MP2240 – SYNCHRONOUS STEP-DOWN CONVERTER

MP2240 Rev. 1.1

www.MonolithicPower.com

7

8/20/2013

MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.

© 2013 MPS. All Rights Reserved.

PIN FUNCTIONS

Package

Pin #

Name

Description

1

AAM

Advanced Asynchronous Modulation. Connect the tap of 2 resistor dividers to force the

MP2240 into non-synchronous mode under light loads. Drive AAM pin high (VCC) to force

the MP2240 into CCM.

2

IN

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

MP2240 operates from a +6V 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

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 ON resistance of the low-side switch and

the internal body diode fixes the negative voltage. Connect using wide PCB traces and

multiple vias.

4

GND

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

extra care. For best results, connect to GND with copper and vias.

5

BST

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

supply across the high-side switch driver.

6

SS

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

regulator.

7

VCC

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

0.22μF capacitor. Do not use a capacitor ≥0.22μF.

8

FB

Feedback. Connect to the tap of an external resistor divider from the output to GND to set

the output voltage. The frequency fold-back comparator lowers the oscillator frequency

when the FB voltage is below 400mV to prevent current limit runaway during a short circuit

fault. Place the resistor divider as close to the FB pin as possible. Avoid placing vias on

the FB traces.