MP8765 ─ 24V, HIGH CURRENT SYNCHRONOUS STEP-DOWN CONVERTER

MP8765 Rev. 1.01

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9

2/10/2015

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PIN FUNCTIONS

PIN #

Name

Description

1

VIN

Supply Voltage. The IN pin supplies power for internal MOSFET and regulator. The

MP8765 operate from a +5V to +22V input rail. An input capacitor is needed to

decouple the input rail. Use wide PCB traces and multiple vias to make the

connection.

2

PGND

Power Ground. Use wide PCB traces and multiple vias to make the connection

4

PG

Power good output, the output of this pin is an open drain signal and is high if the

output voltage is higher than 95% of the nominal voltage. There is a delay from FB ≥

95% to PGOOD goes high.

3, 5

NC

6

MODE

PFM/PWM mode selection pin. Float MODE pin or pull it higher than 2V, MP8765

always works in force PWM mode; Connecting MODE pin to ground enables PFM

mode at light load condition.

7

VOUT

VOUT pin is used to sense the output voltage of the Buck regulator, connect this pin

to the output capacitor of the regulator directly.

8,9

Exposed

Pad 15, 16

SW

Switch Output. Connect this pin to the inductor and bootstrap capacitor. This pin is

driven up to the VIN voltage by the high-side switch during the on-time of the PWM

duty cycle. The inductor current drives the SW pin negative during the off-time. The

on-resistance of the low-side switch and the internal diode fixes the negative

voltage. Use wide and short PCB traces to make the connection. Try to minimize the

area of the SW pattern.

10

BST

Bootstrap. A capacitor connected between SW and BS pins is required to form a

floating supply across the high-side switch driver.

11

VCC

Internal 5V LDO output. The driver and control circuits are powered from this

voltage. Decouple with a minimum 1µF ceramic capacitor as close to the pin as

possible. X7R or X5R grade dielectric ceramic capacitors are recommended for their

stable temperature characteristics.

12

FB

Feedback. An external resistor divider from the output to GND, tapped to the FB pin,

sets the output voltage. It is recommended to place the resistor divider as close to

FB pin as possible. Vias should be avoided on the FB traces.

13

EN

Enable pin. EN is a digital input that turns the regulator on or off. Drive EN high to

turn on the regulator, drive it low to turn it off. Connect EN with VIN through a pull-up

resistor or a resistive voltage divider for automatic startup. Do not float this pin.

14

AGND

Analog ground. The internal reference is referred to AGND. Connect the GND of the

FB divider resistor to AGND for better load regulation.