Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - DC DC Switching Regulators

STMicroelectronics ST1S12G12R

Name: ST1S12G12R
Brand: STMicroelectronics
SKU: ST1S12G12R
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: ST1S12G12R

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: SOT-23-5 Thin, TSOT-23-5

Datasheet:: ST1S12G12R.pdf

Description:: IC REG BUCK 1.2V 700MA TSOT23-5

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:6,614

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

ST1S12G12R from STMicroelectronics is a synchronous step-down DC-DC converter IC optimized for powering low-voltage digital cores (e.g., HDD controller logic, FPGA I/O banks, ASIC cores) with fixed 1.2 V output, 0.7 A load capability, 1.7 MHz switching frequency, ±3% output voltage tolerance, and TSOT23-5L package.

For engineers reviewing the ST1S12G12R datasheet, ST1S12G12R pinout, ST1S12G12R application, or ST1S12G12R equivalent, this page delivers verified technical context, validated pin functions, real-world application constraints, and confirmed alternative options - all grounded in ST's official Doc ID 14314 Rev 5 specification.

Technical Context

This current-mode PWM regulator integrates NMOS and PMOS power switches (R_DS(on) = 250 mΩ / 400 mΩ typ.) and uses internal compensation to eliminate external loop components. Its 1.7 MHz fixed-frequency operation enables compact 2.2 µH inductors and ceramic capacitors (X5R/X7R).

The device implements thermal shutdown (130–150 °C), cycle-by-cycle current limiting (1.6 A), and internal soft-start. Feedback is referenced to a precise 600 mV bandgap (±30 mV over –40 to +125 °C), enabling stable 1.2 V regulation via direct FB/VO pin connection - no external resistor divider required.

Key Specifications

Parameter	Value and Actual Design Meaning
Output Voltage	Fixed 1.2 V ±3% - eliminates need for external feedback resistors; supports tight-core rail requirements.
Max Output Current	0.7 A continuous - sufficient for low-power microcontrollers, DDR I/O, and sensor interface rails.
Switching Frequency	1.7 MHz (typ.) - enables use of sub-3 mm × 3 mm inductors and reduces output ripple without large bulk capacitance.
Quiescent Current	650 µA max (over temp) - preserves battery life in always-on subsystems; drops to 1 µA in shutdown.
Input Voltage Range	2.5 V to 5.5 V - compatible with single-cell Li-ion, USB 5 V, and regulated 3.3 V/5 V system rails.
Efficiency	90% typ. at 100–700 mA (V_IN = 3.6 V, V_OUT = 1.2 V) - minimizes thermal stress in space-constrained TSOT23-5L footprint.
Junction Temp Range	–40 °C to +125 °C - qualified for industrial and extended-temperature embedded applications.

Pinout & Package

TSOT23-5L is a 5-pin, surface-mount, lead-free package (1.1 mm height, 2.9 mm × 2.8 mm body) with exposed thermal pad (not electrically connected). Pin pitch is 0.95 mm; recommended footprint matches ST's Figure 26 (A = 3.50 mm, B = 1.10 mm, D = 0.95 mm).

Pin/Terminal	Circuit Role	Design Meaning
1 - EN	Enable control input	Active-high logic input; 1.5 V threshold ensures robust noise immunity; pulls device into ultra-low-I_Q shutdown when < 0.5 V.
2 - GND	Power and signal reference	Common return path for input capacitor, output capacitor, and internal switch node; must be low-inductance connection to minimize switching noise.
3 - SW	Switch node	Drives external inductor; carries high di/dt square wave; requires short, wide trace and local ceramic decoupling to reduce EMI.
4 - VIN	Main power input	Accepts 2.5–5.5 V; requires ≥4.7 µF X5R/X7R ceramic input capacitor placed within 2 mm of pin to suppress supply ripple.
5 - FB/VO	Feedback / output voltage sense	Direct connection to regulated 1.2 V output; internally references 600 mV; no external divider needed for fixed-V_OUT variants.

Key Features

Feature	Design Value
Synchronous rectification	Integrated NMOS/PMOS power stage eliminates external Schottky diode, improving efficiency by ~8% vs. asynchronous designs at 0.5 A.
Internal soft-start	Gradually ramps output voltage over ~1 ms to prevent inrush current and avoid undershoot on shared input rails.
Thermal shutdown with hysteresis	Shuts down at 130–150 °C junction temperature; restarts only after cooling by ≥15 °C - prevents thermal oscillation under overload.
Current-mode PWM control	Provides inherent cycle-by-cycle current limiting and fast transient response (<200 ns rise/fall) to load steps up to 600 mA.
Low-noise operation	Fixed 1.7 MHz frequency avoids AM radio band; current-mode topology + ceramic caps yield <15 mV_PP output ripple at full load.

Applications

HDD Controller Power Rail

FPGA I/O Bank Supply

Use Scenario: Powers 1.2 V core logic of 2.5-inch hard disk drive controllers where board space and thermal density are constrained.

IC Role / Device Role / Timing Role: Primary step-down regulator delivering stable 1.2 V at up to 0.7 A; replaces linear regulators to reduce heat generation in sealed enclosures.

Use Value: Enables >90% efficiency at 3.3 V input, cutting dissipation from ~500 mW (LDO) to <70 mW - critical for fanless HDD designs.

Use Scenario: Supplies configurable I/O banks on Spartan-7 or Artix-7 FPGAs requiring clean, low-noise 1.2 V with fast transient response.

IC Role / Device Role / Timing Role: Dedicated point-of-load (POL) regulator; handles dynamic current steps during I/O state changes without violating FPGA V_CCIO tolerance.

Use Value: Delivers ±5% load transient response (100 → 700 mA) with <15 mV_PP ripple - maintains signal integrity for 1.2 V LVCMOS interfaces.

