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LM63635-Q1 ACTIVE 3.5-V to 32-V, 3.25-A step-down voltage converter with spread spectrum Best-in-Class BLR Performance, Pin-Spacing for High Reliability and Robustness

Product details

Vin (Min) (V) 3.5 Vin (Max) (V) 42 Vout (Min) (V) 1 Vout (Max) (V) 15 Iout (Max) (A) 3.5 Iq (Typ) (uA) 15 Switching frequency (Min) (kHz) 250 EMI features Low parasitic Hotrod packaging, Spread spectrum Switching frequency (Max) (kHz) 500 Features Enable, Forced PWM, Frequency Synchronization, Light Load Efficiency, Over Current Protection, Power Good, Pre-Bias Start-Up, Soft Start Fixed, Spread Spectrum, Synchronous Rectification, Wettable Flanks Package Rating Automotive Regulated outputs (#) 1 Control mode Current Mode Duty cycle (Max) (%) 98
Vin (Min) (V) 3.5 Vin (Max) (V) 42 Vout (Min) (V) 1 Vout (Max) (V) 15 Iout (Max) (A) 3.5 Iq (Typ) (uA) 15 Switching frequency (Min) (kHz) 250 EMI features Low parasitic Hotrod packaging, Spread spectrum Switching frequency (Max) (kHz) 500 Features Enable, Forced PWM, Frequency Synchronization, Light Load Efficiency, Over Current Protection, Power Good, Pre-Bias Start-Up, Soft Start Fixed, Spread Spectrum, Synchronous Rectification, Wettable Flanks Package Rating Automotive Regulated outputs (#) 1 Control mode Current Mode Duty cycle (Max) (%) 98
VQFN-HR (RNL) 22 20 mm² 4 x 5
  • 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 minimized switch node ringing
  • 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)
  • 18-µA IQ_VIN: quiescent current at 3.3 VOUT and no load (typical)
  • Output voltage: 5 V, 3.3 V, and ADJ (1 V to 20 V)
  • ±1.5% reference voltage tolerance
  • Create a custom design using the LMS3655-Q1 with the WEBENCH Power Designer
  • 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 minimized switch node ringing
  • 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)
  • 18-µA IQ_VIN: quiescent current at 3.3 VOUT and no load (typical)
  • Output voltage: 5 V, 3.3 V, and ADJ (1 V to 20 V)
  • ±1.5% reference voltage tolerance
  • Create a custom design using the LMS3655-Q1 with the WEBENCH Power Designer

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 20 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 LMS3655-Q1 to regulate an input of 24 V to an output of 3.3 V at a fixed frequency of 400 kHz while also enabling a continuous load current of 5.5 A. 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.

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.

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 20 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 LMS3655-Q1 to regulate an input of 24 V to an output of 3.3 V at a fixed frequency of 400 kHz while also enabling a continuous load current of 5.5 A. 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.

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.

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Technical documentation

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Type Title Date
* Data sheet LMS3635-Q1 3.5-A, LMS3655-Q1 5.5-A, 36-V Synchronous, 400-kHz Step-Down Converter datasheet (Rev. C) PDF | HTML 01 Aug 2021
Selection guide Buck Converter Quick Reference Guide (Rev. B) 08 Apr 2021
Analog Design Journal Clutter‐free power supplies for RF converters in radar applications (Part 1)  18 Mar 2021
Technical article Optimizing flip-chip IC thermal performance in automotive designs 11 Dec 2019
Technical article Minimize the impact of the MLCC shortage on your power application 29 Mar 2019
EVM User's guide LMS36x5-Q1 EVM User's Guide (Rev. A) 13 Apr 2018
Application note Designing High Performance, Low-EMI, Automotive Power Supplies 30 Sep 2017

Design & development

For additional terms or required resources, click any title below to view the detail page where available.

