ST1S09PUR - 2A 1.5MHz Sync Buck DC-DC Converter | STMicroelectronics
MPN： ST1S09PUR ✓ 啟用中ST1S09PUR 概覽
A step-down (buck) DC-DC converter is a switched-mode power supply topology that uses an internal MOSFET switch, an inductor, and a capacitor network to convert a higher DC input voltage into a lower DC output voltage. Unlike a linear regulator, a buck converter achieves high efficiency (typically 90-95%) by rapidly switching the input and filtering the resulting waveform, rather than continuously dissipating excess voltage as heat. Synchronous rectification replaces the conventional Schottky diode with a low-RDS(on) MOSFET, which further reduces conduction losses and improves thermal performance at heavy loads. Within the broader taxonomy, the ST1S09 belongs to the DC-DC converter family, which itself sits inside the voltage regulators and power management IC categories commonly used in modern electronics.
Key features of the ST1S09PUR include 1.5 MHz fixed-frequency current-mode PWM control, internal power MOSFETs (high-side and low-side synchronous switch), internal soft-start, current limiting, and thermal shutdown protection. The 1.5 MHz switching frequency allows the use of very small inductors and ceramic capacitors, enabling compact point-of-load designs on densely populated PCBs. The 6-lead DFN package includes an exposed thermal pad that provides a low thermal resistance path to the PCB copper, supporting continuous 2 A output without external heatsinking in properly laid-out boards.
Architecturally, the device uses peak current-mode control with internal compensation, providing cycle-by-cycle current limit, simple external component selection, and good transient response. The internal synchronous MOSFET reduces external part count to just an inductor, input bypass capacitor, output filter capacitor, and feedback resistor divider. According to the STMicroelectronics datasheet, the device includes an enable/shutdown input that allows the regulator to be placed in a low-quiescent state when not needed, supporting battery-powered applications.
Typical applications for the ST1S09PUR include powering DSPs, FPGAs, microcontrollers, and ASIC core or I/O rails from a 3.3 V or 5 V system rail, USB-powered devices, portable and battery-powered equipment, hard-disk drive power, and point-of-load regulation in distributed power architectures. The wide 2.7 V to 6 V input range also makes it compatible with single-cell Li-Ion battery systems (2.7 V to 4.2 V) and 5 V USB rails (4.5 V to 5.5 V under USB specification).
When designing with the ST1S09PUR, place input and output capacitors close to the IC, use a low-ESR ceramic output capacitor of at least 22 uF, and lay out the exposed pad on a continuous ground copper pour of at least 1 cm² to dissipate 2 A of continuous current without overheating. Verify the inductor saturation current rating exceeds the peak switch current limit by at least 20% margin for reliable operation.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical thermal and layout design notes not found in the manufacturer datasheet, helping engineers select, source, and implement the ST1S09PUR in compact high-efficiency power designs.
直接替換替代品，適用於 ST1S09PUR — 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。
ST1S09PUR-Q
✅ 直接替換 ⚠️ 規格未經驗證📋 參考替代品（不在目錄中）
ST1S10PUR
✅ 直接替換📋 參考替代品（不在目錄中）
ST1S06PUR
✅ 直接替換📋 參考替代品（不在目錄中）
ST1S09PUR 最大額定值與電氣特性
| 拓撲 | Synchronous Step-Down (Buck) |
| 輸入電壓範圍 | 2.7 V to 6 V |
| 輸出電壓範圍 | 0.8 V to 5 V (adjustable) |
| 最大輸出電流 | 2 A |
| 切換頻率 | 1.5 MHz (fixed) |
| Control Mode | Peak Current-Mode PWM |
| 同步整流器 | Yes (internal low-side MOSFET) |
| 輸出數量 | 1 |
| 輸出類型 | Adjustable |
| 工作接面溫度 | -30 C to +85 C |
| 封裝 | 6-VDFN Exposed Pad (DFN-6 EP) |
| 安裝類型 | Surface Mount |
| MSL 等級 | 1 |
| RoHS 狀態 | Compliant |
| 致能腳位 | Yes |
ST1S09PUR 腳位配置
| 腳位 1 | VIN — Input voltage supply (2.7 V to 6 V) |
| 腳位 2 | SW — Switch node - connect to power inductor |
| 腳位 3 | GND — Ground return |
| 腳位 4 | FB — Feedback (set Vout via external resistor divider) |
| 腳位 5 | EN — Enable input (drive high to enable regulator) |
| 腳位 6 | AGND — Analog ground (also tied to exposed pad) |
典型應用
ST1S09PUR 適用於 6 應用s: FPGA Core Voltage Rail, USB-Powered 5V to 3.3V Conversion, Portable Li-Ion Battery Power, Hard Disk Drive Power, Point-of-Load Regulation, DSP and Microcontroller Core Supply.
FPGA Core Voltage Rail
The ST1S09PUR's 2 A output capability and 0.8 V minimum output make it well-suited for powering FPGA and ASIC core rails from a 3.3 V or 5 V system bus. With 1.5 MHz switching frequency the regulator can use a 1.0 uH to 2.2 uH inductor, keeping the power stage under 25 mm² of PCB area while still meeting the FPGA's transient response requirements. Synchronous rectification keeps efficiency above 90 percent at typical core loads of 0.5 A to 1.5 A, so the 6-pin DFN package does not require external heatsinking.
