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

STMicroelectronics L5973ADTR

Name: L5973ADTR
Brand: STMicroelectronics
SKU: L5973ADTR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L5973ADTR

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

Package:: 8-SOIC (0.154", 3.90mm Width) Exposed Pad

Datasheet:: L5973ADTR.pdf

Description:: IC REG BUCK ADJ 2A 8HSOP

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Product details

Overview

L5973ADTR from STMicroelectronics is a monolithic step-down switching regulator IC featuring an integrated 2 A P-channel D-MOS power switch, 4–36 V input voltage range, adjustable 1.235–35 V output, 500 kHz fixed switching frequency, and internal 3.3 V ±2% reference. It delivers >1.5 A DC load current in HSOP8 exposed-pad package and is used in 5 V bus-powered computer peripherals, LCD monitors, and industrial DC-DC converters.

For engineers reviewing the L5973ADTR datasheet, L5973ADTR pinout, L5973ADTR application, or L5973ADTR equivalent, key selection criteria include its P-MOS architecture eliminating bootstrap capacitors, voltage feedforward control for line regulation, pulse-by-pulse current limiting with frequency foldback, and thermal shutdown at 150 °C with 20 °C hysteresis.

Technical Context

The L5973ADTR implements a synchronous-buck-derived architecture using an internal high-side P-channel MOSFET (R_DS(on) = 0.25–0.5 Ω) driven by adaptive gate control to manage freewheeling diode recovery and minimize EMI. Its transconductance error amplifier (2.3 mS, 50–57 dB open-loop gain) compares FB against a 1.235 V internal reference, while the PWM comparator uses a sawtooth ramp generated from a 500 kHz oscillator with voltage feedforward compensation.

Current protection combines cycle-by-cycle peak limiting (2–3.5 A) and frequency-shifting foldback triggered by falling FB voltage during overload; synchronization supports master/slave operation via the SYNC pin with external signal frequencies >500 kHz. Thermal shutdown activates at 150 °C with localized sensing near the power MOSFET and 20 °C hysteresis to prevent oscillation.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Voltage Range	4 V to 36 V - enables direct use on 5 V, 12 V, and 24 V industrial/computer buses without pre-regulation.
Output Voltage Range	1.235 V to 35 V - set via external resistor divider on FB pin; 1.235 V output achieved by connecting FB directly to VOUT.
Switch Current Limit	2 A typical, 3.5 A max - defines maximum sustainable inductor current before pulse-by-pulse shutdown engages.
Switching Frequency	500 kHz fixed - reduces size of external inductor (e.g., 15 μH) and output capacitor versus 250 kHz alternatives.
R_DS(on)	0.25 Ω typ, 0.5 Ω max - low conduction loss enables >90% efficiency at 5 V/1.5 A with 12 V input.
Reference Voltage	3.3 V ±2% at VREF pin - stable, unfiltered internal reference usable for auxiliary circuitry or feedback scaling.
Quiescent Current	5–7 mA operating, 50–100 μA standby - INH pin enables ultra-low-power disable mode for battery-backed systems.
Thermal Resistance	R_thJA = 40 °C/W - achieved via HSOP8 exposed pad; allows 1.5 A continuous output at +60 °C ambient without forced air.

Pinout & Package

Package: HSOP8 with exposed thermal pad (JEDEC MO-187AC), optimized for thermal dissipation (R_thJA ≈ 40 °C/W) in space-constrained industrial and consumer power supplies.

