‘1’ when other FCR bits are written to, or they will not

be programmed.

Table 10: RCVR trigger levels

FCR[7] FCR[6] RX FIFO trigger level

0001

0104

1008

1114

Table 9: FIFO Control Register bits description

…continued

Bit Symbol Description

Table 11: Interrupt source

Priority

level ISR[5] ISR[4] ISR[3] ISR[2] ISR[1] ISR[0] Source of the interrupt

1 000110LSR(Receiver Line Status

2 000100RXRDY (Received Data

Ready)

2 001100RXRDY (Receive Data

time-out)

3 000010TXRDY (Transmitter

Holding Register Empty)

4 000000MSR (Modem Status

5 010000RXRDY (Received Xoff

signal) / Special character

6 100000CTS, RTS change of state

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 22 of 47

7.5 Line Control Register (LCR)

The Line Control Register is used to specify the asynchronous data communication

format. The word length, the number of stop bits, and the parity are selected by

writing the appropriate bits in this register.

Table 12: Interrupt Status Register bits description

Bit Symbol Description

7-6 ISR[7-6] FIFOs enabled. These bits are set to a logic 0 when the FIFOs are

not being used in the 16C450 mode. They are set to a logic 1

when the FIFOs are enabled in the SC16C2550 mode.

Logic 0 or cleared = default condition.

5-4 ISR[5-4] INT priority bits 4-3. These bits are enabled when EFR[4] is set to

a logic 1. ISR[4] indicates that matching Xoff character(s) have

been detected. ISR[5] indicates that CTS, RTS have been

generated. Note that once set to a logic 1, the ISR[4] bit will stay a

logic 1 until Xon character(s) are received.

Logic 0 or cleared = default condition.

3-1 ISR[3-1] INT priority bits 2-0. These bits indicate the source for a pending

interrupt at interrupt priority levels 1, 2, and 3 (see Table 11).

Logic 0 or cleared = default condition.

0 ISR[0] INT status.

Logic 0 = An interrupt is pending and the ISR contents may be

used as a pointer to the appropriate interrupt service routine.

Logic 1 = No interrupt pending (normal default condition).

Table 13: Line Control Register bits description

Bit Symbol Description

7 LCR[7] Divisor latch enable. The internal baud rate counter latch and

Enhance Feature mode enable.

Logic 0 = Divisor latch disabled (normal default condition).

Logic 1 = Divisor latch enabled.

6 LCR[6] Set break. When enabled, the Break control bit causes a break

condition to be transmitted (the TX output is forced to a logic 0

state). This condition exists until disabled by setting LCR[6] to a

logic 0.

Logic 0 = no TX break condition (normal default condition)

Logic 1 = forces the transmitter output (TX) to a logic 0 for

alerting the remote receiver to a line break condition.

5-3 LCR[5-3] Programs the parity conditions (see Table 14).

2 LCR[2] Stop bits. The length of stop bit is speciﬁed by this bit in

conjunction with the programmed word length (see Table 15).

Logic 0 or cleared = default condition.

1-0 LCR[1-0] Word length bits 1, 0. These two bits specify the word length to be

transmitted or received (see Table 16).

Logic 0 or cleared = default condition.

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 23 of 47

Table 14: LCR[5-3] parity selection

LCR[5] LCR[4] LCR[3] Parity selection

X X 0 no parity

X 0 1 ODD parity

0 1 1 EVEN parity

001forced parity ‘1’

111forced parity ‘0’

Table 15: LCR[2] stop bit length

LCR[2] Word length Stop bit length (bit times)

0 5, 6, 7, 8 1

15 1-

1⁄2

1 6, 7, 8 2

Table 16: LCR[1-0] word length

LCR[1] LCR[0] Word length

005

016

107

118

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 24 of 47

7.6 Modem Control Register (MCR)

This register controls the interface with the modem or a peripheral device.

Table 17: Modem Control Register bits description

Bit Symbol Description

7 MCR[7] Reserved; set to ‘0’.

6 MCR[6] IR enable.

Logic 0 = Enable the standard modem receive and transmit

input/output interface (normal default condition).

Logic 1 = Enable infrared IrDA receive and transmit inputs/outputs.

While in this mode, the TX/RX output/inputs are routed to the

infrared encoder/decoder. The data input and output levels will

conform to the IrDA infrared interface requirement. As such, while

in this mode, the infrared TX output will be a logic 0 during idle data

conditions.

5 MCR[5] Reserved; set to ‘0’.

4 MCR[4] Loop-back. Enable the local loop-back mode (diagnostics). In this

mode the transmitter output (TX) and the receiver input (RX), CTS,

DSR, CD, and RI are disconnected from the SC16C2550 I/O pins.

Internally the modem data and control pins are connected into a

loop-back data conﬁguration (see Figure 6). In this mode, the receiver

and transmitter interrupts remain fully operational. The Modem

Control Interrupts are also operational, but the interrupts’ sources are

switched to the lower four bits of the Modem Control. Interrupts

continue to be controlled by the IER register.

Logic 0 = Disable loop-back mode (normal default condition).

Logic 1 = Enable local loop-back mode (diagnostics).

3 MCR[3] OP2/INT enable

Logic 0 = Forces INT (A-B) outputs to the 3-State mode and sets

OP2 to a logic 1 (normal default condition).

Logic 1 = Forces the INT (A-B outputs to the active mode and sets

OP2 to a logic 0.

2 MCR[2] (OP1). OP1A/OP1B are not available as an external signal in the

SC16C2550. This bit is instead used in the Loop-back mode only. In

the loop-back mode, this bit is used to write the state of the modem RI

interface signal.

1 MCR[1] RTS

Logic 0 = Force RTS output to a logic 1 (normal default condition).

Logic1=Force RTS output to a logic 0.

0 MCR[0] DTR

Logic 0 = Force DTR output to a logic 1 (normal default condition).

Logic 1 = Force DTR output to a logic 0.

