ADP1972ARUZ-R7 datasheet(13/18 Pages) AD

13 / 18 page

Data Sheet

ADP1972

MAXIMUM DUTY CYCLE

The maximum duty cycle of the ADP1972 can be externally

programmed to any value between 0% and 98% via an external

resistor on the DMAX pin connected from DMAX to ground.

The maximum duty cycle defaults to 98% if DMAX is left

floating, is tied to VREG, or is programmed to a value greater

than 98%.

EXTERNAL FAULT SIGNALING

The ADP1972 is equipped with a FAULT pin that signals the

ADP1972 when an external fault condition occurs. The external

fault signal stops PWM operation of the system to avoid damage to

the application and components. When a voltage less than 1.05

V (typical) is applied to the FAULT pin, the ADP1972 disables.

In this state, the DL and DH PWM drive signals are both driven

low to prevent switching of the system dc-to-dc converter, and

the soft start is reset. When a voltage greater than 1.20 V

(typical) is applied to the FAULT pin, the ADP1972 begins

switching. A voltage ranging from 0 V to 60 V can be applied to

the FAULT pin of the ADP1972.

THERMAL SHUTDOWN (TSD)

The ADP1972 has a TSD protection circuit. The thermal

shutdown triggers and disables switching when the junction

temperature of the ADP1972 reaches 150°C (typical). While in

TSD, the DL and DH signals are driven low and the CSS capacitor

discharges to ground. VREG remains high. When the junction

temperature decreases to 135°C (typical), the ADP1972 restarts

the application control loop.

Rev. B | Page 13 of 18

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