Monolithic Power Systems Inc. MP20045DN-LF-Z

Overview

MP20045DN-LF-Z from Monolithic Power Systems is a low-noise, 1A adjustable-output linear regulator with 140mV dropout at full load, 110μA ground current, and 13μVRMS output noise. It operates from 2.5V to 5.5V input and delivers stable 1.5V–5V output via external resistor feedback. Designed for battery-powered handheld instruments and portable communications equipment requiring high PSRR (56dB @ 1kHz) and precise power-good monitoring.

For engineers reviewing the MP20045DN-LF-Z datasheet, MP20045DN-LF-Z pinout, MP20045DN-LF-Z application, or MP20045DN-LF-Z equivalent, key selection criteria include dropout voltage under 1A load, thermal shutdown threshold at 150°C, open-drain PG output timing, and SOIC8E package compatibility with legacy PCB layouts.

Technical Context

The MP20045DN-LF-Z uses an internal PMOS pass transistor to achieve ultra-low dropout and minimal quiescent current. Its feedback architecture centers on a fixed 1.5V reference at the FB pin, enabling precise output regulation across temperature (±2.5% accuracy) and line/load variations.

It integrates independent protection circuits: thermal shutdown with 20°C hysteresis, foldback current limiting (1.4–3.0A depending on VIN), and open-drain PG assertion when VOUT drops below 80–86% of nominal. The EN pin features internal 550kΩ–1.1MΩ pull-up and logic thresholds of 1.5V (high) and 0.4V (low).

Key Specifications

Pinout & Package

MP20045DN-LF-Z is housed in an SOIC8E package (5.0mm × 6.2mm × 1.75mm), featuring exposed pad thermal enhancement connected internally to GND. Pin 1 is marked by index area; leads are gull-wing, JEDEC MS-012 compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B182MR-G and ADP1740ACPZ-1.8-R7, MP20045DN-LF-Z uniquely combines adjustable output, integrated PG, EN control, and SOIC8E compatibility-making it optimal for redesigns of legacy portable systems requiring flexibility and system-level supervision.

Availability

MP20045DN-LF-Z is available at Aetrix Electronics and suitable for notebook computers, cordless telephones, and hand-held instruments requiring stable component supply, RoHS-compliant packaging, and long-term industrial availability.

Supply support for MP20045DN-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, motor drive, and automotive applications.

The MP20045 belongs to MPS's low-noise LDO product line, engineered specifically for portable and battery-operated systems demanding ultra-low quiescent current, high PSRR, and robust thermal protection without external components.

FAQ

What is the minimum input voltage required for MP20045DN-LF-Z to regulate a 3.3V output?

The minimum input is determined by dropout voltage plus output: 3.3V + 0.14V = 3.44V. However, the device's UVLO activates at 2.3V (rising), so input must exceed 2.3V to enable startup-but regulation only begins once VIN ≥ VOUT + dropout. For guaranteed 3.3V output at 1A, VIN must be ≥ 3.44V.

Can MP20045DN-LF-Z be used with ceramic capacitors smaller than 2.2μF?

No-MPS specifies a minimum 2.2μF ceramic output capacitor with ESR < 0.9Ω for stability. Using smaller values risks oscillation, especially under load transients, as confirmed by Figure 2 in the datasheet showing instability onset below 2.2μF across the 0–1A load range.

How does the power-good (PG) output behave during thermal shutdown?

PG remains asserted (low) during thermal shutdown because VOUT collapses below the 80–86% trip threshold. It only returns high after VOUT recovers to ≥90% of nominal and remains stable for >100μs, ensuring downstream logic sees a clean, debounced power-valid signal post-recovery.

Is the EN pin internally pulled up when left unconnected?

Yes-the EN pin has a factory-trimmed internal pull-up resistor of 550kΩ to 1.1MΩ, sufficient to hold EN > 1.5V and keep the device enabled. However, MPS explicitly warns against floating EN; it must be tied to VIN or grounded for defined behavior in production designs.

What is the maximum allowable power dissipation in SOIC8E at 70°C ambient?

Using θJA = 50°C/W and TJ(MAX) = 125°C: PD(MAX) = (125 − 70) / 50 = 1.1W. This assumes proper PCB layout with GND pad thermal connection. Exceeding this causes thermal shutdown, as verified by the 150°C junction limit and 20°C hysteresis in the datasheet.

Does MP20045DN-LF-Z support reverse-voltage protection?

No-MP20045DN-LF-Z lacks intrinsic reverse-polarity protection. Absolute maximum rating for VOUT-to-GND is −0.5V; applying reverse voltage risks latch-up or permanent damage. External protection (e.g., series Schottky diode) is required in systems prone to battery reversal or hot-swap events.