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 25 of 47

7.7 Line Status Register (LSR)

This register provides the status of data transfers between the SC16C2550 and

the CPU.

Table 18: Line Status Register bits description

Bit Symbol Description

7 LSR[7] FIFO data error.

Logic 0 = No error (normal default condition).

Logic 1 = At least one parity error, framing error or break

indication is in the current FIFO data. This bit is cleared when

there are no remaining error ﬂags associated with the remaining

data in the FIFO.

6 LSR[6] THR and TSR empty. This bit is the Transmit Empty indicator. This

bit is set to a logic 1 whenever the transmit holding register and the

transmit shift register are both empty. It is reset to logic 0 whenever

either the THR or TSR contains a data character. In the FIFO

mode, this bit is set to ‘1’ whenever the transmit FIFO and transmit

shift register are both empty.

5 LSR[5] THR empty. This bit is the Transmit Holding Register Empty

indicator. This bit indicates that the UART is ready to accept a new

character for transmission. In addition, this bit causes the UART to

issue an interrupt to CPU when the THR interrupt enable is set.

The THR bit is set to a logic 1 when a character is transferred from

the transmit holding register into the transmitter shift register. The

bit is reset to a logic 0 concurrently with the loading of the

transmitter holding register by the CPU. In the FIFO mode, this bit

is set when the transmit FIFO is empty; it is cleared when at least

1 byte is written to the transmit FIFO.

4 LSR[4] Break interrupt.

Logic 0 = No break condition (normal default condition).

Logic 1 = The receiver received a break signal (RX was a logic 0

for one character frame time). In the FIFO mode, only one break

character is loaded into the FIFO.

3 LSR[3] Framing error.

Logic 0 = No framing error (normal default condition).

Logic 1 = Framing error. The receive character did not have a

valid stop bit(s). In the FIFO mode, this error is associated with

the character at the top of the FIFO.

2 LSR[2] Parity error.

Logic 0 = No parity error (normal default condition.

Logic 1 = Parity error. The receive character does not have

correct parity information and is suspect. In the FIFO mode, this

error is associated with the character at the top of the FIFO.

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 26 of 47

7.8 Modem Status Register (MSR)

This register provides the current state of the control interface signals from the

modem, or other peripheral device to which the SC16C2550 is connected. Four bits

of this register are used to indicate the changed information. These bits are set to a

logic 1 whenever a control input from the modem changes state. These bits are set to

a logic 0 whenever the CPU reads this register.

1 LSR[1] Overrun error.

Logic 0 = No overrun error (normal default condition).

Logic1=Overrun error. A data overrun error occurred in the

receive shift register. This happens when additional data arrives

while the FIFO is full. In this case, the previous data in the shift

byte in the receive shift register is not transferred into the FIFO,

therefore the data in the FIFO is not corrupted by the error.

0 LSR[0] Receive data ready.

Logic 0 = No data in receive holding register or FIFO (normal

default condition).

Logic 1 = Data has been received and is saved in the receive

holding register or FIFO.

Table 18: Line Status Register bits description

…continued

Bit Symbol Description

Table 19: Modem Status Register bits description

Bit Symbol Description

7 MSR[7] CD. During normal operation, this bit is the complement of the CD

input. Reading this bit in the loop-back mode produces the state of

MCR[3] (OP2).

6 MSR[6] RI. During normal operation, this bit is the complement of the RI

input. Reading this bit in the loop-back mode produces the state of

MCR[2] (OP1).

5 MSR[5] DSR. During normal operation, this bit is the complement of the

DSR input. During the loop-back mode, this bit is equivalent to

MCR[0] (DTR).

4 MSR[4] CTS. During normal operation, this bit is the complement of the

CTS input. During the loop-back mode, this bit is equivalent to

MCR[1] (RTS).

3 MSR[3] ∆CD [1]

Logic 0 = No CD change (normal default condition).

Logic 1 = The CD input to the SC16C2550 has changed state

since the last time it was read. A modem Status Interrupt will be

generated.

2 MSR[2] ∆RI [1]

Logic 0 = No RI change (normal default condition).

Logic 1 = The RI input to the SC16C2550 has changed from a

logic 0 to a logic 1. A modem Status Interrupt will be generated.

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 27 of 47

[1] Whenever any MSR bit 0-3 is set to logic 1, a Modem Status Interrupt will be generated.

7.9 Scratchpad Register (SPR)

The SC16C2550 provides a temporary data register to store 8 bits of user

information.

7.10 Enhanced Feature Register (EFR)

Enhanced features are enabled or disabled using this register.

Bits 0 through 4 provide single or dual character software ﬂow control selection.

When the Xon1 and Xon2 and/or Xoff1 and Xoff2 modes are selected, the double

8-bit words are concatenated into two sequential numbers.

1 MSR[1] ∆DSR [1]

Logic 0 = No DSR change (normal default condition).

Logic1=TheDSR input to the SC16C2550 has changed state

since the last time it was read. A modem Status Interrupt will be

generated.

0 MSR[0] ∆CTS [1]

Logic 0 = No CTS change (normal default condition).

Logic 1 = The CTS input to the SC16C2550 has changed state

since the last time it was read. A modem Status Interrupt will be

generated.

Table 19: Modem Status Register bits description

…continued

Bit Symbol Description

Table 20: Enhanced Feature Register bits description

Bit Symbol Description

7 EFR[7] Automatic CTS ﬂow control.

Logic0=Automatic CTS ﬂow control is disabled (normal default

condition).

Logic 1 = Enable Automatic CTS ﬂow control. Transmission will stop

when CTS goes to a logical 1. Transmission will resume when the CTS

pin returns to a logical 0.

6 EFR[6] Automatic RTS ﬂow control. Automatic RTS may be used for hardware ﬂow

control by enabling EFR[6]. When Auto-RTS is selected, an interrupt will

be generated when the receive FIFO is ﬁlled to the programmed trigger

level and RTS will go to a logic 1 at the next trigger level. RTS will return to

a logic 0 when data is unloaded below the next lower trigger level

(programmed trigger level 1). The state of this register bit changes with the

status of the hardware ﬂow control. RTS functions normally when

hardware ﬂow control is disabled.

