LM5149-Q1 Buck Converter Evaluation Module User's Guide

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1 High Density EVM Description

The LM5149-Q1EVM-400 high-density EVM is designed to use a regulated or non-regulated high-voltage input rail ranging from 15 V to 72 V to produce a tightly regulated output voltage of 12 V at load currents up to 8 A. This wide V_IN range DC/DC solution offers outsized voltage rating and operating margin to withstand supply rail voltage transients.

The free-running switching frequency is 400 kHz and is synchronizable to an external clock signal at a higher or lower frequency. The power-train passive components selected for this EVM, including buck inductors and ceramic input and output capacitors, are automotive AEC-Q200 rated and are available from multiple component vendors.

1.1 Typical Applications

High-current automotive electronic systems
ADAS and body electronics
Infotainment systems and instrument clusters
Automotive HEV/EV powertrain systems

1.2 Features and Electrical Performance

Wide input voltage operating range of 15 V to 72 V
1% accurate fixed 12 V, 5 V, 3.3 V, or adjustable output down to 0.8 V
Switching frequency of 400 kHz externally synchronizable up or down by 20%
Full-load efficiency of 95% at V_IN = 48 V
55-µA controller standby current at V_IN = 48 V
Optimized for ultra-low EMI
- Dual-random spread spectrum and active EMI filtering
- Meets CISPR 25 and UNECE Reg 10 EMI standards
Peak current-mode control architecture provides fast line and load transient response
- Integrated slope compensation adaptive with switching frequency
- Forced PWM (FPWM) or pulsed-frequency modulation (PFM) operation
- Optional internal or external loop compensation
Integrated high-side and low-side power MOSFET gate drivers
- 2.2-A and 3.2-A sink and source gate drive current capability
- 13-ns adaptive dead-time control reduces power dissipation and MOSFET temperature rise
Overcurrent protection (OCP) with hiccup mode for sustained overload conditions
SYNCOUT signal 180° out-of-phase with internal clock
Power Good signal with 100-kΩ pullup resistor to VCC
Internal 3-ms soft start
Fully assembled, tested, and proven PCB layout with 83-mm × 43-mm total footprint