FEATURES
· Member of the Texas Instruments Widebus™
Family
· Operates From 1.65 V to 3.6 V
· Inputs Accept Voltages to 5.5 V
· In Transparent Mode, Max tpd of 5.2 ns
at 3.3 V
· Typical VOLP (Output Ground Bounce)
< 0.8 V at VCC = 3.3 V, TA = 25°C
· Typical VOHV (Output VOH Undershoot)
> 2 V at VCC = 3.3 V, TA = 25°C
· Supports Mixed-Mode Signal Operation on
All Ports (5-V Input/Output Voltage With
3.3-V VCC)
· Ioff Supports Partial-Power-Down Mode
Operation
· Latch-Up Performance Exceeds 250 mA
Per JESD 17
· ESD Protection Exceeds JESD 22
– 2000-V Human-Body Model (A114-A)
– 1000-V Charged-Device Model (C101)

DESCRIPTION/ORDERING INFORMATION
This 16-bit bus transceiver and register is designed for 1.65-V to 3.6-V VCC operation.
The SN74LVC16646A can be used as two 8-bit transceivers or one 16-bit transceiver. The device consists 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 SN74LVC16646A.
Output-enable (OE) and direction-control (DIR) inputs control the transceiver functions. In the transceiver mode,
data present at the high-impedance port can 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 circuitry used for select control
eliminates the typical decoding glitch that occurs in a multiplexer during the transition between stored and
real-time data. DIR determines which bus receives data when OE is low. In the isolation mode (OE high), A data
can be stored in one register and/or B data can be stored in the other register.
This device is fully specified for partial-power-down applications using Ioff. The Ioff circuitry disables the outputs,
preventing damaging current backflow through the device when it is powered down.
When an output function is disabled, the input function still is enabled and can be used to store and transmit
data. Only one of the two buses, A or B, can be driven at a time.
Inputs can be driven from either 3.3-V or 5-V devices. This feature allows the use of these devices as translators
in a mixed 3.3-V/5-V system environment.
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.