MP1498 – SYNCHRONOUS, STEP-DOWN CONVERTER WITH INTERNAL MOSFETS

MP1498 Rev. 1.01

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8

12/18/2012

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PIN FUNCTIONS

Package

Pin #

Name

Description

1

SS

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

mode regulator.

2

IN

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

MP1498 operates from a +4.5V to +16V input rail. Requires a low-ESR, and low-

inductance capacitor (C1) to decouple the input rail. Place the input capacitor very close

to this pin and connect it with wide PCB traces and multiple vias.

3

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 PWM duty cycle ON time. The

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

ON-resistance and the internal body diode fix the negative voltage. Use wide PCB traces

and multiple vias.

4

GND

System Ground. The regulated output voltage reference ground. Connect to GND with

copper and vias.

5

BST

Bootstrap. Connect a capacitor between SW and BST pins to form a floating supply

across the high-side switch driver.

6

EN/SYNC

Enable. EN=high to enable the MP1498. Apply an external clock to change the switching

7

VCC

Internal 5V LDO Output. Powers the driver and control circuits. Decouple with a 0.1μF-

0.22μF capacitor. Avoid capacitor values that exceed 0.22μF.

8

FB

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

the output voltage. The comparator lowers the oscillator frequency linearly with the FB

voltage. It is recommended to place the resistor divider as close to FB pin as possible.

Avoid placing vias on the FB traces.