STMicroelectronics ST1S06PU33R

Overview

ST1S06PU33R from STMicroelectronics is a fixed-output 3.3 V, 1.5 A synchronous step-down DC-DC converter with 1.5 MHz current-mode PWM control, 2% output voltage tolerance, and integrated NMOS/PMOS power switches (R_DS(ON) = 120 mΩ / 150 mΩ). It features an inhibit pin for enable/disable control, internal soft-start, thermal shutdown (130–150 °C), and operates from 4.2 V to 5.5 V input in HDD digital core power applications.

For engineers reviewing the ST1S06PU33R datasheet, ST1S06PU33R pinout, ST1S06PU33R application, or ST1S06PU33R equivalent, this device is selected for high-efficiency, space-constrained low-voltage regulation where ceramic capacitor compatibility, <1.5 mA quiescent current in shutdown, and DFN6D (3×3 mm) thermal performance are critical design requirements.

Technical Context

The ST1S06PU33R implements a constant-frequency, current-mode PWM architecture with internal compensation, enabling stable operation with only two ceramic capacitors and one inductor. Its fixed 3.3 V output is achieved via internal feedback reference (V_FB = 0.8 V), eliminating external resistor divider components.

It integrates dual MOSFETs in a synchronous rectifier configuration, supports cycle-by-cycle current limiting (2.3 A peak), and dynamically reduces switching frequency below 250 mA load to improve light-load efficiency. Thermal protection engages at ~130 °C junction temperature with 15 °C hysteresis.

Key Specifications

Pinout & Package

ST1S06PU33R is housed in a thermally enhanced DFN6D (3 × 3 mm, 0.95 mm pitch) package with exposed pad soldered to PCB ground for optimal thermal dissipation (R_thJA = 55 °C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS62130ARGTR and ADP2303ARDZ-3.3-R7, ST1S06PU33R offers optimal balance of 1.5 A capability, 1.5 MHz switching, 1 µA inhibit current, and DFN6D thermal performance - making it preferred for cost-sensitive, space-constrained 3.3 V HDD and embedded controller rails.

Availability

ST1S06PU33R is available at Aetrix Electronics and suitable for HDD digital core power, embedded microcontroller supply, and portable storage controller applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant DFN packaging.

Supply support for ST1S06PU33R 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 ST1S06xx series was developed specifically for high-efficiency, low-profile DC-DC conversion in disk drive and portable digital systems - emphasizing thermal robustness, ceramic capacitor compatibility, and minimal external component count.

FAQ

What input voltage range is supported for the ST1S06PU33R?

The ST1S06PU33R operates with a minimum input voltage of 4.2 V and a maximum of 5.5 V when delivering its rated 1.5 A output at 3.3 V. This range is specified in Table 7 of the datasheet for the ST1S06PM33 variant, which corresponds to the ST1S06PU33R fixed 3.3 V version. Operation outside this window may cause dropout or instability.

Does the ST1S06PU33R require external compensation components?

No. The ST1S06PU33R features fully internal compensation optimized for ceramic output capacitors, eliminating the need for external RC networks or type-II/type-III compensators. This is confirmed in Section 7 ("Application notes") of the datasheet, which states the device is "a complete 1.5 A switching regulator with its internal compensation eliminating additional component."

How is thermal performance managed in the DFN6D package?

Thermal performance relies on soldering the exposed pad directly to a large PCB copper pour tied to system ground. The datasheet specifies R_thJA = 55 °C/W and R_thJC = 10 °C/W, meaning effective heatsinking through the pad is essential. Layout guidelines in Figure 25 recommend a 3.3 mm × 3.3 mm thermal pad with ≥4 thermal vias to inner ground planes.

Can the ST1S06PU33R be used with input voltages below 4.2 V?

No - for the ST1S06PU33R (3.3 V fixed version), the absolute minimum input voltage is 4.2 V, as defined in Table 7 for ST1S06PM33. Attempting operation below this threshold results in dropout, inability to sustain 1.5 A load, and potential instability. For lower-input applications, the adjustable ST1S06PUR or ST1S06APUR variants should be considered instead.