MIC26901 datasheet(19/39 Pages) MICROCHIP

19 / 39 page



2025-2026 Microchip Technology Inc. and its subsidiaries

DS20007047B-page 19

MIC26901

4.6

Power Good (PG)

The Power Good (PG) pin is an open-drain output that

indicates logic-high when the output is nominally 92%

of its steady state voltage. A pull-up resistor of more

than 10 kΩ should be connected from PG to VDD.

4.7

MOSFET Gate Driver

The Functional Block Diagram shows a bootstrap

circuit, consisting of D1 (a Schottky diode is

recommended) and CBST. This circuit supplies energy

to the high-side drive circuit. Capacitor CBST is

charged, while the low-side MOSFET is on, and the

voltage on the SW pin is approximately 0V. When the

high-side MOSFET driver is turned on, energy from

CBST is used to turn the MOSFET on. As the high-side

MOSFET turns on, the voltage on the SW pin increases

to approximately VIN. Diode D1 is reverse-biased and

CBST floats high while continuing to keep the high-side

MOSFET on. The bias current of the high-side driver is

less than 10 mA, so a 0.1 μF to 1 μF is sufficient to hold

the gate voltage with minimal droop for the power

stroke (high-side switching) cycle (i.e. ΔBST = 10 mA x

1.67 μs/0.1 μF = 167 mV). When the low-side

MOSFET is turned back on, CBST is recharged through

D1. A small resistor RG, which is in series with CBST,

can be used to slow down the turn-on time of the

high-side N-channel MOSFET.

The drive voltage is derived from the VDD supply

voltage. The nominal low-side gate drive voltage is VDD

and the nominal high-side gate drive voltage is

approximately VDD – VDIODE, where VDIODE is the

voltage drop across D1. An approximate 30 ns delay

between the high-side and low-side driver transitions is

used to prevent current from simultaneously flowing

unimpeded through both MOSFETs.

MIC26901 Datasheet(PDF) 19 Page - Microchip Technology