Diodes Incorporated APR34309MPTR-G1

Overview

APR34309MPTR-G1 from Diodes Incorporated is a secondary-side synchronous rectification (SR) controller for DCM-mode flyback converters, integrating output voltage detection for primary-side control coordination. It drives external MOSFETs via DRISR pin with 70 ns turn-on delay, supports 5 V output systems, and eliminates resonant ring interference using volt-second product sensing at the VDET pin.

For engineers reviewing the APR34309MPTR-G1 datasheet, APR34309MPTR-G1 pinout, APR34309MPTR-G1 application, or APR34309MPTR-G1 equivalent, this device is selected for high-efficiency AC/DC adapters requiring precise SR timing, low-component-count auxiliary power supplies, and transient-responsive primary-side feedback coupling in cost-sensitive consumer chargers.

Technical Context

The APR34309MPTR-G1 implements a dynamic oscillator-based SR control architecture that monitors VDET–VCC volt-second product to distinguish valid flyback conduction from parasitic ringing. Its internal trigger voltage (5.25–5.35 V) and discharge circuit (IOVP = 40–100 mA) enable fast OVP response with tOVP_LAST = 2.0 ms.

It operates within –40°C to +85°C ambient, draws only 40–150 µA operating current, and uses AREF resistor programming to set the volt-second threshold (Kqs = 0.325–0.625 mA·µs), ensuring reliable SR activation only during true secondary conduction events.

Key Specifications

Pinout & Package

APR34309MPTR-G1 is housed in a RoHS-compliant, lead-free SOT25 (SC-74A) surface-mount package with 1.3 mm height and 2.82 × 1.50 mm footprint, optimized for compact adapter PCB layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar secondary-side synchronous rectification controller applications.

Compared with APR348 and AP4341, APR34309MPTR-G1 delivers optimal trade-off between ringing immunity (via programmable Kqs), low-IQ operation (40 µA min), and SOT25 footprint-making it the preferred choice for space- and cost-constrained 5 V DCM flyback adapters where new design qualification is required.

Availability

APR34309MPTR-G1 is available at Aetrix Electronics and suitable for USB-C wall adapters, DSL modem power supplies, and wireless phone chargers requiring stable component supply, full RoHS/Green compliance, and IATF 16949 traceability.

Supply support for APR34309MPTR-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-efficiency power management and signal integrity solutions for consumer, industrial, and automotive markets.

The APR343 product line targets cost-sensitive, high-volume AC/DC adapter applications requiring robust synchronous rectification with minimal external components and integrated OVP coordination.

FAQ

What is the minimum VCC voltage required for APR34309MPTR-G1 to initiate synchronous rectification?

The device requires VCC ≥ VS_MIN = 4.5 V to begin integrating the (VDET–VCC)×tONP product and enable SR drive. Below this threshold, the internal comparator disables DRISR output regardless of VDET activity. Startup occurs at VSTARTUP = 2.6–3.4 V, but SR operation remains inactive until VCC exceeds 4.5 V.

How does the AREF resistor prevent false triggering from transformer ringing?

The AREF resistor sets the volt-second threshold (Area2 = Kqs × RAREF) used to distinguish valid flyback conduction (Area1) from parasitic ringing (Area3). When (VDET–VCC)×tONP exceeds Area2, SR activates; otherwise, it remains inhibited. This ensures MOSFET drive only during true secondary current flow, not during resonance decay.

Can APR34309MPTR-G1 be used in continuous conduction mode (CCM) flyback designs?

No. The APR34309MPTR-G1 is explicitly designed for discontinuous conduction mode (DCM) operation, as confirmed by its functional block diagram, timing waveforms, and datasheet description. In CCM, the VDET waveform lacks the distinct zero-current gap required for reliable (VDET–VCC)×tONP detection, leading to erratic SR behavior.

What is the purpose of the VDET pin's dual function as both sense input and dynamic signal output?

VDET serves as the secondary winding voltage sense node for SR timing and also outputs a periodic pulse train when VCC < VTRIGGER. This pulse train provides real-time feedback to the primary-side controller, enabling adaptive duty cycle adjustment and improved transient response-without requiring an optocoupler or auxiliary winding.