推薦
USB-Powered 5V to 3.3V Conversion
The ST1S09PUR's 2.7 V to 6 V input range covers the USB 5 V bus (4.5 V to 5.5 V), making it ideal for stepping down USB rail voltage to 3.3 V at up to 2 A. The high 1.5 MHz switching frequency allows the use of a single 2.2 uH inductor and 22 uF ceramic output capacitor, producing a compact solution that fits inside USB dongles and small peripherals. Internal soft-start limits inrush current to USB-compliant levels, and the enable pin allows the device to be placed in shutdown for suspend-mode power savings.
推薦
Portable Li-Ion Battery Power
The ST1S09PUR's 2.7 V minimum input voltage is designed to follow a single-cell Li-Ion battery down to its cut-off voltage, enabling direct battery-powered designs without a boost pre-regulator. At 2 A peak output the converter maintains 90 percent efficiency across most of the discharge curve, extending battery run-time. The exposed-pad DFN-6 package keeps the footprint under 25 mm², freeing board area for additional sensors or radios in wearable and handheld products.
推薦
Hard Disk Drive Power
The ST1S09PUR's synchronous buck topology delivers the high peak currents demanded by HDD spindle motors and 3.3 V/5 V logic rails from a single 5 V input. 2 A continuous current capability handles simultaneous motor spin-up and read-channel supply transients. The small DFN-6 footprint and 1.5 MHz switching frequency simplify PCB layout inside the tight HDD chassis, and the exposed pad maintains case temperature below 85 C during continuous read/write cycles.
推薦
Point-of-Load Regulation
The ST1S09PUR excels as a point-of-load (POL) converter placed adjacent to high-current digital ICs that need low-voltage supplies derived from a higher system bus. With 1.5 MHz switching frequency and 0.8 V to 5 V adjustable output, the device can supply 1.2 V, 1.5 V, 1.8 V, 2.5 V, or 3.3 V rails directly at the load, minimizing distribution losses and improving transient response. Synchronous rectification achieves over 90 percent efficiency at typical POL loads of 0.5 A to 1.5 A.
推薦
DSP and Microcontroller Core Supply
The ST1S09PUR's 2 A output and 0.8 V minimum Vout make it a strong fit for DSP and MCU core rails in industrial and consumer designs powered from a 3.3 V bus. Peak current-mode control provides fast transient response to digital load steps, and the fixed 1.5 MHz frequency avoids audible noise and simplifies EMI filtering. Internal cycle-by-cycle current limit and thermal shutdown protect the load during fault conditions, while the 6-pin DFN package simplifies manufacturing with a single exposed-pad layout.
推薦
推薦產品摘要
工程參考資料，適用於 ST1S09PUR — 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 | ST1S09PUR-Q | ST1S10PUR | ST1S06PUR |
|---|---|---|---|---|
| Package | DFN-6 (VDFN EP) | DFN-6 (VDFN EP) - same | DFN-6 (VDFN EP) - same | DFN-6 (VDFN EP) - same |
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics |
| Output Current | 2 A | 2 A | 3 A | 1.5 A |
| Input Voltage Range | 2.7 V to 6 V | 2.7 V to 6 V | 2.7 V to 6 V | 2.7 V to 6 V |
| Switching Frequency | 1.5 MHz | 1.5 MHz | 1.5 MHz | 1.5 MHz |
| Output Voltage Range | 0.8 V to 5 V | 0.8 V to 5 V | 0.8 V to 5 V | 0.8 V to 5 V |
| Synchronous Rectifier | Yes | Yes | Yes | Yes |
| Automotive Grade | No | Yes (AEC-Q100 qualified) | No | No |
主要差異化特點
- Higher output current in same package (對比ST1S06PUR)
- Automotive-grade variant available (對比ST1S09PUR)
- Lower output current option available (對比ST1S10PUR)
設計說明
Estimated: At VIN=5 V, VOUT=3.3 V, and 2 A continuous load, the ST1S09PUR dissipates approximately (5 V - 3.3 V) x 2 A = 3.4 W of loss. The DFN-6 exposed-pad package depends on PCB copper for heatsinking - lay out at least 1 cm² of continuous ground copper pour connected to the exposed pad to keep junction temperature below 85 C. Without proper copper, thermal shutdown may trigger at sustained high loads.
Place input bypass capacitor (10 uF ceramic minimum) within 2 mm of the VIN pin and the output filter capacitor (22 uF ceramic minimum) within 2 mm of the inductor/feedback node. Keep the feedback trace short and routed away from the SW node to avoid noise coupling. The exposed pad must be soldered to a continuous ground plane with multiple thermal vias for proper heatsinking.
Do not exceed the absolute maximum VIN of 6 V or the device will be damaged. Select an inductor with saturation current rating at least 20% above the ST1S09's peak current limit (typically 2.5 A to 3 A) to avoid saturation during transient load steps. Always set the output voltage via the FB resistor divider before applying VIN to ensure predictable startup behavior.
合規資訊
RoHS compliant per ST product page. Standard variant is not AEC-Q100 qualified; choose ST1S09PUR-Q suffix variant for automotive applications.
