SP338EER1-L - Exar Corporation - Datasheet.Directory

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • (510) 668-7000 • FAX (510) 668-7017 • www.exar.com

SP338E

RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION

NOVEMBER 2011 REV. 1.0.0

GENERAL DESCRIPTION

The SP338 is an advanced multiprotocol transceiver

supporting RS-232, RS-485, and RS-422 serial

standards in a 40 pin QFN package. Integrated cable

termination and four configuration modes allow all

three protocols to be used interchangeably over a

single cable or connector with no additional switching

components. Full operation requires only four

external charge pump capacitors.

The RS-485/422 modes feature up to two drivers and

four receivers (2TX/4RX) in half, full, and mixed

duplex configurations. The RS-232 mode (3TX/5RX)

provides full support of all eight signals commonly

used with the DB9 RS-232 connector. A dedicated

diagnostic loopback mode is also provided.

The high speed drivers operate up to 20Mbps in RS-

485/422 modes, and up to 1Mbps in RS-232 mode.

All drivers can be slew limited to 250kbps in any

mode to minimize electromagnetic interference (EMI).

All transmitter outputs and receiver inputs feature

robust electrostatic discharge (ESD) protection to

±15kV Human Body Model (HBM) and ±8kV IEC-

61000-4-2 Contact. Each receiver output has full fail-

safe protection to avoid system lockup, oscillation, or

indeterminate states by defaulting to logic-high output

level when the inputs are open, shorted, or

terminated but undriven. No external biasing resistors

are required.

The RS-232 receiver inputs include a 5kΩ pull-down

to ground. The RS-485/422 receiver inputs are high

impedance (>96kΩ when termination is disabled),

allowing up to 256 devices on a single

communication bus (1/8th unit load).

The SP338 operates from a single power supply,

either 3.3V or 5V, with low idle current. The shutdown

mode consumes less than 10µA for low power

standby operation.

FEATURES

•Pin selectable Cable Termination

•No external resistors required for RS-485/422

termination and biasing

•3.3V or 5V Single Supply Operation

•Robust ESD Protection on bus pins

■±15kV Human Body Model (HBM)

■±8kV IEC 61000-4-2 (Contact)

•Max Data Rate of 20Mbps in RS-485/422 Modes

and up to 1Mbps in RS-232 Modes

•Pin selectable 250kbps Slew Limiting

•3 Drivers, 5 Receivers RS-232/V.28

•2 Drivers, 4 Receivers RS-485/422

■Full, Half, and Mixed Duplex Configurations

■1/8th Unit Load, up to 256 receivers on bus

•RS-485/422 Enhanced Failsafe for open, shorted,

or terminated but idle inputs

•Space saving 6mm x 6mm QFN-40 Package

•Pin compatible with SP339E

TYPICAL APPLICATIONS

•Dual Protocol Serial Ports (RS-232 or RS-485/422)

•Industrial Computers

•Industrial and Process Control Equipment

•Point-Of-Sale Equipment

•Networking Equipment

•HVAC Controls Equipment

•Building Security and Automation Equipment

ORDERING INFORMATION

PART NUMBER PACKAGE OPERATING TEMPERATURE RANGE DEVICE STATUS

SP338EER1-L 40-pin QFN -40°C to +85°C Active

SP338EER1-L/TR 40-pin QFN -40°C to +85°C Active

SP338ECR1-L 40-pin QFN 0°C to +70°C Active

SP338ECR1-L/TR 40-pin QFN 0°C to +70°C Active

ABSOLUTE MAXIMUM RATINGS

These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in

the operation sections to the specifications below is not implied. Exposure to absolute maximum rating conditions for

extended periods of time may affect reliability and cause permanent damage to the device.

Supply Voltage VCC -0.3V to +6.0V

Receiver Input Voltage (from Ground) ±18V

Driver Output Voltage (from Ground) ±18V

Short Circuit Duration, TX out to Ground Continuous

Voltage at TTL Input Pins -0.3V to (VCC + 0.5V)

Storage Temperature Range -65°C to +150°C

Lead Temperature (soldering, 10s) +300°C

Power Dissipation 40-pin QFN

(derate 17mW/°C above +70°C) 500mW

SP338E

RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION REV. 1.0.0

CAUTION:

ESD (ElectroStatic Discharge) sensitive device. Permanent damage may occur on unconnected devices subject to high

energy electrostatic fields. Unused devices must be stored in conductive foam or shunts. Personnel should be properly

grounded prior to handling this device. The protective foam should be discharged to the destination socket before devices

are removed.

