MPQ2908 - 48V Buck Converter for Automotive Systems

REFERENCE DESIGN


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Description

New automotive designs are adopting 48V power systems in order to reduce power loss in the vehicle’s cable harnesses and reduce their weight. However, this presents a challenge when trying to comply with EMC regulations. Success is possible through thoughtful component placement and PCB layout, together with techniques like frequency spread-spectrum (FSS).

This reference design showcases a 48V to 12V buck converter, capable of delivering 15A of current and complying with CISPR-25 Class 5 EMC standard.

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  • AEC-Q100 Qualified
  • Wide 4V to 60V Operating Input Range
  • Dual N-Channel MOSFET Driver
  • 0.8V Voltage Reference with ±1.5% Accuracy Over Temperature
  • Low Dropout Operation: Maximum Duty Cycle at 99.5%
  • Programmable Frequency Range: 100kHz - 1000kHz
  • External Sync Clock Range: 100kHz - 1000kHz
  • 180º Out-of-Phase SYNCO Pin
  • Programmable Soft Start (SS)
  • Power Good (PG) Output Voltage Monitor
  • Selectable Cycle-by-Cycle Current Limit
  • Output Over-Voltage Protection (OVP)
  • Over-Current Protection (OCP)
  • Internal LDO with External Power Supply Option
  • Programmable Forced CCM and AAM
  • Available in TSSOP20-EP and QFN-20 (3mmx4mm) Packages
  • Available in a Wettable Flank Package
  • External Frequency Spread-Spectrum modulation (FSS)
  • External Input Over-Voltage Protection (OVP)
  • External Reverse-Polarity Protection (RPP)

1.2 Applications

  • Automotive Power Systems
  • Industrial Systems

1.3 Block Diagram

Buck converter with 48V nominal input, 12V 15A output capability, input EMI filter, RPP and OVP, FSS modulation.

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Figure 1: Block Diagram

1.4 Related Solutions

MPS Integrated Circuit Description
MPQ2908A 4V-60V Input, Current Mode, Synchronous, Step-Down Controller. AEC-Q100 Qualified

Table 1: MPS Solutions

1.5 System Specifications

Parameter Specification
Input voltage range 18VDC to 60VDC
Output voltage 12VDC
Maximum output current 15A (with 12V output)
Switching frequency 430kHz
Board form factor 94mmx78mmx12mm
Peak efficiency 94.2%
12V output ripple 22mVp-p

Table 2: System Specifications

load regulation

Figure 2: Load Regulation

line regulation

Figure 3: Line Regulation

Figure 5: Transient overvoltage test - Figure 6: Cold-crank test