CBT3857
10-bit bus switch with 10 kΩ pull-down
termination resistors
Product specification
Supersedes data of 1998 Dec 10 1999 Sep 14
INTEGRATED CIRCUITS
Philips Semiconductors Product specification
CBT3857
10-bit bus switch with 10 kΩ pull-down
termination resistors
2
1999 Sep 14 853–2168 22329
FEATURES
•Enable signal is SSTL_2 compatible
•Optimized for use in Double Data Rate (DDR) SDRAM
applications
•Flow-through architecture optimizes PCB layout
•Designed to be used with 200 Mbps
•Switch on resistance is designed to eliminate the need for series
resistor to DDR SDRAM
•Internal 10 kΩ pull-down resistors on B port
•Internal 50 kΩ pull-up resistor on output enable input
•Full DDR solution provided when used with SSTL16857 and
PCK857
•Latch-up protection exceeds 500 mA per JESD78
•ESD protection exceeds 2000 V HBM per JESD22-A114,
200 V MM per JESD22-A115 and 1000 V CDM per JESD22-C101
DESCRIPTION
This 10-bit bus switch is designed for 3 V to 3.6 V VCC operation
and SSTL_2 output enable (OE) input levels.
When OE is LOW, the 10-bit bus switch is on and port A is
connected to port B. When OE is HIGH, the switch is open, and a
high-impedance state exists between the two ports.
The low on-state resistance of the switch allows connections to be
made with minimal propagation delay.
The CBT3857 is characterized for operation from 0°C to +85°C.
QUICK REFERENCE DATA
SYMBOL PARAMETER CONDITIONS
Tamb = 25°C; GND = 0 V TYPICAL UNIT
tPLH
tPHL Propagation delay
An to Yn CL = 30 pF; VCC = 3.3 V 720 ps
CIN Input capacitance VI = 0 V or VCC 2.8 pF
COUT Output capacitance Outputs disabled; VO = 0 V or VCC 6.4 pF
ICCZ Total supply current VCC = 3.6 V 1 mA
ORDERING INFORMATION
PACKAGES TEMPERATURE RANGE ORDER CODE DWG NUMBER
24-Pin Plastic TSSOP Type I 0°C to +85°CCBT3857 PW SOT355–1
PIN CONFIGURATION
1
2
3
4
5
6
7
8
9
10
11
12
24
23
22
21
20
19
18
17
16
15
14
13
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
GND
VREF Vcc
B1
B2
B3
B4
B5
B6
B7
B8
B9
B10
ÎÎ
OE
SA00516
PIN DESCRIPTION
PIN NUMBER SYMBOL NAME AND FUNCTION
1 VREF Reference output voltage
2, 3, 4, 5, 6,
7, 8, 9, 10, 11 A1–A10 Inputs
12 GND Ground (V)
22, 21, 20, 19, 18,
17, 16, 15, 14, 13 B1–B10 Outputs
23 OE Output enable
24 VCC Positive supply voltage
FUNCTION TABLE
INPUT
OE FUNCTION
LA port = B port
H Disconnect
H = High voltage level
L = Low voltage level
Philips Semiconductors Product specification
CBT3857
10-bit bus switch with 10 kΩ pull-down
termination resistors
1999 Sep 14 3
LOGIC DIAGRAM (POSITIVE LOGIC)
SW
SW B1
B10
RINT
RINT
A1
A10
2
11
23
1
OE
VREF
22
13
SA00517
SIMPLIFIED SCHEMATIC, EACH FET SWITCH
BA
OE
SA00518
ABSOLUTE MAXIMUM RATINGS1, 3
SYMBOL PARAMETER CONDITIONS RATING UNIT
VCC DC supply voltage –0.5 to +4.6 V
IIK DC input clamp current VI/O < 0 –50 mA
VIDC input voltage range (OE only)2VCC + 0.5 V
Tstg Storage temperature range –65 to 150 °C
VIDC input voltage range (except OE)2–0.5 to 4.6 V
NOTES:
1. Stresses beyond those listed may cause permanent damage to the device. These are stress ratings only and functional operation of the
device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied. Exposure to
absolute-maximum-rated conditions for extended periods may affect device reliability.
