Monolithic Power Systems Inc. MP1531DM-LF-Z

Overview

MP1531DM-LF-Z from Monolithic Power Systems is a triple-output DC/DC converter IC for TFT LCD bias generation, integrating a 250kHz fixed-frequency step-up converter (up to 22V), a ±10mA linear regulator pair (GH up to +38V, GL down to –20V), and internal power-on sequencing. It operates from 2.7V–5.5V input and delivers coordinated VGH/VGL/VMAIN in portable display systems.

For engineers reviewing the MP1531DM-LF-Z datasheet, MP1531DM-LF-Z pinout, MP1531DM-LF-Z application, or MP1531DM-LF-Z equivalent, key selection criteria include its integrated charge-pump–driven linear regulators, 1μA shutdown current, internal soft-start timing control via CT pin, and TSSOP-16 package compatibility with space-constrained display power designs.

Technical Context

The MP1531DM-LF-Z implements current-mode control in its 250kHz step-up converter for fast transient response and stable regulation under dynamic TFT gate drive loads. Its GH and GL linear regulators are powered by external diode-based charge pumps driven from the SW node-positive pump configurable as doubler/tripler/quadrupler, negative pump as inverter-enabling wide output voltage ranges while maintaining tight feedback thresholds (FB3 = 1.25V, FB2 referenced to GND).

Power-on sequencing is fully internal: step-up converter enables first, followed by GL (negative regulator), then GH (positive regulator), each with independent soft-start ramp controlled by a single CT capacitor. Fault detection monitors all three FB inputs; if any falls below 80% of regulation threshold for >6ms (CT = 10nF), RDY goes high-impedance and full shutdown occurs.

Key Specifications

Pinout & Package

MP1531DM-LF-Z is housed in a RoHS-compliant 16-pin TSSOP package (4.4mm × 5.0mm, 1.2mm height) with exposed pad not electrically connected; thermal pad must be soldered to IN2 net for optimal heat dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar TFT LCD bias generator applications.

Compared with MP1531DQ-LF-Z, the MP1531DM-LF-Z trades thermal margin for standard TSSOP manufacturability and legacy compatibility; versus TPS65105RGTR, it delivers true single-chip triple-rail integration with sequencing, fault monitoring, and lower total solution cost.

Availability

MP1531DM-LF-Z is available at Aetrix Electronics and suitable for TFT LCD displays, portable DVD players, tablet PCs, and car navigation displays requiring stable component supply across industrial temperature ranges and long production lifecycles.

Supply support for MP1531DM-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, motor drivers, and display power solutions.

The MP1531 product line targets compact, low-noise TFT LCD bias generation-designed specifically for portable and automotive displays where integration, sequencing, and fault resilience are critical.

FAQ

What is the maximum allowable voltage difference between IN3 and IN2 pins?

The absolute maximum voltage difference between IN3 and IN2 is 60V, as specified in Absolute Maximum Ratings. Exceeding this risks permanent damage to internal circuitry. This limit constrains charge-pump stage selection-for example, using a quadrupler on IN3 with a 2x inverter on IN2 requires VIN < 10V to stay within the 60V differential.

Can the MP1531DM-LF-Z operate without external charge-pump diodes?

No. The MP1531DM-LF-Z requires external Schottky diodes (e.g., BAS40-04-7) to construct the positive and negative charge-pump stages that feed IN3 and IN2. The IC contains no internal diodes for these paths-omitting them prevents GL and GH regulation entirely.

How does the RDY pin behave during normal startup versus fault condition?

During normal startup, RDY remains high-impedance until all three outputs reach >80% of regulation; then it pulls low. During a fault (e.g., open FB2 resistor), RDY goes high-impedance after ~15µs and stays there-if the fault persists >6ms (CT = 10nF), the IC shuts down completely and RDY remains floating until EN or VIN is cycled.

Is the REF pin intended for external use beyond GL regulator feedback?

Yes. While REF is primarily used as the reference for the GL regulator's FB2 feedback string, it is a buffered 1.25V output capable of sourcing/sinking ±100µA. It may serve as a precision reference for external circuits-but loading beyond 200µA degrades regulation accuracy per datasheet load regulation spec (1.2% max).

What is the purpose of the exposed pad on the TSSOP-16 package?

The exposed pad on MP1531DM-LF-Z has no internal electrical connection. It is a thermal pad designed to be soldered to the PCB's IN2 net (–20V plane) to improve heat conduction. Doing so lowers θJA from 90°C/W to ~75°C/W in typical layouts, enhancing thermal reliability under continuous 10mA GL/GH loads.

Does the MP1531DM-LF-Z support adjustable switching frequency?

No. The MP1531DM-LF-Z uses a fixed 250kHz oscillator (±20% tolerance). Frequency cannot be adjusted externally-the CT pin controls soft-start and fault timing only. This simplifies EMI filtering but limits optimization for ultra-low-noise or high-efficiency trade-offs at other frequencies.