State-of-the-Art EPIC-IIBE BiCMOS Design
Significantly Reduces Power Dissipation
ESD Protection Exceeds 2000 V Per
MIL-STD-883C, Method 3015; Exceeds
200 V Using Machine Model (C = 200 pF,
R = 0)
Latch-Up Performance Exceeds 500 mA
Per JEDEC Standard JESD-17
Typical VOLP (Output Ground Bounce)
< 1 V at VCC = 5 V, TA = 25°C
High-Drive Outputs (–32-mA IOH,
64-mA IOL)
Package Options Include Plastic
Small-Outline (DW), Shrink Small-Outline
(DB), and Thin Shrink Small-Outline (PW)
Packages, Ceramic Chip Carriers (FK), and
Plastic (NT) and Ceramic (JT) DIPs

description
These devices consist of bus transceiver circuits,
D-type flip-flops, and control circuitry arranged for
multiplexed transmission of data directly from the
input bus or from the internal registers. Data on the
A or B bus is clocked into the registers on the
low-to-high transition of the appropriate clock
(CLKAB or CLKBA) input. Figure 1 illustrates the
four fundamental bus-management functions that
can be performed with the 4ABT646.
Output-enable (OE) and direction-control (DIR)
inputs are provided to control the transceiver
functions. In the transceiver mode, data present at
the high-impedance port may be stored in either
register or in both.
The select-control (SAB and SBA) inputs can multiplex stored and real-time (transparent mode) data. The
direction control (DIR) determines which bus will receive data when OE is low. In the isolation mode (OE high),
A data may be stored in one register and/or B data may be stored in the other register.
When an output function is disabled, the input function is still enabled and may be used to store and transmit
data. Only one of the two buses, A or B, may be driven at a time.
To ensure the high-impedance state during power up or power down, OE should be tied to VCC through a pullup
resistor; the minimum value of the resistor is determined by the current-sinking capability of the driver.
The SN74ABT646 is available in TI’s shrink small-outline package (DB), which provides the same I/O pin count
and functionality of standard small-outline packages in less than half the printed-circuit-board area.
The SN54ABT646 is characterized for operation over the full military temperature range of –55°C to 125°C. The
SN74ABT646 is characterized for operation from –40°C to 85°C.