Diodes Incorporated ZXGD3105N8TC

Overview

ZXGD3105N8TC from Diodes Incorporated is a synchronous MOSFET controller in SO-8 package designed to replace Schottky diodes in secondary-side rectification. It delivers proportional gate drive with turn-off threshold of −10 mV, supports 100 V drain voltage rating and operates up to 500 kHz in flyback and resonant converters for AC-DC adaptors and telecom power supplies.

For engineers reviewing the ZXGD3105N8TC datasheet, ZXGD3105N8TC pinout, ZXGD3105N8TC application, or ZXGD3105N8TC equivalent, key selection criteria include its −10 mV turn-off threshold, 4.5 V minimum VCC operation, <1 mA quiescent current, 100 V drain rating, and compatibility with CrCM/CCM topologies in isolated DC-DC conversion.

Technical Context

The ZXGD3105N8TC implements a high-voltage detector stage that monitors drain-to-ground voltage to trigger gate drive based on body diode conduction onset. Its proportional gate drive architecture dynamically scales gate voltage (VG) relative to drain voltage (VD), enabling precise zero-current switching and minimizing reverse conduction.

It operates across input supply voltages from 4.5 V to 25 V, supports both critical conduction mode (CrCM) and continuous conduction mode (CCM), and integrates internal bias and reference current sinks (IBIAS = 0.54 mA, IREF = 1.02 mA at default resistor values) to set the −10 mV turn-off threshold.

Key Specifications

Pinout & Package

Package: SO-8, surface-mount, lead-free, RoHS-compliant molded plastic case with matte tin-plated leads (J-STD-020 Level 1 moisture sensitivity).

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP4303DR2G, ZXGD3105N8TC provides superior light-load efficiency via proportional drive and wider V_DRAIN range; versus SiHP4303BD, it offers higher peak gate current, external tuning of threshold and quiescent current, and better EMI resilience through separated sense and drive paths.

Availability

ZXGD3105N8TC is available at Aetrix Electronics and suitable for low-voltage AC-DC adaptors, telecom power supplies, and laptop adaptors requiring stable component supply, long-term lifecycle support, and AEC-Q101 reliability assurance.

Supply support for ZXGD3105N8TC 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, signal integrity, and protection solutions for industrial, computing, and consumer markets.

The ZXGD3105N8TC belongs to Diodes' synchronous rectification controller product line, engineered specifically to replace Schottky diodes in isolated DC-DC converters while delivering measurable efficiency gains across CrCM, CCM, and resonant topologies.

FAQ

What is the purpose of the BIAS and REF pins on the ZXGD3105N8TC?

The BIAS pin sinks a fixed 0.54 mA (typical) to set gate source current and influence turn-on speed, while the REF pin sinks 1.02 mA (typical) to define the −10 mV turn-off threshold and gate sink current. Both require external resistors tied to V_CC, with values selected per Table 1 in the datasheet based on nominal V_CC voltage.

Can the ZXGD3105N8TC be used with 5 V logic-level MOSFETs?

Yes-the ZXGD3105N8TC operates down to 4.5 V V_CC and delivers gate drive voltage proportional to V_DRAIN, reaching ≥5 V at V_DRAIN = −100 mV. Its 1.2 A peak source current ensures fast turn-on of logic-level MOSFETs with gate charge ≤25 nC, verified in 5 V output flyback reference designs.

How does the ZXGD3105N8TC handle drain voltage ringing during MOSFET turn-off?

Drain voltage ringing from primary-side snubber recovery can falsely trigger the ZXGD3105N8TC. The datasheet recommends damping the primary snubber with an R-C network or series resistor (Figure 8), and mandates ≤10 mm PCB trace length between DRAIN pin and MOSFET drain to minimize coupling-verified to prevent spurious turn-on in 350 kHz LLC designs.

Is the ZXGD3105N8TC compatible with continuous conduction mode (CCM) flyback converters?

Yes-its −10 mV turn-off threshold, 500 kHz max frequency, and proportional gate drive are explicitly validated for CCM operation in Section 8.2 of DS35101 Rev. 4-2. In CCM, it maintains MOSFET conduction across the entire secondary current waveform, reducing RMS conduction loss by 32% compared to fixed-threshold controllers under 6 A load conditions.