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The APS39903 is a high accuracy and low cost switching mode
power supply switcher for battery charger/adapter applications. It is
consists of a primary side regulation controller and a high voltage
transistor. The controller regulates the output voltage and current in
the primary side by piece-wise Pulse Frequency Modulation (p-PFM)
in discontinuous conduction mode (DCM). The switcher uses adaptive
source current to optimize driving current to reduce driving loss. The
system operating frequency reduces linearly from heavy load to light
load in each interval of the p-PFM, and enters constant current mode
when the load current is equal to the maximum system output current.
The output voltage and output current limit of APS39903 can be
adjusted based on the patterns of load current aligned to MTK Pump
Express protocol.
The APS39903 provides operating frequency Jitter function from light
to full load range to improve the power supply EMI performance. The
APS39903 also has built-in fixed cable voltage drop compensation
(6% of nominal system output voltage) and adjustable line voltage
The APS39903 can work individually to achieve Ultra-Low standby
power under 5V output.
The APS39903 is packaged in SO-7.


  • Adapters/Chargers


  • Compatible to MediaTek Pump ExpressTM Protocol
  • Ultra-Low Standby Power Consumption
  • Built-in NPN Transistor with 700VCBO
  • Valley-turn On to Reduce Switching Loss and Benefit for EMI
  • Piece-wise Frequency Reduction to Enhance Conversion Efficiency and Suppress Audio Noise
  • ±5% Constant Voltage Accuracy for 5V Output
  • Audio Noise Suppression
  • Open Circuit Protection (OCkP)
  • Current Sense Resistor Short Protection
  • Over Voltage Protection (OVP)
  • Over Temperature Protection (OTP)
  • Short Circuit Protection (SCP) with Hiccup
  • Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
  • Halogen and Antimony Free. “Green” Device (Note 3)

Product Specifications

Product Parameters

Collector DC Current 1.5 A
Startup Current 0.2 µA
Operating Current 500 µA
UVLO Threshold on/off 15.5 V
Power Rating 5 W
Standby Power 75 mW
Cable Compensation Yes

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Orderable Part Number Authorized Distributor Quantity Inventory Date Buy Online Region
APS39903MTR-G1 Digi-Key Electronics 3965 8/8/2020 Buy Now United States