ST1S50PUR - 3A, 18V Synchronous Step-Down Converter | STMicroelectronics
MPN: ST1S50PUR ✓ Active| 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 |
ST1S50PUR Overview
A synchronous buck converter is a type of DC-DC step-down regulator that uses two active switches (typically MOSFETs) instead of a diode for the low-side element, which significantly improves efficiency, especially at lower output voltages. This architecture is fundamental in power management ICs, where efficiency directly impacts battery life, thermal management, and system reliability. The ST1S50PUR belongs to the family of synchronous step-down converters, which are essential building blocks in modern electronic systems, from portable devices to industrial equipment.
Key features of the ST1S50PUR include a fixed 1.5 MHz switching frequency, which allows the use of small, low-cost inductors and capacitors, reducing the overall solution footprint. The device offers a typical efficiency of 90% at 3A load, with a low quiescent current of 1.2 mA in light-load operation. It also features internal soft-start to limit inrush current, overcurrent protection, and thermal shutdown for robust operation. The DFN8 package has an exposed pad for enhanced thermal performance, with a thermal resistance of 40°C/W.
The ST1S50PUR utilizes a current-mode control architecture, providing fast transient response and stable operation over a wide range of input and output voltages. The integrated MOSFETs have low RDS(on) (typically 120 mΩ high-side and 80 mΩ low-side), minimizing conduction losses. The device operates over a junction temperature range of -40°C to +150°C, making it suitable for demanding environments.
Typical applications include point-of-load (POL) converters for FPGAs, DSPs, and microcontrollers, as well as power supplies for set-top boxes, networking equipment, and industrial control systems. The wide input voltage range also supports 12V and 24V bus systems, making it versatile for various power architectures.
When designing with the ST1S50PUR, ensure proper input and output capacitor selection to maintain stability and minimize ripple. The exposed pad should be soldered to a large copper area for effective heat dissipation. The EN pin allows for power sequencing, and the soft-start feature prevents output overshoot during startup.
Drop-in alternatives for ST1S50PUR — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with ST1S50PUR (same form factor and footprint) — differing in Input Voltage Range, Maximum Output Current, Output Voltage Range, Package, Quiescent Current.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
ST1S50PHR
📋 Reference alternative (not in catalog)
ST1S50PURTR
📋 Reference alternative (not in catalog)
TPS54331DR
✓ In Stock
$0.85 / Unit
View Datasheet →MP2307DN
📋 Reference alternative (not in catalog)
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) |
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
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
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
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
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
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
Recommended Products Summary
Engineering reference data for ST1S50PUR — comparison, design guidance, and compliance information.
Selection Guide
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.
Compliance Information
RoHS compliant per STMicroelectronics product page. Not AEC-Q100 qualified. Halogen-free status not specified in available data.