0 = Automatic RTS ﬂow control is disabled (normal default condition).

1 = Enable Automatic RTS ﬂow control.

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 28 of 47

[1] When using a software ﬂow control the Xon/Xoff characters cannot be used for data transfer.

5 EFR[5] Special Character Detect.

Logic 0 = Special character detect disabled (normal default condition).

Logic 1 = Special character detect enabled. The SC16C2550 compares

each incoming receive character with Xoff2 data. If a match exists, the

received data will be transferred to FIFO and ISR[4] will be set to

indicate detection of special character. Bit-0 in the X-registers

corresponds with the LSB bit for the receive character. When this feature

is enabled, the normal software ﬂow control must be disabled (EFR[3-0]

must be set to a logic 0).

4 EFR[4] Enhanced function control bit. The content of IER[7-4], ISR[5-4], FCR[5-4],

and MCR[7-5] can be modiﬁed and latched. After modifying any bits in the

enhanced registers, EFR[4] can be set to a logic 0 to latch the new values.

This feature prevents existing software from altering or overwriting the

SC16C2550 enhanced functions.

Logic 0 = disable/latch enhanced features. IER[7-4], ISR[5-4], FCR[5-4],

and MCR[7-5] are saved to retain the user settings, then IER[7-4]

ISR[5-4], FCR[5-4], and MCR[7-5] are set to a logic 0 to be compatible

with SC16C554 mode. (Normal default condition.)

Logic 1 = Enables the enhanced functions. When this bit is set to a

logic 1, all enhanced features of the SC16C2550 are enabled and user

settings stored during a reset will be restored.

3-0 EFR[3-0] Cont-3-0 Tx, Rx control. Logic 0 or cleared is the default condition.

Combinations of software ﬂow control can be selected by programming

these bits. See Table 21.

Table 21: Software ﬂow control functions[1]

Cont-3 Cont-2 Cont-1 Cont-0 TX, RX software ﬂow controls

0 0 X X No transmit ﬂow control

1 0 X X Transmit Xon1/Xoff1

0 1 X X Transmit Xon2/Xoff2

1 1 X X Transmit Xon1 and Xon2/Xoff1 and Xoff2

X X 0 0 No receive ﬂow control

X X 1 0 Receiver compares Xon1/Xoff1

X X 0 1 Receiver compares Xon2/Xoff2

1 0 1 1 Transmit Xon1/Xoff1

Receiver compares Xon1 and Xon2, Xoff1 and Xoff2

0 1 1 1 Transmit Xon2/Xoff2

Receiver compares Xon1 and Xon2/Xoff1 and Xoff2

1 1 1 1 Transmit Xon1 and Xon2/Xoff1 and Xoff2

Receiver compares Xon1 and Xon2/Xoff1 and Xoff2

Table 20: Enhanced Feature Register bits description

…continued

Bit Symbol Description

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 29 of 47

7.11 SC16C2550 external reset condition

8. Limiting values

Table 22: Reset state for registers

IER IER[7-0] = 0

FCR FCR[7-0] = 0

ISR ISR[7-1] = 0; ISR[0] = 1

LCR LCR[7-0] = 0

MCR MCR[7-0] = 0

LSR LSR[7] = 0; LSR[6-5] = 1; LSR[4-0] = 0

MSR MSR[7-4] = input signals; MSR[3-0] = 0

SPR SFR[7-0] = 1

DLL DLL[7-0] = X

DLM DLM[7-0] = X

Table 23: Reset state for outputs

Output Reset state

TXA, TXB Logic 1

OP2A, OP2B Logic 1

RTSA, RTSB Logic 1

DTRA, DTRB Logic 1

INTA, INTB 3-State condition

Table 24: Limiting values

In accordance with the Absolute Maximum Rating System (IEC 60134).

Symbol Parameter Conditions Min Max Unit

VCC supply voltage - 7 V

Vnvoltage at any pin GND −0.3 VCC + 0.3 V

Tamb operating temperature −40 +85 °C

Tstg storage temperature −65 +150 °C

Ptot(pack) total power dissipation

per package - 500 mW

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 30 of 47

9. Static characteristics

[1] Except x2, VOL = 1 V typical.

Table 25: DC electrical characteristics

amb

−

C to +85

C; V

= 2.5 V, 3.3 V or 5.0 V

10%, unless otherwise speciﬁed.

Symbol Parameter Conditions 2.5 V 3.3 V 5.0 V Unit

Min Max Min Max Min Max

VIL(CK) LOW-level clock input voltage −0.3 0.45 −0.3 0.6 −0.5 0.6 V

VIH(CK) HIGH-level clock input voltage 1.8 VCC 2.4 VCC 3.0 VCC V

VIL LOW-level input voltage

(except X1 clock) −0.3 0.65 −0.3 0.8 −0.5 0.8 V

VIH HIGH-level input voltage

(except X1 clock) 1.6 - 2.0 - 2.2 - V

VOL LOW-level output voltage

on all outputs[1] IOL =5mA

(databus) -----0.4V

IOL =4mA

(other outputs) ---0.4--V

IOL =2mA

(databus) -0.4----V

IOL = 1.6 mA

(other outputs) -0.4----V

VOH HIGH-level output voltage IOH =−5mA

(databus) ----2.4-V

IOH =−1mA

(other outputs) --2.0---V

IOH =−800 µA

(data bus) 1.85 -----V

IOH =−400 µA

(other outputs) 1.85 -----V

ILIL LOW-level input leakage

current -±10 - ±10 - ±10 µA

ICL clock leakage - ±30 - ±30 - ±30 µA

ICC supply current f = 5 MHz - 3.5 - 4.5 - 4.5 mA

Ciinput capacitance - 5 - 5 - 5 pF

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 31 of 47

10. Dynamic characteristics

[1] Applies to external clock, crystal oscillator max 24 MHz.

