STMicroelectronics LF33CPT-TRY

Overview

LF33CPT-TRY from STMicroelectronics is a 3.3 V, ±2% tolerance, automotive-grade low-dropout linear regulator in PPAK-5 package with logic-controlled shutdown (TTL-compatible enable), 0.45 V dropout at 500 mA, 50 µA quiescent current in OFF mode, and qualified to AEC-Q100 Grade 1 (−40 °C to +125 °C). It serves as a local power rail regulator in engine control units and ADAS domain controllers where standby power reduction and thermal robustness are critical.

For engineers reviewing the LF33CPT-TRY datasheet, LF33CPT-TRY pinout, LF33CPT-TRY application, or LF33CPT-TRY equivalent, key selection criteria include its 5-pin PPAK thermal performance (R_thJA = 100 °C/W), 2.2 µF minimum output capacitance requirement, automotive qualification status, and precise 3.3 V output stability across temperature and load.

Technical Context

The LF33CPT-TRY implements a fixed-output, NPN-based LDO architecture with internal current and thermal limiting, enabling safe operation under short-circuit and overload conditions without external protection circuitry. Its inhibit function is implemented via Pin 2 (EN), which accepts TTL-level logic signals to switch between ON (I_Q = 500 µA typ.) and OFF (I_Q = 50 µA typ.) states.

Stability is achieved with only 2.2 µF ceramic output capacitor (ESR 0.1–10 Ω), eliminating need for large electrolytic capacitors. Supply voltage rejection reaches 80 dB at 120 Hz and remains ≥65 dB up to 10 kHz, supporting noise-sensitive analog and digital subsystems in automotive environments.

Key Specifications

Pinout & Package

LF33CPT-TRY is housed in a thermally enhanced PPAK-5 surface-mount package (4.5 × 6.0 mm, 0.95 mm height) with exposed thermal pad electrically connected to GND. The package provides R_thJA = 100 °C/W and R_thJC = 8 °C/W for efficient heat dissipation in compact automotive modules.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LDL1133PU33R, LF33CPT-TRY delivers higher output current and automotive qualification in the same footprint; versus TLD1133EPV50, it adds programmable shutdown at the cost of slightly reduced max junction temperature rating.

Availability

LF33CPT-TRY is available at Aetrix Electronics and suitable for engine control units, ADAS cameras, body control modules, and infotainment head units requiring stable component supply across automotive production lifecycles.

Supply support for LF33CPT-TRY 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 LFXX series was developed specifically for automotive power management, targeting low-noise, low-quiescent-current local regulation in ECU, ADAS, and body electronics where thermal resilience and AEC-Q100 compliance are mandatory.

FAQ

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

The LF33CPT-TRY maintains regulation down to an input voltage of 3.75 V at 500 mA load, based on its 0.45 V typical dropout voltage (V_IN = V_OUT + V_DROP). Below this, output voltage collapses linearly; the absolute maximum input is 16 V per datasheet Table 1.

Can the EN pin be left floating, or must it be actively driven?

The EN pin must never be left floating: it has no internal pull-up or pull-down. An unconnected EN pin may cause erratic startup or unintended shutdown due to noise coupling. For always-on operation, tie EN directly to IN; for controlled shutdown, drive with a clean logic signal referenced to GND.

Is the exposed thermal pad on the PPAK-5 package electrically isolated?

No-the TAB (Pin 5) is internally bonded to GND and must be soldered to a GND copper pour on the PCB. This connection is essential for both electrical functionality and thermal performance; omitting it raises junction temperature by >30 °C at 500 mA and risks thermal shutdown.

Does LF33CPT-TRY require an input capacitor, and if so, what value?

While not strictly required for stability, a 0.1 µF ceramic input capacitor placed close to the IN and GND pins is recommended to suppress high-frequency noise and transient spikes from upstream sources. The datasheet specifies C_I = 0.1 µF in all electrical test conditions.