STMicroelectronics LDFMPUR

Overview

LDFMPUR from STMicroelectronics is an adjustable-output, 500 mA very low dropout linear regulator operating from 2.5 V to 16 V input. It delivers ±1% output voltage accuracy (at 25 °C), 300 mV max dropout at 500 mA, and features logic-controlled enable, open-drain Power Good output, internal thermal/current protection, and operation from –40 °C to 125 °C junction temperature - ideal for powering low-voltage microprocessors and memory in space-constrained portable systems.

For engineers reviewing the LDFMPUR datasheet, LDFMPUR pinout, LDFMPUR application, or LDFMPUR equivalent, this page provides verified electrical specifications, DFN6-3x3 package details, thermal performance data, PG threshold behavior, and design-critical capacitor stability guidance per DS9220 Rev 7.

Technical Context

The LDFMPUR implements a high-precision bandgap reference and error amplifier driving a PMOS pass transistor, enabling ultra-low dropout and fast transient response. Its adjustable architecture uses the ADJ pin as the feedback node with a 0.8 V internal reference, supporting output voltages from 0.8 V to 12 V via external resistor divider.

It integrates active current limiting, thermal shutdown with 10 °C hysteresis, and a dedicated open-drain Power Good output that asserts high when VOUT reaches 92% of target and deasserts at 80%, requiring an external pull-up resistor (10–100 kΩ) for sequencing or fault detection.

Key Specifications

Pinout & Package

Package: DFN6-3x3 mm, exposed thermal pad (GND), RoHS-compliant ECOPACK2, thermal resistance R_thJA = 55 °C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar adjustable LDO applications.

Compared with TPS7A4700RGWR and ADM7172ACPZ-R7, the LDFMPUR offers unique balance of adjustability, compact DFN6-3x3 packaging, integrated PG/EN logic, and robust thermal protection - making it optimal for cost-sensitive, space-constrained, and multi-voltage embedded systems requiring field-programmable output levels.

Availability

LDFMPUR is available at Aetrix Electronics and suitable for portable medical monitors, industrial PLC I/O modules, battery-powered test equipment, and automotive infotainment core supplies requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LDFMPUR 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, Switzerland, designing and manufacturing silicon solutions for automotive, industrial, and consumer markets since 1987.

The LDFM series was developed specifically for high-efficiency, low-noise point-of-load regulation in portable and thermally demanding embedded systems - emphasizing ultra-low dropout, precision output, and integrated power management features.

FAQ

What is the minimum output capacitance required for stable operation of LDFMPUR?

The LDFMPUR requires a minimum 2.2 µF ceramic output capacitor with ESR between 0.01 Ω and 0.1 Ω at 100 kHz for stable operation across all output voltages. Stability is confirmed in Figures 24–25 of DS9220 Rev 7, which define the C_OUT/ESR operating zone for both adjustable and fixed versions. Using capacitors outside this range may cause oscillation or poor transient response.

Can LDFMPUR be used with an input voltage below 2.5 V?

No - the absolute minimum input voltage is 2.5 V per Table 2 (Absolute Maximum Ratings) and electrical characterization conditions in Tables 4–5. Operation below 2.5 V violates specification and risks improper regulation, especially near dropout. For sub-2.5 V inputs, consider ST's STLQ015 or similar ultra-low-VIN LDOs.

How does the Power Good (PG) pin behave during thermal shutdown?

During thermal shutdown, the PG pin is actively pulled low regardless of EN state, as confirmed by functional description in Section 6.3 and Figure 19 transient waveforms. This provides fail-safe indication of fault condition to host controller, enabling immediate system-level response such as forced cooling or graceful shutdown before junction temperature exceeds 170 °C.

Is the exposed thermal pad on the DFN6-3x3 package electrically connected?

Yes - the exposed pad is internally connected to GND, as stated in Table 1 (Pin description) and Figure 27 (package outline). It must be soldered to a PCB thermal pad tied to the main GND plane to achieve the specified R_thJA = 55 °C/W and prevent thermal throttling at full 500 mA load. Omitting this connection degrades thermal performance by >30 °C/W.