Diodes Incorporated AP4305KTR-G1

Overview

AP4305KTR-G1 from Diodes Incorporated is a constant voltage/constant current (CV/CC) controller IC for offline SMPS applications, featuring dual 1.21V and 200mV precision internal references (±0.5% and ±3% accuracy), two operational amplifiers, low supply current (0.5mA typ), and SOT26 packaging. It enables primary-side regulated adapters and battery chargers with low-side current sensing and independent voltage/current loop control.

For engineers reviewing the AP4305KTR-G1 datasheet, AP4305KTR-G1 pinout, AP4305KTR-G1 application, or AP4305KTR-G1 equivalent, this device supports precise CV/CC regulation in compact AC-DC power supplies where output stability, thermal robustness (–40°C to +105°C), and minimal external component count are critical selection criteria.

Technical Context

The AP4305 integrates two independent transconductance amplifier loops: one configured as a voltage controller using the 1.21V reference and VCTRL/VOUT pins, and another as a current limiter using the 200mV reference and ICTRL/VSENSE pins. Both loops drive a common open-drain sinking output (VOUT) that interfaces directly with optocoupler feedback in flyback controllers.

Its architecture eliminates need for secondary-side shunt regulators by enabling accurate primary-side regulation via sensed auxiliary winding voltage and current-sense resistor signals. The device operates from 2.5V to 18V VCC and maintains reference stability across temperature (±1.5mV VREF drift over –40°C to +105°C).

Key Specifications

Pinout & Package

AP4305KTR-G1 is housed in a RoHS-compliant, halogen-free SOT26 package (2.82 × 2.65 × 1.1mm), optimized for high-density PCB layouts and automated assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar constant voltage/constant current controller applications.

Compared with NCP1252ADR2G and UCC28740DR, AP4305KTR-G1 offers the lowest component count for basic CV/CC feedback in analog-controlled flyback converters, delivering ±1% voltage and ±3% current regulation with zero external references or op-amps - ideal for cost- and space-constrained adapter and charger designs.

Availability

AP4305KTR-G1 is available at Aetrix Electronics and suitable for USB-C PD adapters, lithium-ion battery chargers, and industrial auxiliary power supplies requiring stable component supply, long-term lifecycle support, and RoHS/Green compliance.

Supply support for AP4305KTR-G1 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability power management, signal integrity, and protection solutions for industrial, computing, and consumer markets.

The AP4305 belongs to Diodes' Constant Voltage/Constant Current Controller product line, designed specifically for primary-side regulation in cost-sensitive, compact AC-DC power supplies where analog simplicity, thermal robustness, and minimal external component count are essential.

FAQ

What is the maximum recommended VCC voltage for AP4305KTR-G1?

The absolute maximum VCC rating is 20V, but the recommended operating range is 2.5V to 18V. Operation above 18V risks accelerated parametric shift and reduced long-term reliability, especially at elevated temperatures. For 19V adapter auxiliary rails, a series resistor or Zener clamp is advised to maintain VCC within specification.

Can AP4305KTR-G1 be used in secondary-side regulation configurations?

No - AP4305KTR-G1 is designed exclusively for primary-side regulation. Its VSENSE and ICTRL inputs expect low-side current sensing and auxiliary winding-derived voltage signals. Secondary-side use would require level-shifting, isolation, and violates its functional architecture; TL431-based solutions remain appropriate for secondary-side feedback.

How does the 200mV current reference improve battery charge accuracy?

The 200mV ±3% reference sets the exact threshold at which the current control loop activates. When placed across a low-value sense resistor (e.g., 50mΩ), it delivers ±3% current limit accuracy (e.g., 4.0A ±0.12A), directly meeting JEITA and IEC 62133 requirements for lithium-ion charge termination without calibration.

Is AP4305KTR-G1 compatible with quasi-resonant (QR) flyback controllers?

Yes - AP4305KTR-G1 interfaces seamlessly with QR controllers (e.g., ON Semi NCP1377, Diodes AP3765) via standard optocoupler feedback. Its 3.5mA/mV VCTRL transconductance and fast loop response ensure stable regulation across QR frequency modulation, with no timing or synchronization constraints.