Datasheet

LM5102
PUSH
PULL
33 - 76V
HI
V
IN
LM5041
V
CC
HD
LD
COMP
V
DD
HB
LO
V
SS
RT1
LI
RT2
HO
HS
+
+
LM5100
HI
V
DD
HB
LO
LI
HO
HS
FEED
BACK
V
OUT
L1
T1
T1
LM5041
www.ti.com SNVS248D –AUGUST 2003–REVISED MARCH 2013
Soft-start and Shutdown
The soft-start feature allows the power converter to gradually reach the initial steady state operating point,
thereby reducing start-up stresses and surges. At power on, a 10uA current is sourced out of the soft-start pin
(SS) to charge an external capacitor. The capacitor voltage will ramp up slowly and will limit the maximum duty
cycle of the buck stage. In the event of a fault as indicated by V
CC
Under-voltage, line Under-voltage or second
level current limit, the output drivers are disabled and the soft-start capacitor is discharged to ground. When the
fault condition is no longer present, a soft-start sequence will begin again and buck stage duty cycle will
gradually increase as the soft-start capacitor is charged. The SS pin also serves as an enable input. The
controller will enter a low power state if the SS pin is forced below the 0.45V threshold.
Thermal Protection
Internal Thermal Shutdown circuitry is provided to protect the integrated circuit in the event that the maximum
junction temperature is exceeded. When activated, typically at 165 degrees Celsius, the controller is forced into a
low-power standby state, disabling the output drivers and the bias regulator. This feature is provided to prevent
catastrophic failures from accidental device overheating.
Typical Application
Figure 13. Simplified Cascaded Half-Bridge
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