UC1914

UC2914

UC3914

SLUS425A - AUGUST 1999

FEATURES

• 5V to 35V Operation

• Precision Maximum Current Control

• Precision Fault Threshold

• Programmable Average Power

Limiting

• Programmable Overcurrent Limit

• Shutdown Control

High-Side Drive

• Latch Reset Function Available

• Fault Output Indication

• 18 Pin DIL and SOIC Packages

5V to 35V Hot Swap Power Manager

BLOCK DIAGRAM

UDG-95134-2

DESCRIPTION

The UC3914 family of Hot Swap Power Managers provides complete

power management, hot swap and fault handling capability. Integrating this

part and a few external components, allows a board to be swapped in or

out upon failure or system modification without removing power to the hard-

ware, while maintaining the integrity of the powered system. Complemen-

tary output drivers and diodes have been integrated for use with external

capacitors as a charge pump to ensure sufficient gate drive to the external

are integrated and externally programmable and include the fault current

level, maximum output sourcing current, maximum fault time and average

power limiting of the external FET. The UC3914 features a duty ratio cur-

rent limiting technique, which provides peak load capability while limiting

the average power dissipation of the external pass transistor during fault

conditions. The fault level is fixed at 50mV with respect to VCC to minimize

total dropout. The fault current level is set with an external current sense re-

sistor. The maximum allowable sourcing current is programmed by using a

resistor divider from VCC to REF to set the voltage on IMAX. The maximum

current

level,

when

the

output

appears

as

a

current

source

is

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