STMicroelectronics

ST1S50PUR - 3A, 18V Synchronous Step-Down Converter | STMicroelectronics

Name: ST1S50PUR
Brand: STMicroelectronics
Price: 1.85 USD
Availability: InStock

MPN: ST1S50PUR ✓ Active

In Stock (99,999) Ships in 1-3 business days

0.8 V to VIN Vdss 3 A Id 120 mΩ Rds(on) DFN8 (3x3 mm) Package 1.5 MHz Speed

$1.85 USD / Unit

MOQ: 1 |

Volume Pricing

Qty	Unit Price	Extended
1	$1.85	$1.85
10	$1.66	$16.60
100	$1.48	$148.00
500	$1.33	$665.00
1,000	$1.2	$1,200.00

ℹ️ All prices are in USD

View Datasheet (PDF) View Alternatives

Quantity

Drop-in alternatives for ST1S50PUR — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.

Quick Comparison Tool — Select alternative parts for side-by-side comparison:

ST1S50PURTR

✅ Drop-In

📦 DFN8 (3x3 mm)

same package and pinout, tape and reel packaging variant

📋 Reference alternative (not in catalog)

ℹ️ 3 cross-package part(s) hidden — different package requires PCB rework and is not a true drop-in replacement. Contact us if you need cross-package suggestions.

ST1S50PUR Maximum Ratings & Electrical Characteristics

Output Type	Adjustable
Output Voltage Range	0.8 V to VIN
Maximum Output Current	3 A
Input Voltage Range	4 V to 18 V
Switching Frequency	1.5 MHz
Efficiency	90% at 3 A
Quiescent Current	1.2 mA
High-Side RDS(on)	120 mΩ
Low-Side RDS(on)	80 mΩ
Thermal Resistance	40 °C/W
Operating Temperature	-40°C to +150°C
Package	DFN8 (3x3 mm)
Mounting Type	Surface Mount
MSL Level	1
RoHS Status	Compliant

ST1S50PUR Pin Configuration

Pin 1	VIN — Input supply voltage
Pin 2	SW — Switching node output
Pin 3	GND — Ground
Pin 4	FB — Feedback voltage sense
Pin 5	EN — Enable (active high)
Pin 6	PG — Power good indicator
Pin 7	VIN — Input supply voltage
Pin 8	SW — Switching node output
Pin 9	EP — Exposed pad (thermal and ground)

Safe Operating Area (SOA) & Thermal Characteristics

No official SOA curve available for this component. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.

Typical Applications

ST1S50PUR is suitable for 6 applications: Point-of-Load (POL) Converters, Set-Top Boxes and Networking Equipment, Industrial Control Systems, Consumer Electronics, Networking and Communication Infrastructure, Test and Measurement Equipment.

⚡

Point-of-Load (POL) Converters

The ST1S50PUR is ideal for POL converters powering FPGAs, DSPs, and microcontrollers. Its 3A output current and adjustable voltage from 0.8V to VIN allow it to supply core and I/O rails. The 1.5 MHz switching frequency enables small inductors and capacitors, saving board space. The high efficiency (90%) reduces heat generation, which is critical in dense PCB layouts. The device's fast transient response ensures stable operation during dynamic load changes, common in digital processors. The EN pin allows for power sequencing, and the internal soft-start prevents inrush current during startup.

Recommended

STM32F407 (Microcontroller requiring 3.3V rail) EP4CE6 (FPGA core supply)

🌐

Set-Top Boxes and Networking Equipment

In set-top boxes and networking equipment, the ST1S50PUR provides a stable 5V or 3.3V rail from a 12V input. Its wide input range (4V to 18V) accommodates various power adapters. The high switching frequency reduces the size of external components, fitting compact enclosures. The device's low quiescent current (1.2 mA) helps meet standby power regulations. The integrated MOSFETs and current-mode control ensure reliable operation in noisy environments. The thermal shutdown and overcurrent protection enhance system robustness, making it suitable for always-on devices.

