UCC3921DTR Datasheet, PDF (1/16 Pages) Texas Instruments – Latchable Negative Floating Hot Swap Power Manager

Latchable Negative Floating Hot Swap Power Manager
UCC1921
UCC2921
UCC3921
FEATURES
• Precision Fault Threshold
• Programmable:
Average Power Limiting, Linear
Current Control, Overcurrent Limit
and Fault Time
• Fault Output Indication Signal
• Automatic Retry Mode or Latched
Operation Mode
• Shutdown Control
• Undervoltage Lockout
• 250µs Glitch Filter on the SDFLTCH
pin
• 8-Pin DIL and SOIC
DESCRIPTION
The UCC3921 family of negative floating hot swap power managers pro-
vides complete power management, hot swap, and fault handling capa-
bility. The IC is referenced to the negative input voltage and is powered
through an external resistor connected to ground, which is essentially a
current drive as opposed to the traditional voltage drive. The onboard
10V shunt regulator protects the IC from excess voltage and serves as a
reference for programming the maximum allowable output sourcing cur-
rent during a fault. All control and housekeeping functions are integrated
and externally programmable. These include the fault current level, maxi-
mum output sourcing current, maximum fault time, selection of Retry or
Latched mode, soft start time, and average power limiting. In the event of
a constant fault, the internal timer will limit the on time from less than
0.1% to a maximum of 3% duty cycle. The duty cycle modulation de-
pends on the current into PL, which is a function of the voltage across
the FET, thus limiting average power dissipation in the FET. The fault
level is fixed at 50mV across the current sense amplifier to minimize total
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BLOCK DIAGRAM
3/98
UDG-99052