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

STMicroelectronics A5973D

Name: A5973D
Brand: STMicroelectronics
SKU: A5973D
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: A5973D

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - DC DC Switching Regulators

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

Datasheet:: A5973D.pdf

Description:: IC REG BUCK ADJ 2A 8HSOP

Quantity:: RFQ Add To RFQ list

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Product details

Overview

A5973D from STMicroelectronics is a monolithic step-down (buck) switching regulator IC designed for automotive power systems, featuring an internal P-channel DMOS switch (R_DS(on) = 250 mΩ), 2 A DC output capability, 4–36 V input range, and AEC-Q100 qualification for under-hood applications including engine control units and ADAS domain controllers.

For engineers reviewing the A5973D datasheet, A5973D pinout, A5973D application, or A5973D equivalent, key selection considerations include cold-crank operation down to 4 V, synchronization capability across multiple rails, zero-load burst-mode operation, and integrated thermal shutdown with 150 °C trip point and 20 °C hysteresis.

Technical Context

The A5973D implements voltage-mode PWM control with feedforward compensation, using a transconductance error amplifier (g_m = 2.3 mS, 65 dB open-loop gain) referenced to a precision 1.235 V internal bandgap. Its 250 kHz fixed-frequency oscillator includes frequency foldback during overcurrent to maintain inductor current limiting below 3.5 A.

It integrates dual current protection: pulse-by-pulse sensing via split-PDMOS structure with R_SENSE, and dynamic frequency reduction triggered by falling FB voltage; combined with feedback disconnection detection, OVP (130% of V_FB), and inhibit-controlled standby mode drawing ≤100 µA.

Key Specifications

Parameter	Value and Actual Design Meaning
Input Voltage Range	4 V to 36 V - supports automotive cold-crank (4 V) and load-dump (36 V) transients without external protection.
Output Current	Up to 2 A DC - enabled by HSOP8 exposed-pad package (R_thJA ≈ 40 °C/W) and low-R_DS(on) P-MOS switch.
Switching Frequency	250 kHz (±15%) - fixed internal oscillator with synchronization I/O pin for noise-sensitive multi-rail systems.
Reference Voltage	1.235 V (±2.9%) - precise bandgap reference used directly at FB pin; enables adjustable output from 1.235 V to 35 V.
Quiescent Current	3–5 mA operating / ≤100 µA inhibit mode - ensures low system power loss during sleep states in always-on automotive modules.
Thermal Shutdown	150 °C ±10 °C with 20 °C hysteresis - fast-acting protection localized near P-MOS die area prevents thermal runaway.
Protection Features	Integrated pulse-by-pulse current limit, feedback disconnect detection, output overvoltage (130% V_FB), and UVLO with hysteresis.

Pinout & Package

Package: HSOP8 with exposed thermal pad - optimized for automotive thermal cycling and high-power density PCB layouts; R_thJA ≈ 40 °C/W on evaluation board.

Pin/Terminal	Circuit Role	Design Meaning
OUT (Pin 1)	Power output node	Connects directly to LC filter output; carries full 2 A switched current; requires low-inductance layout to minimize ringing.
SYNCH (Pin 2)	Sync I/O terminal	Configurable as master (output) or slave (input); accepts external sync signal ≥275 kHz; requires ≥100 nF cap on VREF when used.
INH (Pin 3)	Inhibit control input	Active-high logic: >2.2 V disables regulator (I_Q ≤100 µA); internal pull-up disables device if left floating.
COMP (Pin 4)	Error amplifier output	Drives external Type II/III compensation network; sink/source capability up to 1.5 mA / 300 µA defines stability margin.
FB (Pin 5)	Feedback input	Senses output via resistive divider; 1.235 V reference sets V_OUT; open-circuit triggers shutdown to prevent overvoltage.
VREF (Pin 6)	3.3 V reference output	Stable 3.3 V ±3% supply for external circuitry; no capacitor required for stability; powers sync circuitry when master.
GND (Pin 7)	Analog/digital ground	Common return for FB, COMP, INH, SYNCH; must be connected to power ground near exposed pad for thermal and noise integrity.
VCC (Pin 8)	Main power input	Supplies internal circuitry; operates from 4–36 V; internal UVLO ensures startup only above ~4.2 V with hysteresis.

Key Features

Feature	Design Value
AEC-Q100 qualified	Qualified per Grade 1 (-40 °C to +125 °C ambient), PPAP-capable - meets automotive reliability and traceability requirements.
Voltage feedforward	Internal modulation of ramp amplitude proportional to V_IN - improves line transient response and stabilizes duty cycle across wide input range.
Zero-load burst mode	Operates without bootstrap capacitor - enables stable regulation at 0 A output via randomized burst frequency, critical for always-on ECUs.
100% duty cycle capability	Supports dropout operation down to V_IN – V_OUT ≈ 0.5 V - maintains regulation during deep cold-crank events where V_IN approaches V_OUT.
Internal current limiting	Min. 2.25 A switch current limit (T_J = 85 °C) - provides robust short-circuit protection without external sense resistor or controller.

Applications

Engine Control Unit (ECU) Power Supply

ADAS Domain Controller Core Rail

Use Scenario: Supplies 5 V/2 A core logic rail in gasoline/diesel ECU under varying battery conditions (4–16 V nominal, 36 V load dump).

IC Role / Device Role / Timing Role: Primary buck regulator delivering regulated voltage to MCU, CAN transceivers, and sensor interfaces.

Use Value: Cold-crank compatibility (4 V start), AEC-Q100 qualification, and thermal robustness ensure uninterrupted operation during cranking and under-hood temperature extremes.

