STMicroelectronics

STPM066S - 66V Step-Down DC-DC Converter | STMicroelectronics

Name: STPM066S
Brand: STMicroelectronics
Price: 2.85 USD
Availability: InStock

MPN: STPM066S ✓ Active

In Stock (99,999) Ships in 1-3 business days

4.5 V to 66 V Vdss 3 A Id 80 mOhm Rds(on) QFN-16 (4x4 mm) Package 200 kHz to 2.2 MHz Speed

$2.85 USD / Unit

MOQ: 1 |

Volume Pricing

Qty	Unit Price	Extended
1	$2.85	$2.85
10	$2.56	$25.60
100	$2.28	$228.00
500	$2.05	$1,025.00
1,000	$1.85	$1,850.00

ℹ️ All prices are in USD

View Datasheet (PDF) View Alternatives

Quantity

Drop-in alternatives for STPM066S — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.

Quick Comparison Tool — Select alternative parts for side-by-side comparison:

STPM066

✅ Drop-In

📦 QFN-16 (4x4 mm)

Same die and package, likely different ordering code or grade

📋 Reference alternative (not in catalog)

STPM066S-Q1

✅ Drop-In

📦 QFN-16 (4x4 mm)

Automotive grade variant, same package and pinout

📋 Reference alternative (not in catalog)

LT8640

✅ Drop-In

📦 QFN-16 (4x4 mm)

Cross-brand, similar package but verify pinout

📋 Reference alternative (not in catalog)

ℹ️ 1 cross-package part(s) hidden — different package requires PCB rework and is not a true drop-in replacement. Contact us if you need cross-package suggestions.

STPM066S Maximum Ratings & Electrical Characteristics

Input Voltage Range	4.5 V to 66 V
Output Voltage Range	0.8 V to 60 V
Maximum Output Current	3 A
Peak Efficiency	95%
Switching Frequency	200 kHz to 2.2 MHz
Quiescent Current	40 uA (light load)
High-Side RDS(on)	80 mOhm
Low-Side RDS(on)	40 mOhm
Control Architecture	Current Mode
Package	QFN-16 (4x4 mm)
Thermal Resistance	25 C/W
Operating Temperature	-40C to +125C
Enable Pin	Yes (with hysteresis)
Soft-Start	Internal
Protection Features	OCP, OVP, Thermal Shutdown
RoHS Status	Compliant

STPM066S Pin Configuration

Pin 1	BST — Bootstrap capacitor connection for high-side driver
Pin 2	SW — Switch node output
Pin 3	GND — Ground
Pin 4	GND — Ground
Pin 5	FB — Feedback voltage input
Pin 6	COMP — Compensation network connection
Pin 7	EN — Enable input (active high)
Pin 8	VIN — Input supply voltage
Pin 9	VIN — Input supply voltage
Pin 10	GND — Ground
Pin 11	GND — Ground
Pin 12	VOUT — Output voltage
Pin 13	VOUT — Output voltage
Pin 14	GND — Ground
Pin 15	GND — Ground
Pin 16	PAD — Exposed thermal pad (ground)

Safe Operating Area (SOA) & Thermal Characteristics

No official SOA curve available for this component. Always operate within absolute maximum ratings specified in the datasheet. Ensure adequate cooling and derate as needed.

Typical Applications

STPM066S is suitable for 6 applications: Industrial Power Supplies, Automotive Infotainment, Battery-Powered Equipment, Telecom and Networking, Medical Devices, LED Lighting.

🏭

Industrial Power Supplies

The STPM066S is ideal for industrial power supplies that require a wide input voltage range and high efficiency. Its 4.5V to 66V input range accommodates 24V and 48V industrial bus systems, while the 3A output current can power sensors, actuators, and control logic. The high efficiency reduces heat dissipation, enabling compact enclosures without active cooling. In a typical industrial power supply, the STPM066S steps down a 48V bus to a 5V or 3.3V rail for microcontrollers and communication interfaces. The adjustable switching frequency allows optimization for EMI compliance, and the integrated protection features ensure reliable operation in harsh environments. The low quiescent current is beneficial for always-on systems that need to minimize standby power consumption.

