Datasheet
SN74FB2040
8-BIT TTL/BTL TRANSCEIVER
SCBS173M – NOVEMBER 1991 – REVISED JUNE 2001
5–63
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
D Compatible With IEEE Std 1194.1-1991
(BTL)
D TTL A Port, Backplane Transceiver Logic
(BTL) B
Port
D Open-Collector B-Port Outputs Sink
100 mA
D High-Impedance State During Power Up
and Power Down
D BIAS V
CC
Pin Minimizes Signal Distortion
During Live Insertion or Withdrawal
D B-Port Biasing Network Preconditions the
Connector and PC Trace to the BTL
High-Level Voltage
RC PACKAGE
(TOP VIEW)
AO2
AI1
AO1
OEB
TCK
14 15 16 17 18 19 20 21 22 23 24 25 26
52 51 50 49 48 47 46 45 44 43 42 41 40
GND
AO7
AI7
BG GND
AO8
TDO
AI8
GND
B8
AI6
GND
B1
V
CC
V
CC
BG V
CC
TMS
GND
AI2
AI3
AO3
GND
AO4
GND
AI4
AI5
AO5
GND
AO6
GND
GND
B2
GND
B3
GND
B4
GND
B5
GND
B6
GND
B7
GND
1
2
3
4
5
6
7
8
9
10
11
12
13
39
38
37
36
35
34
33
32
31
30
29
28
27
BIAS V
CC
OEA
V
CC
OEB
TDI
description
The SN74FB2040 is an 8-bit transceiver designed to translate signals between TTL and backplane transceiver
logic (BTL) environments.
The B
port operates at BTL-signal levels. The open-collector B ports are specified to sink 100 mA. Two output
enables (OEB and OEB
) are provided for the B outputs. When OEB is high and OEB is low, the B port is active
and reflects the inverse of the data present at the A-input pins. When OEB is low, OEB
is high, or V
CC
is less
than 2.1 V, the B
port is turned off.
The A port operates at TTL-signal levels and has separate input and output pins. The A outputs reflect the
inverse of the data at the B
port when the A-port output enable (OEA) is high. When OEA is low or when V
CC
is less than 2.1 V, the A outputs are in the high-impedance state.
Pins are allocated for the four-wire IEEE Std 1149.1 (JTAG) test bus, although currently there are no plans to
release a JTAG-featured version. TMS and TCK are not connected, and TDI is shorted to TDO.
BIAS V
CC
establishes a voltage between 1.62 V and 2.1 V on the BTL outputs when V
CC
is not connected.
Copyright 2001, Texas Instruments Incorporated
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.