MP8762 ― 10A, 18V, SYNCHRONOUS STEP-DOWN CONVERTER

MP8762 Rev. 1.4

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 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 to IN

through a pull-up resistor or a resistive voltage divider for automatic startup.

Do not float this pin. See Enable Control section for more details.

2

2

FREQ

Frequency set during CCM operation. A resistor connected between FREQ

and IN is required to set the switching frequency.

The ON time is

determined by the input voltage and the resistor connected to the FREQ pin.

IN connect through a resistor is used for line feed-forward and makes the

frequency basically constant during input voltage’s variation. An optional

1nF decoupling capacitor can be added to improve any switching frequency

jitter that may be present.

3

3

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.

4

4

SS

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

the switch mode regulator.

5

5

AGND

Analog ground. Select this pin as the control circuit reference point.

6

6

PG

Power good output, the output of this pin is an open drain signal and a pull-

up resistor connected to a DC voltage is required to indicate high if the

output voltage is higher than 91% of the nominal voltage. There is a delay

from FB ≥ 91% to PGOOD goes high.

7

7

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.

8

8

BST

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

form a floating supply across the high-side switch driver.

9,10

15, 16

SW

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

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

Schottky diode fixes the negative voltage. Use wide PCB traces to make the

connection.

11,12

10,11,12,

13

PGND

System Ground. This pin is the reference ground of the regulated output

voltage. For this reason care must be taken in PCB layout. Use wide PCB

traces to make the connection.

13

9, 14

IN

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

regulator. The MP8762 operates from a +2.5V to +5V input rail with 5V

external bias and a +4.5V to +18V input rail with internal bias. An input

capacitor is needed to decouple the input rail. Use wide PCB traces and

multiple vias to make the connection.