UCC284-5/-12/-ADJ

UCC384-5/-12/-ADJ

SLUS234A - JANUARY 2000

FEATURES

• Precision Negative Series

Pass Voltage Regulation

• 0.2V Drop Out at 0.5A

• Wide Input voltage Range

–3.2V to –15V

• Low Quiescent Current

Irrespective of Load

• Simple Logic Shutdown

Interfacing

• –5V, –12V and Adjustable

Output

• 2.5% Duty Cycle Short Circuit

Protection

• Remote Load Sensing for

Accurate Load Regulation

• 8-Pin DP Package

Low Dropout 0.5A Negative Linear Regulator

3

8

2

6

7

5

+

–

R1

R2

1

4

GND

VOUTS

VOUT

+

–

+

–

1.25V

–2.6V

–1.6V

OVERCURRENT

S

Q

Q

R

THERMAL

SHUTDOWN

1

µA

DISCHARGE

40

µA

VPUMP

SD/CT

CHARGE

700mA

50k

GM

TON

TOFF

UVLO

VIN

VIN

VIN

VIN

–2.2V

R1

R2

0

OPEN

UCC384-ADJ

UCC384-5

UCC384-12

375K

375K

125K

43.6K

+

–

+

–

SHUTDOWN

–0.6V

(–)

(–)

(+)

BLOCK DIAGRAM

UDG-99030

The UCC384 family of negative linear series pass regula-

tors is tailored for low drop out applications where low

quiescent

power

is

important.

Fabricated

with

a

BCDMOS technology ideally suited for low input to out-

put differential applications, the UCC384 will pass 0.5A

while requiring only 0.2V of input voltage headroom.

Drop out voltage decreases linearly with output current,

so that drop out at 50mA is less than 20mV.

Quiescent current consumption for the device under nor-

mal (non-drop out) conditions is typically 200

µA. An inte-

grated charge pump is internally enabled only when the

device is operating near drop out with low VIN. This

guarantees that the device will meet the drop out specifi-

cations even for maximum load current and a VIN of

–3.2V with only a modest increase in quiescent current.

Quiescent current is always less than 350

µA, with the

charge pump enabled. Quiescent current of the UCC384

does not increase with load current.

Short circuit current is internally limited. The device re-

sponds to a sustained over current condition by turning

of 2.5%. This drastically reduces the power dissipation

during short circuit such that heat sinking, if at all re-

quired, must only accommodate normal operation. An

external capacitor sets the on time. The off time is al-

The UCC384 can be shutdown to 45

µA (maximum) by

pulling the SD/CT pin more positive than –0.6V. To allow

for simpler interfacing, the SD/CT pin may be pulled up

to +6V above the ground pin without turning on clamping

diodes.

Internal power dissipation is further controlled with ther-

mal overload protection circuitry. Thermal shutdown oc-

curs if the junction temperature exceeds 140°C. The chip

will remain off until the temperature has dropped 20°C.

DESCRIPTION