ESD PROTECTION

MIN. TYP. MAX. UNITS

R1-R9 Tx Output & Rx Input Pins

±15 kV Human Body Model (HBM)

±8 kV IEC 61000-4-2 (Contact)

All Other Pins ±2 kV Human Body Model (HBM)

SP338E

REV. 1.0.0 RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION

PIN DESCRIPTIONS BY MODE (MODE2, MODE1, MODE0)

Pin Name 000,

Figure 1

001,

Figure 2

010,

Figure 3

011,

Figure 4

100,

Figure 5

101,

Figure 6

110,

Figure 7

111,

Figure 8

1L1 R1 Output 1 1 1 1 1 1

2L2 R2 Output R1 Output R1 Output R1 Output R1 Output R1 Output R1 Output

3L3 T1 Input T1 Input T1 Input T1 Input T1 Input T1 Input T1 Input

4L4 T2 Input

5L6 R3 Output 11111R2 Output

6L7 T3 Input T2 Input T2 Input

7L8 R4 Output 1 1 R2 Output 1 1 R3 Output

8L9 R5 Output 11111R4 Output

9VCC VCC

10 GND Ground

11 SLEW SLEW = VCC enables 250kbps slew limiting

12 DIR1 T1 Enable,

R1 Disable T1 Enable T1 Enable T1 Enable T1 Enable,

R1 Disable

T1 Enable,

R1 Disable

13 DIR2 T2 Enable T2 Enable,

R2 Disable

14 MODE0 0 1 0 1 0 1 0 1

15 MODE1 0 0 1 1 0 0 1 1

16 MODE2 0 0 0 0 1 1 1 1

17 TERM Enables RS-485/422 receiver termination

18 INVDIR Inverts DIR1 and DIR2, where applicable

19 ENABLE ENABLE = VCC for operation, ENABLE = 0V for shutdown

20 VCC VCC

SP338E

RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION REV. 1.0.0

PIN DESCRIPTIONS BY MODE (MODE2, MODE1, MODE0)

Pin Name 000,

Figure 1

001,

Figure 2

010,

Figure 3

011,

Figure 4

100,

Figure 5

101,

Figure 6

110,

Figure 7

111,

Figure 8

21 R9 R5 Input R2 Input B R1 Input B R4 Input B

22 R8 R4 Input R2 Input A R4 Input A

23 GND Ground

24 R7 T3 Output T2 Out A R1 Input A R3 Input A

T2 Out A

25 R6 R3 Input T2 Out B R3 Input B

T2 Out B

26 GND Ground

27 R4 T2 Output R1 Input B R1 Input B T1 Out A R1 Input A

T1 Out A R2 Input B

28 R3 T1 Output R2 Input A R1 Input A R2 Input A

29 GND Ground

30 R2 R2 Input R1 Input A

T1 Out A T1 Out A T1 Out A R1 Input A

T1 Out A

31 R1 R1 Input R1 Input B

T1 Out B T1 Out B T1 Out B T1 Out B R1 Input B

T1 Out B

R1 Input B

T1 Out B

32 VCC VCC

33 VSS VSS - Charge pump negative supply, 0.1uF from ground

34 C2- C2+ - Charge pump cap 2 negative lead

35 C1- C1- - Charge pump cap 1 negative lead

36 GND Ground

37 C1+ C1+ - Charge pump cap 1 positive lead, 0.1uF

38 VCC VCC

39 C2+ C2+ - Charge pump cap 2 positive lead, 0.1uF

40 VDD VDD - Charge pump positive supply, 0.1uF to ground

SP338E

REV. 1.0.0 RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION

ELECTRICAL CHARACTERISTICS

UNLESS OTHERWISE NOTED:

VCC = +3.3V ±5% or +5.0V ±5%, C1-C4 = 0.1µF; TA = TMIN to TMAX. Typical values are at VCC = 3.3V, TA = +25°C.

