STMicroelectronics LDFM33PVR

Overview

LDFM33PVR from STMicroelectronics is a 3.3 V fixed-output, 500 mA very low dropout linear regulator in DFN6-2x2 package, featuring 1% output accuracy, 300 mV max dropout at full load, 200 µA typical quiescent current, and integrated Power Good (open-drain) and logic-controlled enable. It powers core voltage rails in space-constrained portable computing and battery-powered medical devices.

For engineers reviewing the LDFM33PVR datasheet, LDFM33PVR pinout, LDFM33PVR application, or LDFM33PVR equivalent, key selection criteria include dropout performance at 500 mA, thermal shutdown threshold (170 °C), PG threshold hysteresis (0.92×/0.8×VOUT), stability with 2.2 µF ceramic output capacitor, and EN logic compatibility with 0.8 V low / 2 V high thresholds.

Technical Context

The LDFM33PVR employs a PMOS pass transistor architecture enabling ultra-low dropout (125–300 mV) across –40 °C to 125 °C junction temperature, with internal current limiting and thermal shutdown (170 °C, 10 °C hysteresis). Its error amplifier supports both fixed and adjustable configurations via ADJ/NC pin.

It integrates an open-drain Power Good output referenced to VOUT (rising edge at 0.92×VOUT, falling at 0.8×VOUT) and a CMOS-compatible enable input requiring external pull-up when unused. Supply voltage rejection reaches 60 dB at 120 Hz and 52 dB at 10 kHz for 5 V output.

Key Specifications

Pinout & Package

Package: DFN6-2x2 mm, 0.65 mm pitch, exposed thermal pad (GND-connected).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLD5098EL and LDL1133PU33R, LDFM33PVR uniquely delivers 500 mA output with integrated PG and EN in DFN6-2x2 - making it optimal for compact, sequenced, battery- or industrial-rail-powered systems requiring robust fault monitoring and full-load dropout performance.

Availability

LDFM33PVR is available at Aetrix Electronics and suitable for portable medical monitors, laptop core voltage rails, industrial PLC I/O modules, and battery-powered test equipment requiring stable component supply across extended temperature and long-lifecycle programs.

Supply support for LDFM33PVR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing analog, MCU, power, and sensing solutions for automotive, industrial, and consumer markets.

LDFM33PVR belongs to ST's high-performance LDO family targeting low-noise, low-dropout regulation in space-constrained, thermally demanding applications - especially where battery life, rail sequencing, and precision voltage stability are critical.

FAQ

What is the minimum input voltage required for LDFM33PVR to maintain regulation at 500 mA?

The minimum input voltage is 3.6 V: 3.3 V nominal output plus maximum dropout of 300 mV at 500 mA and –40 °C to 125 °C. Below this, output voltage drops linearly with input; operation below 2.5 V is prohibited per absolute maximum ratings.

Can the ADJ/NC pin be left floating on the LDFM33PVR?

Yes - for the fixed 3.3 V version (LDFM33PVR), Pin 2 is explicitly designated "NC" (not connected) in Table 1 of DS9220 Rev 7. It must remain unconnected and unbonded; no pull-up, pull-down, or trace routing is permitted.

What external components are mandatory for stable operation?

A 1 µF X7R ceramic input capacitor placed ≤12.7 mm from VIN and a 2.2 µF X7R ceramic output capacitor placed adjacent to VOUT are mandatory. The PG pin requires a 10–100 kΩ pull-up resistor to a valid supply; EN must be tied to VIN or driven actively - never left floating.

How does thermal performance differ between DFN6-2x2 and DFN6-3x3 packages?

DFN6-2x2 has R_thJA = 65 °C/W; DFN6-3x3 improves to 55 °C/W. At 500 mA and 25 °C ambient, junction temperature rise is ~32.5 °C (2x2) vs. ~27.5 °C (3x3). Both use exposed GND pads, but the larger 3x3 variant enables higher continuous power in thermally constrained layouts.