Monolithic Power Systems Inc. MP4689AGN

Overview

MP4689AGN from Monolithic Power Systems is a 100V-input, 1A constant-current LED driver IC with integrated high-side MOSFET (R_DS(ON) = 500 mΩ), hysteresis current-mode control, ±3% LED current accuracy, and 20 kHz PWM dimming capability. It operates in automotive lighting, industrial high-bay fixtures, and 24–95V DC-powered LED arrays where compact size and thermal robustness are critical.

For engineers reviewing the MP4689AGN datasheet, MP4689AGN pinout, MP4689AGN application, or MP4689AGN equivalent, key selection criteria include its 4.5–95V operating input range, 200mV feedback reference voltage, SOIC-8 EP thermal performance (θ_JA = 50°C/W), 170µA quiescent current for battery-backed systems, and dedicated DIM/EN logic-level control inputs.

Technical Context

The MP4689AGN implements adaptive hysteresis current-mode control with dynamically adjusted FB thresholds (185 mV low / 215 mV high) to maintain 200 mV average feedback voltage and ±3% LED current regulation across temperature and line variations. Its internal high-side switch eliminates external gate drivers and supports up to 3.5 A peak current limiting.

Thermal shutdown (150°C trip, 20°C hysteresis), short-circuit protection with 10 µs fault detection, and bootstrap-regulated floating driver (BST UVLO = 2.2 V) ensure fault-tolerant operation in harsh environments. No output capacitor is required due to inherent 15% LED current ripple tolerance.

Key Specifications

Pinout & Package

MP4689AGN is housed in an SOIC-8 package with exposed pad (EP) for enhanced thermal dissipation (θ_JA = 50°C/W, θ_JC = 10°C/W on 4-layer board). The exposed pad must be soldered to a solid GND plane using thermal vias for reliable 2.5 W power handling.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage LED driver applications.

Compared with MPQ4689AGN, the original offers identical performance but lacks AEC-Q100 certification - suitable for industrial lighting but not safety-critical automotive use; versus LM3409HVMM/NOPB, MP4689AGN trades external component flexibility for reduced design cycle time and smaller PCB area.

Availability

MP4689AGN is available at Aetrix Electronics and suitable for automotive headlamps, industrial high-bay fixtures, and smart streetlight nodes requiring stable component supply, long-lifecycle assurance, and RoHS-compliant packaging.

Supply support for MP4689AGN 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 mixed-signal ICs for power management, LED lighting, and motor control, with global manufacturing and quality certifications.

The MP4689A belongs to MPS's high-voltage LED driver product line, engineered specifically for rugged, compact, constant-current lighting solutions in automotive, industrial, and outdoor environments where input transients and thermal stress are dominant design constraints.

FAQ

What is the maximum recommended LED string voltage for MP4689AGN?

The MP4689AGN does not specify a fixed maximum output voltage, but practical limits derive from its 95 V maximum input and typical step-down topology. With a minimum dropout of ~2 V across the internal MOSFET and sense resistor, maximum sustainable LED string voltage is approximately VIN − 2 V. At 95 V input, this yields ~93 V output - sufficient for 25–30 white LEDs in series (3.0–3.5 V each) under nominal conditions.

Can MP4689AGN operate without an external Schottky diode?

No - the MP4689AGN requires an external low-V_F Schottky rectifier connected between SW and GND. This diode provides the freewheeling path for inductor current when the internal high-side MOSFET is off. Omitting it causes catastrophic failure due to unclamped inductive kickback at the SW node, exceeding absolute maximum ratings.

How is thermal performance affected if the exposed pad is not soldered to GND?

Leaving the exposed pad unsoldered degrades θ_JA from 50°C/W to >100°C/W, reducing maximum allowable power dissipation by >50%. At 1 A output and 24 V input, junction temperature may exceed 150°C within seconds, triggering thermal shutdown. Full thermal vias and GND plane connection are mandatory for rated operation.

Does MP4689AGN support analog dimming via the DIM pin?

No - the DIM pin is strictly digital: it accepts only logic-level PWM signals (0 V / 3.3 V or 0 V / 5 V). Analog dimming (voltage-controlled current reduction) is not supported. For analog control, external circuitry (e.g., DAC + comparator) must convert analog voltage to compatible PWM duty cycle before applying to DIM.

What is the minimum inductor value recommended for stable operation at 1 MHz?

Per MPS application guidance, a 47 µH inductor is validated for stable 1 MHz operation at 1 A output with 24 V input. Lower values risk peak current exceeding 3.5 A limit or instability. For 1 MHz, inductance should not fall below 33 µH - verified via Equation (2) in the datasheet - and must sustain ≥1.075 × I_LED peak current without saturation.

Is the FB pin internally clamped, and what happens if R_FB opens?

Yes - the FB pin has internal ESD clamps to ±6 V. If R_FB opens, FB floats near 0 V, causing immediate shutdown after 10 µs (short-circuit protection timeout). The IC attempts automatic recovery every ~300 µs. This behavior prevents uncontrolled current flow and protects downstream LEDs during sense-resistor failure.