Diodes Incorporated APR34309CMPTR-G1

Overview

APR34309CMPTR-G1 from Diodes Incorporated is a secondary-side synchronous rectification (SR) Combo IC integrating an N-channel MOSFET and driver for DCM-mode flyback converters. It features 8 mΩ R_DS(ON) at V_GS = 4.5 V, 20 A continuous drain current, and output voltage detect functionality with 5.15 V internal trigger voltage. It enables high-efficiency 5 V output adapters by replacing Schottky diodes in low-voltage, high-current secondary-side rectification.

For engineers reviewing the APR34309CMPTR-G1 datasheet, APR34309CMPTR-G1 pinout, APR34309CMPTR-G1 application, or APR34309CMPTR-G1 equivalent, key selection criteria include SR timing accuracy (t_DON = 70–130 ns), volt-second product detection via AREF resistor programming, integrated OVP discharge (IOVP = 40–100 mA), and SO-8EP thermal performance (θ_JA = 56 °C/W).

Technical Context

The APR34309C implements a dual-function architecture: a fast-turning SR driver triggered by drain-to-source voltage sensing (V_THOFF = −13 to −5 mV), and a dynamic output voltage monitor that generates periodic pulses at VDET when V_CC < V_TRIGGER (5.15 V typ), then activates OVP discharge above V_DIS = 5.3 V. Its minimum on-time blanking logic uses (V_DET−V_CC)×t_ONP integration to reject primary-side ringing interference.

It operates exclusively in discontinuous conduction mode (DCM) flyback topologies, where SR turn-off timing directly impacts PSR feedback stability. The device's gate drive rise/fall times (t_RG/t_FG = 50–100 ns) and body-diode reverse recovery optimization ensure minimal conduction loss and zero-crossing detection fidelity without external snubbers.

Key Specifications

Pinout & Package

APR34309CMPTR-G1 is housed in an SO-8EP package with exposed drain pad (EP) for thermal and current handling. The 8-pin layout includes three GND pins (6, 7, 8) tied to MOSFET source, and the EP serves as the high-current drain return path. Thermal resistance θ_JC = 12 °C/W confirms direct junction-to-case heat transfer through the exposed pad.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous rectification applications.

Compared with APR34308CMPTR-G1, APR34309CMPTR-G1 adds OVP discharge and lowers R_DS(ON) for better efficiency; versus MP6908AGS-Z, it trades topology flexibility for smaller footprint and lower system-level BOM cost in DCM 5 V adapters.

Availability

APR34309CMPTR-G1 is available at Aetrix Electronics and suitable for USB-C PD adapters, DSL modem power supplies, wireless charging bases, and industrial auxiliary rails requiring stable component supply across production lifecycles.

Supply support for APR34309CMPTR-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 power management, signal integrity, and protection solutions for high-volume consumer and industrial markets.

The APR34309C belongs to Diodes' secondary-side SR controller product line, engineered specifically for high-efficiency, low-component-count DCM flyback converters targeting 5 V output portable and network power applications.

FAQ

What is the purpose of the AREF pin and how is its resistor value determined?

The AREF pin sets the volt-second product threshold for synchronous rectifier activation using an external resistor. Its value is calculated via K_qs × R_AREF = (V_DET−V_CC)×t_ONP, where K_qs ranges from 0.325 to 0.515 mA·μs. Designers select R_AREF to ensure the integrated area exceeds ringing-induced false triggers while remaining below the true flyback conduction event.

How does APR34309CMPTR-G1 handle primary-side ringing interference during DCM operation?

It uses volt-second product detection: the internal integrator only triggers SR turn-on when (V_DET−V_CC)×t_ONP exceeds a threshold set by AREF. Primary-side ringing produces short-duration, low-area voltage spikes well below this threshold, while true secondary conduction yields sustained high-area signals-ensuring immunity without external filters.

Can APR34309CMPTR-G1 be used in continuous conduction mode (CCM) flyback converters?

No. The APR34309C is explicitly designed for discontinuous conduction mode (DCM) operation only. Its timing architecture-including minimum on-time blanking, V_THOFF threshold, and VDET pulsing behavior-relies on the presence of a complete secondary current zero-crossing, which does not occur in CCM. Using it in CCM risks erratic switching and loss of regulation.

What thermal design considerations apply to the SO-8EP package's exposed drain pad?

The exposed drain pad (EP) must be soldered to a ≥1 in² copper pour with ≥2 oz copper thickness to achieve the specified θ_JA = 56 °C/W. Thermal vias (≥6 × 0.3 mm diameter) should connect the EP directly to inner-layer ground planes. The pad layout must follow Diodes' recommended dimensions (X1 = 3.6 mm, Y1 = 2.7 mm) to ensure mechanical reliability and thermal performance under 20 A continuous current.