2. The input and output negative-voltage ratings may be exceeded if the input and output clamp-current ratings are observed.
3. The package thermal impedance is calculated in accordance with JESD 51.
RECOMMENDED OPERATING CONDITIONS
SYMBOL
PARAMETER
LIMITS
UNIT
SYMBOL
PARAMETER
Min Typ Max
UNIT
VCC DC supply voltage 3 3.3 3.6 V
VREF Reference voltage (0.38 x VCC) 1.15 1.25 1.35 V
VIH AC high-level input voltage VREF +
350 mV V
VIL AC low-level Input voltage VREF – 350 mV V
VIH DC high-level input voltage VREF +
180 mV V
VIL DC low-level Input voltage VREF – 180 mV V
Tamb Operating free-air temperature range 0 +85 °C
NOTE:
1. All unused control inputs of the device must be held at VCC or GND to ensure proper device operation.
Philips Semiconductors Product specification
CBT3857
10-bit bus switch with 10 kΩ pull-down
termination resistors
1999 Sep 14 4
DC ELECTRICAL CHARACTERISTICS
LIMITS
SYMBOL PARAMETER TEST CONDITIONS Tamb = 0°C to +85°CUNIT
Min Typ1Max
VIK Input clamp voltage VCC = 3 V ; II = –18 mA –1.2 V
OE ±0.73 ±500 µA
I
In
p
ut leakage current
VCC =36V
;
V=V
CC or GND
A Port ±0.1 ±1µA
I
I
Inp
u
t
leakage
c
u
rrent
V
CC =
3
.
6
V
;
V
I =
V
CC
or
GND
B Port ±20 ±500 µA
VREF ±0.1 ±1µA
ICC Quiescent supply current VCC = 3.6 V ; IO = 0, VI = VCC or GND 0.7 1.5 mA
CIControl pins VI= 3 V or 0 2.8 pF
CiO(OFF) Power-of f leakage current VO = 3 V or 0; OE = VCC 6.4 pF
2
VCC = 3 V to 3.6 V ; VA = 0.8 V; VB = 1.15 V 20 24 30
ron
2
On-resistance VCC = 3 V to 3.6 V ; VA = 1.7 V; VB = 1.35 V 20 24 30 Ω
VCC = 3 V to 3.6 V ; VI = 1.25 V; II = ±10 mA 20 24 30
roff2Off-resistance VCC = 3 V to 3.6 V; VI = 1.65 V 1 MΩ
NOTES:
1. All typical values are at VCC = 3.3 V, Tamb = 25°C
2. Measured by the voltage drop between the A and the B terminals at the indicated current through the switch. On–state resistance is
determined by the lowest voltage of the two (A or B) terminals.
AC CHARACTERISTICS
SYMBOL
PARAMETER
FROM (INPUT)
TO (OUTPUT)
VCC = +3.3 V ±0.3 V
UNIT
SYMBOL
PARAMETER
FROM
(INPUT)
TO
(OUTPUT)
Min Max
UNIT
tpd Propagation delay1A or B B or A 750 ps
ten enable OE A or B 1 3 ns
tdis disable OE A or B 1 3 ns
NOTE:
1. The propagation delay is based on the RC time constant of the typical on–state resistance of the switch and a load capacitance, when driven
by an ideal voltage source (zero output impedance); 24 Ω × 30 pF.
