ISL81601 datasheet(42/54 Pages) RENESAS

42 / 54 page

FN9299 Rev.3.1

Page 42 of 53

May 27, 2021

ISL81601

5. Functional Description

on the upper MOSFET, an action that boosts the 8V gate drive signal above VIN. The current required to drive the

upper MOSFET is drawn from the internal 8V regulator supplied from either VIN or EXTBIAS pin.

The BOOT to PHASE voltage is monitored internally. When the voltage drops to 5.95V at no switching condition,

a minimum off-time pulse is issued to turn off the upper MOSFET and turn on the low-side MOSFET to refresh the

bootstrap capacitor and maintain the upper driver bias voltage.

To optimize EMI performance or reduce phase node ringing, a small resistor can be placed between the BOOT pin

to the positive terminal of the bootstrap capacitor.

Figure 55. Upper Gate Driver Circuit

5.14

Power-Good Indicator

The power-good pin can monitor the status of the output voltage. PGOOD is true (open drain) 1.1ms after the

FB_OUT pin is within ±10% of the reference voltage.

There is no extra delay when the PGOOD pin is pulled LOW.

BOOT

UGATE

PHASE

VDD

VIN

ISL81601

RBOOT

External

Schottky

ISL81601 Datasheet(PDF) 42 Page - Renesas Technology Corp