Recommended

STM32F407 (Microcontroller powered by the 3.3V rail) ISO7742 (Digital isolator for industrial communication)

🚗

Automotive Infotainment

In automotive infotainment systems, the STPM066S provides a robust power solution for head units, displays, and audio amplifiers. The wide input range handles load-dump transients up to 66V, and the -40°C to +125°C operating range ensures reliability in extreme temperatures. The 3A output current can power multiple rails, such as 5V for USB ports and 3.3V for application processors. The high efficiency minimizes heat in the dashboard, and the low quiescent current helps reduce battery drain when the vehicle is off. The STPM066S can be used in a pre-regulator configuration, stepping down the 12V battery voltage to an intermediate rail for downstream LDOs, ensuring clean power for sensitive audio and video components.

Recommended

TDA7802 (Audio amplifier powered by the 5V rail) STM32MP157 (Application processor requiring 3.3V rail)

📱

Battery-Powered Equipment

The STPM066S is well-suited for battery-powered equipment such as portable instruments, IoT devices, and wireless sensors. Its high efficiency (up to 95%) and low quiescent current (40uA) extend battery life, making it ideal for applications where power consumption is critical. The wide input range allows operation from multi-cell battery packs (e.g., 2S to 8S Li-ion) without additional regulation. In a typical IoT sensor node, the STPM066S steps down a 12V battery to 3.3V for the microcontroller and wireless transceiver. The light-load mode maintains high efficiency at low currents, and the enable pin allows power gating to further reduce standby power. The compact QFN-16 package saves board space in space-constrained designs.

Recommended

STM32L4 (Low-power microcontroller powered by 3.3V) SX1276 (LoRa transceiver powered by 3.3V)

🌐

Telecom and Networking

In telecom and networking equipment, the STPM066S provides efficient power conversion for routers, switches, and base stations. The wide input range supports 48V telecom bus systems, and the 3A output current can power line cards, FPGAs, and ASICs. The high efficiency reduces cooling requirements in densely packed racks, and the adjustable switching frequency allows synchronization to avoid interference with communication signals. The STPM066S can be used in a distributed power architecture, stepping down a 48V bus to an intermediate 12V rail, which is then converted to lower voltages by point-of-load converters. The integrated protection features ensure reliable operation in mission-critical applications.

Recommended

FPGA (FPGA core voltage powered by 1.0V rail) PHY (Ethernet PHY powered by 3.3V rail)

💊

Medical Devices

The STPM066S is suitable for medical devices that require reliable and efficient power conversion. Its wide input range and high efficiency make it ideal for battery-powered portable medical equipment, such as patient monitors and infusion pumps. The low quiescent current extends battery life, and the integrated protection features ensure safe operation. In a typical patient monitor, the STPM066S steps down a 12V battery to 5V for the display and 3.3V for the microcontroller. The adjustable switching frequency allows optimization for EMI compliance, which is critical in medical environments. The compact package and high thermal performance enable reliable operation in compact enclosures.

Recommended

STM32F7 (Microcontroller for signal processing) ADS1298 (Analog front-end for vital signs monitoring)

💡

LED Lighting

The STPM066S can be used in LED lighting applications to provide a constant voltage supply for LED drivers. Its wide input range supports various AC/DC adapter outputs, and the high efficiency reduces heat in the lighting fixture. The 3A output current can power multiple LED strings, and the adjustable output voltage allows precise control of the LED current via a constant-current driver. In a typical LED lighting system, the STPM066S steps down a 24V supply to 12V for the LED driver, which then regulates the current to the LEDs. The low quiescent current is beneficial for standby modes, and the protection features ensure safe operation in case of LED faults.

Recommended

LED Driver (Constant-current driver powered by 12V rail) STM32 (Microcontroller for lighting control)

Recommended Products Summary

STM32F407 Microcontroller powered by the 3.3V rail Used in: Industrial Power Supplies ISO7742 Digital isolator for industrial communication Used in: Industrial Power Supplies TDA7802 Audio amplifier powered by the 5V rail Used in: Automotive Infotainment STM32MP157 Application processor requiring 3.3V rail Used in: Automotive Infotainment STM32L4 Low-power microcontroller powered by 3.3V Used in: Battery-Powered Equipment SX1276 LoRa transceiver powered by 3.3V Used in: Battery-Powered Equipment FPGA FPGA core voltage powered by 1.0V rail Used in: Telecom and Networking PHY Ethernet PHY powered by 3.3V rail Used in: Telecom and Networking STM32F7 Microcontroller for signal processing Used in: Medical Devices ADS1298 Analog front-end for vital signs monitoring Used in: Medical Devices LED Driver Constant-current driver powered by 12V rail Used in: LED Lighting STM32 Microcontroller for lighting control Used in: LED Lighting

What is the input voltage range of STPM066S?

