SC4250_05 Datasheet, PDF (1/12 Pages) Semtech Corporation – Negative Voltage Hot Swap Controller

POWER MANAGEMENT
Description
The SC4250 is a negative voltage hotswap controller
that allows the insertion of line cards into a live backplane.
The inrush current is programmable, and the closed loop
operation limits the maximum current even under short
circuit conditions. A built-in timing circuit prevents false
shutdown. The signal from the drain voltage is fed to the
timer, providing safety for the MOSFET when in linear
mode. The SC4250 latches off under abnormal condi-
tions The power has to be recycled in order to resume
operation.
The device comes in two options, PWRGD (SC4250H)
and PWRGD (SC4250L). These high or low signals can
be directly used to enable power modules.
SC4250
Negative Voltage
Hot Swap Controller
Features
‹ Programmable slew of the inrush current when
used for hot insertion in the negative 24V and 48V
backplane
‹ Closed loop operation limits the maximum current
even in short circuit condition
‹ Built in timer prevents false shutdown when the
closed loop operation limits the current
‹ Sensing the drain voltage allows for immediate
shutdown in short circuit conditions where current
spikes and noise are ignored
‹ Power good signal
‹ Input UVLO and OVLO sensing
‹ Circuit breaker and retry
‹ SO-8 package
Applications
‹ Central office switching
‹ -48V Distributed power systems
‹ Power supply hotswap & inrush control
Typical Application Circuit
GND
PWRGD/PWRGD
GND(remote)
R1
562k
R2
9.31k
R3
10.2k
-- 48V
Revision: April 6, 2005
U1
SC4250
1
PWRGD /PWRGD
VCC
8
2
OV
DRAIN
7
3
UV
GATE
6
4
VEE
SENSE
5
C1
0.1
VVeEeE
R6
C4
18k
3.3nF
C2
0.001
R4
0.01
C3
0.33
R5
10
Q1
Figure 1
1
C5
150
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