MIC38C43 datasheet(10/24 Pages) MICROCHIP

10 / 24 page

MIC38C42/43/44/45

DS20006436B-page 10



2020 - 2022 Microchip Technology Inc. and its subsidiaries

FIGURE 4-1:

500 kHz, 25W, Buck Converter.

4.4

Synchronous Buck Converter

Refer to Figure 4-2. This MIC38C43 synchronous buck

converter uses an MIC5022 half-bridge driver to

alternately drive the PWM switch MOSFET (driven by

GATEH, or high-side output) and a MOSFET which

functions as a synchronous rectifier (driven by the

GATEL, or low-side output).

The low-side MOSFET turns on when the high-side

MOSFET is off, allowing current to return from ground.

Current flows through the low-side MOSFET in the

source to drain direction.

The on-state voltage drop of the low-side MOSFET is

lower than the forward voltage drop of an equivalent

Schottky rectifier. This lower voltage drop results in

higher efficiency.

A sense resistor (5 mΩ) is connected to the driver’s

high-side current sense inputs to provide overcurrent

protection. Refer to the MIC5020, MIC5021, and

MIC5022 data sheets for more information.

FIGURE 4-2:

100 kHz Synchronous Buck Converter.

VOUT

12V, 2A

COM P

ISNS

RT/CT GND

OU T

VDD

VR E F

1000pF

1/2W

31DQ10

L1 48μH

3.3μF

0.1μF

6.19k

1.62k

200pF

16k

0.1μF

MBR030

0.1μF

6.8k

0.22μF

100k

IRF820

0.1μF

4.7μF

68k

17V

1N4001

1N765B

VIN

26V to 80V

CT1

4.7Ω

MIC38C42

0.1μF*

*Locate near MIC38C42 supply pins

MK S2

MIC38C43

0.1μF

300k

4.3k

VOUT

5V, 8A

0.15μF

35μH

1000μF

Low ESR

0.1μF

SQP60N06-15

VDD

VR E F

GND

COM P

OU T

RT/CT

ISNS

4.7nF

10k

6.8k

47k

3.3k

2200

470μF

25V

MIC5022

GAT E H

SH+

GAT E L

SH –

SL+

GND

FL T

VDD

+12V

5mΩ

0.1μF*

MK S2

*Locate near the MIC38C43 supply pins.

SL–

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