UC1914
UC2914
UC3914
5V to 35V Hot Swap Power Manager
FEATURES
DESCRIPTION
• 5V to 35V Operation
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
NMOS transistor for low RDS(on). All control and housekeeping functions
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
• Precision Maximum Current Control
• Precision Fault Threshold
• Programmable Average Power
Limiting
• Programmable Overcurrent Limit
• Shutdown Control
• Charge Pump for Low RDS(on)
High-Side Drive
• Latch Reset Function Available
• Output Drive VGS Clamping
• Fault Output Indication
• 18 Pin DIL and SOIC Packages
(VCC – VIMAX)/RSENSE
.
(continued)
BLOCK DIAGRAM
UDG-95134-2
SLUS425A - AUGUST 1999