Monolithic Power Systems Inc. MP2490DQ-LF-Z

Overview

MP2490DQ-LF-Z from Monolithic Power Systems is a 36V, 1.5A synchronous step-down DC/DC converter with programmable output current limit via ISP/ISN sense inputs, fixed 700kHz switching frequency, and integrated 0.25Ω high-side MOSFET. It operates from 4.5V–36V input, delivers adjustable 0.8V–15V output, and supports automotive cigarette lighter adapters and USB power supplies.

For engineers reviewing the MP2490DQ-LF-Z datasheet, MP2490DQ-LF-Z pinout, MP2490DQ-LF-Z application, or MP2490DQ-LF-Z equivalent, this device offers verified programmable current limiting (100mV threshold), thermal shutdown, cycle-by-cycle overcurrent protection, and QFN10 package compatibility for space-constrained industrial and automotive power designs.

Technical Context

The MP2490DQ-LF-Z implements peak-current-mode control with internal slope compensation and a dedicated load current regulation loop that monitors V_ISP–V_ISN. Its error amplifier integrates FB voltage error against a 0.805V reference, while the current limit comparator activates soft-start pin (SS) pull-down when sensed differential exceeds 100mV.

It features an on-chip bootstrap regulator driving the high-side switch gate, EN-controlled startup (QFN-only), open-drain PGOOD monitoring at 90% of nominal output, and stable operation with low-ESR ceramic output capacitors - all optimized for minimal external component count in 4.5V–36V input systems.

Key Specifications

Pinout & Package

MP2490DQ-LF-Z is housed in a thermally enhanced QFN10 (3mm × 3mm) package with exposed thermal pad soldered to PCB ground plane. Pin 1 is marked by a dot; the exposed pad must be connected to GND for optimal thermal performance and electrical stability.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down converter with programmable current limit applications.

Compared with MP2491DQ-LF-Z, the MP2490DQ-LF-Z trades 0.5A output headroom for lower cost and identical thermal profile in QFN10; versus LM5164QDDARQ1, it provides integrated current-limit functionality but lacks AEC-Q100 certification and ultra-wide input support.

Availability

MP2490DQ-LF-Z is available at Aetrix Electronics and suitable for USB power adapters, automotive cigarette lighter ports, and linear charger power supplies requiring stable component supply across production lifecycles.

Supply support for MP2490DQ-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 mixed-signal ICs for power management, motion control, and interface applications.

The MP2490 belongs to MPS's high-voltage buck converter product line, designed specifically for rugged, compact DC/DC conversion in automotive, industrial, and consumer power systems where input transients and programmable current limiting are critical.

FAQ

What is the minimum recommended input capacitance for MP2490DQ-LF-Z?

A 4.7μF X5R or X7R ceramic capacitor placed adjacent to VIN and GND pins is the minimum recommended value. This value suppresses high-frequency switching noise and limits input surge current. Larger values (e.g., 10μF) improve hold-up during line transients but require careful layout to avoid resonance with parasitic inductance.

Can MP2490DQ-LF-Z operate with inductor DCR current sensing only - no external sense resistor?

Yes. The device supports DCR sensing using the ISP/ISN pins with optional RC network (R_a/C_s) to compensate for inductor thermal drift. The current limit is calculated as I_OUT = 100mV / DCR, making it viable for cost-sensitive designs where precision is secondary to simplicity.

Does the EN pin on MP2490DQ-LF-Z support logic-level interfacing with 3.3V microcontrollers?

Yes. The EN pin has a guaranteed high threshold of 1.8V and low threshold of 0.4V, making it fully compatible with standard 3.3V CMOS outputs. No level-shifting is required, and its bias current is ±2μA - negligible loading on GPIO pins.

How does the PGOOD signal behave during output overvoltage or undervoltage conditions?

PGOOD asserts low only when FB voltage drops below 90% of the 0.805V reference (i.e., <0.725V), indicating output undervoltage. It remains high during overvoltage events unless the FB divider fails open - PGOOD is not an overvoltage protection flag but a regulation monitor.

Is the BST capacitor mandatory, and what type is recommended?

Yes, the BST capacitor is mandatory for high-side gate drive. A 0.1μF X5R/X7R ceramic capacitor rated for ≥16V must be placed between BST and SW pins. Its low ESR and stable capacitance ensure reliable bootstrap charging across temperature and lifetime.

What is the maximum achievable output voltage when input is 16.5V or less?

When VIN ≤ 16.5V, the maximum output voltage is limited to (VIN – 1.5V) due to internal headroom constraints - e.g., at VIN = 12V, VOUT max = 10.5V. This ensures sufficient dropout margin for the internal regulator and gate driver circuits.

How does the current limit loop interact with the main voltage regulation loop during a short-circuit event?

During short-circuit, FB collapses below 250mV, triggering oscillator frequency foldback to 200kHz. Simultaneously, the current limit loop pulls down SS, forcing constant-current mode at the programmed 100mV threshold. This dual-action prevents thermal runaway while maintaining control loop stability.