MP8760 — 6A, 18V, SYNCHRONOUS STEP-DOWN CONVERTER

MP8760 Rev. 1.1

www.MonolithicPower.com

5

11/4/2013

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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 jitter.

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 BS 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-

ON time. The 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 MP8760 operates from a +2.5V to +5V 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.