Monolithic Power Systems Inc. MP4690GSD-LF-Z

Overview

MP4690GSD-LF-Z from Monolithic Power Systems is a two-terminal smart bypass IC for open-circuit protection in LED strings, integrating a 0.22Ω N-channel MOSFET with 6V protection threshold, 7V clamp voltage, and 120ns response delay. It operates up to +105°C ambient, supports 0.7A continuous current, and enables automatic reset when an open LED heals or is replaced-used in automotive headlights and streetlights where maintenance access is impractical.

For engineers reviewing the MP4690GSD-LF-Z datasheet, MP4690GSD-LF-Z pinout, MP4690GSD-LF-Z application, or MP4690GSD-LF-Z equivalent, key selection criteria include on-resistance (0.22Ω), off-state leakage (<1µA), thermal resistance (θJA = 340°C/W), SOD123 package compatibility, and hiccup-mode timing behavior under open-LED fault conditions.

Technical Context

The MP4690 monitors drain-to-source voltage across its internal MOSFET; when V_DS exceeds 6V, it triggers conduction to shunt current around an open LED. Its 120ns protection delay and 25kHz hiccup frequency ensure rapid fault response without disrupting adjacent LEDs in the string.

During bypass operation, the device clamps voltage at 7V while maintaining current flow via its low-R_DS(ON) path. The automatic reset function verifies LED continuity every 40–100µs, exiting protection only after confirming the LED has recovered or been replaced.

Key Specifications

Pinout & Package

The MP4690GSD-LF-Z is housed in a SOD123 surface-mount package with gull-wing leads, optimized for high thermal dissipation (θJA = 340°C/W) and compact LED board layouts.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LED open-protection applications.

Compared with MP4690GSD-LF-Z, MP4690GSD-Z lacks RoHS compliance and requires Pb-based reflow, while MP4691GSD-LF-Z trades higher on-resistance and lower voltage thresholds for cost reduction-making the original part optimal for thermally constrained 1W–2W automotive and industrial LED systems.

Availability

MP4690GSD-LF-Z is available at Aetrix Electronics and suitable for automotive LED headlight assemblies, outdoor streetlight strings, aircraft cabin lighting, and industrial machine vision lamps requiring stable component supply and long-term lifecycle support.

Supply support for MP4690GSD-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 across Asia and North America.

The MP4690 belongs to MPS's LED protection product line, engineered specifically for fail-operational reliability in high-reliability lighting systems where open-circuit faults must be mitigated without system-level controller changes.

FAQ

What is the maximum ambient temperature for continuous operation?

The MP4690GSD-LF-Z is rated for continuous operation from –40°C to +105°C ambient temperature. Its 125°C maximum junction temperature and 340°C/W θJA allow safe operation at full 0.7A load in well-ventilated PCB layouts with copper pour under the SOD123 pad.

Does the device require external components to function?

No external components are required for basic open-LED protection. A 3.3nF ceramic decoupling capacitor is recommended only for long PCB traces (>10mm) between the MP4690 and protected LED to suppress voltage spikes caused by parasitic inductance.

How does the MP4690 behave during PWM dimming?

The MP4690 functions transparently during PWM dimming across 100Hz–1kHz frequencies. Its 120ns response time and automatic reset logic ensure no interference with duty-cycle control, preserving color consistency and eliminating flicker artifacts in dimmed LED strings.

Can multiple MP4690 devices be used in series or parallel?

The MP4690 is strictly a two-terminal parallel-connected device and must be placed across individual LEDs-not in series or parallel with other MP4690 units. Series connection would disable voltage-sensing; parallel connection creates unpredictable current sharing and invalidates protection thresholds.

What happens if the LED string voltage exceeds 7V during normal operation?

The MP4690 will not activate unless V_DS exceeds 6V due to an open LED. In normal operation, LED forward voltage (~3V) keeps V_DS below threshold. Sustained >7V across the device indicates either incorrect placement or catastrophic driver failure-not a condition the MP4690 is designed to manage.

Is thermal derating required above 25°C ambient?

Yes. Power dissipation must be derated linearly above +25°C using PD_MAX = (125°C – T_A) / 340°C/W. At +105°C ambient, maximum allowable continuous power drops to 59mW-requiring ≤390mA current to stay within safe junction temperature limits.

Does the device support bidirectional current flow?

No. The MP4690 integrates a unidirectional N-channel MOSFET with Drain and Source pins assigned for anode-to-cathode orientation. Reverse connection prevents proper voltage sensing and disables protection functionality entirely.