SYMBOL PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS

DC CHARACTERISTICS

ICC Supply Current (RS-232) 210 mA No load, idle inputs

ICC Supply Current (RS-485) 410 mA No load, idle inputs

ICC Vcc Shutdown Current 110 µAENABLE = 0V

TRANSMITTER and LOGIC INPUT PINS: Pins 3, 4, 6, 11-19

VIH Logic Input Voltage High 2.0 VVCC = 3.3V

VIH Logic Input Voltage High 2.4 VVCC = 5.0V

VIL Logic Input Voltage Low 0.8 V

IIL Logic Input Leakage Current Low 1µAInput Low (VIN = 0V)

IIH Logic Input Leakage Current High 1µAInput High (VIN = VCC),

pins 3, 4 and 6

IPD Logic Input Pull-down Current 50 µAInput High (VIN = VCC),

pins 11-19

VHYS Logic Input Hysteresis 200 mV

RECEIVER OUTPUTS: Pins 1, 2, 5, 7, 8

VOH Receiver Output Voltage High VCC-0.6 VIOUT = -1.5mA

VOL Receiver Output Voltage Low 0.4 VIOUT = 2.5mA

IOSS Receiver Output ShortCircuit Current ±20 ±60 mA 0 ≤ VO ≤ VCC

IOZ Receiver Output Leakage Current ±0.1 ±1 µA0 ≤ VO ≤ VCC,

Receivers disabled

UNLESS OTHERWISE NOTED:

VCC = +3.3V ±5% or +5.0V ±5%, C1-C4 = 0.1µF; TA = TMIN to TMAX. Typical values are at VCC = 3.3V, TA = +25°C.

SYMBOL PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS

SINGLE-ENDED RECEIVER INPUTS (RS-232)

VIN Input Voltage Range -15 +15 V

VIL Input Threshold Low

0.6 1.2 VVCC = 3.3V

0.8 1.5 VVCC = 5.0V

VIH Input Threshold High

1.5 2.0 VVCC = 3.3V

1.8 2.4 VVCC = 5.0V

VHYS Input Hysteresis 0.3 V

RIN Input Resistance 3 5 7 kΩ-15V ≤ VIN ≤ +15V

SINGLE-ENDED DRIVER OUTPUTS (RS-232)

VOOutput Voltage Swing

±5.0 ±5.5 VOutput loaded with 3kΩ to Gnd

±7.0 VNo load output

ISC Short Circuit Current ±60 mA VO = 0V

ROFF Power Off Impedance 300 10M ΩVCC = 0V, VO = ±2V

SP338E

RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION REV. 1.0.0

ELECTRICAL CHARACTERISTICS (Continued)

SP338E

REV. 1.0.0 RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION

ELECTRICAL CHARACTERISTICS (Continued)

UNLESS OTHERWISE NOTED:

VCC = +3.3V ±5% or +5.0V ±5%, C1-C4 = 0.1µF; TA = TMIN to TMAX. Typical values are at VCC = 3.3V, TA = +25°C.

SYMBOL PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS

DIFFERENTIAL RECEIVER INPUTS (RS-485 / RS-422)

RIN Receiver Input Resistance 96 kΩTERM = 0V,

-7V ≤ VIN ≤ +12V

VTH

Receiver Differential Threshold

Voltage -200 -125 -50 mV

∆VTH Receiver Input Hysteresis 25 mV VCM = 0V

IIN Receiver Input Current

125 µAVIN = +12V

-100 µAVIN = -7V

RTERM Termination Resistance 100 120 155 ΩTERM = VCC, Figure 9

-7V ≤ VCM ≤ +12V

RTERM Termination Resistance 100 120 140 ΩTERM = VCC, Figure 9

VCM = 0V

DIFFERENTIAL DRIVER OUTPUTS (RS-485 / RS-422)

