Monolithic Power Systems Inc. MP2499MGQB-Z

Overview

MP2499MGQB-Z from Monolithic Power Systems is a synchronous step-down DC/DC converter with integrated 85mΩ/55mΩ MOSFETs, 5V–36V input range, 0.8V–VIN×0.97 adjustable output, and built-in output line drop compensation for USB charging applications delivering up to 3A continuous current.

For engineers reviewing the MP2499MGQB-Z datasheet, MP2499MGQB-Z pinout, MP2499MGQB-Z application, or MP2499MGQB-Z equivalent, key selection criteria include its 270kHz default switching frequency, programmable current limit via ISENSE, EN/SYNC synchronization capability (200kHz–2.4MHz), thermal shutdown at 170°C, and QFN-13 package layout constraints for high-current PCB routing.

Technical Context

The MP2499MGQB-Z operates in fixed-frequency peak-current-mode control with internal 0.8V reference and optimized compensation, enabling stable regulation across 0.8V–34.9V output (at VIN=36V, DMAX=97%). Its current-sense architecture supports both cycle-by-cycle OCP and external continuous current limiting via ISENSE pin and RSENSE resistor.

Line drop compensation is implemented by sinking a load-proportional current (4–8μA at 2.4A) into the FB node through an external R1 divider, generating a compensating voltage that offsets trace IR drop-enabling constant load-side voltage in automotive cigarette lighter adapters and USB DCP ports.

Key Specifications

Pinout & Package

MP2499MGQB-Z is housed in a thermally enhanced QFN-13 (2.5mm × 3mm) package with exposed PGND pad for low-impedance thermal and power return path. Pin 1–2 (IN), Pin 9 (SW), and Pins 11–13 (PGND) require wide copper traces; Pin 10 (BST) requires series 20Ω resistor to suppress ringing.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous buck converter applications.

Compared with MP2499MGQB-Z, MP2499AGQB-Z offers extended longevity and tighter regulation, while LM61480RQWR trades line compensation for higher frequency and TI-specific tooling support - making MP2499MGQB-Z uniquely suited for cost-sensitive, cable-drop-critical USB charging where legacy compatibility is required.

Availability

MP2499MGQB-Z is available at Aetrix Electronics and suitable for USB charging ports, automotive accessory adapters, and industrial USB hub power supplies requiring stable component supply with full traceability and long-term sourcing assurance.

Supply support for MP2499MGQB-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 LED lighting controllers.

The MP2499M product line targets cost-effective, high-efficiency buck conversion for consumer and automotive USB power delivery, emphasizing integration, thermal robustness, and application-specific features like line drop compensation.

FAQ

What does "NOT RECOMMENDED FOR NEW DESIGNS" mean for MP2499MGQB-Z?

This designation indicates MPS has superseded the MP2499M with the MP2499A, which features improved specifications including tighter feedback voltage tolerance (±1% vs. ±1.5%), enhanced thermal performance, and updated UVLO thresholds. MP2499MGQB-Z remains fully functional and supported for existing designs, but new projects should use MP2499AGQB-Z to ensure long-term availability and access to latest errata and application guidance.

How is output line drop compensation implemented and configured?

Line drop compensation is achieved by sinking a load-proportional current (ISINK = ILOAD × RSENSE / 16.5kΩ) into the FB pin via the external R1 feedback resistor. With RSENSE = 40mΩ and R1 = 82.5kΩ, a 2.4A load generates ~384mV compensation voltage, raising the regulated output to offset cable IR drop. The compensation current range is 4–8μA per 2.4A, confirmed in electrical characteristics tables.

Can MP2499MGQB-Z synchronize to an external clock, and what are the timing requirements?

Yes - the EN/SYNC pin accepts an external clock signal from 200kHz to 2.4MHz to synchronize switching edges. The external clock must have a pulse width under 3μs and be referenced to AGND. Internal synchronization locks to the rising edge of the external clock, enabling EMI reduction in multi-converter systems and avoiding beat frequencies in noise-sensitive applications.

What is the purpose of the NC pin (Pin 3), and how should it be handled on the PCB?

Pin 3 is a no-connect (NC) terminal - it corresponds to an un-bonded die pad with no internal connection. It must remain electrically floating and unconnected on the PCB. Do not tie it to GND, VCC, or any other net; avoid solder mask openings or copper pours beneath it to prevent unintended coupling or leakage paths that could affect adjacent analog signals like FB or ISENSE.

Does MP2499MGQB-Z support adjustable current limiting, and how is it set?

Yes - continuous output current limit is set externally via a sense resistor (RSENSE) connected between ISENSE and AGND. Using VISENSE = 118mV (typical), the limit is calculated as IOUT(LIMIT) = 0.118V / RSENSE. For example, RSENSE = 40mΩ yields ~2.95A. This is distinct from cycle-by-cycle OCP and allows precise, temperature-stable current limiting independent of inductor saturation behavior.

What thermal derating applies to the 3A maximum output current rating?

The 3A rating is specified under ideal thermal conditions: 2-layer PCB with 2oz copper, 1in² exposed PGND pad, and 200LFM airflow. In typical 4-layer boards with limited copper area, continuous current derates to ~2.4A at TA = +85°C. Thermal shutdown triggers at 170°C junction temperature, with 30°C hysteresis, allowing safe operation up to ~125°C ambient when properly heatsunk via the exposed PGND pad.

Is the BST pin internally regulated, and what capacitor value is recommended?

Yes - the BST pin is charged by an internal PMOS pass transistor and regulated to ~5V relative to SW. A 0.1μF to 1μF ceramic capacitor (X5R/X7R) is recommended between BST and SW, placed as close as possible to the IC. A 20Ω resistor in series with the BST capacitor is strongly advised to dampen ringing and reduce SW node voltage spikes, especially at high duty cycles.