Datasheet

4k
4k
A B
V
CCA
V
CCB
One
Shot
One
Shot
One
Shot
One
Shot
T1
T2
T3
T4
TXB0108
SCES643B –NOVEMBER 2006–REVISED FEBRUARY 2010 www.ti.com
PRINCIPLES OF OPERATION
Applications
The TXB0108 can be used in level-translation applications for interfacing devices or systems operating at
different interface voltages with one another.
Architecture
The TXB0108 architecture (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. In a dc state, the output drivers of the TXB0108 can maintain a high or low,
but are designed to be weak, so that they can be overdriven by an external driver when data on the bus starts
flowing the opposite direction.
The output one shots detect rising or falling edges on the A or B ports. During a rising edge, the one shot turns
on the PMOS transistors (T1, T3) for a short duration, which speeds up the low-to-high transition. Similarly,
during a falling edge, the one shot turns on the NMOS transistors (T2, T4) for a short duration, which speeds up
the high-to-low transition. The typical output impedance during output transition is 70Ω at V
CCO
= 1.2 V to 1.8 V,
50Ω at V
CCO
= 1.8 V to 3.3 V and 40Ω at V
CCO
= 3.3 V to 5 V.
Figure 1. Architecture of TXB0108 I/O Cell
Input Driver Requirements
Typical I
IN
vs V
IN
characteristics of the TXB0108 are shown in Figure 2. For proper operation, the device driving
the data I/Os of the TXB0108 must have drive strength of at least ±2 mA.
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