MP2499– INTEGRATED 100V LOAD DUMP PROTECTION, 2A STEP DOWN REGULATOR

MP2499 Rev. 0.91

www.MonolithicPower.com

4

11/24/2010

MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.

© 2010 MPS. All Rights Reserved.

PIN FUNCTIONS

PIN #

Name

Description

1

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.

2

SS

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

limiting loop.

3

ISP

Positive Current Sense

4

ISN

Negative Current Sense Input for load current limiting.

5

CTR

Control pin. Tie a zener diode from CTR to ground. The zener voltage should equal to

normal output voltage.

6

N/C

No connection

7

IN

Input. Connect input power supply, which may have surge voltage to IN pin.

8

IN

Input. Connect input power supply, which may have surge voltage to IN pin.

9

OUT

Output Pin. Connect to VDD pin.

10

OUT

Output Pin. Connect to VDD pin.

11

N/C

No connection

12

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 bootstrap

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

connected from IN or OUT to charge the external bootstrap capacitor.

13

SW

Switch Output. It is the source of power device.

14

VDD

Supply Voltage Bypass pin. This pin is also the output of the OV protection switch. The

MP2499 operates from a +5V to +36V unregulated input. CIN is needed to prevent large

voltage spikes from appearing at the input. Put CIN as close to the IC as possible. It is

the drain of the internal power device and power supply for the whole chip.

15

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 to

CIN ground path to prevent switching current spikes from inducing voltage noise into the

part.

16

EN

On/Off Control Input.