STMicroelectronics A5973ADTR

Overview

A5973ADTR from STMicroelectronics is a monolithic step-down (buck) switching regulator IC designed for automotive power systems, integrating a P-channel DMOS high-side switch (R_DS(on) = 250 mΩ typ.), delivering up to 1.5 A DC output current with input voltage range 4–36 V, fixed 500 kHz switching frequency, and AEC-Q100 qualification for under-hood applications.

For engineers reviewing the A5973ADTR datasheet, A5973ADTR pinout, A5973ADTR application, or A5973ADTR equivalent, this device is selected for cold-crank-capable 12 V/24 V automotive subsystems requiring adjustable output (1.235 V to V_IN), zero-load operation, synchronization capability, and integrated thermal/current protection.

Technical Context

The A5973ADTR implements voltage-mode PWM control with internal 3.3 V reference (±2%) and transconductance error amplifier (g_m = 2.3 mS), enabling stable closed-loop regulation across temperature (−40 °C to +125 °C). Its feed-forward architecture dynamically adjusts ramp slope with input voltage to maintain consistent loop gain.

Current protection combines pulse-by-pulse limiting (min. 1.8 A switch limit) with frequency foldback during overload, while the inhibit (INH) pin enables <100 µA standby current. Thermal shutdown activates at 150 °C ±10 °C with 20 °C hysteresis, and feedback disconnection detection prevents unregulated high-V_OUT faults.

Key Specifications

Pinout & Package

Package: HSOP8 with exposed thermal pad (RoHS-compliant, moisture sensitivity level 3). Pin 1 marked by dot; top-view pinout as specified in ST DocID13958 Rev 10.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2678SDX-5.0/NOPB and TPS54340DDAR, the A5973ADTR delivers optimal balance of automotive qualification, integrated P-FET simplicity, cold-crank capability, and EMI-controllable fixed-frequency operation in a thermally efficient HSOP8 package-making it ideal for cost- and space-constrained ECU and ADAS sub-systems.

Availability

A5973ADTR is available at Aetrix Electronics and suitable for engine control units, ADAS camera modules, body control modules, and infotainment display power supplies requiring stable component supply, AEC-Q100 compliance, and long-term automotive lifecycle support.

Supply support for A5973ADTR 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 automotive-grade ICs for industrial, automotive, and consumer markets.

The A5973ADTR belongs to ST's automotive power management portfolio, engineered specifically for under-hood and cabin electronics demanding AEC-Q100 reliability, wide input range, and robust protection features in compact packages.

FAQ

What is the maximum junction temperature and thermal shutdown behavior?

The A5973ADTR shuts down at a junction temperature of 150 °C ±10 °C, with approximately 20 °C hysteresis to prevent oscillation. The thermal sensor is placed adjacent to the P-MOSFET die region for accurate, fast response. Once tripped, the device halts switching until junction temperature falls to ~130 °C, then resumes normal operation if INH remains asserted and input conditions permit.

Can the A5973ADTR operate with no output load?

Yes-the A5973ADTR operates reliably at zero load due to its P-channel high-side switch architecture, which eliminates the need for a bootstrap capacitor. Under no-load conditions, it enters burst mode with random burst timing, maintaining output regulation while drawing only 2.7 mA quiescent current (typical), making it suitable for always-on automotive subsystems.

How does the synchronization function work between multiple A5973ADTR devices?

The SYNCH pin operates bidirectionally: when left unconnected, it functions as a master output (2.75–3 V, 500 kHz square wave); when tied together across multiple devices, the unit with highest natural frequency becomes master. External sync signals must exceed 575 kHz and have 10–90% duty cycle. A ≥100 nF capacitor from VREF to ground is mandatory for stable sync operation.

What protection features prevent damage during feedback loop failure?

The A5973ADTR includes dedicated feedback disconnection protection: if the FB pin is left floating or disconnected, the internal comparator detects loss of feedback voltage and forces the device into shutdown within microseconds, clamping output to safe levels. This prevents unregulated output rise that could destroy downstream logic or sensors-a critical safeguard in automotive safety systems.