1 Features

? Functional Safety-Capable

– Documentation available to aid functional safety

system design

? Designed for industrial applications:

– Junction temperature range –40°C to +150°C

– NC pin between critical pins for better reliability

– Best in-class pin FMEA

– Input transient protection up to 42 V

– Wide input voltage range after start-up: 2.7 V

(falling threshold) to 36 V

– Adjustable output up to 95 of VIN, 3.3-V, and

5-V fixed VOUT options available

? Optimized for low EMI requirements:

– Dual random spread spectrum reduces peak

emissions

– Enhanced HotRod? QFN package minimizes

switch node ringing

? Greater than 85 efficiency at 1 mA

? Miniature design size and low component cost:

– 2.6-mm × 2.6-mm enhanced HotRod QFN

package with wettable flanks

– Internal control loop compensation

2 Applications

? Factory automation: PLC, DCS, and PAC

? Test and measurement

? Medical

? Aerospace and defense

3 Description

The LMR664x0 is a small 36-V, 3-A (available in 2-

A and 1-A variants) synchronous step-down DC/DC

converter in an enhanced HotRod QFN package.

This easy-to-use converter supports a wide input

voltage range of 2.7 V to 36 V (after start-up or after

operating) with transients up to 42 V.

The LMR664x0 is specifically designed to meet low

standby power requirements for always-on, industrial

applications. Auto mode enables frequency foldback

when operating at light loads, allowing an unloaded

typical current consumption of 1.5 μA at 13.5 VIN

and high light load efficiency. A seamless transition

between PWM and PFM modes along with very

low MOSFET ON resistances makes sure there is

exceptional efficiency across the entire load range.

The control architecture (peak current mode) and

feature set are optimized for an ultra-small design

size with minimal output capacitance. The device

minimizes input filter size by using dual-random

spread spectrum (DRSS), a low-EMI enhanced

HotRod QFN package, and an optimized pin-out. The

MODE/SYNC and RT pin variants can be used to set

or synchronize the frequency to avoid noise sensitive

frequency bands. There are NC pins between critical

high voltage pins, reducing potential failures (optimal

pin FMEA). The rich feature set of the

LMR664x0 is designed to simplify implementation for

a wide range of industrial end equipment.