VOD Differential Driver Output

2VCC VRL = 100Ω (RS-422), Figure 10

1.5 VCC VRL = 54Ω (RS-485), Figure 10

1.5 VCC VVCM = -7V, Figure 11

1.5 VCC VVCM = +12V, Figure 11

∆VOD

Change In Magnitude of

Differential Output Voltage -0.2 +0.2 VRL = 54Ω or 100Ω, Figure 10

VCM Driver CommonMode Output Voltage 3 V RL = 54Ω or 100Ω, Figure 10

∆VCM

Change In Magnitude of

Common Mode Output Voltage 0.2 VRL = 54Ω or 100Ω, Figure 10

IOSD Driver Output Short Circuit Current ±250 mA -7V ≤ VO ≤ +12V, Figure 12

IODriver Output Leakage Current ±100 µA

ENABLE = 0V,

or DIR1 = 0V and DIR2 = 0V in

full duplex modes,

-7V ≤ VO ≤ +12V

SP338E

RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION REV. 1.0.0

TIMING CHARACTERISTICS

UNLESS OTHERWISE NOTED:

VCC = +3.3V ±5% or +5.0V ±5%, C1-C4 = 0.1µF; TA = TMIN to TMAX. Typical values are at VCC = 3.3V, TA = +25°C.

SYMBOL PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS

ALL MODES

tENABLE Enable from Shutdown 1000 ns

tSHUTDOWN Enable to Shutdown 1000 ns

RS-232, DATA RATE = 250kbps (SLEW = Vcc), ONE TRANSMITTER SWITCHING

Maximum Data Rate 250 kbps RL = 3kΩ, CL = 1000pF

tRHL, tRLH Receiver Propagation Delay 100 ns

CL = 150pF, Figure 13

⏐tRHL-tRLH⏐Receiver Propagation Delay Skew 100 ns

tDHL, tDLH Driver Propagation Delay 1400 ns RL = 3kΩ, CL = 2500pF,

Figure 14

⏐tDHL-tDLH⏐Driver Propagation Delay Skew 600 ns

tSHL, tSLH Transition Region Slew Rate from

+3.0V to -3.0V or -3.0V to +3.0V 430 V/µs

VCC = 3.3V, RL = 3kΩ to 7kΩ,

CL = 150pF to 2500pF,

Figure 14

tSHL, tSLH Transition Region Slew Rate from

+3.0V to -3.0V or -3.0V to +3.0V 630 V/µs

VCC = 3.3V, RL = 3kΩ to 7kΩ,

CL = 150pF to 2500pF,

TA = 25°C, Figure 14

RS-232, DATA RATE = 1Mbps (SLEW = 0V), ONE TRANSMITTER SWITCHING

Maximum Data Rate 1Mbps RL = 3kΩ, CL = 250pF

tRHL, tRLH Receiver Propagation Delay 100 ns

CL = 150pF, Figure 13

⏐tRHL-tRLH⏐Receiver Propagation Delay Skew 100 ns

tDHL, tDLH Driver Propagation Delay 300 ns RL = 3kΩ, CL = 1000pF,

Figure 14

⏐tDHL-tDLH⏐Driver Propagation Delay Skew 150 ns

tSHL, tSLH Transition Region Slew Rate from

+3.0V to -3.0V or -3.0V to +3.0V 15 150 V/µs

VCC = 3.3V, RL = 3kΩ to 7kΩ,

CL = 150pF to 1000pF,

Figure 14

tSHL, tSLH Transition Region Slew Rate from

+3.0V to -3.0V or -3.0V to +3.0V 24 150 V/µs

VCC = 3.3V, RL = 3kΩ to 7kΩ,

CL = 150pF to 1000pF,

TA = 25°C, Figure 14

SP338E

REV. 1.0.0 RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION

TIMING CHARACTERISTICS (Continued)

UNLESS OTHERWISE NOTED:

VCC = +3.3V ±5% or +5.0V ±5%, C1-C4 = 0.1µF; TA = TMIN to TMAX. Typical values are at VCC = 3.3V, TA = +25°C.

