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LM644A2-Q1

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Automotive, 36V, 12A, low-Iq dual-output synchronous step-down converter with top exposed pad

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Data sheet

LM644A2-Q1

ACTIVE
Data sheet Order now

Product details

Rating Automotive Operating temperature range (°C) -40 to 125 Topology Buck Type Converter Iout (max) (A) 12 Vin (min) (V) 3 Vin (max) (V) 36 Switching frequency (min) (kHz) 400 Switching frequency (max) (kHz) 2.2, 2200 Features Enable, Frequency synchronization, Over Current Protection, Power good, Spread Spectrum, Synchronous Rectification, Wettable flanks package EMI features Low parasitic Hotrod packaging, Spread Spectrum Control mode current mode Vout (min) (V) 0.8 Vout (max) (V) 20 Iq (typ) (µA) 40 Duty cycle (max) (%) 98
Rating Automotive Operating temperature range (°C) -40 to 125 Topology Buck Type Converter Iout (max) (A) 12 Vin (min) (V) 3 Vin (max) (V) 36 Switching frequency (min) (kHz) 400 Switching frequency (max) (kHz) 2.2, 2200 Features Enable, Frequency synchronization, Over Current Protection, Power good, Spread Spectrum, Synchronous Rectification, Wettable flanks package EMI features Low parasitic Hotrod packaging, Spread Spectrum Control mode current mode Vout (min) (V) 0.8 Vout (max) (V) 20 Iq (typ) (µA) 40 Duty cycle (max) (%) 98
WQFN-FCRLF (VBG) 24 20 mm² 5 x 4
  • 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
    • Thermally enhanced package provides exposed top and bottom thermal pads and enables dual-side cooling
  • Functional Safety-Capable
  • Designed for Low EMI
    • Symmetrical input voltage pins with > 1mm clearance to ground
    • Pin selectable spread spectrum option
    • Pin selectable FPWM or auto mode operation
    • Enhanced HotRod™ QFN (25) package with wettable flanks
    • Switching frequency from 100kHz to 2.2MHz
    • Meets CISPR 25 class 5 EMI requirements
  • Single and dual-output features
    • Wide input voltage range of 3V to 36V
    • 1% accurate fixed 3.3V, 5V or adjustable outputs from 0.8V to 20V
    • Hiccup-mode overcurrent protection and thermal shutdown protection with hysteresis
    • Precision ENABLE and PGOOD functions
    • 50ns tON(min) for high VIN / VOUT ratio
    • 80ns tOFF(min) for low dropout
  • Versatile dual-output operation
    • Shutdown mode current: 0.5µA typical
    • No-load standby current: 9µA typical
    • Built-in compensation and 3ms soft start
    • Independent precision ENABLE and PGOOD
  • Adaptable single-output operation
    • > 95% efficient for an 8A load, single output, VIN =12V, VOUT = 5V
    • External compensation and adjustable soft start
    • PGOOD, SYNCIN, and SYNCOUT functions
  • Pin-to-pin Compatible with LMQ644A2-Q1
  • 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
    • Thermally enhanced package provides exposed top and bottom thermal pads and enables dual-side cooling
  • Functional Safety-Capable
  • Designed for Low EMI
    • Symmetrical input voltage pins with > 1mm clearance to ground
    • Pin selectable spread spectrum option
    • Pin selectable FPWM or auto mode operation
    • Enhanced HotRod™ QFN (25) package with wettable flanks
    • Switching frequency from 100kHz to 2.2MHz
    • Meets CISPR 25 class 5 EMI requirements
  • Single and dual-output features
    • Wide input voltage range of 3V to 36V
    • 1% accurate fixed 3.3V, 5V or adjustable outputs from 0.8V to 20V
    • Hiccup-mode overcurrent protection and thermal shutdown protection with hysteresis
    • Precision ENABLE and PGOOD functions
    • 50ns tON(min) for high VIN / VOUT ratio
    • 80ns tOFF(min) for low dropout
  • Versatile dual-output operation
    • Shutdown mode current: 0.5µA typical
    • No-load standby current: 9µA typical
    • Built-in compensation and 3ms soft start
    • Independent precision ENABLE and PGOOD
  • Adaptable single-output operation
    • > 95% efficient for an 8A load, single output, VIN =12V, VOUT = 5V
    • External compensation and adjustable soft start
    • PGOOD, SYNCIN, and SYNCOUT functions
  • Pin-to-pin Compatible with LMQ644A2-Q1

The LM644A2-Q1 is a 36V, 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 36A. A high-side switch minimum on-time of 50ns gives large step-down ratios, enabling the direct conversion from 12V, 24V, or automotive inputs to low-voltage rails for reduced system complexity and design cost.

The LM644A2-Q1 incorporates spread spectrum in an optimized enhanced HotRod QFN package, with wettable flanks, and low inductance input bypass configuration 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 LM644A2-Q1 to save losses by powering the device from the output of the converter, achieving a 9µA no-load quiescent current to extend the operating run-time in battery-powered systems. The LM644A2-Q1 can maintain high efficiency light-load operation even when stacking multiple devices for high efficiency over the full load range.

The LM644A2-Q1 is a 36V, 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 36A. A high-side switch minimum on-time of 50ns gives large step-down ratios, enabling the direct conversion from 12V, 24V, or automotive inputs to low-voltage rails for reduced system complexity and design cost.

The LM644A2-Q1 incorporates spread spectrum in an optimized enhanced HotRod QFN package, with wettable flanks, and low inductance input bypass configuration 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 LM644A2-Q1 to save losses by powering the device from the output of the converter, achieving a 9µA no-load quiescent current to extend the operating run-time in battery-powered systems. The LM644A2-Q1 can maintain high efficiency light-load operation even when stacking multiple devices for high efficiency over the full load range.

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Technical documentation

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* Data sheet LM644A2-Q1 3V to 36V, Low IQ , Dual 6A, Automotive, Buck Converter With Multi-Phase Stackability in a Thermally Enhanced Package for Dual Side Cooling datasheet PDF | HTML 26 Nov 2024
Functional safety information LM644xx-Q1 Functional Safety FIT Rate, FMD and Pin FMA PDF | HTML 19 Nov 2024
Certificate LM644A2QEVM-S2100T EU Declaration of Conformity (DoC) 27 Sep 2024

Design & development

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Evaluation board

LM644A2QEVM-S2100T — LM644A2-Q1 evaluation module

The LM644A2QEVM-S2100T showcases the features and performance of the LM644A2-Q1 dual buck DC/DC converter with integrated power MOSFETs. The evaluation module provides a single 12A output with dual-phase interleaved configuration. The output voltages can be programmed to a fixed 3.3V, 5V or (...)
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WQFN-FCRLF (VBG) 24 Ultra Librarian
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