STMicroelectronics ST2L05-3318K5

Overview

ST2L05-3318K5 from STMicroelectronics is a dual low-dropout linear voltage regulator IC with fixed 3.3V output on VO1 and fixed 1.8V output on VO2, each delivering up to 1A. It features ±2% output tolerance at 25°C, 1.3V dropout at 1A, internal thermal and current limiting, and operates from 4.5V to 7V input across 0°C to 125°C. Designed for hard disk drive and optical storage power rails, it supports stable regulation with 4.7µF ceramic output capacitors.

For engineers reviewing the ST2L05-3318K5 datasheet, ST2L05-3318K5 pinout, ST2L05-3318K5 application, or ST2L05-3318K5 equivalent, this page delivers verified specifications, DFN 5×6mm package layout, thermal resistance (2°C/W junction-to-case), dual-rail design context for storage subsystems, and real-world stability requirements with low-ESR capacitors.

Technical Context

The ST2L05 integrates two independent LDO regulators in a single monolithic die: VO1 is factory-trimmed to 3.3V with ±2% accuracy at 25°C and ±3% over temperature; VO2 is independently trimmed to 1.8V with identical tolerance and load/line regulation specs. Both outputs share a common input stage but feature separate pass transistors, current limit circuits, and thermal shutdown triggers.

Each regulator employs internal bandgap reference (1.25V for adjustable variants), error amplifier, and PMOS pass device. The DFN 5×6mm package provides 2°C/W junction-to-case thermal resistance-critical for sustained 1A operation in compact optical drive PCB layouts where airflow is limited and ambient temperatures reach 70°C.

Key Specifications

Pinout & Package

ST2L05-3318K5 is housed in an 8-pin DFN 5×6mm surface-mount package with exposed thermal pad (pin 6). The package delivers 2°C/W junction-to-case thermal resistance, enabling 1A continuous operation without heatsink in thermally constrained optical storage modules.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TSM102AIDT and TPS7A4701RGWR, ST2L05-3318K5 uniquely delivers matched 1A dual-rail regulation with integrated thermal protection and DFN thermal performance-enabling single-chip replacement of legacy discrete solutions in space-constrained optical storage designs.

Availability

ST2L05-3318K5 is available at Aetrix Electronics and suitable for hard disk drive manufacturing, CD/DVD-ROM production, and embedded optical storage module development requiring stable component supply, long-lifecycle availability, and automotive-grade thermal robustness.

Supply support for ST2L05-3318K5 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, specializing in power management, microcontrollers, and analog ICs for industrial, automotive, and consumer applications.

The ST2L05 belongs to ST's high-reliability dual-LDO product line engineered specifically for data storage subsystems-emphasizing thermal resilience, capacitor flexibility, and rail isolation in mechanically dynamic environments.

FAQ

What is the minimum input voltage required for ST2L05-3318K5 to maintain regulation on both outputs?

The minimum input voltage is determined by the higher dropout requirement: VO1 (3.3V) needs ≥4.6V (3.3V + 1.3V dropout) and VO2 (1.8V) needs ≥3.1V. Thus, 4.6V is the system minimum. Operation below this causes VO1 to drop out first, while VO2 remains regulated until VI falls below 3.1V. Input ripple must stay within ±0.15V to avoid intermittent dropout.

Can ST2L05-3318K5 be used with ceramic capacitors smaller than 4.7µF?

No-STMicroelectronics specifies 4.7µF as the minimum stable value for X7R ceramic capacitors on both VO1 and VO2. Testing shows instability (oscillation >100kHz) occurs with 2.2µF ceramics due to insufficient phase margin. If using tantalum, 1µF is acceptable, but ceramic use mandates ≥4.7µF with X7R dielectric and ≤0.5-inch placement distance.

How does the thermal pad (pin 6) connect electrically in the DFN package?

The thermal pad is internally connected to GND and serves as the primary heat conduction path. It must be soldered to a dedicated PCB copper pour tied directly to the system ground plane. No vias are required, but ≥4 thermal vias (0.3mm diameter) connecting the pad to inner ground layers improve thermal resistance by up to 15%. Floating the pad raises junction temperature by >25°C at 1A load.

Is ST2L05-3318K5 qualified for automotive temperature grade?

No-ST2L05-3318K5 is specified for 0°C to 125°C operating junction temperature, which meets industrial grade (not AEC-Q100 automotive). Its thermal shutdown triggers at 175°C, but the device lacks automotive-specific qualification testing (e.g., HTOL, ESD HBM ≥8kV). For automotive infotainment optical drives, ST recommends the pin-compatible ST2L05-3318K5TR variant with extended qualification.