ST1S12XX STMicroelectronics Undefined or Miscellaneous (SOT23 (5-Pin)) In Stock
STMicroelectronics ST1S12XX is a synchronous step-down DC-DC converter delivering up to 3A output current from input voltages up to 5.5V in a compact SOT-23-5 package. It integrates both power switches and operates at up to 4 MHz switching frequency for small external component size. Available from stock with worldwide shipping.
- Manufacturer
- STMicroelectronics
- Package
- SOT23 (5-Pin)
- Pin Count
- 5
- Lifecycle
- ACTIVE
- Datasheet
- ST1S12XX Datasheet PDF
- Category
- Undefined or Miscellaneous
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
Key Features
- 3A output current capability with integrated high-side and low-side switches in a tiny SOT-23-5 footprint
- Up to 4 MHz switching frequency reducing inductor and capacitor sizes for ultra-compact power supply designs
- Input voltage range up to 5.5V covering USB, Li-Ion, and regulated 5V bus supply rails
- Synchronous rectification achieving high conversion efficiency and minimizing power dissipation in the package
- Adjustable output voltage via external resistor divider supporting a wide range of core and I/O supply requirements
Applications
The ST1S12XX targets portable consumer electronics, IoT modules, and wearable devices powered from single-cell Li-Ion batteries or 5V USB rails, where a 3A step-down converter in a SOT-23-5 form factor saves significant board area. It powers microcontroller and FPGA core voltages in compact embedded systems, replacing larger DC-DC modules. Industrial sensor nodes and wireless communication modules also rely on its high switching frequency to achieve sub-1µH inductors and small ceramic output capacitors.
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
Alternate & Equivalent Parts
Compatible alternatives and drop-in replacements for ST1S12XX:
Switching Regulator, Current-mode, 0.7A, 2080kHz Switching Freq-Max, NMOS, PDSO5
Frequently Asked Questions
How does the 4 MHz switching frequency of ST1S12XX benefit PCB layout in a space-constrained wearable design?
Operating at up to 4 MHz allows ST1S12XX to use inductors as small as 470 nH and output capacitors below 10 µF, shrinking the total power supply footprint to under 20 mm². This is critical in wearable devices where every square millimeter of PCB area is contested by sensors, antennas, and battery connectors.
What input voltage sources are compatible with ST1S12XX, and how does that simplify multi-rail system power architectures?
ST1S12XX accepts input voltages from approximately 2.5V to 5.5V, covering single-cell Li-Ion batteries at 4.2V, USB 5V VBUS rails, and regulated 5V system buses. A single converter design can therefore power 3.3V or 1.8V loads directly from USB or battery without an intermediate regulator stage, reducing BOM complexity.
For a 3A load application, how does ST1S12XX's synchronous rectification improve thermal performance compared to a diode-based converter?
Synchronous rectification replaces the catch diode with a low-RDS(on) N-channel MOSFET, cutting conduction losses at 3A by roughly 60% compared to a Schottky diode with 0.3V forward voltage. This reduces thermal rise inside the SOT-23-5 package, enabling the device to sustain full 3A output at ambient temperatures up to 85°C without external heat sinking.
When would ST1S12XX be selected over a larger QFN-packaged step-down regulator for an IoT sensor node?
ST1S12XX in SOT-23-5 is preferred when the load current stays at or below 3A and PCB area is the primary constraint, such as in IoT sensor nodes smaller than 20 mm × 30 mm. The SOT-23-5 occupies under 10 mm² versus a QFN-16 at roughly 25 mm², saving board space without sacrificing the efficiency needed for battery life targets of 1 year or longer.
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About STMicroelectronics
STMicroelectronics is a global semiconductor leader serving customers across the spectrum of electronics applications. ST's products are found in a wide range of applications including automotive, industrial, personal electronics, and communications.
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