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.