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LMR66420
  • LMR66420
  • LMR66420
  • LMR66420

LMR66420

ACTIVE

36V, 2A synchronous step-down converter with 1.5uA IQ and low EMI

Texas Instruments LMR66420 Product Info

1 April 2026 0

Parameters

Rating

Catalog

Topology

Buck

Iout (max) (A)

2

Vin (max) (V)

36

Vin (min) (V)

3

Vout (max) (V)

35

Vout (min) (V)

1

Features

Enable, Fixed Output, Light Load Efficiency, Over Current Protection, Power good, Soft Start Fixed, Spread Spectrum, Synchronous Rectification

Control mode

current mode

Operating temperature range (°C)

-40 to 150

Iq (typ) (A)

0.0000015

Duty cycle (max) (%)

98

TI functional safety category

Functional Safety-Capable

Package

VQFN-FCRLF (RXB)-14-6.76 mm² 2.6 x 2.6

Features

  • Functional Safety-Capable
  • 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
  • Functional Safety-Capable
  • 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

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.

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.

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