STMicroelectronics LF90CDT

Overview

LF90CDT from STMicroelectronics is a 9.0 V fixed-output, very low dropout (LDO) linear voltage regulator in TO-220FP package with logic-controlled shutdown, 500 mA output current capability, ±2% output voltage accuracy at 25°C, and 0.45 V typical dropout at 200 mA. It serves as a local power supply for microcontroller peripherals and sensor interfaces in battery-powered industrial monitoring systems.

For engineers reviewing the LF90CDT datasheet, LF90CDT pinout, LF90CDT application, or LF90CDT equivalent, key selection criteria include its 0.45 V dropout at 200 mA, 50 µA quiescent current in OFF mode, ±2% output tolerance, -40 to 125°C operating junction temperature, and TTL-compatible enable input for system-level power sequencing.

Technical Context

The LF90CDT implements a PNP pass transistor architecture enabling ultra-low dropout operation and stable regulation with only a 2.2 µF ceramic output capacitor. Its internal current and thermal limiting protect against fault conditions without external circuitry.

It features a dedicated TTL-compatible control input (pin 2) that enables full electronic shutdown - reducing quiescent current to 50 µA - and supports dynamic power management in multi-rail embedded systems where selective subsystem standby is required.

Key Specifications

Pinout & Package

LF90CDT is housed in a TO-220FP (Full Pack) thermally enhanced 5-pin package with isolated tab, optimized for high-power dissipation in compact industrial enclosures.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LD1086DTR and TPS7A4701RGWR, LF90CDT uniquely balances 500 mA capability, 0.45 V dropout, integrated shutdown, and rugged TO-220FP packaging - making it optimal for cost-sensitive, thermally demanding, and battery-aware industrial designs where simplicity and reliability are prioritized over ultra-low noise or ultra-high current.

Availability

LF90CDT is available at Aetrix Electronics and suitable for industrial sensor nodes, automotive body control modules, and programmable logic controller I/O cards requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LF90CDT 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 power management applications.

LF90CDT belongs to the LF00 series of very low-dropout linear regulators, engineered specifically for battery-powered and thermally constrained systems requiring high efficiency, wide input range, and robust protection features.

FAQ

What is the minimum input voltage required for stable 9.0 V output at 500 mA?

The LF90CDT requires a minimum input voltage of 9.45 V to maintain regulation at 500 mA, based on its maximum dropout voltage of 0.45 V. At 500 mA, the actual dropout rises to 0.7 V per datasheet Table 9, so 9.7 V is recommended for margin. Operation below this threshold causes output collapse or unregulated behavior.

Can LF90CDT be used without the control pin connected?

Yes - leaving pin 2 (CTRL) open or connecting it to IN places the device permanently in ON mode with 500 µA quiescent current. However, tying CTRL to GND forces shutdown (50 µA IQ). For reliable operation, avoid floating CTRL; use a pull-up resistor to IN if shutdown functionality is unused.

Is an input capacitor required for stability?

An input capacitor is not mandatory for stability but strongly recommended: a 0.1 µF ceramic capacitor placed near the IN pin suppresses high-frequency noise and improves transient response. The datasheet specifies CI = 0.1 µF in all electrical test conditions, and omitting it may degrade PSRR and line regulation performance.

Does LF90CDT support ceramic output capacitors with low ESR?

Yes - LF90CDT is explicitly characterized and stabilized with 2.2 µF ceramic capacitors having ESR between 0.1 Ω and 10 Ω. Unlike older LDOs, it does not require high-ESR tantalum or aluminum electrolytic capacitors, enabling smaller footprint, longer lifetime, and improved reliability in harsh environments.