[2]

= 333 ns (for Baudratemax = 1.5 Mbits/s)

= 1 µs (for Baudratemax = 460.8 kbits/s)

= 4 µs (for Baudratemax = 115.2 kbits/s)

[3] When in both DMA mode 0 and FIFO enable mode, the write cycle delay should be larger than one x1, clock cycle.

Table 26: AC electrical characteristics

amb

−

C to +85

C; V

= 2.5 V, 3.3 V or 5.0 V

10%, unless otherwise speciﬁed.

Symbol Parameter Conditions 2.5 V 3.3 V 5.0 V Unit

Min Max Min Max Min Max

t1w, t2w clock pulse duration 10 - 6 - 6 - ns

t3w oscillator/clock frequency [1] - 48 - 80 80 MHz

t6s address set-up time 0 - 0 - 0 - ns

t6h address hold time 0 - 0 - 0 - ns

t7d IOR delay from chip select 10 - 10 - 10 - ns

t7w IOR strobe width 25 pF load 77 - 26 - 23 - ns

t7h chip select hold time from IOR 0 - 0 - 0 - ns

t9d read cycle delay 25 pF load 20 - 20 - 20 - ns

t12d delay from IOR to data 25 pF load - 77 - 26 - 23 ns

t12h data disable time 25 pF load - 15 - 15 - 15 ns

t13d IOW delay from chip select 10 - 10 - 10 - ns

t13w IOW strobe width 20 -[2] 20 -[2] 15 -[2] ns

t13h chip select hold time from IOW 0-0-0-ns

t15d write cycle delay [3] 25 - 25 - 20 - ns

t16s data set-up time 20 - 20 - 15 - ns

t16h data hold time 15 - 5 - 5 - ns

t17d delay from IOW to output 25 pF load - 100 - 33 - 29 ns

t18d delay to set interrupt from Modem

input 25 pF load - 100 - 24 - 23 ns

t19d delay to reset interrupt from IOR 25 pF load - 100 - 24 - 23 ns

t20d delay from stop to set interrupt - 1 - 1 - 1 Rclk

t21d delay from IOR to reset interrupt 25 pF load - 100 - 29 - 28 ns

t22d delay from start to set interrupt - 100 - 45 - 40 ns

t23d delay from IOW to transmit start 8 24 8 24 8 24 Rclk

t24d delay from IOW to reset interrupt - 100 - 45 - 40 ns

t25d delay from stop to set RXRDY -1-1-1R

clk

t26d delay from IOR to reset RXRDY - 100 - 45 - 40 ns

t27d delay from IOW to set TXRDY - 100 - 45 - 40 ns

t28d delay from start to reset TXRDY -8-8-8R

clk

tRESET Reset pulse width 200 - 40 - 40 - ns

N baud rate divisor 1 216 −11 2

16 −11 2

16 −1R

clk

IOWstrobemax 1

2Baudratemax

()

--------------------------------------

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 32 of 47

10.1 Timing diagrams

Fig 7. General write timing.

DATA

ACTIVE

VALID

ADDRESS

002aaa109

t6s t13h

t13d t13w t15d

t16s t16h

A0–A2

CSx

IOW

D0–D7

t6h

Fig 8. General read timing.

DATA

ACTIVE

VALID

ADDRESS

002aaa110

t6s t7h

t7d t7w t9d

t12d t12h

A0–A2

CSx

IOR

D0–D7

t6h

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 33 of 47

Fig 9. Modem input/output timing.

t17d

ACTIVEIOW

CHANGE OF STATE CHANGE OF STATE

RTS

DTR

DCD

CTS

DSR

CHANGE OF STATE CHANGE OF STATE

CHANGE OF STATE

ACTIVE ACTIVE ACTIVE

t18d t18d

INT

ACTIVE ACTIVE ACTIVEIOR

t19d

002aaa111

t18d

Fig 10. External clock timing.

EXTERNAL

CLOCK

002aaa112

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 34 of 47

Fig 11. Receive timing.

D0 D1 D2 D3 D4 D5 D6 D7

ACTIVE

16 BAUD RATE CLOCK

002aaa113

t21d

DATA

START

BIT

STOP

BIT

PARITY

BIT

START

BIT

t20d

INT

IOR

DATA BITS (5-8)

5 DATA BITS

6 DATA BITS

7 DATA BITS

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 35 of 47

Fig 12. Receive ready timing in non-FIFO mode.

D0 D1 D2 D3 D4 D5 D6 D7

ACTIVE

DATA

READY

ACTIVE

002aaa114

26d

DATA

START

BIT

STOP

BIT

PARITY

BIT

START

BIT

25d

RXRDY

IOR

DATA BITS (5–8)

Fig 13. Receive ready timing in FIFO mode.

D0 D1 D2 D3 D4 D5 D6 D7

ACTIVE

DATA

READY

ACTIVE

002aaa115

26d

STOP

BIT

PARITY

BIT

START

BIT

25d

RXRDY

IOR

DATA BITS (5–8)

FIRST BYTE THAT

REACHES THE

TRIGGER LEVEL

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 36 of 47

Fig 14. Transmit timing.

D0 D1 D2 D3 D4 D5 D6 D7

ACTIVE TX READ Y

ACTIVE

16 BAUD RATE CLOCK

002aaa116

24d

DATA

START

BIT

STOP

BIT

PARITY

BIT

START

BIT

22d

INT

IOW

DATA BITS (5–8)

5 DATA BITS

6 DATA BITS

7 DATA BITS

ACTIVE

23d

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 37 of 47

Fig 15. Transmit ready timing in non-FIFO mode.

D0 D1 D2 D3 D4 D5 D6 D7

TRANSMITTER

NOT READY

002aaa117

DATA

START

BIT

STOP

BIT

PARITY

BIT

START

BIT

t27d

TXRDY

IOW

DATA BITS (5-8)

ACTIVE

D0–D7 BYTE #1

ACTIVE

TRANSMITTER READY

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 38 of 47

Fig 16. Transmit ready timing in FIFO mode (DMA mode ‘1’).

