Monolithic Power Systems Inc. MP6902DS-LF-Z

Overview

MP6902DS-LF-Z from Monolithic Power Systems is a fast turn-off intelligent synchronous rectifier controller for flyback converters, replacing Schottky diodes with an external MOSFET to achieve ultra-low forward voltage regulation (70 mV) and 20 ns total turn-off delay. It supports both high-side and low-side rectification in DCM and quasi-resonant topologies, operates from 8 V to 24 V VDD, and delivers up to 1.5 W power savings in notebook adapters.

For engineers reviewing the MP6902DS-LF-Z datasheet, MP6902DS-LF-Z pinout, MP6902DS-LF-Z application, or MP6902DS-LF-Z equivalent, key selection criteria include V_DS regulation accuracy, light-load sleep current (<300 µA), gate drive capability (2 A pull-down), UVLO thresholds (6.0 V rising), and thermal shutdown behavior (150 °C trip).

Technical Context

The MP6902 implements dual-threshold sensing on the VD pin: −70 mV for forward conduction regulation and −30 mV for fast turn-off, with blanking logic preventing false triggering during switching transients. Its internal 15 µA VDD regulator powers circuitry while enabling operation across 8–24 V input range.

Light-load mode is triggered by programmable timing via the LL pin (R_LL = 30–300 kΩ), latching off VG after sustained sub-threshold conduction; exit occurs when body-diode conduction exceeds −250 mV for >T_LL+0.2 µs. The gate driver delivers 14 V high-level output (VDD >17 V) and 0.1 V low-level sink with 1–2 Ω pull-down impedance.

Key Specifications

Pinout & Package

MP6902DS-LF-Z is housed in an SOIC-8 package (JEDEC MS-012 AA), with exposed pad not connected internally. Pin 7 is NC (no connection); all other pins are electrically functional and validated per MPS Rev. 1.14 datasheet.

Key Features

Applications

Equivalent & Alternatives

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

Compared with NCP4306DR2G and AP3410GMT, MP6902DS-LF-Z offers superior timing precision (20 ns turn-off), programmable efficiency optimization (R_LL), and broader topology support (high/low-side, up to 180 V VD), making it optimal for high-efficiency QR adapters and industrial power supplies.

Availability

MP6902DS-LF-Z is available at Aetrix Electronics and suitable for USB-C PD adapters, industrial AC-DC modules, and medical power supplies requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for MP6902DS-LF-Z 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

Monolithic Power Systems (MPS) is a fabless semiconductor company specializing in high-performance analog and power ICs, with design centers in the US, China, and Taiwan, and global manufacturing partnerships.

The MP6902 belongs to MPS's intelligent synchronous rectifier controller product line, engineered specifically to replace Schottky diodes in flyback converters while maximizing efficiency across load ranges - especially critical for energy-constrained and thermally sensitive applications.

FAQ

What is the maximum allowable V_D voltage on the VD pin?

The absolute maximum rating for the VD pin is +180 V relative to VSS. This enables direct connection to the drain of high-voltage secondary MOSFETs in 48 V or higher input flyback systems. Exceeding this voltage risks permanent damage; designers must ensure V_DS spikes (including leakage inductance effects) stay below 180 V × 0.7–0.8 de-rating margin.

How does the MP6902 regulate V_DS to ~70 mV during conduction?

The MP6902 uses a closed-loop comparator that monitors V_DS via the VD pin and dynamically adjusts the VG output voltage to maintain −70 mV across the external MOSFET. When V_DS rises above −70 mV, the driver reduces gate voltage to increase R_DS(on), thereby lowering V_DS; this active regulation occurs continuously during forward conduction.

Can MP6902DS-LF-Z be used in high-side rectification configurations?

Yes - MP6902DS-LF-Z explicitly supports high-side rectification, as confirmed in its datasheet features and Figure 10 application circuit. In high-side mode, VSS connects to the MOSFET source, VD connects to drain, and VG drives the gate. An auxiliary winding or LDO is required for VDD supply since output voltage is not directly accessible.

What is the purpose of the LL pin resistor, and how is its value selected?

The LL pin accepts a resistor (R_LL) to set the light-load timing window: T_LL ≈ R_LL × 100 kΩ × 2.2 µs. For example, a 100 kΩ resistor yields ~220 µs. Selection balances efficiency gain (longer T_LL extends sleep time) against transient response (shorter T_LL enables faster wake-up). Typical values range from 47 kΩ to 220 kΩ.

Does MP6902DS-LF-Z require external components for basic operation?

Yes - minimal external components include: a pull-up resistor on EN (if not driven actively), R_LL on LL pin (even if light-load mode is disabled, a 100 kΩ default is recommended), and a small RC filter (e.g., 100 Ω + 100 pF) on VD for noise immunity. No external bootstrap or gate resistors are needed due to integrated 2 A sink and rail-to-rail drive.

How does thermal shutdown behave, and is hysteresis provided?

Thermal shutdown activates at 150 °C junction temperature, pulling VG low to halt switching. Hysteresis is 30 °C - the device resumes normal operation only after junction temperature falls to 120 °C. This prevents oscillation near the trip point and ensures robust protection during sustained overload or inadequate heatsinking.