STMicroelectronics ST1L05APU33R

Overview

ST1L05APU33R from STMicroelectronics is a fixed-output 3.3 V, 1.3 A low-dropout linear voltage regulator in BiCMOS technology, delivering ±2% output voltage accuracy at 25 °C, 650 µA max quiescent current, and 0.3 V typical dropout at full load - deployed in HDD read-channel and memory power rails.

For engineers reviewing the ST1L05APU33R datasheet, ST1L05APU33R pinout, ST1L05APU33R application, or ST1L05APU33R equivalent, this page provides verified electrical specs, DFN6 (3×3 mm) package details, thermal shutdown behavior, enable functionality, and real-world use cases in storage and embedded power systems.

Technical Context

The ST1L05APU33R implements a BiCMOS-based error amplifier with internal bandgap reference and current-limiting circuitry, enabling stable regulation across 0–125 °C junction temperature. Its architecture supports fast transient response (≤3.6 V load-dip recovery) and maintains regulation down to 0 mA output current.

It features a dedicated enable input (EN) with 0.8 V/2 V logic thresholds and operates without external compensation - stabilized by ≤10 µF low-ESR ceramic capacitors on input and output. No Power Good (PG) function is present in the 'A' version.

Key Specifications

Pinout & Package

ST1L05APU33R uses the DFN6 (3 × 3 mm, 0.75 mm height) package with exposed thermal pad - requires solder connection of the pad to PCB ground plane for thermal performance and EMI control.

Key Features

Applications

Equivalent & Alternatives

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

Compared with XC6210B332MR-G and AP2204K-3.3TRG1, the ST1L05APU33R uniquely delivers 1.3 A output, integrated enable, thermal hysteresis, and DFN6 packaging - making it irreplaceable in high-current, thermally constrained storage applications where reliability and regulation precision are mandatory.

Availability

ST1L05APU33R is available at Aetrix Electronics and suitable for HDD read-channel power, NAND flash memory supply, and industrial embedded controller designs requiring stable component supply, consistent parametric performance, and long-term production support.

Supply support for ST1L05APU33R 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 microcontrollers, power management ICs, sensors, and analog devices for industrial, automotive, and consumer markets.

The ST1L05 series targets ultra-low-quiescent-current linear regulation in space- and power-constrained storage and embedded systems - emphasizing thermal robustness, ceramic-capacitor compatibility, and precise voltage accuracy for mission-critical data-path power.

FAQ

What is the minimum input voltage required for ST1L05APU33R to maintain regulation at 1.3 A?

The ST1L05APU33R requires a minimum input voltage of 3.6 V to sustain 3.3 V output at 1.3 A, based on its 0.3 V typical dropout voltage. At higher temperatures or worst-case process corners, the dropout may reach 0.5 V, so 3.8 V input is recommended for margin in production designs.

Can ST1L05APU33R be used with 2.2 µF output capacitors?

No - the datasheet specifies stability with ≥4.7 µF ceramic capacitors (X7R). Using 2.2 µF violates the minimum capacitance requirement and risks oscillation or poor transient response, especially under 1 A load steps. Always adhere to the 4.7 µF minimum with ≤10 mΩ ESR.

Does ST1L05APU33R include Power Good (PG) signaling?

No - the 'A' suffix denotes the base version without Power Good functionality. Only ST1L05B and ST1L05D variants include the open-drain PG pin. For power sequencing feedback, an external supervisor IC or voltage monitor is required with ST1L05APU33R.

How should the exposed thermal pad on the DFN6 package be connected?

The exposed pad must be soldered to a solid copper ground plane using ≥4 thermal vias (0.3 mm diameter) spaced evenly beneath the pad. This connection is mandatory for thermal performance (R_thJA = 55 °C/W) and electrical noise immunity - floating or unconnected pads cause thermal throttling and instability.