STMicroelectronics ST1L08SPU33R

Overview

ST1L08SPU33R from STMicroelectronics is a fixed-output 3.3 V, 800 mA ultra-low-dropout linear regulator in DFN8 2×3 mm package, featuring 90 mV max dropout at full load, ±2.0% output voltage tolerance at 25 °C, and integrated Power Good (PG) and input voltage control functions. It delivers stable low-noise power for point-of-load regulation in battery-powered SSDs and hard disk drives.

For engineers reviewing the ST1L08SPU33R datasheet, ST1L08SPU33R pinout, ST1L08SPU33R application, or ST1L08SPU33R equivalent, key selection criteria include its 70–90 mV dropout performance at 800 mA, 80 dB PSRR at 100 Hz, 35 μA no-load ground current, PG open-drain output with 0.92×V_OUT rising threshold, and bias-input architecture requiring V_BIAS ≥ V_OUT + 1.5 V.

Technical Context

The ST1L08SPU33R employs an N-channel pass transistor with separate bias rail (V_BIAS) to achieve ultra-low dropout while maintaining high PSRR and low quiescent current. Its dual-rail architecture decouples bias supply from input voltage, enabling stable operation even when VIN approaches V_OUT.

It integrates logic-controlled shutdown (EN pin), thermal shutdown at 165 °C with 20 °C hysteresis, current limiting at 1.8 A, and a dedicated open-drain Power Good output that asserts high when V_OUT reaches 92% of nominal and deasserts at 80%. The device is stabilized with ≥1 μF ceramic capacitors on VIN, V_BIAS, and V_OUT.

Key Specifications

Pinout & Package

ST1L08SPU33R is housed in a thermally enhanced DFN8 (2×3 mm) package with exposed pad (EXP) that must be soldered to GND for optimal thermal performance and EMI reduction.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar ultra-low-dropout LDO applications.

Compared with XC6210B332MR-G and ADM7172ACPZ-3.3-R7, the ST1L08SPU33R uniquely balances ultra-low dropout (70 mV), bias-rail optimization for minimal VIN headroom, and integrated PG with hysteresis-making it optimal for space-constrained, battery-sensitive 3.3 V point-of-load designs where thermal efficiency and precise power sequencing are critical.

Availability

ST1L08SPU33R is available at Aetrix Electronics and suitable for solid-state drives, hard disk drive electronics, and battery-powered industrial sensors requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ST1L08SPU33R 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, and analog/mixed-signal devices for industrial, automotive, and consumer markets.

The ST1L08 belongs to ST's high-performance LDO family targeting ultra-low-noise, ultra-low-dropout regulation in space- and power-constrained applications-specifically engineered for next-generation storage and portable computing systems demanding precise rail control and robust thermal behavior.

FAQ

What is the minimum required VBIAS voltage for ST1L08SPU33R?

The minimum VBIAS voltage is 2.7 V, but it must be at least 1.5 V higher than the output voltage (i.e., ≥4.8 V for 3.3 V output). This ensures proper gate drive for the N-channel pass transistor and guarantees specified dropout and PSRR performance across temperature and load.

Can ST1L08SPU33R operate with VIN = 3.3 V?

No-VIN must be ≥ VOUT + dropout voltage. With 3.3 V output and 90 mV max dropout, VIN must be ≥3.39 V to maintain regulation at 800 mA. At VIN = 3.3 V, the device enters dropout and cannot sustain 3.3 V output under load.

Is an external pull-up resistor required for the PG pin?

Yes-the PG pin is open-drain and requires an external pull-up resistor (typically 10–100 kΩ to VCC or V_REF) to generate a valid logic-high signal. Without it, PG remains floating and cannot assert power-good status to the host system.

Does ST1L08SPU33R require a minimum load current for stability?

No-it is unconditionally stable with ≥1 μF ceramic output capacitance and does not require a minimum load. Stability is maintained from zero load up to 800 mA, as confirmed by the datasheet's stability area plot (Figure 21) and transient response testing (Figures 24–25).