184/200-pin DDR SDRAM DIMM
SDRAM
SDRAM
SDRAM
SDRAM
SDRAM
SDRAM
SDRAM
SDRAM
SDRAM
The PLL clock distribution device and SSTL registered drivers reduce
signal loads on the memory controller and prevent timing delays and
waveform distortions that would cause unreliable operation
SW00393
CBT3857 (9)
CBT CBT CBT CBT CBT CBT CBT CBT CBT
SDRAM
SDRAM
SDRAM
SDRAM
SDRAM
SDRAM
SDRAM
SDRAM
SDRAM
SSTL16857 PCK857SSTL16857
BACK SIDE
FRONT SIDE
Philips Semiconductors Product specification
CBT3857
10-bit bus switch with 10 kΩ pull-down
termination resistors
1999 Sep 14 5
AC WAVEFORMS
VM = 1.5 V, VIN = GND to 3.0 V
INPUT 1.375V
OUTPUT
tPLH tPHL
1.375V
1.25V 1.25V
2.75 V
0 V
VOH
VOL
SA00513
W aveform 1. Input (An) to Output (Yn) Propagation Delays
Output Control
(Low-level
enabling
1.25 V
tPZH tPHZ VOH
VOL
tPZL tPLZ 3.5V
0V
VOL + 0.15V
VOH – 0.15V
1.25 V
VREF VREF
VIH (AC)
Output
Waveform 1
S1 at 4.3 V
(see Note)
Note:
Waveform 1 is for an output with internal conditions such that
the output is low except when disabled by the output control.
Waveform 2 is for an output with internal conditions such that
the output is high except when disabled by the output control.
Output
Waveform 2
S1 at Open
(see Note) *
VIL (AC)
* VIH = 3.0V with 25Ω input line impedance
SA00514
W aveform 2. 3-State Output Enable and Disable Times
TEST CIRCUIT AND WAVEFORMS
CL = 30 pF 500 Ω
Load Circuit
DEFINITIONS
CL = Load capacitance includes jig and probe capacitance
TEST S1
tpd open
tPLZ/tPZL 4.3 V
tPHZ/tPZH GND
500 Ω
From Output
Under Test
S1 4.3 V
Open
GND
SA00515
NOTES:
1. All input pulses are supplied by generators having the following
characteristics: PRR ≤ 10 MHz, ZO = 50 Ω, tr ≤ 2.5 ns, tf ≤ 2.5 ns.
2. The outputs are measured one at a time with one transition per
measurement.
Philips Semiconductors Product specification
CBT3857
10-bit bus switch with 10 kΩ pull-down
termination resistors
1999 Sep 14 6
TSSOP24: plastic thin shrink small outline package; 24 leads; body width 4.4 mm SOT355-1
Philips Semiconductors Product specification
CBT3857
10-bit bus switch with 10 kΩ pull-down
termination resistors
1999 Sep 14 7
NOTES
Philips Semiconductors Product specification
CBT3857
10-bit bus switch with 10 kΩ pull-down
termination resistors
1999 Sep 14 8
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 134). 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 af fect 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.
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, without notice, in the products, including circuits, standard
cells, and/or software, described or contained herein in order to improve design and/or performance. Philips Semiconductors assumes no
responsibility or liability for the use of any of these products, conveys no license 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.
Philips Semiconductors
811 East Arques Avenue
P.O. Box 3409
Sunnyvale, California 94088–3409
Telephone 800-234-7381
Copyright Philips Electronics North America Corporation 1999
All rights reserved. Printed in U.S.A.
Date of release: 09-99
Document order number: 9397-750 -06413
Data sheet
status
Objective
specification
Preliminary
specification
Product
specification
Product
status
Development
Qualification
Production
Definition [1]
This data sheet contains the design target or goal specifications for product development.
Specification may change in any manner without notice.
This data sheet contains preliminary data, and supplementary data will be published at a later date.
Philips Semiconductors reserves the right to make changes at any time without notice in order to
improve design and supply the best possible product.
This data sheet contains final specifications. Philips Semiconductors reserves the right to make
changes at any time without notice in order to improve design and supply the best possible product.
Data sheet status
[1] Please consult the most recently issued datasheet before initiating or completing a design.
