STMicroelectronics LF85CP

Overview

LF85CP from STMicroelectronics is a very low dropout (LDO) linear voltage regulator delivering 8.5 V output at up to 500 mA, with 0.45 V dropout at 200 mA, ±1% output accuracy (AB grade), and logic-controlled shutdown (TTL-compatible enable pin). It operates across –40°C to +125°C and requires only a 2.2 µF ceramic output capacitor for stability - used as a local power rail in battery-powered industrial sensors and portable instrumentation.

For engineers reviewing the LF85CP datasheet, LF85CP pinout, LF85CP application, or LF85CP equivalent, this page provides verified electrical specifications, thermal performance data, package-specific pin functions, real-world use cases in low-noise embedded systems, and validated alternative parts with documented functional differences.

Technical Context

The LF85CP implements a PNP pass transistor architecture enabling ultra-low dropout voltage and high PSRR (80 dB typ. at 120 Hz). Its internal current and thermal limiting protect against fault conditions without external components.

It features a dedicated TTL-compatible control input (pin 2 in PENTAWATT/PPAK) that enables full electronic shutdown with <100 µA quiescent current, making it suitable for dynamic power management in multi-rail systems where subsystem-level standby is required.

Key Specifications

Pinout & Package

LF85CP is supplied in the PENTAWATT-5 (vertical mount, 5-pin) package with exposed tab for thermal dissipation. Pin 1 = Input, Pin 2 = Enable (TTL-compatible), Pin 3 = Ground, Pin 4 = Output, Pin 5 = Bypass (not connected in standard configuration).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LF85CP, LDL112PU33R and LD3985PU33R provide lower dropout and modern packaging but are fixed at 3.3 V - making them unsuitable as direct replacements where 8.5 V output and AB-grade accuracy are mandatory.

Availability

LF85CP is available at Aetrix Electronics and suitable for industrial sensor nodes, portable medical monitors, automotive body control modules, and test & measurement equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LF85CP 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, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The LF00 series was developed specifically for low-noise, low-power, wide-temperature LDO applications in battery-operated and harsh-environment systems - emphasizing dropout minimization, shutdown control, and capacitor-free stability.

FAQ

What is the minimum input voltage required for LF85CP to maintain regulation at 500 mA?

At 500 mA load, the maximum dropout voltage is 0.7 V (per Table 9–20 electrical characteristics). Therefore, minimum input voltage = 8.5 V + 0.7 V = 9.2 V. Below this, output voltage will droop proportionally with input reduction.

Can LF85CP be used with an aluminum electrolytic output capacitor instead of ceramic?

Yes, but only if ESR is within 0.1–10 Ω and capacitance is ≥2.2 µF. Ceramic is preferred due to lower ESR, smaller footprint, and longer lifetime; electrolytics may degrade over time and increase noise under temperature cycling.

Is the enable pin (Pin 2) 5 V tolerant when the input is 16 V?

No. The enable pin absolute maximum rating is VI = –0.5 V to +6 V (Table 1). Driving it above 6 V risks damage. Use a resistive divider or level shifter if controlled by a 5 V or higher logic source.

Does LF85CP require an input bypass capacitor?

Yes. A 0.1 µF ceramic capacitor is specified in all electrical characteristic test conditions (Tables 3–20) and is required for high-frequency stability and transient response. Place it within 5 mm of Pins 1 and 3.