Datasheet

GND
V
SYS
LM25061
PLUG-IN CARD
CARD EDGE
CONNECTOR
Q1
R
S
To
Load
R1
C
IN
To System
Ground
SENSE
VIN
UVLO
FB
GND
GATE
OUT
PGD
PWR
TIMER
R2
R4 R3
a)
Delay Rising Edge Only
b)
Long delay at rising edge,
short delay at falling edge
c)
Short Delay at Rising Edge and
Long Delay at Falling Edge or
Equal Delays
GND
PGD
R
PG1
V
PGD
Power
Good
C
PG
GND
PGD
R
PG1
V
PGD
Power
Good
C
PG
GND
PGD
R
PG1
V
PGD
Power
Good
C
PG
R
PG2
R
PG2
LM25061
LM25061
LM25061
LM25061
www.ti.com SNVS611E –FEBRUARY 2011–REVISED MARCH 2013
Figure 35. Adding Delay to the Power Good Output Pin
Figure 36. Recommended Board Connector Design
System Considerations
1. Continued proper operation of the LM25061 hot swap circuit requires capacitance be present on the supply
side of the connector into which the hot swap circuit is plugged in, as depicted in Figure 22. The capacitor in
the “Live Power Source” section is necessary to absorb the transient generated whenever the hot swap
circuit shuts off the load current. If the capacitance is not present, inductance in the supply lines will generate
a voltage transient at shut-off which can exceed the absolute maximum rating of the LM25061, resulting in its
destruction.
2. If the load powered by the LM25061 hot swap circuit has inductive characteristics, a Schottky diode is
required across the LM25061’s output, along with some load capacitance. The capacitance and the diode
are necessary to limit the negative excursion at the OUT pin when the load current is shut off. If the OUT pin
transitions more than 0.3V negative the LM25061 will internally reset, interfering with the latch-off feature of
the LM25061-1, or the restart cycle of the LM25061-2. See Figure 37.
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