ST1S12GR - 3A, 18V Synchronous Step-Down Regulator | STMicroelectronics
MPN： ST1S12GR ✓ 啟用中ST1S12GR 概覽
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, improving efficiency by reducing conduction losses. In the power management hierarchy, a synchronous buck converter falls under DC-DC converters, which are a subset of voltage regulators, which in turn are part of power management ICs. This architecture is essential in battery-powered and high-current systems where thermal performance and efficiency are critical.
Key features of the ST1S12GR include a 3A output current capability, an adjustable output voltage from 0.8V to VIN, and a high efficiency of up to 95% at light loads. The device also features internal soft-start to limit inrush current, overcurrent protection, and thermal shutdown. The 1.5MHz switching frequency enables a compact solution footprint, and the SOT-23-6 package (also known as TSOT-6) is widely used in portable electronics.
Technically, the ST1S12GR employs a current-mode control architecture, providing fast transient response and stable operation with ceramic output capacitors. The integrated MOSFETs have low RDS(on), minimizing conduction losses, while the synchronous rectification improves efficiency at heavy loads. The device supports 100% duty cycle operation, allowing the output to be very close to the input voltage, which is beneficial for battery-powered applications where the input voltage can drop near the output.
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 range also makes it suitable for 12V and 24V industrial bus systems, providing a regulated 3.3V or 5V rail.
When designing with the ST1S12GR, ensure proper input and output capacitor selection to maintain stability and low output ripple. The inductor value should be chosen based on the desired ripple current, typically 30% of the maximum load current. Place the input capacitor close to the VIN pin to minimize parasitic inductance, and use a solid ground plane for thermal management.
直接替換替代品，適用於 ST1S12GR — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： ST1S12GR （相同外形與佔位） — 差異在於 Input Voltage Range, Output Voltage Range, Package, Switching Frequency, Maximum Output Current.
ST1S12GR
✅ 直接替換聯絡詢價
查看資料表 →ST1S12G
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
TPS54331DR
✅ 直接替換 ⚠️ 規格未經驗證聯絡詢價
查看資料表 →MP2307
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
RT8059
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
ST1S12GR 最大額定值與電氣特性
| 輸出類型 | Adjustable |
| 輸出電壓範圍 | 0.8 V to VIN |
| 最大輸出電流 | 3 A |
| 輸入電壓範圍 | 4.5 V to 18 V |
| 切換頻率 | 1.5 MHz |
| 效率 | Up to 95% |
| 同步整流 | Yes |
| Control Architecture | Current Mode |
| 軟啟動 | Internal |
| 過電流保護 | Yes |
| 過熱關機 | Yes |
| 工作溫度 | -40C to +150C |
| 封裝 | SOT-23-6 (TSOT-6) |
| 安裝類型 | Surface Mount |
| RoHS 狀態 | Compliant |
ST1S12GR 腳位配置
| 腳位 1 | SW — Switch node output |
| 腳位 2 | GND — Ground |
| 腳位 3 | FB — Feedback input |
| 腳位 4 | EN — Enable input |
| 腳位 5 | IN — Input supply |
| 腳位 6 | GND — Ground (exposed pad) |
典型應用
ST1S12GR 適用於 6 應用s: Point-of-Load (POL) Converters, Set-Top Boxes and Networking Equipment, Industrial Control Systems, Battery-Powered Devices, FPGA and DSP Power Supplies, Automotive Infotainment.
Point-of-Load (POL) Converters
The ST1S12GR 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 1.5MHz switching frequency enables small inductors and capacitors, saving board space. In a typical POL design, the ST1S12GR is placed close to the load, with input and output capacitors to minimize parasitic inductance. The high efficiency reduces heat dissipation, improving system reliability. Compared to linear regulators, the buck converter offers higher efficiency, especially at higher input-to-output voltage differences.
推薦
Set-Top Boxes and Networking Equipment
The ST1S12GR provides a regulated 3.3V or 5V rail from a 12V input in set-top boxes and networking equipment. Its wide input range (4.5V to 18V) accommodates various power supplies. The synchronous rectification ensures high efficiency, reducing heat and improving reliability in enclosed spaces. The compact SOT-23-6 package fits into dense PCB layouts. In a set-top box, the ST1S12GR can power the main SoC, memory, and interface ICs. The 1.5MHz switching frequency minimizes EMI, which is critical for consumer electronics. The internal soft-start prevents inrush current during power-up, protecting the input supply.
