Monolithic Power Systems Inc. MP4690GSD-LF-P

Overview

MP4690GSD-LF-P from Monolithic Power Systems is a two-terminal smart bypass IC for LED open-circuit protection, integrating an N-channel MOSFET with 0.22 Ω typical R_DS(ON), 6 V protection threshold, and 7 V clamp voltage. It automatically resets upon LED healing or replacement and delivers <1 µA off-state leakage, enabling reliable operation in automotive headlight and streetlight strings with 1W–2W LEDs.

For engineers reviewing the MP4690GSD-LF-P datasheet, MP4690GSD-LF-P pinout, MP4690GSD-LF-P application, or MP4690GSD-LF-P equivalent, key selection criteria include its SOD123 package thermal resistance (θ_JA = 340 °C/W), 120 ns protection delay, hiccup-mode recovery, and compatibility with PWM-dimming LED drivers requiring crowbar-level open-circuit resilience.

Technical Context

The MP4690 operates as a voltage-sensing shunt: it monitors drain-to-source voltage and triggers conduction when V_DS exceeds 6 V, clamping to 7 V while routing up to 0.7 A through its internal MOSFET. Its 120 ns detection delay and 25 kHz hiccup frequency enable rapid response without disrupting string current continuity.

Thermal performance is defined by SOD123 package constraints: 0.37 W max power dissipation at T_A = 25 °C, junction temperature limit of 150 °C, and θ_JC = 150 °C/W. The device requires no external bias or control signals-only direct parallel connection across individual LEDs.

Key Specifications

Pinout & Package

SOD123 surface-mount package: compact 2.7 mm × 1.6 mm footprint, JEDEC DO-219 compliant, with gull-wing leads and 0.10 mm max lead coplanarity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AP1696TSG-13 and LT3518EDD#TRPBF, MP4690GSD-LF-P uniquely combines automatic reset, ultra-low R_DS(ON), and true two-terminal simplicity-making it the only option that preserves existing LED driver architecture while delivering automotive-grade reliability without firmware or external logic.

Availability

MP4690GSD-LF-P is available at Aetrix Electronics and suitable for automotive headlight modules, municipal streetlight upgrades, and aircraft cabin lighting systems requiring stable component supply, RoHS-compliant packaging, and long-term lifecycle support.

Supply support for MP4690GSD-LF-P 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 MP4690 belongs to MPS's LED Protection & Management product line, engineered specifically for fail-operational solid-state lighting in safety-critical environments where open-circuit resilience cannot be compromised.

FAQ

What is the maximum LED string current the MP4690GSD-LF-P can handle continuously?

The MP4690GSD-LF-P supports up to 0.7 A continuous current per device, validated across its full operating temperature range (−40 °C to +105 °C). At 0.7 A and 25 °C ambient, power dissipation is 108 mW (I² × R_DS(ON)), well within its 0.37 W thermal limit. Derating applies above 25 °C per θ_JA = 340 °C/W.

Does the MP4690GSD-LF-P require external components to function?

No external components are required for basic operation: the MP4690GSD-LF-P functions as a standalone two-terminal device. However, a 3.3 nF ceramic decoupling capacitor is recommended for long PCB traces (>10 mm) to suppress voltage spikes caused by parasitic inductance during open-circuit transients.

Can MP4690GSD-LF-P be used with constant-voltage LED drivers?

No-it is designed exclusively for constant-current LED drivers. In constant-voltage configurations, the MP4690 will not activate reliably because the open-circuit voltage rise needed to exceed its 6 V threshold is not guaranteed. Its operation depends on current-source behavior to generate detectable V_DS across the protected LED.

How does the MP4690GSD-LF-P behave during PWM dimming?

The MP4690GSD-LF-P remains fully transparent during PWM dimming: it neither distorts duty cycle nor introduces timing jitter. Its 120 ns detection window and 25 kHz hiccup frequency operate independently of PWM frequencies up to 1 kHz, preserving consistent brightness control and eliminating visible flicker or color shift.

Is thermal derating required when mounting MP4690GSD-LF-P on a 2-layer PCB?

Yes-θ_JA = 340 °C/W is measured on a 4-layer JEDEC test board. On a standard 2-layer board with minimal copper pour, θ_JA increases to ~450 °C/W. For 0.7 A operation at 85 °C ambient, junction temperature would reach ~135 °C, approaching the 150 °C limit. Use thermal vias and 1 oz copper polygons to mitigate.

What happens if multiple LEDs in a string open simultaneously?

The MP4690GSD-LF-P protects only against single-LED open faults. If two or more LEDs open, the resulting voltage may exceed the 7 V clamp, causing uncontrolled current redistribution or driver shutdown. System-level redundancy (e.g., multiple strings or driver-level OVP) is required for multi-fault tolerance.

Does MP4690GSD-LF-P support reverse-polarity protection?

No-it has no reverse-blocking capability. The internal MOSFET conducts only when V_DS > 6 V in the forward direction. Reverse voltage applied across Drain–Source will forward-bias the body diode, allowing conduction and potentially damaging the device or LED string. External polarity protection is mandatory in bidirectional or miswiring-prone designs.