Monolithic Power Systems Inc. EV6908-J-00A

Overview

MP6908 from Monolithic Power Systems is a fast turn-off intelligent rectifier IC designed to replace Schottky diodes in high-efficiency flyback converters. It regulates external SR MOSFET forward drop to ~40mV, enables self-powered operation down to 0V output, supports both high-side and low-side configurations without auxiliary winding, and features programmable ringing detection for DCM and quasi-resonant operation - used in USB PD quick chargers and ultra-low-voltage adapters.

For engineers reviewing the MP6908 datasheet, MP6908 pinout, MP6908 application, or MP6908 equivalent, key selection criteria include its 25–55mV forward regulation voltage, ~30ns turn-off delay, 100µA quiescent current, TSOT23-6 package compatibility, and support for CCM/DCM/quasi-resonant topologies without auxiliary bias winding.

Technical Context

The MP6908 implements adaptive gate control using dual threshold detection: a -86mV turn-on threshold with slew-rate–gated activation (programmable via external resistor on SLEW pin), and a -3mV turn-off threshold with 25ns propagation delay. Its internal VDD regulator dynamically selects charging source (HVC or VD) and regulates output at 5V or 9V depending on HVC voltage level.

It integrates blanking timers (1.1µs turn-on, variable turn-off), body-diode conduction prevention logic, and gate drive capable of 3A sink / 0.5A source current. The control loop maintains V_DS ≈ -40mV during conduction by modulating VG, minimizing conduction loss to ~I_OUT × 40mV regardless of MOSFET R_DS(ON).

Key Specifications

Pinout & Package

MP6908 is housed in a space-saving TSOT23-6 package with exposed pad for thermal performance. Pin functions are validated per MPS Rev. 1.2 datasheet and functional block diagram.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP6907 and SRK1001, the MP6908 uniquely combines 0V–150V output support, programmable ringing immunity, and auxiliary-winding–free high-side operation - making it the only option for next-gen USB PD PPS and ultra-wide-range flyback designs requiring sub-40mV regulation precision.

Availability

MP6908 is available at Aetrix Electronics and suitable for USB PD quick chargers, universal-input AC/DC adapters, and low-voltage industrial power supplies requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant sourcing.

Supply support for MP6908 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 MP6908 belongs to MPS's Intelligent Rectifier product line, engineered specifically to eliminate Schottky diodes in flyback converters while enabling auxiliary-winding–free, high-efficiency synchronous rectification across 0V–20V output ranges.

FAQ

What is the minimum output voltage the MP6908 supports in low-side configuration?

The MP6908 supports true 0V output in low-side rectification. Its VDD generation circuit uses VD directly when HVC < 4.7V, regulating VDD at 5V even when V_OUT = 0V. This is confirmed in the "Typical Application" section and Figure 5 of the Rev. 1.2 datasheet, where VDD remains stable with V_OUT = 0V and no auxiliary winding.

How does the MP6908 prevent false turn-on during DCM ringing?

The MP6908 uses a programmable slew-rate detection circuit tied to the SLEW pin. An external resistor (e.g., 400kΩ) sets a time window (~90ns) - if V_DS crosses the -86mV turn-on threshold slower than this rate, the gate remains off. This rejects typical DCM ringing (sub-1V/ns) while allowing valid turn-on events (>2V/ns), as verified in Figures 3 and 4 of the datasheet.

Can the MP6908 be used in high-side rectification without an auxiliary winding?

Yes - the MP6908 supports high-side SR without auxiliary winding via three self-powering methods: (1) HVC connected to VD (Figure 6-A, 9V VDD), (2) HVC connected to secondary ground via fast diode (Figure 6-B, 9V VDD), or (3) HVC shorted to VSS (Figure 7, 5V VDD). All are documented in the "Typical System Implementations" section (pages 10–11).

What is the maximum recommended R_DS(ON) for the external SR MOSFET?

There is no upper limit, but a lower bound is specified: for a given I_OUT, R_DS(ON) should be ≥ 20/I_OUT (mΩ) to ensure >50% conduction period at full load. For example, at 5A output, R_DS(ON) ≥ 4mΩ. This ensures sufficient V_DS swing for reliable regulation near -40mV, per Equation (3) and Figure 8 in the datasheet.

Does the MP6908 require a minimum load to maintain VDD regulation?

No - VDD regulation is maintained across no-load to full-load conditions. The IC draws only 100–130µA quiescent current from VDD, and the internal charge pump dynamically switches between HVC and VD sources. Test waveforms in Figure 6-A and Figure 7 (page 11) confirm stable VDD under no-load and short-circuit conditions.

What is the purpose of the turn-on blanking time?

The 0.75–1.45µs turn-on blanking time prevents accidental turn-off caused by V_DS ringing immediately after gate activation. During this period, the control circuit ignores V_DS transitions below 2–3V, ensuring the MOSFET stays fully on for minimum conduction duration. This is measured and specified in the Electrical Characteristics table (page 3).

Is the MP6908 compatible with logic-level and standard-gate MOSFETs?

Yes - the MP6908's VG output delivers 4.9V high-level drive and 20mV low-level pull-down, compatible with both logic-level (V_GS(th) ≤ 2.5V) and standard (V_GS(th) ≤ 4V) SR MOSFETs. Gate drive strength (0.5A source / 3A sink) ensures fast switching with Q_G up to 50nC, as confirmed in the "Works with Standard and Logic Level SR MOSFETs" feature list.