Diodes Incorporated

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AP4312Q (Not Recommended for new design)

NRND = Not Recommended for New Design

Constant Voltage and Constant Current Controller

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AP4312Q is an Automotive Grade product that is AEC-Q100 grade 1 qualified. It is a highly integrated solution for the constant voltage/constant current mode SMPS application and linear DC-DC regulator (used in Automotive application).

The AP4312Q contains one 1.21V voltage reference, one low voltage reference used in current sensing circuit and two operational amplifiers. The 1.21V voltage reference, combined with one operational amplifier, makes of an ideal voltage controller for use in adapters and battery chargers. The low voltage reference, combined with another operational amplifier, makes of an ideal current limiter for output low side current sensing.

The AP4312Q is fully compatible with AP4306 in functionality and electrical characteristics except its lower reference voltage for current control loop, thus higher power efficiency in SMPS applications such as low power charger can be realized with AP4312Q compared to AP4306.


  • Constant Voltage and Constant Current Control
  • Precision Internal Voltage Reference
  • Low External Component Count
  • Easy Compensation
  • Low Supply Current: 180mA
  • Current Control Loop Reference: 70mV
  • Operating Supply Voltage: 1.7V to 18V
  • Totally Lead-free & Fully RoHS Compliant
  • Halogen and Antimony Free. “Green” Device
  • PPAP Capable


  • Adapters
  • Battery Chargers
  • Automotive
  • Power Train
  • Adapters
  • Chargers


Product Specifications

Product Parameters

Constant VoltageReference Tolerance (%) ±0.5
ReferenceVoltage (V) 1.21
SupplyCurrent (mA) 0.18
VCC Maximum Rating 18
VSENSE (mV) 70

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Technical Documents

Recommended Soldering Techniques


Product Change Notices (PCNs)

A PCN may only apply to specific orderable part numbers in this datasheet. Please refer to the corresponding PCN to see the exact orderable part number(s) affected.

PCN # Issue Date Implementation Date Subject
PCN-2481 2020-08-26 2021-02-26 Device End of Life (EOL)