Pin/Terminal	Circuit Role	Design Meaning
1 - OUT	Power switch drain output	Connects to inductor and freewheeling diode anode; carries full switched current and must be routed with low-inductance layout.
2 - SYNC	Master/slave synchronization I/O	Accepts external clock >500 kHz to force slave operation; outputs synchronized turn-off signal when floating or unused.
3 - INH	Enable/disable logic input	Active-high inhibit: ≥2.2 V disables device (I_Q < 100 μA); ≤0.8 V enables; internal pull-up disables if left floating.
4 - COMP	Error amplifier output	Drives external RC compensation network to stabilize loop response; requires 200–300 μA sink/source capability.
5 - FB	Feedback input	High-impedance input referenced to 1.235 V; open-circuit detection shuts down device to prevent overvoltage failure.
6 - VREF	3.3 V reference output	Stable, low-noise 3.3 V supply (±2%) for external biasing or precision feedback scaling; no bypass capacitor required.
7 - GND	Analog and power ground	Common return for internal circuitry, feedback, and reference; must be connected to exposed pad for thermal and noise integrity.
8 - VCC	Unregulated input supply	Power source for internal regulators and gate driver; accepts 4–36 V; bypass capacitor mandatory for stability.

Key Features

Feature	Design Value
Voltage feedforward control	Compensates for input voltage variation in real time, improving line regulation to ±5 mV/V without additional components.
P-MOS high-side switch	Eliminates need for bootstrap capacitor and associated timing constraints, enabling 100% duty cycle and true low-dropout operation.
Pulse-by-pulse current limiting	Detects overcurrent each switching cycle and forces immediate turn-off, providing robust short-circuit protection without latch-up.
Zero-load burst-mode operation	Maintains regulation at no load by entering randomized burst mode-critical for always-on consumer electronics with standby power budgets.
Feedback disconnection protection	Monitors FB pin continuity; disables regulator if open, preventing uncontrolled output rise to input rail and load destruction.
Thermal shutdown with hysteresis	Shuts down at 150 °C junction temperature and re-enables only after cooling to ~130 °C, avoiding thermal oscillation under sustained overload.

Applications

USB-C Power Delivery Adapter

LCD Monitor Main Rail Supply

Use Scenario: Generating 5 V/3 A and 9 V/2 A from 12–20 V adapter input using dual-output buck topology with auxiliary winding.

IC Role / Device Role / Timing Role: Primary controller for main 5 V buck stage; regulates output via FB divider while SYNC coordinates secondary converter timing.

Use Value: 500 kHz operation minimizes inductor size (15 μH) and enables compact 25 mm × 25 mm PCB layout; P-MOS architecture avoids bootstrap complexity in multi-rail designs.

Use Scenario: Providing stable 3.3 V/2 A logic rail for display timing controller (TCON) and backlight driver ICs in 24-inch LCD monitor.

IC Role / Device Role / Timing Role: Step-down regulator converting 12 V board bus to 3.3 V; operates in continuous conduction mode with tight ±1% output tolerance.

Use Value: 90% efficiency at full load reduces thermal load on densely packed TCON board; exposed-pad HSOP8 ensures reliable operation at 60 °C ambient.

Industrial PLC I/O Module Power

Automotive Infotainment Core Supply

Use Scenario: Converting 24 V vehicle or factory bus to isolated 5 V/1.5 A for microcontroller and CAN transceiver in DIN-rail mounted I/O module.

IC Role / Device Role / Timing Role: Primary non-isolated DC-DC stage; INH pin enables firmware-controlled sleep mode during communication idle periods.

Use Value: Wide 4–36 V input accommodates 24 V nominal with ±25% transients; 100 μA standby current extends battery backup runtime during brownout events.

Use Scenario: Supplying 1.2 V/2 A core voltage to ARM-based application processor in head unit, derived from 5 V pre-regulator rail.

IC Role / Device Role / Timing Role: Secondary buck regulator with external feedback divider; VREF pin sources bias for ADC reference and sensor interface.

Use Value: 1.235 V reference enables precise 1.2 V output with ±1% accuracy; thermal shutdown protects against enclosure overheating in sealed automotive enclosures.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
L5973D	Same architecture but rated for 2.5 A switch current; higher R_DS(on) (0.3 Ω typ) and 250 kHz switching frequency.	Better suited for higher-current, lower-frequency designs where EMI filtering is prioritized over component size.	Select L5973D when >2 A continuous load or lower EMI is required; L5973ADTR preferred for compact 500 kHz designs up to 1.5 A.
L5972D	2 A switch current like L5973ADTR but operates at 250 kHz; lacks SYNC pin and voltage feedforward; R_DS(on) = 0.35 Ω typ.	Targeted at cost-sensitive industrial supplies where board space and transient response are less critical.	Choose L5972D for legacy 250 kHz designs or where SYNC coordination is unnecessary; L5973ADTR offers superior line regulation and synchronization.

