UCC3916

SLUS206A - JANUARY 2000

FEATURES

• Integrated Circuit Breaker Function

• Integrated 0.2 Power FET

• SCSI, SCSI-2, SCSI-3 Compliant

• 1µA ICC When Disabled

• Programmable On Time

• Accurate 1.65A Trip Current and

2.0A Max Current

• Fixed 3% Duty Cycle

• Uni-Directional Switch

• Thermal Shutdown

DESCRIPTION

The UCC3916 SCSI termpower manager provides complete power man-

agement, hot swap capability, and circuit breaker functions with minimal ex-

ternal components. For most applications, the only external component

required to operate the device, other than supply bypassing, is a timing ca-

pacitor which sets the fault time.

The current trip level is internally set at 1.65A, and the maximum current

level is also internally programmed for 2A. While the output current is below

the trip level of 1.65A, the internal power MOSFET is switched on at a nom-

inal 220m

Ω. When the output current exceeds the trip level but remains

less than the maximum current level, the MOSFET remains switched on,

but the fault timer starts charging CT. Once the fault time is reached, the cir-

cuit will shut off for a time which equates to a 3% duty cycle. Finally, when

the output current reaches the maximum current level, the MOSFET transi-

tions from a switch to a constant current source.

The UCC3916 is designed for uni-directional current flow, emulating a diode

in series with the power MOSFET.

The UCC3916 can be put in a sleep mode, drawing only 1

µA of supply cur-

rent.

Other features include thermal shutdown and low thermal resistance Small

Outline Power package.

SCSI Termpower Manager

8

OUTPUT

OUTPUT

CURRENT SENSE

H=OPEN

REVERSE VOLTAGE

COMPARATOR

50mV

CHARGE

PUMP

POWER

FET

ON TIME CONTROL

3% DUTY CYCLE

LINEAR

CURRENT

AMPLIFIER

THERMAL

SHUTDOWN

INTERNAL

BIAS

+

–

1.5V

5

SHTDWN

4

CT

OVER CURRENT

COMPARATOR

2

3

6

7

GND

GND

GND

GND

MAXIMUM

CURRENT

LEVEL

2A

4 HEATSINK PINS

CURRENT

TRIP LEVEL

1.65A

1

VIN

4V TO 6V

BLOCK DIAGRAM

UDG-99172