Datasheet
SN74FB2033A
8-BIT TTL/BTL REGISTERED TRANSCEIVER
SCBS174M – NOVEMBER 1991 – REVISED SEPTEMBER 2001
5–40
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
description (continued)
Data flow in the B-to-A direction, regardless of the logic element selected, is further controlled by the
LOOPBACK input. When LOOPBACK is low, B
-port data is the B-to-A input. When LOOPBACK is high, the
output of the selected A-to-B logic element (prior to inversion) is the B-to-A input.
The AO port-enable/-disable control is provided by OEA. When OEA is low or when V
CC
is less than 2.5 V, the
AO port is in the high-impedance state. When OEA is high, the AO port is active (high or low logic levels).
The B
port is controlled by OEB and OEB. If OEB is low, OEB is high, or V
CC
is less than 2.5 V, the B port is
inactive. If OEB is high and OEB
is low, the B port is active.
BG V
CC
and BG GND are the bias-generator reference inputs.
The A-to-B and B-to-A logic elements are active, regardless of the state of their associated outputs. The logic
elements can enter new data (in flip-flop and latch modes) or retain previously stored data while the associated
outputs are in the high-impedance (AO port) or inactive (B port) states.
Output clamps are provided on the BTL outputs to reduce switching noise. One clamp reduces inductive ringing
effects on V
OH
during a low-to-high transition. The other clamps out ringing below the BTL V
OL
voltage of 0.75 V.
Both clamps are active only during ac switching and do not affect the BTL outputs during
steady-state conditions.
BIAS V
CC
establishes a voltage between 1.62 V and 2.1 V on the BTL outputs when V
CC
is not connected.
ORDERING INFORMATION
T
A
PACKAGE
†
ORDERABLE
PART NUMBER
TOP-SIDE
MARKING
0°C to 70°C QFP – RC Tube SN74FB2033ARC FB2033A
†
Package drawings, standard packing quantities, thermal data,
symbolization, and PCB design guidelines are available at
www.ti.com/sc/package.