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Texas Instruments LMQ644xx-Q1 36V Synchronous Buck DC-DC Converters

Texas Instrument LMQ644xx-Q1 36V Synchronous Buck DC-DC Converters are designed for high-current single or dual outputs. The device uses an interleaved, stackable, current-mode control architecture for a fast transient response, easy loop compensation, line regulation, excellent load, and accurate current sharing with an output clock supporting up to six 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 Texas Instruments LMQ644xx-Q1 incorporates spread spectrum in an optimized enhanced HotRod QFN package, with wettable flanks and four 22nF high-frequency integrated capacitors to minimize EMI. Dual Random Spread Spectrum (DRSS) frequency hopping is set to ±10% (typical), drastically reducing emissions through triangular and pseudo-random modulation. A bias pin allows the LMQ644xx-Q1 to save losses by powering the device from the converter’s output, achieving a 9µA no-load quiescent current to extend the operating run-time in battery-powered systems. The LMQ644xx-Q1 can maintain high-efficiency light-load operation even when stacking multiple devices for high efficiency over the full load range.

Features

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
Functional Safety-Capable
- Documentation available to aid functional safety system design
Designed for Low EMI
- Symmetrical input voltage pins with > 1mm clearance to ground
- Four 22nF integrated V_IN to GND bypass capacitors
  - Two bypass capacitors are placed in series between each V_IN and GND for high reliability
- 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 t_ON(min) for a high V_IN/V_OUT ratio
- 80ns t_OFF(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, V_IN =12V, V_OUT = 5V
- External compensation and adjustable soft start
- PGOOD, SYNCIN, and SYNCOUT functions

Applications

Automotive infotainment and cluster: head unit, media hub, USB charge, display

Automotive ADAS and body electronics
General-purpose dual buck converters

Texas Instruments LMQ644xx-Q1 36V Synchronous Buck DC-DC Converters

Features

Applications

Functional Block Diagram

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