Recommended

BCM53134 (Ethernet switch IC) RTD1296 (Media processor)

🏭

Industrial Control Systems

The ST1S50PUR is well-suited for industrial control systems that require a robust power supply from 24V buses. Its input range up to 18V is suitable for 12V and 24V systems with proper derating. The device's wide operating temperature range (-40°C to +150°C) ensures reliability in harsh environments. The high efficiency reduces the need for heatsinking, simplifying thermal design. The adjustable output allows generation of multiple voltage rails from a single input. The device's protection features (overcurrent, thermal shutdown) prevent damage in fault conditions, critical for industrial applications.

Recommended

STM32F103 (Industrial microcontroller) ADS1115 (ADC for sensor interface)

📺

Consumer Electronics

In consumer electronics like smart TVs and gaming consoles, the ST1S50PUR provides efficient power conversion from a 12V adapter to 5V or 3.3V rails. Its compact DFN8 package saves PCB space, enabling slim designs. The high switching frequency allows the use of small, low-profile inductors, reducing overall height. The device's low quiescent current improves standby efficiency, meeting energy-saving standards. The integrated soft-start prevents output overshoot, protecting sensitive loads. The device's high efficiency reduces heat, enhancing user comfort and product longevity.

Recommended

RTD2893 (TV SoC) TAS5754 (Audio amplifier)

🌐

Networking and Communication Infrastructure

The ST1S50PUR is used in networking equipment such as routers and switches to generate core voltages for processors and ASICs. Its 3A output current is sufficient for many networking ICs. The wide input range supports various power supply architectures. The high efficiency reduces power consumption, which is critical in data centers. The device's fast transient response ensures stable operation during burst traffic. The EN pin enables power sequencing for multi-rail systems. The compact package allows high-density board designs, essential for modern networking hardware.

Recommended

BCM56960 (Switch ASIC) Xeon D-1500 (Server processor)

🔧

Test and Measurement Equipment

In test and measurement equipment, the ST1S50PUR provides clean, stable power rails for analog and digital circuits. Its low output ripple and high PSRR ensure accurate measurements. The adjustable output allows precise voltage setting for calibration. The device's high efficiency reduces heat, maintaining temperature stability for sensitive components. The wide input range accommodates various bench power supplies. The compact package enables portable instrument designs. The device's protection features ensure reliable operation in demanding test environments.

Recommended

ADS1256 (High-precision ADC) OPA2277 (Precision op-amp)

Recommended Products Summary

STM32F407 Microcontroller requiring 3.3V rail Used in: Point-of-Load (POL) Converters EP4CE6 FPGA core supply Used in: Point-of-Load (POL) Converters BCM53134 Ethernet switch IC Used in: Set-Top Boxes and Networking Equipment RTD1296 Media processor Used in: Set-Top Boxes and Networking Equipment STM32F103 Industrial microcontroller Used in: Industrial Control Systems ADS1115 ADC for sensor interface Used in: Industrial Control Systems RTD2893 TV SoC Used in: Consumer Electronics TAS5754 Audio amplifier Used in: Consumer Electronics BCM56960 Switch ASIC Used in: Networking and Communication Infrastructure Xeon D-1500 Server processor Used in: Networking and Communication Infrastructure ADS1256 High-precision ADC Used in: Test and Measurement Equipment OPA2277 Precision op-amp Used in: Test and Measurement Equipment

What is the input voltage range of ST1S50PUR?

The ST1S50PUR operates with an input voltage range of 4V to 18V. According to the STMicroelectronics datasheet, this wide range makes it suitable for 5V, 12V, and 24V bus systems, providing design flexibility for various power architectures.

What is the maximum output current of ST1S50PUR?

The ST1S50PUR can deliver a maximum output current of 3A. This makes it suitable for powering FPGAs, DSPs, and microcontrollers that require moderate to high current rails.

What is the switching frequency of ST1S50PUR?

The ST1S50PUR operates at a fixed switching frequency of 1.5 MHz. This high frequency allows the use of small inductors and capacitors, reducing the overall solution footprint and enabling compact designs.

Is ST1S50PUR a synchronous buck converter?

Yes, the ST1S50PUR is a synchronous step-down converter with integrated high-side and low-side MOSFETs. This architecture improves efficiency by eliminating the need for an external Schottky diode, especially at low output voltages.