SYMBOL PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS

RS-485/RS-422, DATA RATE = 250kbps (SLEW = Vcc), ONE TRANSMITTER SWITCHING

Maximum Data Rate 250 kbps RL = 54Ω, CL = 50pF

tRPHL, tRPLH Receiver Propagation Delay 50 150 ns

CL = 15pF, Figure 15

⏐tRPHL-tRPLH⏐Receiver Propagation Delay Skew 20 ns

tDPHL, tDPLH Driver Propagation Delay 500 1000 ns

RL = 54Ω, CL = 50pF,

Figure 16

⏐tDPHL-tDPLH⏐Driver Propagation Delay Skew 100 ns

tDR, tDF Driver Rise and Fall Time 300 650 1200 ns

tRZH, tRZL Receiver Output Enable Time 200 ns

CL = 15pF, Figure 17

tRHZ, tRLZ Receiver Output Disable Time 200 ns

tDZH, tDZL Driver Output Enable Time 1000 ns RL = 500Ω, CL = 50pF,

Figure 18

tDHZ, tDLZ Driver Output Disable Time 200 ns

RS-485/RS-422, DATA RATE = 20Mbps (SLEW = 0V), ONE TRANSMITTER SWITCHING

Maximum Data Rate 20 Mbps RL = 54Ω, CL = 50pF

tRPHL, tRPLH Receiver Propagation Delay 50 150 ns

CL = 15pF, Figure 15

⏐tRPHL-tRPLH⏐Receiver Propagation Delay Skew 10 ns

tDPHL, tDPLH Driver Propagation Delay 30 100 ns

RL = 54Ω, CL = 50pF,

Figure 16

⏐tDPHL-tDPLH⏐Driver Propagation Delay Skew 10 ns

tDR, tDF Driver Rise and Fall Time 10 20 ns

tRZH, tRZL Receiver Output Enable Time 200 ns

CL = 15pF, Figure 17

tRHZ, tRLZ Receiver Output Disable Time 200 ns

tDZH, tDZL Driver Output Enable Time 200 ns RL = 500Ω, CL = 50pF,

Figure 18

tDHZ, tDLZ Driver Output Disable Time 200 ns

SP338E

RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION REV. 1.0.0

BLOCK DIAGRAM BY MODE (MODE2, MODE1, MODE0)

FIGURE 1. MODE 000 - LOOPBACK

FIGURE 2. MODE 001 - RS-232

SP338E

REV. 1.0.0 RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION

FIGURE 3. MODE 010 - RS-485 HALF DUPLEX #1

SP338E

RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION REV. 1.0.0

FIGURE 4. MODE 011 - RS-485/422 FULL DUPLEX #1

SP338E

REV. 1.0.0 RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION

FIGURE 5. MODE 100 - RS-485/422 FULL DUPLEX #2

SP338E

RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION REV. 1.0.0

FIGURE 6. MODE 101 - RS-485/422 FULL DUPLEX #3

SP338E

REV. 1.0.0 RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION

FIGURE 7. MODE 110 - RS-485 HALF DUPLEX #2

SP338E

RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION REV. 1.0.0

FIGURE 8. MODE 111 - RS-485/422 MIXED DUPLEX

SP338E

REV. 1.0.0 RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION

FIGURE 9. RS-485/422 RECEIVER TERMINATION RESISTANCE

FIGURE 10. RS-485/422 DIFFERENTIAL DRIVER OUTPUT VOLTAGE

FIGURE 11. RS-485/422 DIFFERENTIAL DRIVER OUTPUT VOLTAGE OVER COMMON MODE

SP338E

RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION REV. 1.0.0

TEST FIXTURES

FIGURE 12. RS-485/422 DRIVER OUTPUT SHORT CIRCUIT CURRENT

FIGURE 13. RS-232 RECEIVER PROPAGATION DELAY

SP338E

REV. 1.0.0 RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION

FIGURE 14. RS-232 DRIVER PROPAGATION DELAY

FIGURE 15. RS-485/422 RECEIVER PROPAGATION DELAY

SP338E

RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION REV. 1.0.0

FIGURE 16. RS-485/422 DRIVER PROPAGATION DELAY AND RISE/FALL TIMES

FIGURE 17. RS-485/422 RECEIVER OUTPUT ENABLE/DISABLE TIMES

SP338E

REV. 1.0.0 RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION

FIGURE 18. RS-485/422 DRIVER OUTPUT ENABLE/DISABLE TIMES

SP338E

RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION REV. 1.0.0

SP338E

REV. 1.0.0 RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION

PRODUCT SUMMARY

The SP338 is an advanced multiprotocol transceiver supporting RS-232, RS-485, and RS-422 serial standards

in a 40 pin QFN package. Integrated cable termination and four configuration modes allow all three protocols to

be used interchangeably over a single cable or connector with no additional switching components. The RS-

