STMicroelectronics LF120CPT-TR

Overview

LF120CPT-TR from STMicroelectronics is a 12 V fixed-output, very low dropout linear voltage regulator in PENTAWATT-5 package with logic-controlled shutdown (TTL-compatible enable), 500 mA output current capability, 0.45 V typical dropout at 200 mA, and ±2% output voltage accuracy at 25°C. It serves as a local power supply for battery-powered microcontroller peripherals requiring stable low-noise 12 V bias under variable load and thermal conditions.

For engineers reviewing the LF120CPT-TR datasheet, LF120CPT-TR pinout, LF120CPT-TR application, or LF120CPT-TR equivalent, key selection criteria include dropout voltage at 500 mA, quiescent current in ON/OFF modes, thermal resistance (R_thJC = 3°C/W), stability with 2.2 µF ceramic output capacitor, and logic-level shutdown compatibility in automotive and industrial embedded systems.

Technical Context

The LF120CPT-TR implements a PNP pass transistor architecture enabling ultra-low dropout operation, with internal current and thermal limiting ensuring robustness across -40°C to +125°C junction temperature range. Its TTL-compatible control input (pin 2) enables precise system-level power sequencing and standby mode activation without external level-shifting circuitry.

Stability is achieved with only 2.2 µF output capacitance (ESR 0.1–10 Ω), eliminating need for large electrolytic capacitors. Supply voltage rejection reaches 80 dB at 120 Hz and remains ≥60 dB up to 10 kHz, supporting noise-sensitive analog and RF subsystems powered from noisy DC rails.

Key Specifications

Pinout & Package

PENTAWATT-5 (vertical mount, 5-pin) package with integrated heat slug; pin 1 = Input, pin 2 = Shutdown (TTL-compatible), pin 3 = Ground, pin 4 = Output, pin 5 = Bypass (not used in standard configuration).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12 V LDO regulator applications.

Compared with LD120CDT-TR and TLV1117-12CDR, the LF120CPT-TR uniquely combines PENTAWATT-5's superior thermal performance (R_thJC = 3°C/W), integrated shutdown, and lowest dropout (0.45 V), making it optimal for thermally demanding, battery-conscious, and sequenced-power applications.

Availability

LF120CPT-TR is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC I/O modules, medical sensor interfaces, and test equipment requiring stable component supply with long-term manufacturability.

Supply support for LF120CPT-TR 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 LF00 series was developed specifically for low-power, low-noise, battery-sensitive applications requiring ultra-low dropout and logic-controlled shutdown - targeting automotive infotainment, industrial IoT nodes, and portable medical devices.

FAQ

What is the minimum input voltage required for regulation at full 500 mA load?

The LF120CPT-TR maintains regulation down to VI = VO + Vd = 12 V + 0.7 V = 12.7 V at 500 mA (max dropout per datasheet Table 9). Below this, output voltage drops linearly with input; operation below 12.7 V is permissible but results in unregulated output.

Can the bypass (pin 5) terminal be left floating or must it be grounded?

Pin 5 (Bypass) must remain unconnected - it is an internal reference node not intended for external connection. The datasheet explicitly states "NC" (no connect) for this pin in all standard configurations; grounding or capacitive loading may destabilize regulation or degrade noise performance.

Does the LF120CPT-TR require an input capacitor, and if so, what value and type?

Yes: a minimum 0.1 µF ceramic capacitor must be placed between pin 1 (Input) and pin 3 (Ground), located within 5 mm of the device. This prevents oscillation due to input trace inductance and ensures stability during fast load transients, as verified in ST's application schematics and layout guidelines.

How does thermal performance differ between PENTAWATT-5 and TO-220FP packages for the same LF120 part?

PENTAWATT-5 has R_thJC = 3°C/W and R_thJA = 50°C/W; TO-220FP has identical R_thJC = 3°C/W but higher R_thJA = 60°C/W due to reduced exposed copper area. Both deliver equal junction-to-case cooling, but PENTAWATT-5 offers better natural convection performance on standard PCBs without heatsinks.