SN74FB2032 Datasheet, PDF (2/10 Pages) Texas Instruments – 9-BIT TTL/BTL COMPETITION TRANSCEIVER

SN74FB2032
9-BIT TTL/BTL COMPETITION TRANSCEIVER
SCBS175H – NOVEMBER 1991 – REVISED SEPTEMBER 1999
description (continued)
The A port operates at TTL-signal levels. 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.
The A-port data is latched when the latch enable (LE) is high. When LE is low, the latches are transparent.
The Futurebus protocol logic can be activated by taking COMPETE low. The module (device) then compares
its A data (arbitration number) against the A data of another identical module also connected to the B arbitration
bus, and sets WIN high if the A data is greater than the A data of the other module (i.e., has higher priority). A8
and B8 are the most-significant bits, and A1 and B1 are the least-significant bits. If OEB is high and OEB is low
during this operation, and the A bus of the first module wins priority, the A bus asserts its arbitration number on
the B-arbitration bus.
AP and BP are the bus-parity bits. The winning module can assert BP low if its parity bit (AP) is high.
In a typical operating sequence, a Futurebus arbitration controller latches its arbitration number into the A port
and waits for the results of a competition. When the competition is complete, and if the controller’s arbitration
number did not win, the controller reads back the current value of the B bus (by taking OEA high) and determines
the winning arbitration number. This allows the module to change its arbitration number for the next competition
cycle, if desired.
Pins are allocated for the four-wire IEEE Std 1149.1 (JTAG) test bus. 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.
BG V_CC and BG GND are the supply inputs for the bias generator.
The SN74FB2032 is characterized for operation from 0°C to 70°C.
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