Diodes Incorporated AP4305UKTR-G1

Overview

AP4305UKTR-G1 from Diodes Incorporated is a constant voltage/constant current (CV/CC) controller IC for switch-mode power supplies, integrating a 1.21 V ±0.5% voltage reference, 200 mV current-sense reference, two op-amps, and low-side current sensing capability. It operates from 2.5–18 V supply, draws 0.5 mA typical supply current, and supports –40°C to +105°C ambient range in SOT26 package - ideal for USB adapters and Li-ion battery chargers.

For engineers reviewing the AP4305UKTR-G1 datasheet, AP4305UKTR-G1 pinout, AP4305UKTR-G1 application, or AP4305UKTR-G1 equivalent, key selection criteria include dual-loop CV/CC accuracy, low quiescent current, temperature-stable references, and compatibility with primary-side controlled flyback topologies requiring precise output regulation and foldback current limiting.

Technical Context

The AP4305 implements two independent control loops: one voltage loop using the 1.21 V reference and VCTRL input to regulate output voltage via feedback to the primary-side controller; the other current loop uses the 200 mV reference and ICTRL/VSENSE inputs to enforce accurate current limit during charging or overload. Both loops drive a single open-drain VOUT pin that sinks up to 50 mA.

Its transconductance gains - 3.5 mA/mV (Gmv) for voltage control and 7 mA/mV (Gmi) for current control - enable stable compensation with minimal external components. The device requires no external reference or op-amp, reducing BOM count and layout sensitivity while maintaining tight regulation across temperature.

Key Specifications

Pinout & Package

AP4305UKTR-G1 is housed in a 6-pin SOT26 package (2.82 × 2.65 × 1.1 mm), surface-mount, lead-free, RoHS-compliant, with exposed pad not connected internally.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP1252A and UCC28740, the AP4305UKTR-G1 delivers higher CV/CC accuracy through dedicated analog references and independent loop tuning, making it preferable for applications demanding tight regulation without compromising secondary-side observability or flexibility.

Availability

AP4305UKTR-G1 is available at Aetrix Electronics and suitable for USB wall adapters, lithium-ion battery chargers, and industrial SMPS modules requiring stable component supply, long-term lifecycle support, and RoHS/Green compliance.

Supply support for AP4305UKTR-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, energy-efficient solutions for power management, signal integrity, and protection.

The AP4305 belongs to Diodes' AC/DC control IC product line, designed specifically for cost-sensitive, high-volume secondary-side regulation in offline SMPS - emphasizing minimal external components, thermal robustness, and seamless interoperability with leading primary-side controllers.

FAQ

What is the maximum recommended sink current at VOUT?

The AP4305UKTR-G1 specifies a short-circuit output current of 27–50 mA depending on temperature and VCC. At 25°C and VCC = 5 V, the typical sink current is 35 mA. Exceeding 50 mA risks exceeding junction temperature limits or violating absolute maximum ratings; design should ensure VOUT load remains within this range with adequate PCB copper for heat dissipation.

Can AP4305UKTR-G1 operate without an external voltage reference?

Yes. The AP4305UKTR-G1 integrates a precision 1.21 V ±0.5% bandgap reference and a 200 mV current-sense reference, eliminating the need for external references. Its two internal op-amps are configured to compare feedback signals directly against these references, enabling full CV/CC functionality with only passive resistors and capacitors externally.

How does the device handle temperature variation in current regulation?

The 200 mV current-sense reference exhibits ±6 mV drift over –40°C to +105°C (192–208 mV), corresponding to ±3% relative error in current limit setting. This is compensated by selecting R_sense with appropriate tolerance and TCR; typical designs achieve ±1.5% total current accuracy using 0.5% 50 ppm/°C metal-film resistors.

Is AP4305UKTR-G1 compatible with primary-side controllers using optocoupler feedback?

Yes. The open-drain VOUT pin is designed to drive standard PC817-type optocoupler LEDs. With a 1 kΩ series resistor and 5 V VCC, it delivers ~4 mA LED current - well within linear optocoupler CTR range. The device's low propagation delay and high transconductance ensure sub-10 µs response to overcurrent events, maintaining system stability under dynamic load conditions.