MP2498 –INTEGRATED 100V LOAD DUMP PROTECTION, 2A STEP-DOWN REGULATOR

MP2498 Rev. 1.0

www.MonolithicPower.com

7

8/7/2012

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© 2012 MPS. All Rights Reserved.

BLOCK DIAGRAM

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LOGIC

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1.5ms SS

SS

COMP

ISW

VDD

BST

SW

FREQ

AGND

GND

COMP

FB

EN

CTR

VIN

SS

0V8

OVP

REFERENCE

UVLO

INTERNAL

REGULATORS

OSCILLATOR

Figure 1—Functional Block Diagram

OPERATION

The MP2498 is a programmable frequency,

non-synchronous, step-down buck switching

regulator with an integrated high-side high

voltage power MOSFET. A normally on 100V/350

mΩ over-voltage protection device is also

intergrated to protect the buck regulator input

from load dump surge (up to 100V). It provides a

single highly efficient solution with current mode

control for fast loop response and easy

compensation. It features a wide input voltage

range, internal soft-start control and precision

current limiting. Its very low operational quiescent

current makes it suitable for battery powered

applications.

PWM Control Mode

At moderate to high output current, the MP2498

operates in a fixed frequency, peak current

control mode to regulate the output voltage. A

PWM cycle is initiated by the internal clock. The

power MOSFET is turned on and remains on

until its current reaches the value set by the

COMP voltage. When the power switch is off, it

remains off for at least 100ns before the next

cycle starts. If, in one PWM period, the current in

the power MOSFET does not reach the COMP

set current value, the power MOSFET remains

on, saving a turn-off operation.

Pulse Skipping Mode

Under

light

load

condition

the

switching

frequency stretches down zero to reduce the

switching loss and driving loss.

Error Amplifier

The error amplifier compares the FB pin voltage

with the internal reference (REF) and outputs a

current proportional to the difference between the

two. This output current is then used to charge

the external compensation network to form the

COMP voltage, which is used to control the

power MOSFET current.