Monolithic Power Systems Inc. MP3388SGR-Z

Overview

MP3388SGR-Z from Monolithic Power Systems is an 8-channel, current-mode step-up white LED driver IC designed for LCD panel backlighting. It delivers up to 55V output from a 4.3V–25V input, regulates each string with ±2.5% matching accuracy, supports selectable 625kHz/1.25MHz switching frequency, and features integrated open/short-LED protection and thermal shutdown. It is used in notebook PCs and tablet displays requiring precise multi-string luminance control.

For engineers reviewing the MP3388SGR-Z datasheet, MP3388SGR-Z pinout, MP3388SGR-Z application, or MP3388SGR-Z equivalent, key selection criteria include its 8-string current-source architecture, 600mV LED regulation voltage, FPWM-programmable dimming frequency (1.2–1.6 kHz), ISET-based current programming (e.g., 20 mA with 60.4 kΩ), and QFN24 (4mm × 4mm) thermal performance with θJA = 42°C/W.

Technical Context

The MP3388SGR-Z implements a fixed-frequency, peak-current-mode boost converter with independent 8-channel current sinks, each driven by an internal open-drain switch and regulated against a 600 mV reference. Its feedback loop uses COMP pin compensation and automatically selects the highest active LEDx voltage to set VOUT.

Dimming is implemented via dual modes: external PWM applied to PWMI (filtered internally to DC at PWMO) or direct DC voltage (0.2–1.2 V) applied to PWMO, both modulated by a triangle waveform generated from FPWM capacitor timing. OVP is set externally via resistor divider on OVP pin with 1.23 V threshold, and fault handling includes 1.6 ms short-string detection and automatic string disable.

Key Specifications

Pinout & Package

MP3388SGR-Z is housed in a thermally enhanced QFN24 package (4 mm × 4 mm, 0.5 mm pitch) with exposed pad connected to GND for low-θJC (9°C/W) thermal performance.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-channel step-up LED driver applications.

Compared with RT9701GSP and ISL97693IRTZ-T7A, MP3388SGR-Z uniquely combines 55 V capability, FPWM-programmable dimming, integrated VFAULT PMOS driver, and 2.5% current matching - making it optimal for high-brightness, thermally constrained, and fault-critical backlight systems.

Availability

MP3388SGR-Z is available at Aetrix Electronics and suitable for notebook PCs, tablet computers, and automotive infotainment displays requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP3388SGR-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 in the US, China, and Taiwan, and global manufacturing partnerships.

The MP3388S product line targets high-efficiency, multi-string LED backlighting for portable and automotive displays, emphasizing thermal robustness, integrated protection, and flexible dimming without external controllers.

FAQ

What is the minimum recommended input voltage for reliable startup?

The MP3388SGR-Z requires VIN ≥ 4.3 V to exit under-voltage lockout (UVLO), with a rising-edge threshold of 3.9 V typical and 200 mV hysteresis. Below 4.3 V, the internal 5 V LDO cannot sustain gate drive, causing erratic enable behavior or failure to initiate soft-start. For VIN < 5.5 V, VCC must be externally supplied or tied to VIN.

How does the MP3388SGR-Z handle an open LED string during operation?

When an LED string opens, the corresponding LEDx pin voltage drops below 175 mV; the IC records that string as open and disables its current sink. The remaining active strings force VOUT regulation, and the boost converter continues operating. If all strings open, the device shuts down the converter and pulls VFAULT low to disconnect input via external PMOS.

Can the FPWM pin be left unconnected?

No - the FPWM pin must be connected to GND through a capacitor (e.g., 2.2 nF) to generate the internal triangle waveform for PWM dimming. An unconnected FPWM pin results in undefined dimming frequency and unstable brightness control, as the DPWM oscillator requires this timing element to function.

What is the purpose of the VFAULT pin and how is it used?

VFAULT is an open-drain driver that controls an external PMOS transistor between VIN and the boost input. During normal startup, it ramps up to turn on the PMOS; during faults (OVP, thermal, UVLO), it pulls low to disconnect input power. This provides fail-safe isolation without requiring additional supervisor ICs.

Is the ISET pin compatible with standard E24 resistor values?

Yes - for common LED currents, standard E24 resistors suffice: 60.4 kΩ yields 20.0 mA, 49.9 kΩ yields 24.2 mA, and 36.5 kΩ yields 33.1 mA, all within ±1% of target using the formula ILED = 1000 × 1.21 V / RSET. No trimming or precision tolerance required for typical backlight applications.

Does the MP3388SGR-Z support synchronization to an external clock?

No - the MP3388SGR-Z has no external clock sync input. Switching frequency is fixed at either 625 kHz or 1.25 MHz, selected solely by the OSC pin state (GND or floating/VCC). Synchronization to system clocks is not supported; EMI reduction must rely on spread-spectrum techniques or layout optimization.

What is the maximum allowable LED string voltage imbalance before triggering short-string protection?

Short-string protection triggers when any LEDx pin voltage exceeds 5.5 V for longer than 1.6 ms (with VOSC = HIGH). This corresponds to a string with significantly fewer LEDs or degraded forward voltage - e.g., a 10-LED string dropping to ≤3 LEDs at typical VF ≈ 3.2 V. The IC disables only the affected string, preserving others.