Precision Positive Linear Series Pass

Voltage Regulation

0.45 V Dropout at 3 A

50 mV Dropout at 10 mA

Quiescent Current Under 650 μA

Irrespective of Load

Adjustable (5-Lead) Output Voltage Version

Fixed (3-Lead) Versions for 3.3-V and 5-V

Outputs

Logic Shutdown Capability

Short-Circuit Power Limit of

(3% × VIN × ISHORT)

Low VOUT to VIN Reverse Leakage

Thermal Shutdown

description

The UCC283−3/−5/−ADJ family of positive linear

series pass voltage regulators are 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 UCC283−5 passes

3 A while requiring only 0.45 V of typical input

voltage headroom (ensured 0.6-V dropout).

These regulators include reverse voltage sensing that prevents current in the reverse direction. Quiescent

current is always less than 650 μA. These devices have been internally compensated in such a way that the

need for a minimum output capacitor has been eliminated.

UCC283−3 and UCC283−5 versions are in 3-lead packages and have preset outputs at 3.3 V and 5.0 V

respectively. The output voltage is regulated to 1.5% at room temperature. The UCC283−ADJ version, in a

5-lead package, regulates the output voltage programmed by an external resistor ratio.

Short-circuit current is internally limited. The device responds to a sustained overcurrent condition by turning

off after a tON time delay. The device then stays off for a period, tOFF, that is 32 times the tON delay. The device

then begins pulsing on and off at the tON/(tON+tOFF) duty cycle of 3%. This drastically reduces the power

dissipation during short-circuit and means heat sinks need only accommodate normal operation. On the

3-leaded versions of the device tON is fixed at 750 μs, on the adjustable 5-leaded versions an external capacitor

sets the on time. The off time is always 32 × tON. The external timing control pin, CT, on the 5-leaded versions

also serves as a shutdown input when pulled low.

Internal power dissipation is further controlled with thermal overload protection circuitry. Thermal shutdown

occurs if the junction temperature exceeds 165°C. The chip remains off until the temperature has dropped 20°C.

The UCC283 series is specified for operation over the industrial range of −40°C to 85°C, and the UCC383 series

is specified from 0°C to 70°C. These devices are available in 3- and 5-pin TO−220 and TO−263 power packages.