LM25005

42V, 2.5A Step-Down Switching Regulator

General Description

The LM25005 switching regulator features all of the func-

tions necessary to implement an efficient, high voltage buck

regulator using a minimum of external components. This

easy to use regulator includes a 42V, 160m

Ω, N-channel

MOSFET, with an output current capability of 2.5 Amps. The

regulator control method is based upon current mode control

utilizing an emulated current ramp. Current mode control

provides inherent line voltage feed-forward, cycle-by-cycle

current limiting and ease of loop compensation. The use of

an emulated control ramp reduces noise sensitivity of the

pulse-width modulation circuit, allowing reliable control of

very small duty cycles necessary in high input voltage appli-

cations. The operating frequency is programmable from

50kHz to 500kHz. An oscillator synchronization pin allows

multiple LM25005 regulators to self-synchronize or to be

synchronized to an external clock. Additional protection fea-

tures include: current limit, thermal shutdown and remote

shutdown capability. The device is available in a power

enhanced TSSOP-20 package featuring an exposed die

attach pad to aid thermal dissipation.

Features

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Integrated 42V, 160m

Ω N-channel MOSFET

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Ultra-wide input voltage range from 7V to 42V

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Internal bias regulator

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Adjustable output voltage from 1.225V

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1.5% feedback reference accuracy

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Current mode control with emulated inductor current

ramp

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Single resistor oscillator frequency setting

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Oscillator synchronization input

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Programmable soft-start

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Shutdown / Standby input

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Wide bandwidth error amplifier

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Thermal Shutdown

Package

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TSSOP-20EP (Exposed Pad)

Simplified Application Schematic

20170001

February 2006

© 2006 National Semiconductor Corporation

DS201700

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