Monolithic Power Systems Inc. MP3385BGR-P

Overview

MP3385BGR-P from Monolithic Power Systems is a 4-string, 80V-output WLED controller IC with I²C interface, peak-current-mode step-up architecture, and four regulated current sinks for LCD backlighting. It operates from 4.5V–33V input, delivers up to 300mA per string with 1.8% current matching, and supports analog/PWM/mixed dimming modes. Used in mid-to-large LCD panels including desktop monitors and all-in-one PCs.

For engineers reviewing the MP3385BGR-P datasheet, MP3385BGR-P pinout, MP3385BGR-P application, or MP3385BGR-P equivalent, key selection criteria include its 80V string rating, I²C-configurable switching frequency (100–900kHz), 10-bit internal dimming resolution, OVP/OCP/OTP protection setpoints, and QFN-20 package thermal performance.

Technical Context

The MP3385BGR-P implements a constant-frequency, peak-current-mode boost controller with four independent current-regulated LED sinks. Its internal 6V LDO powers gate drive and logic, while cycle-by-cycle current limiting (150–500mV threshold) and auto-detection of unused strings during startup prevent OVP faults.

Dimming is fully configurable via I²C: internal 23kHz PWM, analog amplitude control, or mixed mode with programmable transfer points (25% or 50%). Protection includes recoverable thermal shutdown (150°C), latch-off OCP, 18–75.5V OVP (2V/step), and short-string detection via VLEDx monitoring.

Key Specifications

Pinout & Package

The MP3385BGR-P is housed in a thermally enhanced QFN-20 (4mm × 4mm) package with exposed pad tied to PGND for optimal power dissipation (θ_JA = 42°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with RT8547GSP and LM3409QMYX/NOPB, the MP3385BGR-P uniquely integrates 4-string current matching, I²C-configurable protection thresholds, and unused-string auto-detection-making it the only option qualified for mid-to-large LCD backlight systems demanding factory-calibration-free uniformity and debug-friendly startup behavior.

Availability

MP3385BGR-P is available at Aetrix Electronics and suitable for desktop LCD flat-panel displays, all-in-one PCs, and 2D/3D LCD TVs requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP3385BGR-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 power management ICs, with design focus on efficiency, integration, and thermal robustness.

The MP3385BGR-P belongs to MPS's WLED backlight controller product line, engineered specifically for LCD panel manufacturers needing precise multi-string current regulation, programmable protection, and seamless I²C integration into display subsystems.

FAQ

What is the absolute maximum voltage rating per LED string?

The MP3385BGR-P has an absolute maximum rating of +80V on each LEDx pin (LED1–LED4). This allows safe operation with high-forward-voltage LED strings, such as 14× white LEDs at ~5.7V each. Exceeding this voltage risks permanent damage to the internal current-sink transistors and is not recoverable.

How does the unused string auto-detection function work during startup?

At power-on, the MP3385BGR-P monitors VLEDx pin voltages before enabling the boost converter. If any LEDx pin remains below 206mV (indicating an open or disconnected string), that channel is automatically disabled in hardware before VOUT ramps up - preventing OVP triggering and ensuring reliable startup even with partial string configurations.

Can the MP3385BGR-P operate without an external MOSFET?

No. The MP3385BGR-P is a controller-only IC and requires an external N-channel power MOSFET driven by the DRV pin. It does not integrate a power switch. The DRV output is rated for 6V gate drive with 4Ω source / 2Ω sink impedance, necessitating a discrete MOSFET with appropriate R_DS(on) and voltage rating (≥80V).

What is the minimum pulse width supported for external PWM dimming?

The MP3385BGR-P supports external PWM dimming with a minimum pulse width of 2µs. Pulses narrower than this may be ignored or cause inconsistent dimming response due to internal digital filtering and synchronization logic - especially critical for high-frequency dimming in 3D TV applications.

Is the I²C interface compatible with standard 400kHz Fast Mode?

Yes. The MP3385BGR-P supports standard I²C Fast Mode at up to 400kHz, with guaranteed timing parameters including t_HIGH ≥ 0.6µs, t_LOW ≥ 1.3µs, and t_{SU_DAT} ≥ 100ns. The device uses a fixed 7-bit slave address of 0x70 (0b1110000), with R/W bit appended per I²C protocol.

Does the MP3385BGR-P support daisy-chaining multiple devices on one I²C bus?

Yes. Multiple MP3385BGR-P units can share the same I²C bus because each device uses the identical fixed slave address (0x70). To avoid bus contention, users must implement sequential write access - either via software arbitration or hardware isolation (e.g., I²C multiplexer) - since simultaneous register writes to different units are not supported.

What thermal derating applies above 25°C ambient?

With θ_JA = 42°C/W, the MP3385BGR-P's maximum allowable power dissipation decreases linearly above 25°C: PD_MAX = (150°C − T_A) / 42°C/W. At 85°C ambient, maximum continuous power drops to ~1.55W. Layout with full thermal pad soldering and 2oz copper is essential to sustain rated current in enclosed environments.