D0 D1 D2 D3 D4 D5 D6 D7

FIFO FULL

002aaa118

STOP

BIT

PARITY

BIT

START

BIT

27d

TXRDY

IOW

DATA BITS (5-8)

ACTIVE

D0–D7 BYTE #16

5 DATA BITS

6 DATA BITS

7 DATA BITS

28d

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 39 of 47

11. Package outline

Fig 17. DIP40 package outline (SOT129-1).

UNIT A

max. 1 2 b1cD E e M

REFERENCES

OUTLINE

VERSION EUROPEAN

PROJECTION ISSUE DATE

IEC JEDEC EIAJ

inches

DIMENSIONS (inch dimensions are derived from the original mm dimensions)

SOT129-1 95-01-14

99-12-27

min. A

max. bZ

max.

1.70

1.14 0.53

0.38 0.36

0.23 52.50

51.50 14.1

13.7 3.60

3.05 0.2542.54 15.24 15.80

15.24 17.42

15.90 2.254.7 0.51 4.0

0.067

0.045 0.021

0.015 0.014

0.009 2.067

2.028 0.56

0.54 0.14

0.12 0.010.10 0.60 0.62

0.60 0.69

0.63 0.089 0.19 0.020 0.16

051G08 MO-015 SC-511-40

(e )

seating plane

pin 1 index

0 5 10 mm

scale

Note

1. Plastic or metal protrusions of 0.25 mm maximum per side are not included.

(1)

(1)(1)

DIP40: plastic dual in-line package; 40 leads (600 mil) SOT129-1

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 40 of 47

Fig 18. PLCC44 package outline (SOT187-2).

UNIT A A1

min. A4

max. bpeywv β

REFERENCES

OUTLINE

VERSION EUROPEAN

PROJECTION ISSUE DATE

IEC JEDEC JEITA

mm 4.57

4.19 0.51 3.05 0.53

0.33

0.021

0.013

16.66

16.51 1.27 17.65

17.40 2.16 45o

0.18 0.10.18

DIMENSIONS (mm dimensions are derived from the original inch dimensions)

Note

1. Plastic or metal protrusions of 0.25 mm (0.01 inch) maximum per side are not included.

SOT187-2

D(1) E(1)

16.66

16.51

HDHE

17.65

17.40

ZD(1)

max. ZE(1)

max.

2.16

0.81

0.66

1.22

1.07

0.180

0.165 0.02 0.12

0.25

0.01 0.656

0.650 0.05 0.695

0.685 0.085

0.007 0.0040.007

1.44

1.02

0.057

0.040

0.656

0.650 0.695

0.685

eDeE

16.00

14.99

0.63

0.59

16.00

14.99

0.63

0.59 0.085

0.032

0.026 0.048

0.042

2939

717

detail X

(A )

AA4

βk

vMB

vMA

pin 1 index

112E10 MS-018 EDR-7319

0 5 10 mm

scale

99-12-27

01-11-14

inches

PLCC44: plastic leaded chip carrier; 44 leads SOT187-2

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 41 of 47

Fig 19. LQFP48 package outline (SOT313-2).

UNIT A

max. A1A2A3bpcE

(1) eH

ELL

pZywv θ

REFERENCES

OUTLINE

VERSION EUROPEAN

PROJECTION ISSUE DATE

IEC JEDEC EIAJ

mm 1.60 0.20

0.05 1.45

1.35 0.25 0.27

0.17 0.18

0.12 7.1

6.9 0.5 9.15

8.85 0.95

0.55 7

0.12 0.10.21.0

DIMENSIONS (mm are the original dimensions)

Note

1. Plastic or metal protrusions of 0.25 mm maximum per side are not included.

0.75

0.45

SOT313-2 MS-026136E05 99-12-27

00-01-19

D(1) (1)(1)

7.1

6.9

9.15

8.85

0.95

0.55

vMB

vMA

36 25

detail X

(A )

0 2.5 5 mm

scale

pin 1 index

LQFP48: plastic low profile quad flat package; 48 leads; body 7 x 7 x 1.4 mm SOT313-2

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 42 of 47

12. Soldering

12.1 Introduction

This text gives a very brief insight to a complex technology. A more in-depth account

of soldering ICs can be found in our

Data Handbook IC26; Integrated Circuit

Packages

(document order number 9398 652 90011).

There is no soldering method that is ideal for all IC packages. Wave soldering is often

preferred when through-hole and surface mount components are mixed on one

printed-circuit board. Wave soldering can still be used for certain surface mount ICs,

but it is not suitable for ﬁne pitch SMDs. In these situations reﬂow soldering is

recommended.

12.2 Surface mount packages

12.2.1 Reﬂow soldering

Reﬂow soldering requires solder paste (a suspension of ﬁne solder particles, ﬂux and

binding agent) to be applied to the printed-circuit board by screen printing, stencilling

or pressure-syringe dispensing before package placement.

Several methods exist for reﬂowing; for example, convection or convection/infrared

heating in a conveyor type oven. Throughput times (preheating, soldering and

cooling) vary between 100 and 200 seconds depending on heating method.

Typical reﬂow peak temperatures range from 215 to 250 °C. The top-surface

temperature of the packages should preferably be kept:

•below 220 °C for all the BGA packages and packages with a thickness ≥2.5mm

and packages with a thickness <2.5 mm and a volume ≥350 mm3 so called

thick/large packages

•below 235 °C for packages with a thickness <2.5 mm and a volume <350 mm3 so

called small/thin packages.

12.2.2 Wave soldering

Conventional single wave soldering is not recommended for surface mount devices

(SMDs) or printed-circuit boards with a high component density, as solder bridging

and non-wetting can present major problems.

To overcome these problems the double-wave soldering method was speciﬁcally

developed.

If wave soldering is used the following conditions must be observed for optimal

results:

•Use a double-wave soldering method comprising a turbulent wave with high

upward pressure followed by a smooth laminar wave.

