SCES643E datasheet(11/27 Pages) TI

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IIN

VIN

VT/4 kW

–(VD – VT)/4 kW

A. VT is the input threshold voltage of the TXB0108 (typically VCCI/2).

B. VD is the supply voltage of the external driver.

TXB0108

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SCES643E – NOVEMBER 2006 – REVISED MAY 2012

Figure 2. Typical IIN vs VIN Curve

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. The TXB0108 has circuitry that disables all

output ports when either VCC is switched off (VCCA/B = 0 V).

Enable and Disable

The TXB0108 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 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.

Pullup or Pulldown Resistors on I/O Lines

The TXB0108 is designed to drive capacitive loads of up to 70 pF. The output drivers of the TXB0108 have low

dc drive strength. If pullup or pulldown resistors are connected externally to the data I/Os, their values must be

kept higher than 50 k

Ω to ensure that they do not contend with the output drivers of the TXB0108.

For the same reason, the TXB0108 should not be used in applications such as I2C or 1-Wire where an open-

drain driver is connected on the bidirectional data I/O. For these applications, use a device from the TI TXS01xx

series of level translators.

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Product Folder Link(s): TXB0108

SCES643E Datasheet(PDF) 11 Page - Texas Instruments