STMicroelectronics A6986F3V3

Overview

A6986F3V3 from STMicroelectronics is an AEC-Q100 qualified automotive synchronous step-down switching regulator delivering 1.5 A DC output at fixed 3.3 V, operating from 4 V to 38 V input, featuring 30 µA quiescent current in Low Consumption Mode (LCM), peak current mode architecture, and embedded output voltage supervisor for microcontroller reset sequencing.

For engineers reviewing the A6986F3V3 datasheet, A6986F3V3 pinout, A6986F3V3 application, or A6986F3V3 equivalent, this device supports critical automotive power rail design requiring cold-crank resilience (100% duty cycle), low-noise operation (LNM), and precise power-up sequencing with adjustable RST delay and threshold.

Technical Context

The A6986F3V3 implements a peak current mode control architecture with pulse-by-pulse high-side/low-side current sensing, enabling robust constant-current protection and foldback under short-circuit. Its dual-mode operation-Low Noise Mode (LNM) enforces constant-frequency PWM for minimal output ripple in audio-sensitive applications, while Low Consumption Mode (LCM) enables burst-mode operation to achieve 30 µA IQ at light load.

Internal blocks include a transconductance error amplifier (100 dB gain), programmable soft-start via SS/INH pin, synchronization capability (master/slave in LNM), and switchover functionality allowing VBIAS to supply part of the analog circuitry-reducing VIN current draw when VBIAS ≥ 3.3 V. The RST open-collector output provides configurable reset assertion with external DELAY capacitor timing and MLF-strapped threshold (e.g., 93% of VOUT = 3.07 V typ).

Key Specifications

Pinout & Package

Package: HTSSOP16 (exposed pad, R_thJA = 40 °C/W), RoHS-compliant, thermally enhanced for automotive under-hood use.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM61480-Q1 and TPS62933-Q1, the A6986F3V3 uniquely combines automotive-grade 38 V input tolerance, 30 µA LCM IQ, integrated RST supervisor with adjustable delay/threshold, and dedicated LNM for EMI-sensitive applications-making it optimal for cost-constrained, space-limited body and infotainment rails where full feature integration matters.

Availability

A6986F3V3 is available at Aetrix Electronics and suitable for automotive body electronics, infotainment subsystems, and ADAS camera modules requiring stable component supply across long production lifecycles and stringent AEC-Q100 compliance.

Supply support for A6986F3V3 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 automotive-grade power, analog, microcontroller, and sensor solutions since 1987.

The A6986F belongs to ST's Automotive Power Switching Regulators product line, engineered specifically for demanding vehicle electrical systems requiring high reliability, wide input range, and intelligent power management features like LNM/LCM and embedded supervision.

FAQ

What is the purpose of the VBIAS pin on the A6986F3V3?

The VBIAS pin enables switchover functionality: when connected to a stable ≥3.3 V external rail (e.g., main 5 V or 3.3 V output), it supplies part of the internal analog circuitry, reducing VIN current draw by up to 50% in Low Consumption Mode. If unused, it must be tied to GND. This feature improves light-load efficiency without requiring additional external components.

How does the RST output behave during power-up and fault conditions?

The RST open-collector output is held low until VOUT reaches the MLF-strapped threshold (e.g., 93% of 3.3 V = ~3.07 V). After crossing the threshold, an external DELAY capacitor sets the hold time before RST releases. During faults-such as VOUT dropping below threshold or overvoltage-the RST asserts low again within microseconds, providing fast reset signaling to connected microcontrollers or FPGAs.

Can the A6986F3V3 operate in Low Noise Mode (LNM) with external clock synchronization?

Yes. In LNM, the SYNCH/ISKP pin accepts an external clock signal (266.5 kHz to 2.2 MHz) to synchronize switching frequency across multiple regulators, reducing beat frequencies and EMI peaks. Up to six slave devices can be synchronized to one master. The pin must be left floating when synchronization is not used, and internal pull-down ensures reliable default operation.

What is the maximum achievable output current and what limits it?

The A6986F3V3 delivers up to 1.5 A DC output continuously under typical conditions (T_A ≤ 85 °C, proper PCB layout, 2-layer board with 1 oz copper). Current is limited by internal peak current detection (2.3 A typ.), thermal shutdown (165 °C), and package thermal resistance (R_thJA = 40 °C/W). At higher ambient temperatures or with insufficient copper area, derating applies-e.g., ~1.2 A at 105 °C ambient.