STMicroelectronics A5973AD

Overview

A5973AD from STMicroelectronics is a monolithic step-down switching regulator with internal P-channel DMOS switch (R_DS(on) = 250 mΩ), delivering up to 1.5 A DC output current across 4–36 V input range, fixed 500 kHz switching frequency, and AEC-Q100 qualification for automotive cold-crank operation down to 4 V.

For engineers reviewing the A5973AD datasheet, A5973AD pinout, A5973AD application, or A5973AD equivalent, key selection criteria include its HSOP8 exposed-pad thermal performance (R_th(JA) ≈ 40 °C/W), voltage feed-forward control, synchronization capability, and zero-load burst-mode operation in automotive power rails.

Technical Context

The A5973AD implements a voltage-mode PWM architecture with an internal transconductance error amplifier (g_m = 2.3 mS, gain = 57 dB), sawtooth oscillator with voltage feed-forward, and dual current protection: pulse-by-pulse limiting (min. 1.8 A) plus frequency foldback during overload. Its high-side P-MOS switch eliminates bootstrap capacitor requirements.

Functional blocks include a dedicated inhibit circuit (active-high, 0.8 V/2.2 V thresholds), feedback disconnection detection, thermal shutdown at 150 °C ± 10 °C with 20 °C hysteresis, and a 3.3 V reference (±0.3% over temperature) usable as stable bias source for external circuitry.

Key Specifications

Pinout & Package

HSOP8 package with exposed thermal pad (R_th(JA) ≈ 40 °C/W on evaluation board); pin 1–8 arranged in single-row surface-mount configuration with GND and VCC on opposite ends for optimal thermal and power routing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM2678SD-5.0/NOPB and TPS54332DR, the A5973AD uniquely combines AEC-Q100 compliance, P-MOS integration, 4 V cold-crank support, and HSOP8 thermal performance-making it the only drop-in solution for space-constrained, safety-critical automotive buck rails requiring 1.5 A.

Availability

A5973AD is available at Aetrix Electronics and suitable for automotive infotainment systems, ADAS camera modules, and body control units requiring stable component supply, long-term lifecycle assurance, and AEC-Q100-compliant sourcing.

Supply support for A5973AD 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, designing and manufacturing microcontrollers, power ICs, sensors, and automotive-grade analog devices.

The A5973AD belongs to ST's automotive power management portfolio, engineered specifically for harsh-environment DC-DC conversion in passenger vehicles-emphasizing cold-crank resilience, thermal robustness, and functional safety readiness.

FAQ

What is the minimum input voltage required for A5973AD to regulate under load?

The A5973AD maintains regulation down to 4 V input, verified across temperature (-40 °C to +125 °C) and load (0–1.5 A). This enables operation during automotive cold-crank events where battery voltage dips below 6 V. Below 4 V, the UVLO circuit disables the device to protect internal circuitry.

Can A5973AD operate without an output capacitor?

No. An output capacitor is mandatory for stability and ripple suppression. The device requires a minimum 22 µF ceramic capacitor at the OUT pin, as specified in Section 8.1 of the datasheet. Zero-load operation is supported, but the output capacitor remains essential for loop compensation and transient response.

How does the synchronization feature work when multiple A5973AD devices share one SYNC net?

When multiple A5973AD devices connect their SYNCH pins, the unit with the highest natural switching frequency (up to 575 kHz) becomes the master and drives the shared net. Slaves lock to this frequency, eliminating beat frequencies. No external clock source is needed, and all devices retain independent feedback control.

Is the 3.3 V VREF pin intended for external load current?

Yes-the VREF pin delivers up to 5 mA while maintaining ±0.3% accuracy across temperature and line. It is designed to power external analog circuitry such as sensor biasing, ADC references, or op-amp supplies, eliminating need for a separate LDO in many automotive subsystems.