Universal input reference design for 12-V lead acid battery charger
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Key Document


This reference design takes a Universal AC input (85 VAC - 265 VAC) and converts to a 17.5-V isolated output using a PSR flyback topology. It is then followed by a battery charger circuit, which outputs up to 15 V to a lead acid battery. This is a fast-charge design capable of delivering 12 V @ 2.5 A (30 W) to the battery.

  • Universal input (85 VAC - 265 VAC), which can be used to power up the charger worldwide
  • Conducted EMI testing provided
  • Primary side regulated (PSR) flyback topology provides a cost-effective solution
  • Small form factor to fit any mechanical housing of typical battery chargers

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(Output Voltage 1)
Vin (Min) (V)85
Vin (Max) (V)265
Vout (Nom) (V)12
Iout (Max) (A)2.5
Output Power (W)30
Input TypeAC
TopologyBuck- Synchronous
Flyback- Non Sync

TI Devices (3)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
BQ24725A  1-4 cell Li-ion battery SMBus charge controller with N-Channel power MOSFET selector  Battery management ICs  Sample & Buy View Design Kits & Evaluation Modules
TLV701  150-mA, 24-V, ultra-low-IQ, low-dropout voltage regulator for 3 V and 3.3 V  Power management  Sample & Buy Not Available
UCC28704  Off-line constant-voltage constant-current Flyback controller with primary-side regulation (PSR)<  Offline & isolated DC/DC controllers & converters  Sample & Buy View Design Kits & Evaluation Modules

CAD/CAE symbols

Part # Package | Pins CAD File (.bxl) STEP Model (.stp)
BQ24725A Download Download
TLV701 Download Download
UCC28704 Download Download

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Technical documentation

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User guide (1)
Title Type Size (KB) Date
PDF 3580 13 Mar 2019
Design files (6)
Title Type Size (KB) Date
ZIP 2155 13 Mar 2019
ZIP 2310 13 Mar 2019
PDF 755 13 Mar 2019
PDF 115 13 Mar 2019
PDF 59 13 Mar 2019
PDF 190 13 Mar 2019

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