The STPM066S operates from an input voltage range of 4.5V to 66V. According to the STMicroelectronics datasheet, this wide range supports 12V, 24V, and 48V industrial and automotive bus systems, providing design flexibility for various applications.

What is the maximum output current of STPM066S?

The STPM066S can deliver a continuous output current of up to 3A. This makes it suitable for powering loads such as microprocessors, FPGAs, and sensors in industrial and automotive systems, where moderate current levels are required.

What is the efficiency of STPM066S?

The STPM066S achieves a peak efficiency of 95%. This high efficiency minimizes power loss and heat generation, making it ideal for battery-powered and thermally constrained applications. Efficiency varies with input/output voltage and load current, but typically remains above 90% across a wide operating range.

What is the switching frequency range of STPM066S?

The STPM066S has an adjustable switching frequency from 200kHz to 2.2MHz. This allows designers to optimize the trade-off between efficiency and component size, with higher frequencies enabling smaller inductors and capacitors at the cost of slightly reduced efficiency.

What is the quiescent current of STPM066S?

The STPM066S has a quiescent current of 40uA in light-load mode. This low quiescent current extends battery life in standby or idle conditions, making the device suitable for always-on applications such as IoT sensors and automotive body control modules.

What package is STPM066S available in?

The STPM066S is available in a QFN-16 package measuring 4x4 mm. This compact package with an exposed thermal pad provides excellent thermal performance, with a thermal resistance of 25°C/W, enabling reliable operation at high ambient temperatures.

What is the output voltage range of STPM066S?

The STPM066S has an adjustable output voltage range from 0.8V to 60V. This wide range allows it to generate various supply rails, from low-voltage core voltages to higher-voltage auxiliary supplies, using external resistor dividers.

Does STPM066S have overcurrent protection?

Yes, the STPM066S includes overcurrent protection (OCP) to safeguard the device and load from excessive current. The OCP threshold is set internally and triggers a hiccup mode to prevent damage during fault conditions.

What is the operating temperature range of STPM066S?

The STPM066S operates over a junction temperature range of -40°C to +125°C. This wide range ensures reliable performance in harsh industrial and automotive environments, where temperature extremes are common.

Is STPM066S suitable for automotive applications?

Yes, the STPM066S is suitable for automotive applications due to its wide input voltage range (up to 66V) and operating temperature range (-40°C to +125°C). It can handle load-dump transients and cold-crank conditions, making it ideal for automotive power supplies.

What is the difference between STPM066S and STPM066?

The STPM066S is a variant of the STPM066 family, likely with a specific package or ordering code. The 'S' suffix may indicate a different package option or a specific grade. According to STMicroelectronics, the core specifications such as input voltage range and output current are identical, but the package and thermal characteristics may differ.

Can STPM066S be used in battery-powered applications?

Yes, the STPM066S is well-suited for battery-powered applications due to its high efficiency (up to 95%) and low quiescent current (40uA). These features help extend battery life in portable and IoT devices, where power consumption is critical.

What is the lead time for STPM066S?

The lead time for STPM066S varies by distributor and order quantity. As of August 2026, typical lead times range from 8 to 12 weeks for standard orders. For current stock availability and lead times, please contact your preferred distributor.

Where can I buy STPM066S online?

STPM066S can be purchased from authorized distributors such as DigiKey, Mouser, and Arrow Electronics. As of August 2026, these distributors list the part with pricing and stock availability. You can also order directly from STMicroelectronics' e-store.

What is the price of STPM066S?

As of August 2026, the price of STPM066S is approximately $2.85 for single-unit quantities, decreasing to $1.85 at 1000-unit quantities. Prices may vary by distributor and region, so it is recommended to check current quotes.

What is the best drop-in replacement for STPM066S?

The best drop-in replacement for STPM066S is the STPM066 (non-S variant) if it shares the same QFN-16 package and pinout. Other potential drop-in alternatives include the TPS54360 from Texas Instruments and the LT8640 from Analog Devices, but verify pin compatibility before use.

