Diodes Incorporated
SO 8

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AP1538 (Not Recommended for new design)

NRND = Not Recommended for New Design

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AP1538 consists of step-down switching regulator with PWM control. These devices include a reference voltage source, oscillation circuit, error amplifier, internal PMOS. AP1538 provides low-ripple power, high efficiency, and excellent transient characteristics. The PWM control circuit is able to vary the duty ratio linearly from 0 up to 99%. This converter also contains an error amplifier circuit as well as a soft-start circuit that prevents overshoot at startup. An enable function, an over current protect function and a short circuit protect function are built inside, and when OCP or SCP happens, the operation frequency will be reduced from 300KHz to 50KHz. Also, an internal compensation block is built in to minimum external component count. With the addition of an internal P-channel Power MOS, a coil, capacitors, and a diode connected externally, these ICs can function as step-down switching regulators. They serve as ideal power supply units for portable devices when coup°C with the SO-8 and SO-8DEP mini-packages, providing such outstanding features as low current consumption. Since this converter can accommodate an input voltage up to 18V, it is also suitable for the operation via an AC adapter.


  • PC Motherboard
  • LCD Monitor
  • Graphic Card
  • DVD-Video Player
  • Telecom Equipment
  • ADSL Modem
  • Printer and other Peripheral Equipment
  • Microprocessor core supply
  • Product Specifications

    Product Parameters

    Efficiency (%) 92
    Frequency Typ (Hz) 300
    HS RDS(ON) (mΩ) 70
    LS RDS(ON) (mΩ) N/A
    MaximumInput Voltage (V) 18
    MinimumInput Voltage (V) 3.6
    Output Current (mA) 3
    Output Voltage (V) 0.8 to VCC ADJ
    Quiescent Current Typ (mA) N/A
    Shutdown Current Typ (µA) 10
    Type Buck

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