Monolithic Power Systems Inc. MP4473GL-Z

Overview

MP4473GL-Z from Monolithic Power Systems is a fully integrated, synchronous step-down DC/DC converter delivering 3.5A continuous output current across a 4.5V–36V input range. It integrates 40mΩ high-side and 20mΩ low-side MOSFETs, supports 200kHz–1MHz programmable switching frequency, features 0.815V ±8mV reference voltage, and provides fast transient response for POL applications in automotive and industrial power rails.

For engineers reviewing the MP4473GL-Z datasheet, MP4473GL-Z pinout, MP4473GL-Z application, or MP4473GL-Z equivalent, key selection criteria include its 3.5A guaranteed load capability, 1% reference accuracy, integrated bootstrap circuitry, hiccup-mode short-circuit protection, and QFN-20 (3mm×4mm) thermal performance with θJA = 48°C/W.

Technical Context

The MP4473GL-Z employs fixed-frequency PWM control with input-voltage feed-forward to maintain stable switching frequency across 4.5V–36V input. Its proprietary dead-time management prevents shoot-through between internal 40mΩ/20mΩ MOSFETs, while cycle-by-cycle over-current detection triggers 100μs hiccup-mode recovery during sustained overload.

It operates in CCM at full load and transitions to skip mode at light loads to sustain >85% efficiency down to 10mA. The 8.5μA soft-start current source enables precise ramp control via external capacitor, and the open-drain PGOOD pin asserts after 700μs once FB reaches 90% of 0.815V reference.

Key Specifications

Pinout & Package

MP4473GL-Z is housed in a thermally enhanced 3mm×4mm, 20-pin QFN package with exposed thermal pad (pins 8,19,21,22,23 as IN; 9,10,17,18,24,25 as SW; 11–16 as PGND). The package supports 2.6W continuous power dissipation at +25°C ambient and achieves θJA = 48°C/W on 4-layer PCB.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down converter applications.

Compared with MPQ4473GQ-A, the MP4473GL-Z offers identical performance at lower cost for non-automotive use; versus LM61480RQR, it delivers superior light-load efficiency via skip mode and integrated bootstrap charging-critical for battery-backed or always-on systems.

Availability

MP4473GL-Z is available at Aetrix Electronics and suitable for notebook I/O power, automotive infotainment, and industrial PLC applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP4473GL-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.

The MP4473 belongs to MPS's high-efficiency synchronous buck converter product line, engineered for compact, high-transient-response POL applications in automotive, industrial, and communications infrastructure where thermal density and reliability are critical.

FAQ

What is the minimum recommended output capacitance for stable operation?

The MP4473GL-Z requires ≥22μF ceramic output capacitance with X5R/X7R dielectric for stable CCM operation. For systems using POSCAP or high-ESR capacitors, external ramp compensation is not needed; with low-ESR ceramics, a 390pF–1nF ramp capacitor (C4) and 620kΩ resistor (R4) are recommended per typical application circuit.

How does the bootstrap capacitor charge during low-duty-cycle operation?

During low-duty-cycle (high-VOUT/VIN) operation, the MP4473GL-Z uses an internal UVLO-controlled refresh circuit that activates the LS-FET to discharge the SW node, creating VIN–VSW headroom for BST capacitor recharge. This ensures reliable HS-FET turn-on even at 95% duty cycle, enabling true low-dropout functionality.

Can the MP4473GL-Z operate without an external frequency-setting resistor?

No. The FREQ pin must be connected to GND via a resistor (30kΩ–300kΩ) to set the ON-time and thus the switching frequency. Leaving FREQ floating or shorted to GND disables regulation; the default frequency is undefined and device behavior is not guaranteed.

What is the maximum allowable input voltage ripple before affecting regulation?

Input ripple must remain below 100mV_pp at the IN pin under full load to prevent false triggering of the 3.7V–4.3V UVLO rising threshold. This requires ≥47μF X5R/X7R ceramic input capacitance placed within 3mm of the IN/PGND pins, with parallel 10μF tantalum for bulk energy storage.

Does the PGOOD pin require an external pull-up resistor?

Yes. The PGOOD pin is an open-drain NMOS output and must be pulled up to a voltage ≤VCC (typically 5V) via a 10kΩ–100kΩ resistor. Without this pull-up, the pin remains floating and cannot assert a valid logic HIGH signal for system sequencing.

How is thermal performance affected by PCB copper area under the exposed pad?

Thermal resistance θJA drops from 48°C/W (4-layer board, 1in² copper) to ≤35°C/W with ≥4in² of 2oz copper connected to the exposed pad via ≥9 thermal vias (0.3mm diameter). Insufficient copper or vias causes junction temperature to exceed 125°C at 3.5A, triggering thermal shutdown.

Is the MP4473GL-Z compatible with ceramic output capacitors having zero ESR?

Yes, but external ramp compensation (R4/C4 network) is mandatory to ensure stability. Zero-ESR ceramics eliminate natural output ripple slope needed for loop compensation; the external ramp restores required phase margin. Omitting R4/C4 risks oscillation or erratic PGOOD assertion under load transients.