Evaluation board

LMS3635MQEVM — LMS3635-Q1 3.5A, 5V Synchronous, 400kHz Step-Down Converter Evaluation Module

The LMS3635MQEVM evaluation module (EVM) demonstrates the capabilities of the LMS3635-Q1 automotive integrated buck converter. For optimized EMI performance, the LMS3635-Q1 has Spread Spectrum built in and the  EVM has an EMI filter on the back side that assists with noise reduction. The user (...)
User guide: PDF
Not available on TI.com
Simulation model

LMS36353-Q1 PSpice Transient Model

SNAM212.ZIP (106 KB) - PSpice Model
Simulation model

LMS36353-Q1 Unencrypted PSpice Transient Model

SNAM211.ZIP (8 KB) - PSpice Model
Simulation model

LMS36355-Q1 PSpice Transient Model

SNAM209.ZIP (122 KB) - PSpice Model
Simulation model

LMS36355-Q1 Unencrypted PSpice Transient Model

SNAM210.ZIP (8 KB) - PSpice Model
Simulation model

LMS3635A-Q1 PSpice Transient Model

SNAM208.ZIP (123 KB) - PSpice Model
Simulation model

LMS3635A-Q1 Unencrypted PSpice Transient Model

SNAM207.ZIP (7 KB) - PSpice Model
Simulation tool

PSPICE-FOR-TI — PSpice® for TI design and simulation tool

PSpice® for TI is a design and simulation environment that helps evaluate functionality of analog circuits. This full-featured, design and simulation suite uses an analog analysis engine from Cadence®. Available at no cost, PSpice for TI includes one of the largest model libraries in the (...)
Reference designs

PMP20249 — CISPR 25 Class 4 Rated Design for Dual Automotive USB Charger Reference Design

PMP20249 is an EMI optimized design for dual automotive USB charger system utilizing the LMS3635 and LMS3655 regulator ICs (400kHz fully-integrated synchronous buck for automotive application) and TPS2549 USB switch (TPS2549-Q1 automotive USB charging port controller with integrated power switch (...)
Test report: PDF
Schematic: PDF
Reference designs

TIDA-01057 — Reference Design Maximizing Signal Dynamic Range for True 10 Vpp Differential Input to 20 bit ADC

This reference design is designed for high performance data acquisition(DAQ) systems to improve the dynamic range of 20 bit differential input ADCs. Many DAQ systems require the measurement capability at a wide FSR (Full Scale Range) in order to obtain sufficient signal dynamic range. Many earlier (...)
Design guide: PDF
Schematic: PDF
Reference designs

TIDA-01056 — 20-bit 1MSPS DAQ Reference Design Optimizing Power Supply Efficiency While Minimizing EMI

This reference design for high performance data acquisition (DAQ) systems optimizes power stage in order to reduce power consumption and minimize the effect of EMI from switching regulator by using LMS3635-Q1 buck converter.  This reference designs yields 7.2% efficiency improvement at most (...)
Design guide: PDF
Schematic: PDF
Reference designs

PMP40270 — Dual USB Type-C™ 1.5A DFPs Car Charger Reference Design

PMP40270 is a dual USB type-C DFPs reference design, as a cigar lighter adapter. It has a high effieicny DCDC converter LMS3635  inside, combined with a low cost USB type-C source controller TPS25821 for each port. Full voltage range of a 12V car battery, as well as the transistion voltage up (...)
Test report: PDF
Schematic: PDF
Reference designs

PMP40268 — Automotive USB Type-C™ DFP 5V 3A Charger with Linear Droop Compensation Reference Design

The PMP40268 is a USB Type-C™ DFP car charger reference design which provides 5V 3A for USB Type-C™ device. The design includes a synchronous step-down converter LMS3635, and high integrated USB Type-C™ controller and power switch TPS25810. The design is capable of compensating (...)
Test report: PDF
Schematic: PDF
Reference designs

TIDA-01432 — Automotive Passive Media Hub Reference Design With Charging and Enhanced Data Path Performance

This automotive reference design demonstrates a unique approach for media ports that require data transfers. This design has the capability to support USB 2.0 through a 15-W USB Type-C™ port. Customers can accelerate their media port systems by taking advantage of a complete reference design (...)
Design guide: PDF
Schematic: PDF
Reference designs

PMP20807 — Compact 27W USB Type C Power Delivery Reference Design

The PMP20807 reference design is a USB Type C power delivery solution configurable for 5V or 9V output. This compact reference design has a total solution size of 44mm x 18mm x 7.8mm. The low quiescent current capability of LMS3635A and TPS25740A  minimizes the amount of necessary input (...)
Test report: PDF
Schematic: PDF
Package Pins Download
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