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 43 of 47

•For packages with leads on two sides and a pitch (e):

–larger than or equal to 1.27 mm, the footprint longitudinal axis is preferred to be

parallel to the transport direction of the printed-circuit board;

–smaller than 1.27 mm, the footprint longitudinal axis must be parallel to the

transport direction of the printed-circuit board.

The footprint must incorporate solder thieves at the downstream end.

•For packages with leads on four sides, the footprint must be placed at a 45° angle

to the transport direction of the printed-circuit board. The footprint must

incorporate solder thieves downstream and at the side corners.

During placement and before soldering, the package must be ﬁxed with a droplet of

adhesive. The adhesive can be applied by screen printing, pin transfer or syringe

dispensing. The package can be soldered after the adhesive is cured.

Typical dwell time is 4 seconds at 250 °C. A mildly-activated ﬂux will eliminate the

need for removal of corrosive residues in most applications.

12.2.3 Manual soldering

Fix the component by ﬁrst soldering two diagonally-opposite end leads. Use a low

voltage (24 V or less) soldering iron applied to the ﬂat part of the lead. Contact time

must be limited to 10 seconds at up to 300 °C.

When using a dedicated tool, all other leads can be soldered in one operation within

2 to 5 seconds between 270 and 320 °C.

12.3 Through-hole mount packages

12.3.1 Soldering by dipping or by solder wave

The maximum permissible temperature of the solder is 260 °C; solder at this

temperature must not be in contact with the joints for more than 5 seconds. The total

contact time of successive solder waves must not exceed 5 seconds.

The device may be mounted up to the seating plane, but the temperature of the

plastic body must not exceed the speciﬁed maximum storage temperature (Tstg(max)).

If the printed-circuit board has been pre-heated, forced cooling may be necessary

immediately after soldering to keep the temperature within the permissible limit.

12.3.2 Manual soldering

Apply the soldering iron (24 V or less) to the lead(s) of the package, either below the

seating plane or not more than 2 mm above it. If the temperature of the soldering iron

bit is less than 300 °C it may remain in contact for up to 10 seconds. If the bit

temperature is between 300 and 400 °C, contact may be up to 5 seconds.

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 44 of 47

12.4 Package related soldering information

[1] For more detailed information on the BGA packages refer to the

(LF)BGA Application Note

(AN01026); order a copy from your Philips Semiconductors sales ofﬁce.

[2] All surface mount (SMD) packages are moisture sensitive. Depending upon the moisture content, the

maximum temperature (with respect to time) and body size of the package, there is a risk that internal

or external package cracks may occur due to vaporization of the moisture in them (the so called

popcorn effect). For details, refer to the Drypack information in the

Data Handbook IC26; Integrated

Circuit Packages; Section: Packing Methods

[3] For SDIP packages, the longitudinal axis must be parallel to the transport direction of the

printed-circuit board.

[4] These packages are not suitable for wave soldering. On versions with the heatsink on the bottom

side, the solder cannot penetrate between the printed-circuit board and the heatsink. On versions with

the heatsink on the top side, the solder might be deposited on the heatsink surface.

[5] If wave soldering is considered, then the package must be placed at a 45° angle to the solder wave

direction. The package footprint must incorporate solder thieves downstream and at the side corners.

[6] Wave soldering is suitable for LQFP, QFP and TQFP packages with a pitch (e) larger than 0.8 mm; it

is deﬁnitely not suitable for packages with a pitch (e) equal to or smaller than 0.65 mm.

[7] Wave soldering is suitable for SSOP and TSSOP packages with a pitch (e) equal to or larger than

0.65 mm; it is deﬁnitely not suitable for packages with a pitch (e) equal to or smaller than 0.5 mm.

Table 27: Suitability of IC packages for wave, reﬂow and dipping soldering methods

Mounting Package[1] Soldering method

Wave Reﬂow[2] Dipping

Through-hole

mount DBS, DIP, HDIP, SDIP, SIL suitable[3] −suitable

Surface mount BGA, LBGA, LFBGA,

SQFP, TFBGA, VFBGA not suitable suitable −

DHVQFN, HBCC, HBGA,

HLQFP, HSQFP, HSOP,

HTQFP, HTSSOP,

HVQFN, HVSON, SMS

not suitable[4] suitable −

PLCC[5], SO, SOJ suitable suitable −

LQFP, QFP, TQFP not recommended[5][6] suitable −

SSOP, TSSOP, VSO,

VSSOP not recommended[7] suitable −

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 45 of 47

13. Revision history

Table 28: Revision history

Rev Date CPCN Description

02 20030314 - Product data (9397 750 11204). ECN 853-2368 29624 of 07 March 2003.

Modiﬁcations:

•Maximum data rate changed from 1.5 Mbits/s to 5 Mbits/s at 5 V and 3.3 V, and 3 Mbits/s

at 2.5 V.

•Section 6.8 on page 13, second paragraph: change from “... frequency up to 24 MHz.” to

“... frequency up to 80 MHz.” Delete “(parallel resonant 22-33 pF load)”.

•Figure 5 on page 13: capacitors’ values changed to 68 pF.

•Table 7 on page 16: added shading.

•Tables 25 and 26 replaced with Table 25 “DC electrical characteristics” on page 30.

•Tables 27 and 28 replaced with Table 26 “AC electrical characteristics” on page 31.

01 20020904 - Product data (9397 750 08831). ECN 853-2368 28865 of 04 September 2002.

9397 750 11204

Philips Semiconductors SC16C2550

Dual UART with 16 bytes of transmit and receive FIFOs

and infrared (IrDA) encoder/decoder

Product data Rev. 02 — 14 March 2003 46 of 47

Contact information

For additional information, please visit http://www.semiconductors.philips.com.

For sales ofﬁce addresses, send e-mail to: sales.addresses@www.semiconductors.philips.com.Fax: +31 40 27 24825

14. Data sheet status

[1] Please consult the most recently issued data sheet before initiating or completing a design.

