MP8763 — 12A, 18V, SYNCHRONOUS STEP-DOWN CONVERTER

MP8763 Rev. 1.3

www.MonolithicPower.com

5

6/21/2016

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PIN FUNCTIONS

PIN #

13-Pin

QFN

PIN#

16-Pin

QFN

Name Description

1

1

EN

Enable. Digital input to turn the regulator ON or OFF. Drive EN HIGH to turn on

the regulator. Drive it LOW to turn it off. Connect EN to IN through a pull-up

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

2

2

FREQ

Frequency Set. Requires a resistor connected between FREQ and IN to set the

switching frequency. The input voltage and the resistor connected to the FREQ pin

determine the ON time. The connection to the IN pin provides line feed-forward

and stabilizes the frequency during input voltage variation.

3

3

FB

Feedback. Connect to the tab of an external resistor divider from the output to

GND to set the output voltage. FB is also configured to realize over-voltage

protection (OVP) by monitoring output voltage. Place the resistor divider as close

to FB pin as possible. Avoid using vias on the FB traces.

4

4

SS

Soft-Start. Connect an external capacitor to program the soft start time for the

switch mode regulator.

5

5

AGND Analog ground. The control circuit reference.

6

6

PG

Power Good, the output is an open drain signal. Require a pull-up resistor to a DC

voltage to indicate high if the output voltage exceeds 91% of the nominal voltage.

There is a delay from FB ≥ 91% to PG goes high.

7

7

VCC

Internal 4.8V LDO output. Power the driver and control circuits. 5V external bias

can disable the internal LDO. Decoupling with ≥1µF ceramic capacitor as close to

the pin as possible. Use X7R or X5R dielectric ceramic capacitors for their stable

temperature characteristics.

8

8

BST

Bootstrap. Require a capacitor connected between SW and BST pins to form a

floating supply across the high-side switch driver.

9, 10

15, 16

SW

Switch Output. Connect to the inductor and bootstrap capacitor. The high-side

inductor current drives the SW pin negative during the OFF-time. The low-side

switch’s ON-resistance and the internal Schottky diode clamp the negative

voltage. Connect using wide PCB traces

11, 12

10,11,12,

13

PGND

System Ground. Reference ground of the regulated output voltage. PCB layout

requires extra care. Connect using wide PCB traces.

13

9, 14

IN

Supply Voltage. Supplies power to the internal MOSFET and regulator. The

MP8763 operates from a +2.5V to +18V input rail with 5V external bias and a

+4.5V to +18V input rail with internal bias. Requires an input decoupling capacitor.

Connect using wide PCB traces and multiple vias.