1 Features

? Functional Safety-Capable

– Documentation available to aid functional safety

system design

? Configured for rugged industrial applications

– 4V to 42V input voltage range

– Input transient protection up to 50V

– 300mA continuous output current

– 80ns minimum switching on time

– Fixed 400kHz and 1.1MHz switching frequency

– –40°C to 150°C junction temperature range

– 96% maximum duty cycle

– Monotonic start-up with prebiased output

– Short-circuit protection with hiccup mode

– Precision enable

– ±1.5% tolerance voltage reference

? Small design size and ease of use

– Integrated synchronous rectification

– Internal compensation for ease of use

– SOT-23 package

? Various options in pin-to-pin compatible package

– PFM and forced PWM (FPWM) options

? Pin-to-pin compatible with the LMR51610,

LMR51406, LMR16006, LV2862, LMR50410,

TPS560430, and LMR54410

? Create a custom design using the LMR51403 with

the WEBENCH Power Designer

2 Applications

? Major appliances

? PLC, DCS, and PAC

? Smart meters

? Power delivery

3 Description

The LMR51403 is a wide-VIN, easy-to-use

synchronous buck converter capable of driving up to

300mA load current. With a wide input range of 4V

to 42V, the device is designed for a wide range of

industrial applications for power conditioning from an

unregulated source.

The LMR51403 operates at 400kHz and 1.1MHz

switching frequency to support use of relatively

small inductors for an optimized design size. The

LMR51403 has a pulse frequency modulation (PFM

version) to realize high efficiency at light load

and forced pulse width modulation (FPWM version)

to achieve constant frequency and small output

voltage ripple over the full load range. Soft-start

and compensation circuits are implemented internally,

which allow the device to be used with minimal

external components.

The device has built-in protection features, such as

cycle-by-cycle current limit, hiccup mode short-circuit

protection, and thermal shutdown in case of excessive

power dissipation.