Diodes Incorporated AP3108LGSTR-G1

Overview

AP3108LGSTR-G1 from Diodes Incorporated is a current-mode PWM controller for offline AC-DC power supplies, delivering ultra-low standby power (<50 mW), green-mode frequency modulation (22–65 kHz), and integrated high-voltage startup (700 V HV pin). It enables constant-voltage/constant-current (CV/CC) regulation when paired with AP4320 secondary-side controller, supports X-CAP discharge (1.7 mA), and operates across -40°C to +85°C ambient.

For engineers reviewing the AP3108LGSTR-G1 datasheet, AP3108LGSTR-G1 pinout, AP3108LGSTR-G1 application, or AP3108LGSTR-G1 equivalent, key selection criteria include its 65 kHz max switching frequency, 2.5 V internal OCP reference, VCC LDO input range (10–50 V), and SSOP-9 package compatibility with high-density adapter designs.

Technical Context

The AP3108LGSTR-G1 implements current-mode control with built-in slope compensation to ensure stability at duty cycles >50%. Its green-mode operation dynamically reduces switching frequency under light load while clamping minimum frequency at ~22 kHz to suppress audible noise.

It integrates an HV-startup circuit that delivers 0.2 mA typical charge current (ICHARGE-H) at VCC < 6 V and 1.8 mA at VCC > 6 V, plus fault-mode ICHARGE-FAULT of 75 µA. The embedded VCC LDO accepts 10–50 V on VCC_IN and regulates output to 9.8–21 V depending on input, enabling wide-output-voltage adaptability.

Key Specifications

Pinout & Package

AP3108LGSTR-G1 is housed in a lead-free, RoHS-compliant SSOP-9 (Type CJ) package with 0.65 mm pitch and exposed thermal pad. The package supports high-power-density layouts and meets IPC/JEDEC J-STD-020 moisture sensitivity level MSL3.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PWM controller applications.

Compared with ICE2QS03G and OB2263MP, AP3108LGSTR-G1 uniquely combines HV startup, X-CAP discharge, and line-compensated COCP in SSOP-9 - reducing component count by 4 and enabling <25 mW no-load power in compact adapters.

Availability

AP3108LGSTR-G1 is available at Aetrix Electronics and suitable for USB PD adapters, smartphone chargers, LED driver power supplies, and industrial open-frame PSUs requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant manufacturing.

Supply support for AP3108LGSTR-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, headquartered in Plano, Texas, with design centers across Asia and manufacturing facilities in China, Taiwan, and the U.S.

The AP3108L belongs to Diodes' high-efficiency AC-DC controller product line, engineered specifically for ultra-low-standby, green-mode offline power conversion in consumer and industrial adapter applications.

FAQ

What is the purpose of the HV pin on AP3108LGSTR-G1?

The HV pin serves three critical functions: (1) provides high-voltage startup current (1.8 mA typical) to charge VCC without external resistor, (2) detects AC line presence for brown-in/out protection (VBR-IN = 100 V), and (3) enables automatic X-CAP discharge (1.7 mA) when AC is removed. It is rated for 700 V DC and eliminates four external components in typical designs.

How does AP3108LGSTR-G1 achieve constant output current during short-circuit conditions?

It uses primary-side constant OCP (COCP) control, where the product of SENSE and DEM pin voltages is compared to a 2.5 V internal reference. This method maintains fixed output current regardless of input voltage or load transients, limiting peak primary current to safe levels while preserving startup reliability - unlike cycle-by-cycle peak limiting alone.

Can AP3108LGSTR-G1 operate without an auxiliary winding?

No. The VCC_IN pin requires a rectified auxiliary winding supply (10–50 V) to power the internal LDO, which generates the regulated VCC rail. There is no internal charge pump or alternative VCC source; the HV pin only provides startup current until VCC reaches 15.8 V, after which the LDO takes over.

What is the role of the DEM pin in AP3108LGSTR-G1?

The DEM pin samples transformer de-magnetization voltage to detect zero-crossing timing. This enables precise secondary-side OVP (SOVP = 4.0 V) and UVP (SUVP = 0.60 V) protection, as well as accurate primary constant OCP calculation by synchronizing SENSE sampling to the demag event - critical for stable CV/CC regulation in flyback topologies.