80%

82%

84%

86%

88%

90%

92%

94%

96%

98%

100%

0.001

0.01

0.1

1

10

Output Current (A)

V

V

L1=10µH

PVIN 1

PGND1

CBIAS

VCC

CBOOT

SW

EN

AVIN

FPWM

RESET

LMS3635/55

AGND

3 X 47µF

10µF

470nF

PVIN 2

PGND2

SYNC

FB

NC

VIN

3.5V to 36V

10µF

2.2µF

10µF

0.1µF

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An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. ADVANCE INFORMATION for pre-production products; subject to

change without notice.

LMS3655-Q1, LMS3635-Q1

SNAS701 – SEPTEMBER 2016

LMS3635/55-Q1, 3.5-A /5.5-A, 36-V Synchronous, 400-kHz, Step-Down Converter

1

1 Features

1

•

AEC-Q100 Qualified for Automotive Applications

–

Device Temperature Grade 1: –40°C to

+125°C Ambient Operating Temperature

–

Device HBM Classification Level 2

–

Device CDM Classification Level C6

•

96% Peak Efficiency While Converting 12 V to 5 V

•

Low EMI and Switch Noise

–

Minimized Switch Node Ringing

–

Pseudo-Random Spread Spectrum

•

400-kHz (±10%) Fixed Switching Frequency

•

–40°C to +150°C Junction Temperature Range

•

External Frequency Synchronization

•

RESET Output With Internal Filter and 3-ms

Release Timer

•

Automatic Light Load Mode for Improved

Efficiency

•

Pin-Selectable Forced PWM Mode

•

Built-In Compensation, Soft Start, Current Limit,

Thermal Shutdown, and UVLO

•

0.35-V Dropout With 3.5-A Load at 25°C (Typical)

•

•

3.5-A or 5.5-A Continuous Load Current

•

Output Voltage Options: 5 V, 3.3 V, and ADJ (1 V

to 15 V)

•

±2% Output Voltage Tolerance

•

4-mm × 5-mm, 0.5-mm Pitch SON Package

2 Applications

•

Automotive Systems

•

Industrial Performance

•

In-Dash Instrumentation

•

Battery-Powered Applications

3 Description

The LMS3635-Q1 and LMS3655-Q1 synchronous

buck regulators are optimized for high performance

applications, providing an output voltage of 3.3 V, 5

V, or an adjustable output of 1 V to 15 V. Seamless

transition between PWM and PFM modes, along with

a low quiescent current, ensures high efficiency and

superior transient responses at all loads.

Advanced high-speed circuitry allows the LMS3635-

Q1 and LMS3655-Q1 to regulate an input of 24 V to

an output of 3.3 V at a fixed frequency of 400 kHz.

An innovative frequency foldback architecture allows

this device to regulate a 3.3-V output from an input

voltage of only 3.5 V. The input voltage can range up

to 36 V, with transient tolerance up to 42 V, easing

input surge protection design. The LMS3655-Q1

enables a continuous load current of 5.5 A across the

wide input voltage range.

An open-drain reset output, with built-in filtering and

delay, provides a true indication of system status.

This feature negates the requirement for an additional

supervisory

component,

saving

cost

and

board

space.

Device Information(1)

DEVICE NAME

PACKAGE

BODY SIZE

LMS3635-Q1

SON (22)

4.00 mm × 5.00 mm

LMS3655-Q1

(1) For all available packages, see the orderable addendum at

the end of the data sheet.

Typical Application Circuit