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http://www.union-ic.com

Rev.06 May.2012

8/13

UM3204

Applications Information

The UM3204 can be used in level-translation applications for interfacing devices or systems

operating at different interface voltages with one another. The UM3204 is ideal for use in

application where an open-drain driver is connected to the data I/Os. The UM3204 can also be

used in applications where a push-pull driver is connected to the data I/Os, but the UM3304 might

be a better option for such push-pull applications.

Block Diagram

The UM3204 (block diagram see Figure 1) does not require a direction-control signal to control

the direction of data flow from A to B or from B to A. Each A-port I/O has an internal 10-kΩ

During a rising edge, the one-shot turns on the PMOS transistors (PU1, PU2) for a short duration,

which speeds up the low-to-high transition.

Figure 1 Block Diagram of UM3204 I/O Cell

Input Driver Requirements

the data sheet assume that the output impedance of the external driver is less than 50Ω.

Power Up

does not damage the device, so any power supply can be ramped up first.

Enable and Disable

The UM3204 has an OE input that is used to disable the device by setting OE = low, which places

all I/Os in the high-impedance (Hi-Z) state. The disable time (tdis) indicates the delay between the

time when OE goes low and when the outputs actually get disabled (Hi-Z). The enable time (ten)

indicates the amount of time the user must allow for the one-shot circuitry to become operational

after OE is taken high.