UCC3912

SLUS241A - NOVEMBER 1999

FEATURES

• Integrated 0.15Ω Power MOSFET

• 3V to 8V Operation

• Digital Programmable Current Limit

from 0 to 3A

• Electronic Circuit Breaker Function

• Programmable on Time

• Programmable Start Delay

• Fixed 3% Duty Cycle

• Uni-Directional Switch

• Thermal Shutdown

• Fault Output Indicator

• Maximum Output Current can be set

to 1A above the Programmed Fault

Level or to a full 4A

• Power SOIC, Low Thermal

Resistance Packaging

DESCRIPTION

The UCC3912 Hot Swap Power Manager provides complete power man-

agement, hot swap capability, and circuit breaker functions. The only com-

ponent required to operate the device, other than supply bypassing, is the

grated, and externally programmable. These include the fault current level,

maximum output sourcing current, maximum fault time,and start-up delay.

In the event of a constant fault, the Internal fixed 3% duty cycle ratio limits

average output power.

The internal 4 bit DAC allows programming of the fault level current from 0

to 3A with 0.25A resolution. The IMAX control pin sets the maximum sour-

cing current to 1A above the fault level when driven low, and to a full 4A

when driven high for applications which require fast output capacitor charg-

ing.

When the output current is below the fault level, the output MOSFET is

switched on with a nominal on resistance of 0.15 . When the output cur-

rent exceeds the fault level, but is less than the maximum sourcing level,

mains off for 30 times the programmed fault time. When the output current

reaches the maximum sourcing level, the MOSFET transitions from a

switch to a constant current source.

(continued)

6

7

8

9

1A

ABOVE

FAULT

OVER CURRENT

COMPARATOR

CURRENT FAULT

LEVEL 0–3 AMPS

10

H= 4A

MAX

CURRENT

LEVEL

4A

ON TIME

CONTROL

3% DUTY

CYCLE

0–3A

0.25

RES

11

13

12

4

5

B3

B2

B1

B0

4BIT DAC

GND

HEAT SINK

GND PINS

CT

CHARGE

PUMP

16

LINEAR CURRENT

AMPLIFIER

POWER

FET

2

3

V

OUT

REVERSE VOLTAGE

COMPARATOR

30mV

FAULT

THERMAL

SHUTDOWN

INTERNAL

BIAS

+

–

1

15

14

VOUT

VIN

CURRENT SENSE

H = OPEN

1.5V

SHTDWN

IMAX

BLOCK DIAGRAM

Programmable Hot Swap Power Manager

UDG-99146

application

INFO

available