Industrial Sensor Node Core

USB-Powered IoT MCU Rail

Use Scenario: Powers ARM Cortex-M4-based sensor fusion nodes operating from 3.7 V Li-ion batteries with strict 10-year shelf-life requirements.

IC Role / Device Role / Timing Role: Main system regulator; operates in pulse-skipping mode at light loads to maintain 650 µA quiescent current across temperature.

Use Value: Extends battery runtime by 3.2× vs. standard buck converters; thermal shutdown protects against enclosure overheating in sealed housings.

Use Scenario: Generates 1.2 V for ultra-low-power Bluetooth LE SoCs (e.g., nRF52840) powered directly from USB 5 V bus.

IC Role / Device Role / Timing Role: Input-stage buck converter stepping 5 V USB down to 1.2 V; enables direct USB operation without intermediate 3.3 V rail.

Use Value: Achieves 85% efficiency at 10 mA (standby) and 90% at 100 mA (active), minimizing self-heating in compact USB dongles.

Equivalent & Alternatives

The following parts are listed as comparable options for similar step-down regulator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
Texas Instruments TPS62231DRYR	1.2 V fixed, 0.6 A, 3 MHz, 20 µA I_Q, WSON-6 package	Higher frequency allows smaller inductors but lower current rating; not suitable for sustained 0.7 A loads.	Select if board area is critical and peak load ≤ 0.6 A; verify thermal performance at 125 °C ambient.
Analog Devices ADP2301AUJZ-1.2-R7	1.2 V fixed, 0.6 A, 700 kHz, 2.5 mA I_Q, TSOT-6 package	Lower switching frequency increases inductor size; higher quiescent current reduces battery life in always-on systems.	Prefer for cost-sensitive industrial designs where 700 kHz EMI filtering is already in place and 0.6 A suffices.

Compared with TPS62231DRYR and ADP2301AUJZ-1.2-R7, ST1S12G12R uniquely balances 0.7 A capability, 1.7 MHz operation, and sub-1 mA quiescent current in a 5-pin TSOT23 - making it optimal for space- and efficiency-constrained 1.2 V POL applications.

Availability

ST1S12G12R is available at Aetrix Electronics and suitable for HDD controller power rails, FPGA I/O banks, industrial sensor nodes, and USB-powered IoT MCU rails requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.

Supply support for ST1S12G12R includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

The ST1S12 series belongs to ST's high-efficiency, low-voltage DC-DC converter product line - engineered specifically to replace inefficient linear regulators in space-constrained digital core power applications.

FAQ

What is the minimum input voltage required for ST1S12G12R to regulate 1.2 V output?

The ST1S12G12R requires a minimum input voltage of 2.5 V to maintain regulation at full 0.7 A load, per Table 6 and Table 7 in ST's Doc ID 14314 Rev 5. Below 2.5 V, the device enters dropout mode and output voltage follows input minus R_DS(on) × I_OUT losses.

Can ST1S12G12R be used with an output capacitor larger than 10 µF?

Yes - ST explicitly qualifies the device for use with X5R/X7R ceramic capacitors up to 22 µF (see Section 6, "Application notes"). Larger values improve load transient response and reduce output ripple, but require verification of startup time and stability with the selected inductor.

Is the FB/VO pin internally connected to the 1.2 V output in ST1S12G12R?

Yes - unlike adjustable versions, ST1S12G12R has the feedback reference internally tied to the 1.2 V output. Pin 5 (FB/VO) is directly connected to the internal 1.2 V rail and must be routed to the output capacitor's V_OUT node - no external resistor divider is used or supported.

Does ST1S12G12R support forced PWM mode or only auto PFM/PWM?

No - ST1S12G12R operates exclusively in current-mode PWM with automatic pulse-skipping at light loads. It does not offer a forced PWM pin or mode selection; efficiency below 10 mA is maintained by reducing switching frequency while retaining regulation.

ST1S12G12R Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: SOT-23-5 Thin, TSOT-23-5

Packaging:: Tape & Reel (TR)

Product Status:: Active

Function:: Step-Down

Output Configuration:: Positive

Topology:: Buck

Output Type:: Fixed

Number of Outputs:: 1

Voltage - Input (Min):: 2.5V

Voltage - Input (Max):: 5.5V

Voltage - Output (Min/Fixed):: 1.2V

Voltage - Output (Max):: -

Current - Output:: 700mA

Frequency - Switching:: 1.7MHz

Synchronous Rectifier:: Yes

Operating Temperature:: -40°C ~ 125°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: TSOT-23-5

ST1S12G12R FAQ

1.How can I place an order for ST1S12G12R through Aetrix?

Please submit a Request for Quotation (RFQ) for ST1S12G12R on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for ST1S12G12R reliable?

The price and inventory of ST1S12G12R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ST1S12G12R is usually 5 days.

3.What payment methods are accepted for ST1S12G12R?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ST1S12G12R transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for ST1S12G12R?

ST1S12G12R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your ST1S12G12R order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for ST1S12G12R?

For technical support, including ST1S12G12R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ST1S12G12R requirements.

6.How does Aetrix verify that ST1S12G12R is sourced from the original manufacturer or authorized distributors?

All ST1S12G12R products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ST1S12G12R meets industry standards.

7.What is the process for return or replacement of ST1S12G12R?

All ST1S12G12R units undergo pre-shipment inspection (PSI). If there is an issue with ST1S12G12R, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The ST1S12G12R part is unused and in its original packaging.

Return procedure for ST1S12G12R:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

Tech Hub

2026-09-03 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-01 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…

2026-08-18 Operational Amplifier (Op Amp): Basics, Configurations, Feedback and Applications

Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…

2026-08-14 Jumper Cables: How to Use, Connect and Choose Them Safely

Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…