ADP2442ACPZ-R7 datasheet(18/36 Pages) AD

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ADP2442

Data Sheet

Rev. B | Page 18 of 36

Figure 56. Precision Enable Used as a Programmable UVLO

CURRENT-LIMIT AND SHORT-CIRCUIT PROTECTION

The ADP2442 has a current-limit comparator that compares the

current sensed across the low-side power MOSFET to the

internally set reference current. If the sensed current exceeds the

reference current, the high-side power MOSFET does not turn

on in the next cycle and the low-side power MOSFET stays on until

the inductor current ramps down below the current-limit level.

If the output is overloaded and the peak inductor current exceeds

the preset current limit for more than eight consecutive clock

cycles, the hiccup mode current-limit condition occurs. The

output goes to sleep for 6 ms, during which time the output

discharges, the average power dissipation reduces, and the device

wakes up with a soft start period. If the current-limit condition

is triggered again, the output goes to sleep and wakes up after 6 ms.

Figure 37 shows the current-limit hiccup mode when the output is

shorted to ground.

THERMAL SHUTDOWN

If the ADP2442 junction temperature rises above 150°C, the

thermal shutdown circuit turns off the switching regulator. Extreme

junction temperatures can be the result of high current operation,

poor circuit board design, or high ambient temperature. A 25°C

hysteresis is included so that when a thermal shutdown occurs,

the ADP2442 does not return to normal operation until the

junction temperature drops below 125°C. Soft start is active

upon each restart cycle.

VIN

FREQ AGND COMP

ADP2442

VOUT

VIN

BST

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