1 Features

? AEC-Q100-qualified for automotive applications:

– Device temperature grade 1: –40°C to +125°C

ambient operating temperature

– Operation up to 150°C junction temperature

? Functional Safety-Capable

– Documentation available to aid functional safety

system design

? Designed for Low EMI

– Symmetrical input voltage pins with > 1 mm

clearance to ground

– Four 22-nF integrated VIN to GND bypass

capacitors

? Two bypass capacitors placed in series

between each VIN and GND for high

reliability

– Pin selectable spread spectrum option

– Pin selectable FPWM or auto mode operation

– Enhanced HotRod? QFN (25) package with

wettable flanks

– Switching frequency from 100 kHz to 2.2 MHz

– Meets CISPR 25 class 5 EMI requirements

? Single and dual-output features

– Wide input voltage range of 3 V to 36 V

– 1 accurate fixed 3.3 V, 5 V or adjustable

outputs from 0.8 V to 20 V

– Hiccup-mode overcurrent protection and

thermal shutdown protection with hysteresis

– Precision ENABLE and PGOOD functions

– 50 ns tON(min) for high VIN / VOUT ratio

– 80 ns tOFF(min) for low dropout

? Versatile dual-output operation

– Shutdown mode current: 0.5-μA typical

– No-load standby current: 9-μA typical

– Built-in compensation and 3-ms soft start

– Independent precision ENABLE and PGOOD

? Adaptable single-output operation

– > 95 efficient for an 8-A load, single output,

VIN =12 V, VOUT = 5 V

– External compensation and adjustable soft start

– PGOOD, SYNCIN, and SYNCOUT functions

2 Applications

? Automotive infotainment and cluster: head unit,

media hub, USB charge, display

? Automotive ADAS and body electronics

? General-purpose dual buck converters

3 Description

The LMQ644xx-Q1 is a 36-V, synchronous, buck

DC/DC converter for high-current single or dual

outputs. The device uses an interleaved, stackable,

current-mode control architecture for easy loop

compensation, fast transient response, excellent load

and line regulation, and accurate current sharing with

an output clock supporting up to 6 phases for currents

up to 36 A. A high-side switch minimum on-time of

50 ns gives large step-down ratios, enabling the direct

conversion from 12 V, 24 V, or automotive inputs to

low-voltage rails for reduced system complexity and

design cost.

The LMQ644xx-Q1 incorporates spread spectrum

in an optimized enhanced HotRod QFN package,

with wettable flanks, and four 22-nF high frequency

integrated capacitors to minimize EMI. Dual Random

Spread Spectrum (DRSS) frequency hopping is set to

±10 (typical), drastically reducing emissions through

a combination of triangular and pseudo-random

modulation. A bias pin allows the LMQ644xx-Q1

to save losses by powering the device from the

output of the converter, achieving a 9-μA no-load

quiescent current to extend the operating run-time

in battery-powered systems. The LMQ644xx-Q1 can

maintain high efficiency light-load operation even

when stacking multiple devices for high efficiency over

the full load range.