STMicroelectronics ST1S50PUR

Overview

ST1S50PUR from STMicroelectronics is a monolithic 4 A synchronous step-down DC-DC converter with fixed 500 kHz switching frequency, integrated 95 mΩ high-side and 69 mΩ low-side MOSFETs, adjustable output (0.8 V to 0.88 × VIN), and Power Good signaling - used for core/I/O supplies in FPGA, ASIC, and DSP point-of-load applications.

For engineers reviewing the ST1S50PUR datasheet, ST1S50PUR pinout, ST1S50PUR application, or ST1S50PUR equivalent, key selection criteria include light-load PFM efficiency, programmable soft-start timing via external capacitor, cycle-by-cycle current limiting, thermal shutdown hysteresis (150 °C trip / 130 °C recovery), and VFDFPN10 package compatibility with all-ceramic output designs.

Technical Context

The ST1S50PUR implements peak current mode control with internal slope compensation to prevent subharmonic oscillation above 50% duty cycle. Its trans-conductance error amplifier (250 µS, 240 MΩ output resistance) interfaces with an external RC compensation network on the COMP pin to stabilize the loop across load and input variations.

It integrates UVLO (3.0 V turn-off / 3.5 V turn-on), hiccup-mode short-circuit protection triggered at FB < 0.3 V, and dual-level overcurrent response: cycle-by-cycle limiting up to 5.6 A, then frequency halving (FSW/2) if FB drops below 0.734 V for >256 cycles, followed by thermal-foldback shutdown and auto-restart.

Key Specifications

Pinout & Package

ST1S50PUR is housed in a VFDFPN10 (3 mm × 3 mm × 1 mm) thermally enhanced package with exposed power pad (GNDP). Pin 1 is marked by a dot; top-view pin numbering follows standard counter-clockwise layout.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar synchronous step-down regulator applications.

Compared with TPS54332DR and MP2315DJ-LF-Z, ST1S50PUR delivers higher current (4 A vs. ≤3.5 A), integrated MOSFETs with lower R_DS(on), built-in PG and hiccup protection, and superior light-load efficiency - making it optimal for space-constrained, reliability-critical embedded PoL systems.

Availability

ST1S50PUR is available at Aetrix Electronics and suitable for FPGA core supplies, ASIC I/O domains, optical drive motor controllers, and smart TV SoC auxiliary rails requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for ST1S50PUR 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 automotive, industrial, and consumer markets.

The ST1S50PUR belongs to ST's monolithic synchronous buck regulator product line, designed specifically for high-efficiency, low-footprint point-of-load conversion in space- and thermal-constrained embedded systems.

FAQ

What is the minimum recommended output capacitance for stable operation?

The ST1S50PUR requires ≥22 µF total ceramic output capacitance with low ESR (≤5 mΩ) to maintain stability and meet ripple specifications. Recommended configurations include two 10 µF/6.3 V X5R 0805 MLCCs in parallel, placed within 3 mm of the SW and GNDA pins. Larger values improve transient response but require re-optimization of the COMP compensation network per Section 6.4 of the datasheet.

How does the soft-start capacitor value affect hiccup behavior during overload?

The EN_SS pin capacitor (CSS) directly sets both soft-start duration and hiccup timeout: THICCUP = 2,853,934 × CSS (seconds). For example, a 100 nF capacitor yields ~285 ms hiccup interval. This linear scaling allows designers to tune fault recovery timing without modifying firmware or adding external timers - critical for meeting IEC 62368-1 fault containment requirements.

Can ST1S50PUR operate with input voltage below 4.0 V?

No - the absolute minimum operating input voltage is 4.0 V per datasheet specification. Below this, UVLO disables the device (VINOFF = 3.0 V), and attempting operation risks unstable regulation, premature thermal shutdown, or failure to initiate soft-start. For sub-4 V applications, consider ST's ST1S41 (2.5–5.5 V input) or discrete controller + external FET solutions.

Is the VFDFPN10 package RoHS and REACH compliant?

Yes - ST1S50PUR is manufactured in ST's RoHS-compliant and REACH-conformant facilities. The VFDFPN10 package uses lead-free matte tin plating and meets JEDEC J-STD-020 moisture sensitivity level 3 (MSL3) - requiring bake before reflow if exposed to ambient >30 °C/60% RH for >168 hours. Full compliance documentation is available via ST's Quality Portal using order code ST1S50PUR.