5V to 3.3V 1.2A DC-DC Converter with 200mS Vout Hold-up Time Circuit Reference Design
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Key Document


The PMP4494 is a 5V to 3.3V 1.2A DC-DC converter with a Vout hold-up circuit. The synchronous buck converter LM20242 is used in the design to provide high efficiency for the system voltage. A boost converter TPS61170 boosts an auxiliary rail from 10V up to 20V to provide the backup voltage. A supply voltage supervisor TLV809 monitors the system voltage and switches the supply to the backup voltage once the system voltage falls below the threshold voltage. Along with the boost circuit, the hold-up capacitance is significantly reduced while still meeting the 200mS hold-up time specification.

  • Main power supply 5V to 3.3V 1.2A output synchronous buck
  • Back-up power supply  boost up from 10Vin to 20V hold-up voltage
  • Minimum 200ms hold-up time for 3.3V
  • Bus voltage monitor and switch
  • Size: 73.5mm x 50mm x 10mm

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(Output Voltage 1)
(Output Voltage 2)
Vin (Min) (V)510
Vin (Max) (V)2010
Vout (Nom) (V)3.320
Iout (Max) (A)1.2.1
Output Power (W)3.962
Input TypeDCDC
TopologyBuck- SynchronousBoost- Integrated Switch

TI Devices (2)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
LM20242  4.5-36V, 2A Current Mode Synchronous Buck Regulator with Adjustable Frequency  Step-down (buck) regulators  Sample & Buy View Design Kits & Evaluation Modules
TPS61170  1.2A Switch, 38V High Voltage Boost Converter in 2x2mm QFN Package  Step-up (boost) regulators  Sample & Buy View Design Kits & Evaluation Modules

CAD/CAE symbols

Part # Package | Pins CAD File (.bxl) STEP Model (.stp)
LM20242 Download Download
TPS61170 Download Download

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Technical documentation

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User guide (1)
Title Type Size (KB) Date
PDF 349 29 Sep 2016
Design files (6)
Title Type Size (KB) Date
ZIP 185 29 Sep 2016
ZIP 26 29 Sep 2016
PDF 255 29 Sep 2016
PDF 66 29 Sep 2016
PDF 190 29 Sep 2016
PDF 143 29 Sep 2016

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