[2] The product status of the device(s) described in this data sheet may have changed since this data sheet was published. The latest information is available on the Internet at

URL http://www.semiconductors.philips.com.

[3] For data sheets describing multiple type numbers, the highest-level product status determines the data sheet status.

15. Deﬁnitions

Short-form speciﬁcation — The data in a short-form speciﬁcation is

extracted from a full data sheet with the same type number and title. For

detailed information see the relevant data sheet or data handbook.

Limiting values deﬁnition — Limiting values given are in accordance with

the Absolute Maximum Rating System (IEC 60134). Stress above one or

more of the limiting values may cause permanent damage to the device.

These are stress ratings only and operation of the device at these or at any

other conditions above those given in the Characteristics sections of the

speciﬁcation is not implied. Exposure to limiting values for extended periods

may affect device reliability.

Application information — Applications that are described herein for any

of these products are for illustrative purposes only. Philips Semiconductors

make no representation or warranty that such applications will be suitable for

the speciﬁed use without further testing or modiﬁcation.

16. Disclaimers

Life support — These products are not designed for use in life support

appliances, devices, or systems where malfunction of these products can

reasonably be expected to result in personal injury. Philips Semiconductors

customers using or selling these products for use in such applications do so

at their own risk and agree to fully indemnify Philips Semiconductors for any

damages resulting from such application.

Right to make changes — Philips Semiconductors reserves the right to

make changes in the products - including circuits, standard cells, and/or

software - described or contained herein in order to improve design and/or

performance. When the product is in full production (status ‘Production’),

relevant changes will be communicated via a Customer Product/Process

Change Notiﬁcation (CPCN). Philips Semiconductors assumes no

responsibility or liability for the use of any of these products, conveys no

licence or title under any patent, copyright, or mask work right to these

products, and makes no representations or warranties that these products are

free from patent, copyright, or mask work right infringement, unless otherwise

speciﬁed.

Level Data sheet status[1] Product status[2][3] Deﬁnition

I Objective data Development This data sheet contains data from the objective speciﬁcation for product development. Philips

Semiconductors reserves the right to change the speciﬁcation in any manner without notice.

II Preliminary data Qualiﬁcation This datasheet contains data from the preliminary speciﬁcation. Supplementary data will be published

at a later date. Philips Semiconductors reserves the right to change the speciﬁcation without notice, in

order to improve the design and supply the best possible product.

III Product data Production This data sheet contains data from the product speciﬁcation. Philips Semiconductors reserves the

right to make changes at any time in order to improve the design, manufacturing and supply. Relevant

changes will be communicated via a Customer Product/Process Change Notiﬁcation (CPCN).

© Koninklijke Philips Electronics N.V. 2003.
Printed in the U.S.A
All rights are reserved. Reproduction in whole or in part is prohibited without the prior
written consent of the copyright owner.
The information presented in this document does not form part of any quotation or
contract, is believed to be accurate and reliable and may be changed without notice. No
liability will be accepted by the publisher for any consequence of its use. Publication
thereof does not convey nor imply any license under patent- or other industrial or
intellectual property rights.
Date of release: 14 March 2003 Document order number: 9397 750 11204
Contents
Philips Semiconductors SC16C2550
Dual UART with 16 bytes of transmit and receive FIFOs
and infrared (IrDA) encoder/decoder
Description. . . . . . . . . . . . . . . . . . . . . . . . . . . . .  1
Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  1
Ordering information. . . . . . . . . . . . . . . . . . . . .  2
Block diagram  . . . . . . . . . . . . . . . . . . . . . . . . . .  3
Pinning information. . . . . . . . . . . . . . . . . . . . . .  4
1 Pinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . .  6
Functional description  . . . . . . . . . . . . . . . . . . .  9
1 UART A-B functions . . . . . . . . . . . . . . . . . . . . .  9
2 Internal registers. . . . . . . . . . . . . . . . . . . . . . .  10
3 FIFO operation . . . . . . . . . . . . . . . . . . . . . . . .  11
4 Hardware ﬂow control. . . . . . . . . . . . . . . . . . .  11
5 Software ﬂow control  . . . . . . . . . . . . . . . . . . .  11
6 Special feature software ﬂow control . . . . . . .  12
7 Hardware/software and time-out interrupts. . .  12
8 Programmable baud rate generator . . . . . . . .  13
9 DMA operation . . . . . . . . . . . . . . . . . . . . . . . .  14
10 Loop-back mode. . . . . . . . . . . . . . . . . . . . . . .  14
Register descriptions . . . . . . . . . . . . . . . . . . .  16
1 Transmit (THR) and Receive (RHR)
 Holding Registers  . . . . . . . . . . . . . . . . . . . . .  17
2 Interrupt Enable Register (IER)  . . . . . . . . . . .  17
2.1 IER versus Transmit/Receive FIFO interrupt
 mode operation . . . . . . . . . . . . . . . . . . . . . . .  18
2.2 IER versus Receive/Transmit FIFO polled
 mode operation . . . . . . . . . . . . . . . . . . . . . . .  19
3 FIFO Control Register (FCR) . . . . . . . . . . . . .  19
3.1 DMA mode . . . . . . . . . . . . . . . . . . . . . . . . . . .  19
3.2 FIFO mode . . . . . . . . . . . . . . . . . . . . . . . . . . .  20
4 Interrupt Status Register (ISR) . . . . . . . . . . . .  21
5 Line Control Register (LCR) . . . . . . . . . . . . . .  22
6 Modem Control Register (MCR). . . . . . . . . . .  24
7 Line Status Register (LSR). . . . . . . . . . . . . . .  25
8 Modem Status Register (MSR). . . . . . . . . . . .  26
9 Scratchpad Register (SPR)  . . . . . . . . . . . . . .  27
10 Enhanced Feature Register (EFR) . . . . . . . . .  27
11 SC16C2550 external reset condition . . . . . . .  29
Limiting values  . . . . . . . . . . . . . . . . . . . . . . . .  29
Static characteristics  . . . . . . . . . . . . . . . . . . .  30
Dynamic characteristics. . . . . . . . . . . . . . . . .  31
1 Timing diagrams. . . . . . . . . . . . . . . . . . . . . . .  32
Package outline . . . . . . . . . . . . . . . . . . . . . . . .  39
Soldering . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  42
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . .  42
2 Surface mount packages . . . . . . . . . . . . . . . .  42
2.1 Reﬂow soldering. . . . . . . . . . . . . . . . . . . . . . .  42
2.2 Wave soldering. . . . . . . . . . . . . . . . . . . . . . . .  42
2.3 Manual soldering . . . . . . . . . . . . . . . . . . . . . .  43
3 Through-hole mount packages  . . . . . . . . . . .  43
3.1 Soldering by dipping or by solder wave . . . . .  43
3.2 Manual soldering . . . . . . . . . . . . . . . . . . . . . .  43
4 Package related soldering information. . . . . .  44
Revision history  . . . . . . . . . . . . . . . . . . . . . . .  45
Data sheet status. . . . . . . . . . . . . . . . . . . . . . .  46
Deﬁnitions . . . . . . . . . . . . . . . . . . . . . . . . . . . .  46
Disclaimers  . . . . . . . . . . . . . . . . . . . . . . . . . . .  46