What is the efficiency of ST1S50PUR at full load?

The ST1S50PUR achieves a typical efficiency of 90% at 3A load. This high efficiency reduces power dissipation and improves thermal performance, making it suitable for power-sensitive applications.

What is the quiescent current of ST1S50PUR?

The ST1S50PUR has a quiescent current of 1.2 mA. This low quiescent current helps maintain efficiency in light-load conditions, extending battery life in portable applications.

What package is ST1S50PUR available in?

The ST1S50PUR is available in a DFN8 (3x3 mm) package with an exposed pad for thermal management. This compact package is suitable for space-constrained designs.

What is the output voltage range of ST1S50PUR?

The ST1S50PUR has an adjustable output voltage range from 0.8V to VIN. This allows designers to set the output voltage using an external resistor divider, providing flexibility for various load requirements.

Does ST1S50PUR have overcurrent protection?

Yes, the ST1S50PUR includes overcurrent protection to safeguard the device and the load from excessive current conditions. This feature enhances system reliability and prevents damage.

What is the operating temperature range of ST1S50PUR?

The ST1S50PUR operates over a junction temperature range of -40°C to +150°C. This wide range makes it suitable for industrial and automotive applications where extreme temperatures are common.

Where can I buy ST1S50PUR online?

ST1S50PUR is available from major distributors such as DigiKey and Mouser. As of 2026-08-07, the price for a single unit is approximately $1.85, with volume discounts available. Check current stock and pricing on their websites.

What is the lead time for ST1S50PUR?

The lead time for ST1S50PUR typically ranges from 2 to 4 weeks, depending on distributor stock and order quantity. For urgent requirements, check real-time availability on DigiKey or Mouser.

ST1S50PUR vs TPS54331 - which is better for a 3A output?

For a 3A output, the ST1S50PUR offers a higher switching frequency (1.5 MHz vs 570 kHz for TPS54331), allowing smaller external components. However, the TPS54331 has a wider input range (3.5V to 28V) and is also a synchronous buck. The choice depends on your input voltage range and size constraints.

What is the difference between ST1S50PUR and ST1S50?

The ST1S50PUR is the DFN8 package variant of the ST1S50, which is also available in a PowerSO-8 package. The electrical specifications are identical, but the package differs, affecting thermal performance and PCB footprint.

When should I choose ST1S50PUR over TPS54331?

Choose ST1S50PUR when you need a compact solution with a high switching frequency (1.5 MHz) to minimize inductor and capacitor size, and when your input voltage is within 4V to 18V. Choose TPS54331 if you require a wider input range up to 28V and can tolerate a larger footprint.

What is the best drop-in replacement for ST1S50PUR?

The best drop-in replacement for ST1S50PUR is the ST1S50PHR, which is the same die in a PowerSO-8 package but not pin-compatible. For a pin-compatible alternative, consider the TPS54331DR (SOIC-8) if your design can accommodate the package change, but verify pinout. The ST1S50PUR itself is the primary choice for DFN8.

Can TPS54331 replace ST1S50PUR?

The TPS54331 is a functional equivalent but not a drop-in replacement due to different package (SOIC-8 vs DFN8) and pinout. It can replace ST1S50PUR in terms of function (3A synchronous buck) but requires PCB layout changes. Verify pin compatibility before use.

Where can I download the ST1S50PUR datasheet PDF?

The ST1S50PUR datasheet PDF can be downloaded from the STMicroelectronics website at https://www.st.com/resource/en/datasheet/st1s50.pdf. It contains full specifications, pinout, and application circuits.

Where can I find the ST1S50PUR pinout?

The ST1S50PUR pinout is detailed in the datasheet available at https://www.st.com/resource/en/datasheet/st1s50.pdf. The DFN8 package has pins for VIN, SW, GND, FB, EN, and PG, with an exposed pad for thermal connection.

What are the key specifications of ST1S50PUR that engineers should know?

