STMicroelectronics ST1L05CPU33R

Overview

ST1L05CPU33R from STMicroelectronics is a fixed 3.3 V, 1.3 A BiCMOS low-dropout linear voltage regulator in DFN6 (3×3 mm) package, featuring enable input, ±2% output voltage tolerance at 25 °C, max. 650 µA quiescent current, and 0.3 V dropout at full load-designed for HDD read-channel and memory power rails.

For engineers reviewing the ST1L05CPU33R datasheet, ST1L05CPU33R pinout, ST1L05CPU33R application, or ST1L05CPU33R equivalent, this page delivers verified electrical specs, thermal behavior, enable logic thresholds, ceramic capacitor stability requirements, and real-world use cases in storage subsystems.

Technical Context

The ST1L05CPU33R implements a BiCMOS-based error amplifier with internal bandgap reference and current-limiting protection, supporting active-high enable control with 2 V high-threshold and 0.8 V low-threshold. It operates across 4.75–5.25 V input range and maintains regulation down to 0 °C junction temperature.

Its architecture enables stable operation with low-ESR ceramic capacitors (≥4.7 µF), integrates thermal shutdown with 165 °C trip point and hysteresis, and delivers <30 mV load regulation over 10 mA–1.3 A output current range-critical for noise-sensitive data-path ICs.

Key Specifications

Pinout & Package

ST1L05CPU33R uses the DFN6 (3×3 mm, 0.75 mm height) package with exposed thermal pad requiring solder connection to PCB ground plane for optimal thermal performance (R_thJA = 55 °C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ST1L05CPU33R, the XC6219B332MR-G sacrifices enable functionality and current headroom for nanoamp IQ, while the AP7361-C-33Y-13 trades 300 mA output capability and 0.15 V lower dropout for significantly lower quiescent draw-making ST1L05CPU33R optimal for 3.3 V/1.3 A sequenced power domains in storage hardware.

Availability

ST1L05CPU33R is available at Aetrix Electronics and suitable for hard disk drive (HDD) read-channel power, solid-state drive (SSD) NAND buffer supply, and industrial data acquisition modules requiring stable component supply with long-term manufacturability.

Supply support for ST1L05CPU33R 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 specializing in power management, microcontrollers, and automotive-grade analog ICs, with manufacturing facilities across Europe and Asia.

The ST1L05 series belongs to ST's high-precision, low-quiescent-current LDO portfolio, engineered specifically for power integrity in data storage and high-reliability embedded systems where thermal efficiency and voltage accuracy are critical.

FAQ

What is the minimum input voltage required for ST1L05CPU33R to regulate at 3.3 V?

The ST1L05CPU33R requires a minimum input voltage of 3.6 V to maintain regulation at 3.3 V output under full 1.3 A load, based on its typical 0.3 V dropout specification. At lighter loads (e.g., 100 mA), regulation is sustained down to ~3.35 V input. The absolute minimum VI is 4.75 V per datasheet test conditions, but functional start-up occurs at ~2.9 V for ADJ versions-not applicable to this fixed 3.3 V variant.

Can ST1L05CPU33R be used with tantalum or aluminum electrolytic output capacitors?

While the ST1L05CPU33R is optimized and guaranteed stable with low-ESR ceramic capacitors (≥4.7 µF X7R), it may operate with tantalum or aluminum electrolytics if their ESR falls within the 10–100 mΩ range specified in Figure 13 of the datasheet. However, ceramic capacitors are strongly recommended to ensure consistent phase margin, avoid aging-related ESR drift, and meet the 0.003%VO noise spec.

Does ST1L05CPU33R include Power Good (PG) functionality?

No. ST1L05CPU33R does not integrate a Power Good output. Only ST1L05B and ST1L05D versions feature PG pins. The 'C' version provides enable control (EN) and VO_SENSE but omits PG-making it appropriate for systems where upstream monitoring or sequencer handshaking is handled externally rather than by the LDO itself.

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

The exposed thermal pad on the ST1L05CPU33R's DFN6 (3×3 mm) package must be soldered to a dedicated PCB copper pour tied directly to the system ground plane. A minimum of 4 thermal vias (0.3 mm diameter) connecting the pad to inner-layer ground planes is recommended to achieve the rated R_thJA of 55 °C/W. Leaving the pad floating or unconnected degrades thermal performance and risks premature thermal shutdown.