LMQ644A0QRXARQ1

LMQ644xx-Q1 is a 36V synchronous buck DC/DC converter capable of delivering high-current single or dual outputs. The device employs an interleaved, stackable current-mode control architecture that enables simple loop compensation, fast transient response, excellent load and line regulation, and precise current sharing, with output clock support for up to six phases (current up to 36A). A 50ns high-side switch minimum on-time enables large step-down ratios, supporting direct conversion from 12V, 24V, or automotive inputs to low-voltage rails, reducing system complexity and design cost. The LMQ644xx-Q1 features an optimized enhanced HotRod QFN package with wettable flanks, adds spread spectrum functionality, and integrates four 22nF high-frequency capacitors to minimize EMI. Dual Random Spread Spectrum (DRSS) frequency hopping is set to ±10% (typical), significantly reducing emissions through a combination of triangular and pseudo-random modulation. The BIAS pin powers the LMQ644xx-Q1 from the converter output, reducing device power dissipation and achieving 9μA no-load quiescent current to extend runtime in battery-powered systems. The LMQ644xx-Q1 maintains high-efficiency light-load operation even when multiple devices are stacked, delivering high efficiency across the full load range.

Applications

• Automotive infotainment systems and instrument clusters: head units, media hubs, USB chargers, displays
• Automotive ADAS and body electronics
• General-purpose dual-channel buck converter

Key features

• AEC-Q100 qualified for automotive applications:
• Device temperature grade 1: -40°C to +125°C ambient operating temperature range
• Operating junction temperature up to 150°C
• Functional Safety (FuSa) capable with documentation available for functional safety system design
• Low EMI:
• Symmetrical input voltage pins with greater than 1mm clearance to GND
• Four integrated 22nF VIN-to-GND bypass capacitors
• High reliability achieved by two series bypass capacitors between each VIN and GND:
• Pin-selectable spread spectrum option
• Pin-selectable FPWM or auto mode operation
• Enhanced HotRod QFN (25) package with wettable flanks
• Switching frequency range: 100kHz to 2.2MHz
• Meets CISPR 25 Class 5 EMI requirements
• Single and dual output capability:
• Wide input voltage range: 3V to 36V
• 1% accuracy, 3.3V/5V fixed or 0.8V to 20V adjustable output voltage
• Discontinuous mode overcurrent protection with hysteresis and thermal shutdown protection
• Precision ENABLE and PGOOD
• 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)
• Integrated compensation and 3ms soft-start
• Independent precision ENABLE and PGOOD
• Adjustable single output operation:
• Efficiency greater than 95% at 8A load, single output, VIN = 12V, VOUT = 5V
• External compensation and adjustable soft-start
• PGOOD, SYNCIN, and SYNCOUT