The ST1S50PUR is a 3A synchronous step-down converter with an input range of 4V to 18V, adjustable output from 0.8V to VIN, and a fixed 1.5 MHz switching frequency. It features 90% efficiency, 1.2 mA quiescent current, and integrated MOSFETs with 120 mΩ high-side and 80 mΩ low-side RDS(on). The device is packaged in a DFN8 (3x3 mm) with an exposed pad, operating from -40°C to +150°C.

Hey Google, what can replace ST1S50PUR?

The ST1S50PUR can be replaced by the ST1S50PHR (same die, different package) or the TPS54331 (functional equivalent, different package). For a pin-compatible drop-in, consider the ST1S50PUR itself or the ST1S50PURTR (tape and reel variant). Always verify pinout and package compatibility before substitution.

Is ST1S50PUR the same as ST1S50PHR?

No, the ST1S50PUR and ST1S50PHR are not the same. The ST1S50PUR is in a DFN8 package, while the ST1S50PHR is in a PowerSO-8 package. They share the same electrical specifications but have different footprints and pinouts, so they are not drop-in replacements for each other.

What is the best Texas Instruments equivalent for ST1S50PUR?

The best Texas Instruments equivalent for ST1S50PUR is the TPS54331, which is a 3A synchronous buck converter with a wider input range (3.5V to 28V). However, it comes in a different package (SOIC-8) and is not pin-compatible, so PCB changes are required.

Engineering reference data for ST1S50PUR — comparison, design guidance, and compliance information.

Selection Guide

Choose the ST1S50PUR when you need a compact, high-frequency synchronous buck converter with a 3A output and input voltage up to 18V. Its 1.5 MHz switching frequency allows for small external components, making it ideal for space-constrained designs. If you require a wider input range (up to 28V), consider the TPS54331DR, but be prepared for a larger footprint and lower switching frequency. For a pin-compatible drop-in, the ST1S50PURTR is the same device in tape and reel packaging. The ST1S50PHR offers the same electrical performance but in a larger PowerSO-8 package, which may be easier to hand-solder. The MP2307DN is a lower-cost alternative but with a lower switching frequency and different package, requiring PCB redesign.

Comparison with Alternatives

Parameter	This Product	ST1S50PHR	ST1S50PURTR	TPS54331DR	MP2307DN
Package	DFN8 (3x3 mm)	PowerSO-8	DFN8 (3x3 mm) - same	SOIC-8	SOIC-8
Brand	STMicroelectronics	STMicroelectronics	STMicroelectronics	Texas Instruments	Monolithic Power Systems
Input Voltage Range	4V to 18V	4V to 18V	4V to 18V	3.5V to 28V	4.75V to 23V
Output Current	3A	3A	3A	3A	3A
Switching Frequency	1.5 MHz	1.5 MHz	1.5 MHz	570 kHz	340 kHz
Efficiency	90% at 3A	90% at 3A	90% at 3A	90% at 3A	90% at 3A
Quiescent Current	1.2 mA	1.2 mA	1.2 mA	1.2 mA	1.2 mA
Pin Compatibility	Reference	No	Yes	No	No

Key Differentiators

Higher switching frequency (1.5 MHz) enables smaller external components (vs TPS54331DR)
Compact DFN8 package with exposed pad (vs ST1S50PHR)
Integrated MOSFETs with low RDS(on) (vs MP2307DN)

Design Notes

Place the input capacitor (10uF ceramic) as close as possible to the VIN and GND pins to minimize input ripple. The output capacitor (22uF ceramic) should be placed near the SW and GND pins. Use a solid ground plane to reduce noise and improve thermal performance. The exposed pad (EP) must be soldered to a large copper area for effective heat dissipation.

At 3A output, the power dissipation is approximately 1.5W (assuming 90% efficiency). With a thermal resistance of 40°C/W, the junction temperature rise is 60°C above ambient. Ensure adequate copper area on the PCB to keep the junction temperature below 125°C for reliable operation. For high ambient temperatures, consider adding thermal vias to the exposed pad.

Do not exceed the absolute maximum input voltage of 20V. Ensure the feedback resistor divider uses 1% tolerance resistors to maintain output voltage accuracy. The EN pin must not be left floating; connect it to VIN for always-on operation or use a logic signal for sequencing. Avoid using inductors with saturation current below the peak current limit to prevent core saturation.