3-V to 65-V, 0.3-A ultra-small synchronous buck converter with 6 μA IQ


Product details


Vin (Min) (V) 3 Vin (Max) (V) 65 Vout (Min) (V) 1 Vout (Max) (V) 60 Iout (Max) (A) 0.3 Iq (Typ) (mA) 0.004 Iq (Typ) (uA) 7 Switching frequency (Min) (kHz) 200 Switching frequency (Max) (kHz) 2200 Features Enable, Fixed Output, Forced PWM, Light Load Efficiency, Over Current Protection, Power Good, Pre-Bias Start-Up, Soft Start Fixed, Synchronous Rectification, Wettable Flanks Package Operating temperature range (C) -40 to 150 Rating Catalog open-in-new Find other Buck converters (integrated switch)


  • Designed for rugged industrial applications:
    • Junction temperature range –40°C to +150°C
    • Input transient protection up to 70 V
    • Wide input voltage range: 3.0 V (falling threshold) to 65 V
    • Low EMI and minimized switch node ringing
    • Adjustable, 5-V fixed output voltage options available
  • Suited for scalable industrial power supplies:
    • Pin compatible with LMR36506 (65 V, 600 mA)
    • Adjustable switching frequency: 200 kHz to 2.2 MHz with RT pin variant
  • Minimized solution size and cost:
    • Highest power density with internal compensation and reduced external component count
    • Ultra-small, 2-mm × 2-mm HotRod™ package with wettable flanks
  • High efficiency across load range with low power dissipation:
    • >90% peak efficiency at 1 MHz (5 VOUT adjustable)
  • Ultra-low operating quiescent current at no load
    • 6 µA at 24 VIN to 5 VOUT (fixed output option)

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The LMR36503 is the industry’s smallest 65 V, 0.3 A synchronous step-down DC/DC converter in 2-mm x 2-mm HotRod™ package. This robust and highly reliable converter can handle input voltage transients up to 70 V, provide excellent EMI performance and support fixed 5 V and other adjustable output voltages. The transient tolerance reduces the necessary design effort to protect against input overvoltage and meets the surge immunity requirements of IEC 61000-4-5.

The LMR36503 uses the peak current mode control architecture with internal compensation to maintain stable operation with minimal output capacitance. The LMR36503 with the right resistor selection from the RT pin to ground can be externally programmed to any desired switching frequency of operation over a wide range from 200 kHz to 2.2 MHz. The precision EN/UVLO feature allows precise control of the device during the start-up and shutdown. The power-good flag, with built-in glitch filter and delayed release, offers a true indication of the system status, eliminating the requirement for an external supervisor. The compact solution size and rich feature set of LMR36503 simplifies implementation for a wide range of industrial applications.

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Sample availability

Preproduction samples are available (PLMR36503RFRPET). Request now

Technical documentation

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Type Title Date
* Datasheet LMR36503 3 V–65 V, 0.3-A Ultra-Small Synchronous Buck Converter with Ultra-Low IQ datasheet Dec. 01, 2019
Technical articles Choosing buck converters and LDOs for miniature industrial automation equipment: what to consider Jan. 29, 2020
User guides LMR36503RFEVM User's Guide Apr. 03, 2019
Technical articles Minimize the impact of the MLCC shortage on your power application Mar. 29, 2019

Design & development

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Hardware development

document-generic User guide
The LMR36503 evaluation module (EVM) is a fully assembled and tested circuit for evaluating the LMR36503 synchronous step-down converter.
  • Integrated synchronous rectification
  • Low operating quiescent current
  • High efficiency at light loads
  • Low minimum on-time

Design tools & simulation

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PSPICE-FOR-TI — 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 (...)
  • Leverages Cadence PSpice Technology
  • Preinstalled library with a suite of digital models to enable worst-case timing analysis
  • Dynamic updates ensure you have access to most current device models
  • Optimized for simulation speed without loss of accuracy
  • Supports simultaneous analysis of multiple products
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