Monolithic Power Systems Inc. MP1518DJE-LF-Z

Overview

MP1518DJE-LF-Z from Monolithic Power Systems is a fixed-frequency, current-mode boost LED driver IC designed to drive up to 6 series white LEDs from a 2.5V–6V input (e.g., single-cell Li-ion). It features 1.3MHz switching frequency, 104mV feedback voltage, internal MOSFET, open-load shutdown at 28V, and operates in TSOT23-6 package with top marking F6. Used in compact portable displays requiring high efficiency and low EMI.

For engineers reviewing the MP1518DJE-LF-Z datasheet, MP1518DJE-LF-Z pinout, MP1518DJE-LF-Z application, or MP1518DJE-LF-Z equivalent, key selection criteria include its 104mV FB threshold for precision current regulation, OV pin-based open-circuit protection, soft-start timing (120µs), thermal shutdown at 160°C, and suitability for PWM or analog dimming in space-constrained handheld devices.

Technical Context

The MP1518DJE-LF-Z implements a constant-frequency peak-current-mode boost architecture with an internal 0.5Ω N-channel MOSFET switch. Its control loop regulates LED current via a 104mV reference across an external sense resistor, minimizing power loss and enabling accurate ±5% current setting.

It integrates dedicated protection functions: OV pin monitors output voltage and disables switching above 28V; under-voltage lockout activates below 2.25V (with 92mV hysteresis); thermal shutdown triggers at 160°C; and internal current limiting caps peak switch current at 350mA (duty cycle ≤60%).

Key Specifications

Pinout & Package

MP1518DJE-LF-Z is packaged in a 6-pin TSOT23 (3.0 × 1.7 × 0.95 mm) with exposed pad not connected internally. Pin 1 is bottom-left when reading top marking "F6" left-to-right.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar white LED boost driver applications.

Compared with MP1518DG-LF-Z, the MP1518DJE-LF-Z trades thermal performance for ultra-compact size and lower EMI; versus RT9397BZSP, it delivers higher integration, superior fault protection, and tighter current regulation-critical for portable consumer electronics.

Availability

MP1518DJE-LF-Z is available at Aetrix Electronics and suitable for cell phones, digital still cameras, handheld computers and PDAs requiring stable component supply, RoHS-compliant packaging, and lead-free assembly compatibility.

Supply support for MP1518DJE-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 core expertise in DC/DC conversion, LED drivers, and motor control solutions.

The MP1518 product line targets portable backlighting applications, delivering highly integrated, thermally robust, and EMI-optimized boost drivers for space- and efficiency-constrained handheld devices.

FAQ

What is the purpose of the OV pin on MP1518DJE-LF-Z?

The OV pin monitors the LED string anode voltage and disables the internal switch if it exceeds 28V. This provides open-circuit protection-critical when an LED fails open, preventing uncontrolled output voltage rise that could damage downstream components or violate safety standards.

Can MP1518DJE-LF-Z drive more than 6 white LEDs?

No. The device is rated for up to 6 series white LEDs (typically ~3.2V each), resulting in a maximum output voltage of ~25V. Exceeding this violates the absolute maximum rating of the SW pin (28V) and risks latch-up or permanent damage due to overvoltage stress on the internal MOSFET.

How does the DJE suffix differ from the standard MP1518DJ?

The DJE variant features a deliberately reduced gate drive slew rate compared to MP1518DJ, lowering high-frequency EMI emissions without affecting regulation accuracy or efficiency. It is optimized for applications where EMC compliance is critical, such as FCC/CE-certified handheld devices.

What is the minimum recommended input capacitance for MP1518DJE-LF-Z?

A 1µF X5R/X7R ceramic capacitor placed as close as possible to the IN and GND pins is recommended. This stabilizes the input rail during high di/dt switching events, suppresses high-frequency noise, and prevents voltage droop that could trigger UVLO during peak current demand.

Does MP1518DJE-LF-Z support analog dimming?

Yes. Analog dimming is implemented by injecting a DC control voltage into the FB node through a resistor divider. As the injected current increases, the regulator reduces LED current to maintain 104mV at FB-enabling smooth, flicker-free brightness control without PWM frequency limitations.

Is thermal derating required for TSOT23-6 operation at 85°C ambient?

Yes. With θ_JA = 220°C/W, junction temperature rise at full load (0.57W P_D) is ~125°C above ambient. At 85°C ambient, T_J would exceed 125°C-triggering thermal shutdown. Derate output current or add copper pour to reduce θ_JA to <100°C/W for continuous operation.

What happens if the EN pin is left floating?

The EN pin must never be left floating-it has no internal pull-up/down. An undefined voltage may cause erratic startup, intermittent operation, or unintended shutdown. Always tie EN to VIN for always-on use or to a controlled GPIO; use a 100kΩ pull-down if default-off behavior is needed.