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Application Report
SLUU076A - August 2000
1
UCC3913 or UCC3921 Hot Swap Power Manager
Evaluation Board
Power Management Products
1 Evaluation Board Operation
This user’s guide highlights the UCC3913/ UCC3921 evaluation board in a typical –48-Vdc, 1-A
application circuit.
Many battery-powered and telecommunications power supplies use some form of protection to
prevent high currents from flowing during a short-circuit or overload condition. This function is
often performed by a self-resetting circuit breaker as opposed to a fuse, which requires manual
replacement whenever triggered. Circuit breakers can be implemented in a number of different
ways, but the most popular approach is to use a MOSFET transistor, which can be switched on
and off as required. Load current is typically sensed with a low value resistor and compared to a
reference level to determine when an overcurrent condition exists. This function can be achieved
with discrete circuitry or with a fully-integrated solution, such as the UCC3913 and the UCC3921
negative voltage hot swap power manager.
UDG–99127
4 6
1
2
7
8
5
3
IMAX
SDFLTCH
OUT
PL
VDD
CT SNS
VSS
U1
UCC3913/21
Q1
R8
R9
C4 R7C3
3
2
1
LOAD
GND
TB1
R6
Q2D1
R3 C2C1
R5
R4
R1
1
2
5
4
U2
U3
J1
J2
1
2
7
6
3
5
4
8
TB2
1
2
5
4
R10
–V
IN
Figure 1. Evaluation Board Schematic