485/422 modes feature up to two drivers and four receivers (2TX/4RX) in half, full, and mixed duplex

configurations. The RS-232 mode (3TX/5RX) provides full support of all eight signals commonly used with the

DB9 RS-232 connector. A dedicated mode is also available for diagnostic loopback testing.

INTERNALLY SWITCHED CABLE TERMINATION

Enabling and disabling the RS-485/422 termination resistor is one of the largest challenges system designers

face when sharing a single connector or pair of lines between multiple serial protocols. A termination resistor

may be necessary for accurate RS-485/422 communication, but must be removed when the lines are used for

RS-232. SP338 provides an elegant solution to this problem by integrating the termination resistor and

switching control, and allowing it to be switched in and out of the circuit with a single pin. No external switching

components are required.

ENHANCED FAILSAFE

Ordinary RS-485 differential receivers will be in an indeterminate state whenever the data bus is not being

actively driven. The enhanced failsafe feature of the SP338 guarantees a logic-high receiver output when the

receiver inputs are open, shorted, or terminated but idle/undriven. The enhanced failsafe interprets 0V

differential as a logic high with a minimum 50mV noise margin, while maintaining compliance with the EIA/TIA-

485 standard of ±200mV. No external biasing resistors are required, further easing the usage of multiple

protocols over a single connector.

±15kV ESD PROTECTION

ESD protection structures are incorporated on all pins to protect against electrostatic discharges encountered

during handling and assembly. The bus pins (driver outputs and receiver inputs) have extra protection

structures, which have been tested up to ±15kV without damage. These structures withstand high ESD in all

states: normal operation, shutdown and powered down.

ESD protection is be tested in various ways. Exar uses the following methods to qualify the protection

structures designed into SP338:

±15kV using the Human Body Model (HBM)

±-8kV using IEC 61000-4-2 Contact Discharge

The IEC 61000-4-2 standard is more rigorous than HBM, resulting in lower voltage levels compared with HBM

for the same level of ESD protection. Because IEC 61000-4-2 specifies a lower series resistance, the peak

current is higher than HBM. The SP338 has passed both HBM and IEC 61000-4-2 testing without damage.

DIAGNOSTIC LOOPBACK MODE

The SP338 includes a diagnostic digital loop back mode for system testing as shown in Figure 1. The loopback

mode connects the TTL driver inputs to the TTL receiver outputs, bypassing the analog driver and receiver

circuitry. The analog/bus pins are internally disconnected in this mode.

FIGURE 19. QFN40

SP338E

RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION REV. 1.0.0

PACKAGE DRAWINGS

REVISION HISTORY

DATE REVISION DESCRIPTION

November 2011 1.0.0 Production Release

NOTICE

EXAR Corporation reserves the right to make changes to the products contained in this publication in order to

improve design, performance or reliability. EXAR Corporation assumes no responsibility for the use of any

circuits described herein, conveys no license under any patent or other right, and makes no representation that

the circuits are free of patent infringement. Charts and schedules contained here in are only for illustration

purposes and may vary depending upon a user’s specific application. While the information in this publication

has been carefully checked; no responsibility, however, is assumed for inaccuracies.

EXAR Corporation does not recommend the use of any of its products in life support applications where the

failure or malfunction of the product can reasonably be expected to cause failure of the life support system or

to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless

EXAR Corporation receives, in writing, assurances to its satisfaction that: (a) the risk of injury or damage has

been minimized; (b) the user assumes all such risks; (c) potential liability of EXAR Corporation is adequately

protected under the circumstances.

Datasheet November 2011.

For technical support please email Exar’s Serial Technical Support group at: serialtechsupport@exar.com.

Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited.

SP338E

RS-232/RS-485/RS-422 TRANSCEIVER WITH INTERNAL TERMINATION REV. 1.0.0