CISPR 25 Class 5 Rated Multi-Output Power Supply with Pre-Boost for Automotive Cluster Unit
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The PMP9477 design is a conducted EMI optimized multi-output power supply for automotive cluster units.  The power supply has a pre-boost stage for cold crank and start-stop operation and two buck regulators.  The pre-boost stage features the LM3481 boost controller and will start to operate and regulate a 9.5V output when the input voltage drops below 9.5V.  It makes the design a wide input voltage range of 4.5V to 38V suitable for 12V automotive battery systems.  The design has two buck regulators following the pre-boost to generate 3 output voltages: the first stage buck generates a 5V, 2A output using the LM26003, and the second stage generates two outputs of 2.8V, 2A and 1.8V, 2A using the LM26420 (the max output power is 15W).  The LM26003 is a wide Vin non-synchronous buck regulator, and the LM26420 is a 5V input dual 2A, high frequency synchronous buck regulator.  All three ICs are available in automotive grade versions, qualified in AEC-Q100 Grade 1.  The board layout is optimized for improved conducted EMI performance.  The power inductor in the pre-boost stage is utilized as an input EMI filter, and thus no additional filter components are required.  The board is tested under the automotive EMC standard, CISPR 25, and its conducted emissions are in compliance with the CISPR 25 Class 5 requirements.

  • Conducted EMI optimized PCB layout, no extra filter components needed
  • In compliance with the CISPR 25 Class 5 conducted emissions standard
  • 4.5V to 38V wide Vin range with pre-boost stage
  • LM3481, LM26003 and LM26420 are all available in AEC-Q100 qualified versions
  • Power enable/shutdown configurable via the jumper
  • Circuit board is tested, and the design files and test report are included

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Design Files

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(Output Voltage 1)
(Output Voltage 2)
(Output Voltage 3)
Vin (Min) (V)
Vin (Max) (V)383838
Vout (Nom) (V)2.81.85
Iout (Max) (A)222
Output Power (W)5.63.610
Input TypeDCDCDC
TopologyBuck- Integrated SwitchBuck- Integrated SwitchBuck- Non Sync

TI Devices (3)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
LM26003  3A Switching Regulator with High Efficiency Sleep Mode  Step-down (buck) regulators  Sample & Buy View Design Kits & Evaluation Modules
LM26420  Dual 2 A, high-efficiency synchronous DC/DC converter  Step-down (buck) regulators  Sample & Buy View Design Kits & Evaluation Modules
LM3481  2.97V to 48V High-Efficiency Controller for Boost, SEPIC and Flyback  Step-up (boost) regulators  Sample & Buy View Design Kits & Evaluation Modules

CAD/CAE symbols

Part # Package | Pins CAD File (.bxl) STEP Model (.stp)
LM26003 Download Download
LM26420 Download Download
Download Download
LM3481 Download Download

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Technical documentation

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User guide (1)
Title Type Size (KB) Date
PDF 1383 16 Oct 2014
Design files (4)
Title Type Size (KB) Date
ZIP 211 16 Oct 2014
PDF 1399 16 Oct 2014
PDF 396 16 Oct 2014
PDF 335 16 Oct 2014

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