MPQ2490

–INDUSTRIALGRADE,1.5A,36V,700kHzSTEP-DOWNWITHPROGRAMMABLEOUTPUTCURRENTLIMIT

MPQ2490 Rev. 1.02

www.MonolithicPower.com

4

7/26/2013

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PIN FUNCTIONS

QFN10

Pin #

Name

Description

1

VIN

to the IC as possible. It is the drain of the internal power device and power supply for

the whole chip.

2

GND

Ground. This pin is the voltage reference for the regulated output voltage. For this

reason care must be taken in its layout. This node should be placed outside of the D1

the part.

3

EN

On/Off Control Input. (Only available for the MPQ2490DQ)

4

FB

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

sets the output voltage. To prevent current limit run away during a short circuit fault

condition the frequency-fold-back comparator lowers the oscillator frequency when the

FB voltage is below 250mV.

5

SS

Connect to an external capacitor used for Soft-Start and compensation for current

limiting loop.

6

ISN

Negative Current Sense Input for load current limiting.

7

ISP

Positive Current Sense

8

PGOOD

Power good signal. When FB is less than 90% of 0.8V, PGOOD is low. It is an open-

drain output. Use a high value pull-up resistor externally to pull it up to system power

supply. (Only available for the MPQ2490DQ)

9

BST

Bootstrap. This capacitor is needed to drive the power switch’s gate above the supply

voltage. It is connected between SW and BST pins to form a floating supply across the

power switch driver. An on-chip regulator is used to charge up the external boot-strap

capacitor. If the on-chip regulator is not strong enough, one optional diode can be

connected from IN or OUT to charge the external boot-strap capacitor.

10

SW

Switch Output. It is the source of power device.