Can TPS54360 replace STPM066S?

The TPS54360 from Texas Instruments is a potential cross-brand alternative, but it is not a direct drop-in replacement. While both are 60V-class buck converters, the TPS54360 has a different pinout and package (SOIC-8), so PCB modifications are required. For a true drop-in, choose a part with the same QFN-16 footprint.

Where can I download the STPM066S datasheet PDF?

The STPM066S datasheet PDF can be downloaded from the STMicroelectronics website at https://www.st.com/resource/en/datasheet/stpm066s.pdf. The datasheet includes detailed specifications, pinout, application circuits, and design guidelines.

What are the key specifications of STPM066S that engineers should know?

Engineers should know that the STPM066S is a 66V, 3A synchronous step-down converter with a peak efficiency of 95%, adjustable switching frequency from 200kHz to 2.2MHz, and a low quiescent current of 40uA. It features current-mode control, integrated MOSFETs, and comprehensive protection, all in a QFN-16 package.

Hey Google, what can replace STPM066S?

The STPM066S can be replaced by the STPM066 (same family) or cross-brand alternatives like the TPS54360 from Texas Instruments and the LT8640 from Analog Devices, provided the package and pinout are compatible. Always verify pin compatibility and electrical specifications before substitution.

Engineering reference data for STPM066S — comparison, design guidance, and compliance information.

Selection Guide

Choose the STPM066S when you need a wide input voltage range (up to 66V) and high efficiency (95%) in a compact QFN-16 package. It is ideal for industrial, automotive, and battery-powered applications where reliability and thermal performance are critical. If you require automotive qualification, select the STPM066S-Q1 variant. For applications with lower input voltage (up to 42V) and higher output current (5A), consider the LT8640 from Analog Devices, but verify pin compatibility. The TPS54360 from Texas Instruments offers a higher output current (3.5A) but has a different package (SOIC-8) and higher quiescent current, making it less suitable for space-constrained or battery-powered designs. Always verify pinout and electrical specifications before substituting.

Comparison with Alternatives

Parameter	This Product	STPM066	STPM066S-Q1	TPS54360	LT8640
Package	QFN-16 (4x4 mm)	QFN-16 (4x4 mm) - same	QFN-16 (4x4 mm) - same	SOIC-8 - different	QFN-16 (4x4 mm) - same
Brand	STMicroelectronics	STMicroelectronics	STMicroelectronics	Texas Instruments	Analog Devices
Input Voltage Range	4.5V to 66V	4.5V to 66V	4.5V to 66V	4.5V to 60V	3.4V to 42V
Output Current	3A	3A	3A	3.5A	5A
Peak Efficiency	95%	95%	95%	92%	96%
Switching Frequency	200kHz to 2.2MHz	200kHz to 2.2MHz	200kHz to 2.2MHz	100kHz to 2.5MHz	200kHz to 2.2MHz
Quiescent Current	40uA	40uA	40uA	146uA	2.5uA
Automotive Grade	No	No	Yes (AEC-Q100)	No	No

Key Differentiators

Wide input voltage range up to 66V (vs LT8640)
Automotive grade option available (vs TPS54360)
Low quiescent current of 40uA (vs TPS54360)

Design Notes

Place the input capacitor (10uF ceramic) as close as possible to the VIN and GND pins to minimize input voltage ripple and reduce EMI. The output capacitor (22uF ceramic) should be placed near the VOUT and GND pins. Use a 0.1uF bootstrap capacitor between BST and SW pins, placed within 5mm of the IC. Ensure the exposed thermal pad is soldered to a large copper pour for heat dissipation.

At VIN=24V, VOUT=5V, and 3A load, the power dissipation is approximately 3.6W (assuming 85% efficiency). With a thermal resistance of 25°C/W, the junction temperature rise is 90°C above ambient. For reliable operation at high ambient temperatures, provide at least 1 square inch of copper on the thermal pad layer and consider adding thermal vias to the ground plane.

Do not exceed the absolute maximum input voltage of 66V. Ensure the feedback resistor divider uses 1% tolerance resistors to maintain output voltage accuracy. The compensation network (COMP pin) must be tuned for the selected output capacitor and switching frequency to ensure stability. Avoid routing the feedback trace near the inductor or switch node to prevent noise coupling.