Monolithic Power Systems Inc. MP8903DG-2.85-LF-P

Overview

MP8903DG-2.85-LF-P from Monolithic Power Systems is a fixed-output 2.85V, 150mA low-dropout linear regulator with 2% output accuracy, 100mV dropout at 100mA, thermal shutdown protection, and operation from 2.7V to 6.5V input. It delivers stable bias for RF PLL circuits in mobile handsets where tight voltage tolerance and low noise are critical.

For engineers reviewing the MP8903DG-2.85-LF-P datasheet, MP8903DG-2.85-LF-P pinout, MP8903DG-2.85-LF-P application, or MP8903DG-2.85-LF-P equivalent, key selection criteria include dropout performance at full load, thermal resistance in QFN8 package, FB threshold voltage for adjustable configurations, PSRR at 1MHz, and compatibility with low-ESR ceramic output capacitors.

Technical Context

The MP8903DG-2.85-LF-P uses a PMOS pass transistor architecture enabling low dropout and inherent reverse-current blocking. Its internal 1.222V bandgap reference feeds a precision error amplifier that regulates output via feedback from the FB pin.

Thermal protection activates at 155°C with 30°C hysteresis, and the device remains stable with X5R/X7R ceramic output capacitors ≥1μF. The EN pin supports controlled startup and shutdown with 0.4V logic-low disable threshold.

Key Specifications

Pinout & Package

MP8903DG-2.85-LF-P is housed in a thermally enhanced QFN8 (2mm × 2mm, 0.5mm pitch) package with exposed thermal pad. Pin 7 is NC; pin 8 is GND-connected thermal paddle requiring soldered PCB land for optimal θJA = 80°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout linear regulator applications.

Compared with MCP1700-2802E/TO and XC6206P282MR-G, MP8903DG-2.85-LF-P provides integrated enable control, thermal shutdown, and tighter 2% output accuracy - eliminating need for external supervisors and improving system-level reliability in compact, thermally constrained layouts.

Availability

MP8903DG-2.85-LF-P is available at Aetrix Electronics and suitable for mobile handset PLL power, audio codec bias supply, and 802.11 PC card core rail applications requiring stable component supply, RoHS-compliant packaging, and QFN8 thermal performance.

Supply support for MP8903DG-2.85-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 power ICs, with design centers in the US, China, and Taiwan.

The MP8903 belongs to MPS's low-IQ LDO product line, engineered specifically for space-constrained, battery-powered RF and audio subsystems demanding precision regulation, low noise, and robust thermal behavior.

FAQ

What is the minimum input voltage required to maintain regulation at 150mA load?

The MP8903DG-2.85-LF-P requires VIN ≥ VOUT + VDROPOUT. At 150mA, typical dropout is 125mV (per datasheet Fig. 4), so minimum VIN = 2.85V + 0.125V = 2.975V. For guaranteed 2% accuracy across temperature, design for ≥3.0V input under worst-case conditions.

Can the MP8903DG-2.85-LF-P be used in adjustable mode despite its fixed 2.85V marking?

Yes - the "2.85" marking indicates factory-trimmed internal resistor ratio, but the FB pin remains fully accessible. Connecting an external R1/R2 divider (with R1+R2 ≤100kΩ) reconfigures it as an adjustable regulator per VOUT = 1.222V × (1 + R1/R2), supporting outputs from 1.25V to 5V.

Is the exposed thermal pad on the QFN8 package electrically connected?

Yes - the exposed pad (pin 8) is internally tied to GND. It must be soldered to a dedicated PCB GND plane with ≥4 thermal vias (0.3mm diameter) to achieve the specified θJA = 80°C/W and prevent thermal shutdown under 150mA continuous load.

What is the maximum allowable output capacitance?

The datasheet specifies stability with 1–10μF X5R/X7R ceramic capacitors. While larger values improve transient response, capacitance >10μF may cause startup overshoot or oscillation due to zero placement in the control loop; no absolute maximum is defined, but 10μF is the validated upper limit.

Does the EN pin require a pull-up resistor for automatic startup?

No - EN can be directly tied to IN (pin 4) for automatic enable at power-on. This configuration draws no additional current and ensures immediate regulation when VIN rises above 2.7V, eliminating need for external biasing components.

How does PSRR degrade above 100kHz, and what design steps mitigate it?

PSRR drops from 50dB at 1kHz to 20dB at 1MHz due to internal error amplifier bandwidth limits. To maintain noise rejection, place a 100nF feed-forward capacitor across R1 in adjustable configurations and ensure short, low-inductance FB trace routing - both reduce high-frequency gain peaking.

What is the impact of using Y5V dielectric for the output capacitor?

Y5V capacitors exhibit >80% capacitance loss over –40°C to +85°C and significant voltage coefficient. Using them risks instability and output droop under load or temperature extremes; X5R/X7R ceramics are mandatory for guaranteed performance per datasheet specifications.