Compared with L5973D and L5972D, the L5973ADTR uniquely combines 500 kHz operation, voltage feedforward, and SYNC capability-enabling smaller magnetics, tighter line regulation, and coordinated multi-converter systems not achievable with the 250 kHz variants.

Availability

L5973ADTR is available at Aetrix Electronics and suitable for USB-C adapters, LCD monitor power rails, industrial PLC modules, and automotive infotainment systems requiring stable component supply across extended temperature and input voltage ranges.

Supply support for L5973ADTR 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, power, microcontroller, and sensor solutions for industrial, automotive, and consumer markets.

The L5973ADTR belongs to ST's L597x family of monolithic step-down regulators, engineered specifically for high-efficiency, space-constrained DC-DC conversion in computing peripherals, displays, and industrial equipment where reliability and thermal performance are critical.

FAQ

What is the minimum input voltage required for L5973ADTR to regulate a 3.3 V output?

The L5973ADTR requires a minimum input voltage of 4 V to maintain regulation, as specified in its absolute maximum ratings and electrical characteristics tables. At 3.3 V output, this provides sufficient headroom for the P-MOS switch's R_DS(on) drop and control circuitry, enabling stable operation even with 100 mV input ripple or PCB trace losses.

Can the L5973ADTR operate without an external feedback resistor divider?

Yes - connecting the FB pin directly to the output sets the regulated voltage to the internal 1.235 V reference. This configuration eliminates external resistors and is valid for low-voltage applications such as powering DDR memory termination or FPGA core rails, provided load current remains within thermal limits.

How does the SYNC pin function when used in master mode?

In master mode, the SYNC pin outputs a signal synchronous with the internal power switch turn-off edge. This signal can drive the SYNC input of other L5973ADTR or compatible devices, ensuring phase-aligned switching to reduce input capacitor RMS current and system-level EMI without external clock generators.

Is the VREF pin intended for powering external circuitry?

Yes - the VREF pin delivers a stable 3.3 V ±2% output capable of sourcing up to 5 mA, making it suitable for biasing op-amps, ADC references, or level-shifters. No external filter capacitor is required, and its low noise supports precision analog functions adjacent to the regulator IC.

L5973ADTR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: 8-SOIC (0.154", 3.90mm Width) Exposed Pad

Packaging:: Tape & Reel (TR)

Product Status:: Active

Function:: Step-Down

Output Configuration:: Positive

Topology:: Buck

Output Type:: Adjustable

Number of Outputs:: 1

Voltage - Input (Min):: 4V

Voltage - Input (Max):: 36V

Voltage - Output (Min/Fixed):: 1.235V

Voltage - Output (Max):: 35V

Current - Output:: 2A

Frequency - Switching:: 500kHz

Synchronous Rectifier:: No

Operating Temperature:: -40°C ~ 150°C (TJ)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-HSOP

L5973ADTR FAQ

1.How can I place an order for L5973ADTR through Aetrix?

Please submit a Request for Quotation (RFQ) for L5973ADTR 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 L5973ADTR reliable?

The price and inventory of L5973ADTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L5973ADTR is usually 5 days.

3.What payment methods are accepted for L5973ADTR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L5973ADTR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L5973ADTR?

L5973ADTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L5973ADTR 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 L5973ADTR?

For technical support, including L5973ADTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L5973ADTR requirements.

6.How does Aetrix verify that L5973ADTR is sourced from the original manufacturer or authorized distributors?

All L5973ADTR 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 L5973ADTR meets industry standards.

7.What is the process for return or replacement of L5973ADTR?

All L5973ADTR units undergo pre-shipment inspection (PSI). If there is an issue with L5973ADTR, 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 L5973ADTR part is unused and in its original packaging.

Return procedure for L5973ADTR:

1.Submit a request within 90 days.

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

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