UCC2920 Datasheet, PDF (1/7 Pages) Texas Instruments – –3V to –15V Hot Swap Power Manager

–3V to –15V Hot Swap Power Manager
UCC2920
UCC3920
PRELIMINARY
FEATURES
• Integrated 0.1Ω
Power MOSFET
• –3V to –15V Operation
• Programmable
Electronic Circuit
Breaker
• Digital Programmable
Current Limit from 0A
to 3A
• Programmable
Maximum Output
Current from 0A to 4A
• Programmable On
Time
• Fixed 2% Fault Duty
Cycle
• Thermal Shutdown
• Fault Output Indicator
• Power SOIC Package
DESCRIPTION
The UCC3920 Low RDSon Hot Swap Power Manager provides complete power man-
agement, hot swap capability, and circuit breaker functions. The only component
needed to operate the device, other than supply bypassing, is the fault timing capaci-
tor, CT. All control and housekeeping functions are integrated and externally program-
mable. These include the fault current level, maximum output sourcing current, maxi-
mum fault time, and start up delay. In the event of a constant fault, the internal fixed
2% duty cycle ratio limits the average output power.
The internal 3 bit DAC allows programming of the fault level current from 0mA to
500mA with 250mA resolution, and from 500mA to 3A with 500mA resolution. The
IMAX control pin sets the maximum sourcing current to 1A above the fault level when
driven low, and to a full 4A when driven high for applications which require fast output
charging.
When the output current is below the fault level, the output MOSFET is switched on
with a nominal resistance of 0.1Ω. When the output current exceeds the fault level or
the maximum sourcing level, the output remains on, but the fault timer starts charging
CT. Once CT charges to a preset threshold, the switch is turned off, and remains off
for 50 times the programmed fault time. When the output current reaches the maxi-
mum sourcing level, the MOSFET transitions form a switch to a constant current
source, regulating the output current at a constant level.
Other features include an Open Drain Fault Output Indicator, Thermal Shutdown, Un-
dervoltage Lockout, –3V to –15V operation, and a low thermal resistance Small Out-
line Power Package. All level shifting is done internally, which means that the DAC,
IMAX and Shutdown Inputs can be driven form the logic supply. The fault output is
also referenced to the logic GND, so this can easily interface back to the logic supply.
BLOCK DIAGRAM
4/97
UDG-96235-1