Monolithic Power Systems Inc. MP20045DQ-33-LF-P

Overview

MP20045DQ-33-LF-P from Monolithic Power Systems is a low-noise, 1A adjustable-output LDO linear regulator with 140mV dropout at full load, 13μVRMS output noise, and 56dB PSRR at 1kHz. It operates from 2.5V to 5.5V input, delivers up to 1A output current, and features an open-drain power-good (PG) signal and thermal/short-circuit protection - used in battery-powered handheld instruments requiring stable, low-noise voltage rails.

For engineers reviewing the MP20045DQ-33-LF-P datasheet, MP20045DQ-33-LF-P pinout, MP20045DQ-33-LF-P application, or MP20045DQ-33-LF-P equivalent, key selection criteria include dropout voltage at 1A, ground current under light load, PG threshold accuracy, FB reference voltage tolerance, and QFN8 thermal resistance for thermally constrained PCB layouts.

Technical Context

The MP20045DQ-33-LF-P uses an internal PMOS pass transistor enabling ultra-low dropout and 110μA quiescent current. Its feedback loop references a precise 1.5V internal bandgap, supporting both fixed and adjustable output configurations via external resistor dividers.

It integrates active protection: thermal shutdown triggers at 150°C with 20°C hysteresis, current limiting activates at 1.4–3.0A depending on input voltage, and the EN pin provides logic-level enable/disable control with defined high/low thresholds (1.5V/0.4V) and internal pull-up.

Key Specifications

Pinout & Package

MP20045DQ-33-LF-P is housed in an RoHS-compliant 8-pin QFN package (3mm × 3mm, exposed thermal pad). The exposed pad must be soldered to a PCB ground plane for optimal thermal performance (θJA = 50°C/W, θJC = 12°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-noise, 1A LDO applications.

Compared with XC6210B332MR-G and ADM7172ACPZ-3.3-R7, MP20045DQ-33-LF-P uniquely balances low dropout (140mV), low noise (13μVRMS), integrated PG, and adjustable output in a thermally optimized QFN8 - making it optimal for space-constrained, battery-sensitive designs requiring both precision and protection.

Availability

MP20045DQ-33-LF-P is available at Aetrix Electronics and suitable for notebook computers, cordless telephones, cellular phones, and hand-held instruments requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for MP20045DQ-33-LF-P 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 automotive applications.

The MP20045 belongs to MPS's low-noise LDO product line, engineered specifically for battery-powered portable electronics demanding ultra-low dropout, minimal quiescent current, and robust fault protection in compact packages.

FAQ

What is the minimum input voltage required for MP20045DQ-33-LF-P to regulate a 3.3V output?

The MP20045DQ-33-LF-P requires a minimum input voltage of 3.44V to maintain regulation at 3.3V output under 1A load, based on its 140mV dropout specification. Input voltage must also exceed the 2.3V UVLO threshold to enable operation - so practical minimum is 3.44V for full-load stability.

Can MP20045DQ-33-LF-P be used in adjustable-output configuration despite its -33 suffix?

Yes. The "-33" suffix denotes tape-and-reel packaging and RoHS compliance (LF), not fixed output - MP20045DQ-33-LF-P is the adjustable version. Output is set via external resistors between VOUT, FB, and GND using the 1.5V feedback reference, supporting 1.5V–5V range.

How should the exposed thermal pad on the QFN8 package be connected?

The exposed pad (Pin 6) must be soldered to a dedicated PCB copper pour connected to the system ground plane. Use ≥4 thermal vias (0.3mm diameter) under the pad to transfer heat to inner layers or bottom-side copper, ensuring junction temperature stays below 125°C at full 1A load.

Does MP20045DQ-33-LF-P require an input capacitor, and what value is recommended?

Yes - a minimum 2.2μF X5R/X7R ceramic capacitor with low ESR (<1Ω) is required at VIN to stabilize the control loop and absorb input transients. Place it within 5mm of VIN pins and connect directly to the GND plane using short, wide traces to minimize inductance.

What is the behavior of the PG pin during thermal shutdown?

During thermal shutdown, the PG pin remains asserted (low) as long as VOUT drops below 80–86% of nominal voltage. Once the device cools and resumes regulation, PG deasserts (high-impedance) only after VOUT stabilizes within tolerance - providing accurate fault indication without false resets.

Is the EN pin internally pulled up, and what happens if left unconnected?

Yes - the EN pin has an internal 550kΩ to 1.1MΩ pull-up resistor to VIN. If left unconnected, the regulator powers on by default. However, this is not recommended: noise coupling or leakage may cause erratic enable behavior. Always tie EN to VIN (for always-on) or drive actively with a clean logic signal.

How does load transient response depend on output capacitance selection?

Load transient response improves with larger output capacitance and lower ESR: a 2.2μF ceramic capacitor is minimum, but 10μF–22μF further reduces undershoot/overshoot. ESR must remain below 0.9Ω (per datasheet Figure 2) to ensure stability - higher ESR risks oscillation during fast load steps.