Gate Bias

Generator

10 k

Rise Time

Logic

VCCB

A

B

Fall Time

Logic

VCCB

Rise Time

Logic

VCCA

Fall Time

Logic

VCCA

10 k

Figure 8-1. Architecture of a TCA9416 Cell

These two bidirectional channels support both directions of data flow without a direction-control signal. By

to ~ 1 voltage threshold below the lowest of the two supplies.

The TCA9416 is part of the TI "Switch" type voltage translator family and employs key circuits to enable this

voltage translation:

1. An N-channel pass-gate transistor topology that ties the A-port to the B-port.

2. Output rise time accelerator circuitry to detect and accelerate rising edges on the A or B ports

3. Output fall time accelerator circuitry to detect and accelerate falling edges on the A or B ports

For bidirectional voltage translation, pull up resistors are included on the device for dc current sourcing

The rise and fall time accelerator (RTA and FTA, respectively) circuitry speeds up the output slew rate by

monitoring the input edge for transitions, helping maintain the data rate through the device. During a low-to-high

signal rising edge, the rise time accelerator (RTA) circuit turns on to increase the current drive capability of

the driver. This edge-rate acceleration provides high ac drive by bypassing the internal 10-kΩ pull up resistors

during the low-to-high transition to speed up the signal. The output resistance of the driver is decreased to

approximately 150 Ω during this acceleration phase. During a high-to-low signal falling edge, the fall time

accelerator (FTA) turns on to increase the current drive capability of the driver, similar to the rise time

accelerator. This helps reduce the fall time for large capacitive loads. For light capacitive loads, the fall time

accelerator will not enable.

Both the rise and fall time accelerators have logic to control the rate at which they turn on and off, in order to

reduce ringing and over/undershoots.

8.3.2 Enable and Disable

The TCA9416 has an OE input that is used to disable the device by setting OE low, which prevents any signals

become operational after OE is taken high.

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TCA9416

SCPS238A – FEBRUARY 2021 – REVISED AUGUST 2021

Copyright © 2021 Texas Instruments Incorporated

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