Datasheet

GND
CARD EDGE
CONNECTOR
SENSE
VCC
UVLO
OVLO
VEE
GATE
OUT
PGD
PWR
TIMER
R1
R2
R3
R
IN
LM5067
R
S
C
IN
To
Load
PLUG - IN CARD
V
SYS
Q1
LM5067
SNVS532C –OCTOBER 2007–REVISED MARCH 2013 www.ti.com
• If power dissipation within the LM5067 is high, an exposed copper pad should be provided beneath the
package, and that pad should be connected to exposed copper on the board’s other side with as many vias
as possible. See Thermal Considerations.
Figure 21. Suggested Board Connector Design
Thermal Considerations
The LM5067 should be operated so that its junction temperature does not exceed 125°C. The junction
temperature is equal to:
T
J
= T
A
+ (R
θJA
x P
D
)
where
• T
A
is the ambient temperature
• R
θJA
is the thermal resistance of the LM5067 (17)
P
D
is the power dissipated within the LM5067, calculated from:
P
D
= 13V x I
CC
where
• I
CC
is the current into the VCC pin (the current through the R
IN
resistor). (18)
Values for R
θJA
and R
θJC
are in Electrical Characteristics.
System Considerations
1. Continued proper operation of the LM5067 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 5. The capacitor in
the “Live Backplane” 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 LM5067, resulting in its
destruction.
2. If the load powered via the LM5067 hot swap circuit has inductive characteristics, a diode is required across
the LM5067’s output to provide a recirculating path for the load’s current. Adding the diode prevents possible
damage to the LM5067 as the OUT pin will be taken above ground by the inductive load at shutoff. See
Figure 22.
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