推薦
Industrial Control Systems
The ST1S12GR is suitable for industrial control systems that operate from 24V buses. Its input range up to 18V covers 12V and 24V systems with proper derating. The high efficiency reduces thermal stress in industrial enclosures. The device's overcurrent and thermal protection ensure robust operation in harsh environments. In a PLC, the ST1S12GR can generate a 5V rail for logic circuits and a 3.3V rail for microcontrollers. The current-mode control provides fast transient response, essential for motor control and actuator loads. The wide operating temperature range (-40C to +150C) meets industrial requirements.
推薦
Battery-Powered Devices
The ST1S12GR is ideal for battery-powered devices where efficiency is critical. Its synchronous architecture achieves up to 95% efficiency, extending battery life. The 100% duty cycle operation allows the output to track the input voltage as the battery discharges, maximizing usable capacity. The low quiescent current in light-load conditions further improves efficiency. In a portable device, the ST1S12GR can step down a 2-cell Li-ion battery (6-8.4V) to a 3.3V rail for the main processor. The small package and high switching frequency reduce the solution size, fitting into compact designs. The internal soft-start prevents battery voltage dips during startup.
推薦
FPGA and DSP Power Supplies
The ST1S12GR provides core and I/O voltages for FPGAs and DSPs, which often require multiple rails with tight voltage tolerances. The adjustable output and 3A current capability make it suitable for powering high-current cores. The fast transient response of current-mode control ensures stable operation during dynamic load changes. In an FPGA design, the ST1S12GR can generate a 1.0V core rail and a 3.3V I/O rail. The high switching frequency allows the use of small ceramic capacitors, reducing board space. The device's efficiency reduces heat, which is critical in high-density designs. The enable pin (if available) allows power sequencing.
推薦
Automotive Infotainment
The ST1S12GR is suitable for automotive infotainment systems that operate from a 12V battery. Its input range up to 18V handles load dump transients. The device's thermal shutdown and overcurrent protection ensure reliability in automotive environments. The high efficiency reduces heat in the dashboard. In an infotainment system, the ST1S12GR can power the main processor, display, and audio amplifier. The 1.5MHz switching frequency minimizes EMI, which is important for EMC compliance. The compact package fits into space-constrained head units. The wide operating temperature range meets automotive requirements.
推薦
推薦產品摘要
工程參考資料，適用於 ST1S12GR — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | ST1S12G | TPS54331DR | MP2307 | RT8059 |
|---|---|---|---|---|---|
| Package | SOT-23-6 | SOT-23-5 | SOT-23-6 | SOT-23-6 | SOT-23-6 |
| Brand | STMicroelectronics | STMicroelectronics | Texas Instruments | Monolithic Power Systems | Richtek |
| Input Voltage Range | 4.5V to 18V | 4.5V to 18V | 3.5V to 28V | 4.75V to 23V | 4.5V to 23V |
| Output Current | 3A | 3A | 3A | 3A | 3A |
| Switching Frequency | 1.5MHz | 1.5MHz | 570kHz | 340kHz | 1.5MHz |
| Synchronous Rectification | Yes | Yes | Yes | Yes | Yes |
| Control Architecture | Current Mode | Current Mode | Current Mode | Current Mode | Current Mode |
| Efficiency | Up to 95% | Up to 95% | Up to 92% | Up to 90% | Up to 95% |
主要差異化特點
- Higher switching frequency (1.5MHz) enables smaller external components (對比TPS54331DR)
- Higher efficiency at light loads (對比MP2307)
- Same-brand package variant available (對比ST1S12G)
設計說明
Place the input capacitor (10uF ceramic) as close as possible to the IN pin to minimize parasitic inductance. Use a solid ground plane and connect the exposed pad to the ground plane with multiple vias for thermal dissipation. Keep the feedback trace short and away from the SW node to avoid noise coupling.
The ST1S12GR in SOT-23-6 has a thermal resistance of approximately 90C/W (theta_JA). At 3A output with a 12V to 3.3V conversion, power dissipation is about 1.5W, resulting in a 135C temperature rise. Ensure adequate copper area and airflow to keep the junction temperature below 125C for reliable operation.
Do not exceed the absolute maximum input voltage of 20V. Use an inductor with a saturation current rating higher than the peak current (typically 1.2x the maximum output current). The feedback resistor divider should use 1% tolerance resistors to maintain output voltage accuracy. Ensure the EN pin is not left floating; tie it to VIN if not used.
合規資訊
RoHS compliant per STMicroelectronics product page. Not AEC-Q100 qualified.
