UTXS0102

Preliminary

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

12 of 13

www.unisonic.com.tw

QW-R140-034.b



DETAILED DESCRIPTION

Overview

The UTXS0102 device is a directionless voltage-level translator specifically designed for translating logic voltage

levels. The A port is able to accept I/O voltages ranging from 1.65V to 3.6V, while the B port can accept I/O voltages

from 2.3V to 5.5V. The device is a pass gate architecture with edge rate accelerators (one shots) to improve the

overall data rate. 10kΩ pull-up resistors, commonly used in open-drain applications, have been conveniently

integrated so that an external resistor is not needed. While this device is designed for open-drain applications, the

device can also translate push-pull CMOS logic outputs.

Architecture

The UTXS0102 architecture does not require a direction-control signal to control the direction of data flow from A

to B or from B to A.

A

10kΩ

B

Gate Bias

10kΩ

One-Shot

VCCA

VCCB

One-Shot

T2

T1

N2

Figure 1. Architecture of UTXS0102 I/O Cell

Each A-port I/O has an internal 10kΩ pull up resistor to VCCA, and each B-port I/O has an internal 10kΩ pull-up

resistor to VCCB. The output one-shots detect rising edges on the A or B ports. During a rising edge, the one-shot

turns on the PMOS transistors (T1, T2) for a short duration, which speeds up the low-to-high transition.

Input Driver Requirements

The fall time (tfA, tfB) of a signal depends on the output impedance of the external device driving the data I/Os of

the UTXS0102.Similarly,the tPHL and max data rates also depend on the output impedance of the external driver. The

values for tfA, tfB, tPHL, and maximum data rates in the data sheet assume that the output impedance of the external

driver is less than 50Ω.

Power-Up

During operation, ensure that VCCA ≤ VCCB at all times. During power-up sequencing, VCCA ≥ VCCB does not

damage the device, so any power supply can be ramped up first.

Enable and Disable

The UTXS0102 has an OE input that is used to disable the device by setting OE low, which places all I/Os in the

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.

Pull-up or Pull-down Resistors on I/O Lines

Each A-port I/O has an internal 10kΩ pull-up resistor to VCCA, and each B-port I/O has an internal 10 kΩ pull-up

resistor to VCCB. If a smaller value of pull-up resistor is required, an external resistor must be added from the I/O to

VCCA or VCCB (in parallel with the internal 10 kΩ resistors).

Device Functional Modes

The UTXS0102 device has two functional modes, enabled and disabled. To disable the device set the OE input

low, which places all I/Os in a high impedance state. Setting the OE input high will enable the device.