Use Scenario: Generates 3.3 V/2 A supply for radar processor SoCs and image signal processors in centralized ADAS domain controllers.

IC Role / Device Role / Timing Role: High-efficiency synchronous buck converter with low-noise operation and synchronization capability for multi-rail timing alignment.

Use Value: 250 kHz sync I/O enables deterministic EMI profile across multiple power rails; exposed-pad HSOP8 ensures thermal compliance at 125 °C ambient.

Body Control Module (BCM) Subsystem

Infotainment System PMIC Front-End

Use Scenario: Powers microcontroller, LIN transceivers, and LED drivers in BCM with intermittent load profiles and long sleep periods.

IC Role / Device Role / Timing Role: Always-on buck regulator supporting zero-load burst mode and ultra-low inhibit current (<100 µA) for battery conservation.

Use Value: Eliminates need for external enable logic or auxiliary LDO; reduces BOM count while meeting OEM quiescent current targets (<50 µA system sleep).

Use Scenario: First-stage buck converter in infotainment PMIC, stepping 12 V battery to 5 V intermediate rail feeding downstream DC-DCs and LDOs.

IC Role / Device Role / Timing Role: High-current front-end regulator with feedback disconnect protection and OVP to safeguard downstream power stages.

Use Value: Integrated OVP (130% of FB) and open-FB shutdown prevent cascading failure; 36 V max input eliminates need for upstream TVS clamping.

Equivalent & Alternatives

The following parts are listed as comparable options for similar automotive buck regulator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
LM2678-5.0/NOPB	Fixed 5 V output; no adjustable FB; 60 V max input; no AEC-Q100 qualification; TO-220-5 package.	Targeted at industrial/non-automotive 5 V supplies; lacks cold-crank support and automotive reliability testing.	Select only for non-automotive 5 V applications requiring higher input voltage tolerance (60 V) and through-hole assembly.
TPS54202HDDCR	2 A synchronous buck; 4.5–28 V input; 500 kHz switching; no exposed-pad package; no AEC-Q100 grade.	Designed for consumer/industrial DC/DC; smaller solution size but higher R_thJA (~60 °C/W); unsuitable for under-hood thermal environments.	Prefer for space-constrained non-automotive designs needing higher frequency and synchronous rectification; avoid for AEC-Q100 or >85 °C ambient.

Compared with LM2678-5.0/NOPB and TPS54202HDDCR, the A5973D uniquely combines AEC-Q100 Grade 1 qualification, 4 V cold-crank operation, HSOP8 thermal performance, and integrated feedback disconnect protection - making it the only drop-in solution for safety-critical automotive buck conversion where reliability and thermal resilience are mandatory.

Availability

A5973D is available at Aetrix Electronics and suitable for engine control units, ADAS domain controllers, body control modules, and infotainment subsystems requiring stable component supply across extended automotive temperature and lifetime requirements.

Supply support for A5973D 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, specializing in automotive, industrial, and power management ICs with vertical manufacturing and AEC-Q100 validation infrastructure.

The A5973D belongs to ST's automotive-grade power management portfolio, engineered specifically for under-hood DC-DC conversion where cold-crank immunity, thermal robustness, and functional safety readiness are essential.

FAQ

What is the minimum input voltage required for A5973D to start regulation?

The A5973D features an undervoltage lockout (UVLO) with hysteresis that enables startup only when V_CC exceeds approximately 4.2 V. This ensures reliable operation during automotive cold-crank events where battery voltage may dip to 4 V, and guarantees stable regulation once enabled.

Can A5973D operate with no output load?

Yes - the A5973D supports zero-load operation via burst-mode control, enabled by its internal P-channel MOSFET architecture (no bootstrap capacitor required). In this mode, it delivers regulated output with randomized burst frequency and quiescent current below 5 mA, ideal for automotive always-on modules.

How does the synchronization feature work between multiple A5973D devices?

The SYNCH pin functions as bidirectional I/O: when tied together, the device with highest natural switching frequency becomes master and drives the others as slaves. External sync signals must exceed 275 kHz and include ≥100 nF filtering on the VREF pin of the master device to ensure jitter-free operation.

What happens if the FB pin becomes disconnected during operation?

If the FB pin is left floating or disconnected, the A5973D detects loss of feedback and immediately disables the power stage to prevent uncontrolled output voltage rise. This hardware-level protection avoids potential damage to downstream loads and complies with ISO 26262 functional safety expectations for power ICs.

A5973D Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

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

Packaging:: Tube

Product Status:: Obsolete

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:: 250kHz

Synchronous Rectifier:: No

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

Grade:: Automotive

Qualification:: AEC-Q100

Mounting Type:: Surface Mount

Supplier Device Package:: 8-HSOP

A5973D FAQ

1.How can I place an order for A5973D through Aetrix?

Please submit a Request for Quotation (RFQ) for A5973D 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 A5973D reliable?

The price and inventory of A5973D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for A5973D is usually 5 days.

3.What payment methods are accepted for A5973D?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for A5973D transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for A5973D?

A5973D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your A5973D 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 A5973D?

For technical support, including A5973D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your A5973D requirements.

6.How does Aetrix verify that A5973D is sourced from the original manufacturer or authorized distributors?

All A5973D 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 A5973D meets industry standards.

7.What is the process for return or replacement of A5973D?

All A5973D units undergo pre-shipment inspection (PSI). If there is an issue with A5973D, 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 A5973D part is unused and in its original packaging.

Return procedure for A5973D:

1.Submit a request within 90 days.

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

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