Philips Semiconductors - PIP - SC16C2550; Dual UART with 16 bytes of transmit and receive FIFOs and infrared (IrDA) encoder/decoder
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SC16C2550; Dual 
UART with 16 bytes 
of transmit and 
receive FIFOs and 
infrared (IrDA) 
encoder/decoder
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 General description 
The SC16C2550 is a 2 channel Universal Asynchronous Receiver and Transmitter (UART) used for serial 
data communications. Its principal function is to convert parallel data into serial data and vice versa. The 
UART can handle serial data rates up to 5 Mbits/s. 
The SC16C2550 is pin compatible with the ST16C2550. It will power-up to be functionally equivalent to the 
16C2450. The SC16C2550 provides enhanced UART functions with 16-byte FIFOs, modem control 
interface, DMA mode data transfer. The DMA mode data transfer is controlled by the FIFO trigger levels 
and the TXRDY and RXRDY signals. On-board status registers provide the user with error indications and 
operational status. System interrupts and modem control features may be tailored by software to meet 
specific user requirements. An internal loop-back capability allows on-board diagnostics. Independent 
programmable baud rate generators are provided to select transmit and receive baud rates. 
The SC16C2550 operates at 5 V, 3.3 V and 2.5 V and the Industrial temperature range, and is available in 
plastic PLCC44, LQFP48 and DIP40 packages. 
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Philips Semiconductors - PIP - SC16C2550; Dual UART with 16 bytes of transmit and receive FIFOs and infrared (IrDA) encoder/decoder

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Features

● 2 channel UART

● 5 V, 3.3 V and 2.5 V operation

● Industrial temperature range

● Pin and functionally compatible to 16C2450 and software compatible with INS8250, SC16C550

● Up to 5 Mbits/s data rate at 5 V and 3.3 V, and 3 Mbits/s at 2.5 V

● 16 byte transmit FIFO to reduce the bandwidth requirement of the external CPU

● 16 byte receive FIFO with error flags to reduce the bandwidth requirement of the external CPU

● Independent transmit and receive UART control

● Four selectable Receive FIFO interrupt trigger levels

● Automatic software/hardware flow control

● Programmable Xon/Xoff characters

● Software selectable Baud Rate Generator

● Sleep mode

● Standard asynchronous error and framing bits (Start, Stop, and Parity Overrun Break)

● Transmit, Receive, Line Status, and Data Set interrupts independently controlled

● Fully programmable character formatting:

❍ 5-, 6-, 7-, or 8-bit characters

❍ Even-, Odd-, or No-Parity formats

❍ 1-, 1 1/2 -, or 2-stop bit

❍ Baud generation (DC to 1.5 Mbit/s)

● False start-bit detection

● Complete status reporting capabilities

● 3-State output TTL drive capabilities for bi-directional data bus and control bus

● Line Break generation and detection

● Internal diagnostic capabilities:

❍ Loop-back controls for communications link fault isolation

● Prioritized interrupt system controls

● Modem control functions (CTS, RTS, DSR, DTR, RI, DCD).

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Datasheet

Type number Title Publication

release date Datasheet status Page

count File

size

(kB)

Datasheet

SC16C2550 Dual UART with 16

bytes of transmit and

receive FIFOs and

infrared (IrDA)

encoder/decoder

3/14/2003 Product

specification 47 604

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PDF

File

View

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Blockdiagram(s)

Block diagram of

SC16C2550IA44

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Philips Semiconductors - PIP - SC16C2550; Dual UART with 16 bytes of transmit and receive FIFOs and infrared (IrDA) encoder/decoder

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Products, packages, availability and ordering

Type number North

American

type

number

Ordering code

(12NC) Marking/Packing

Download

PDF

File

IC packing info Package Device status Buy

online

SC16C2550IA44 9352 700 19512 Standard Marking *

Tube Dry Pack SOT187-2

(PLCC44) Full production -

9352 700 19518 Standard Marking *

Reel Dry Pack,

SMD, 13"

SOT187-2

(PLCC44) Full production -

9352 700 19529 SOT187-2

(PLCC44) Full production -

SC16C2550IB48 9352 700 20128 Standard Marking *

Reel Pack, SMD,

13", Turned

SOT313-2

(LQFP48) Full production -

9352 700 20151 Standard Marking *

Tray Pack, Bakeable,

Single

SOT313-2

(LQFP48) Full production -

9352 700 20157 Standard Marking *

Tray Pack, Bakeable,

Multiple

SOT313-2

(LQFP48) Full production -

SC16C2550IN40 9352 700 24112 Standard Marking *

Tube SOT129-1

(DIP40) Full production -

Products in the above table are all in production. Some variants are discontinued; click here for information

on these variants.

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