FEATURES

? Precision Positive Linear Voltage

Regulation

? 0.5V Dropout at 1A

? Guaranteed Reverse Input/ Output

Voltage Isolation with Low Leakage

? Low Quiescent Current Irrespective of

Load

? Adjustable Output Voltage Version

? Fixed Versions for 3.3V and 5V

Outputs

? Logic Shutdown Capability

? Short Circuit Power Limit of

3% ? VIN ? Current Limit

? Remote Load Voltage for Accurate

Load Regulation

DESCRIPTION

The UCC381-3/-5/-ADJ family of positive linear series pass regulators is

tailored for low drop out applications where low quiescent power is important.

Fabricated with a BiCMOS technology ideally suited for low input to

output differential applications, the UCC381 will pass 1A while requiring

only 0.5V of input voltage headroom. Dropout voltage decreases linearly

with output current, so that dropout at 200mA is less than 100mV. Quiescent

current is always less than 650μA. To prevent reverse current conduction,

on-chip circuitry limits the minimum forward voltage to typically 50mV.

Once the forward voltage limit is reached, the input-output differential voltage

is maintained as the input voltage drops until undervoltage lockout disables

the regulator.

UCC381-3 and UCC381-5 versions have on-chip resistor networks preset

to regulate either 3.3V or 5.0V, respectively. Furthermore, remote sensing

of the load voltage is possible by connecting the VOUTS pin directly at the

load. The output voltage is then regulated to 1.5% at room temperature and

better than 2.5% over temperature. The UCC381-ADJ version has a regulated

output voltage programmed by an external user-definable resistor ratio.