STMicroelectronics A7986ATR

Overview

A7986ATR from STMicroelectronics is an AEC-Q100 qualified automotive step-down switching regulator with integrated 3.7 A (min.) P-channel MOSFET, delivering up to 3 A DC output current. It operates from 4.5 V to 38 V input, supports adjustable output down to 0.6 V, features 250 kHz–1 MHz programmable switching frequency, and enables low-dropout operation via 100% duty cycle capability - deployed in automotive LED driving systems.

For engineers reviewing the A7986ATR datasheet, A7986ATR pinout, A7986ATR application, or A7986ATR equivalent, key selection criteria include its HSOP8 thermal performance (R_th(JA) = 40 °C/W), voltage feed-forward architecture for line transient stability, zero-load quiescent current (20–30 µA), and synchronized multi-phase operation via SYNCH pin.

Technical Context

The A7986ATR implements voltage-mode PWM control with a sawtooth oscillator whose slope is dynamically adjusted by both input voltage (voltage feed-forward) and switching frequency (frequency feed-forward), maintaining constant PWM gain across operating conditions. Its error amplifier features 100 dB DC gain, 4.5 MHz GBWP, and rail-to-rail output swing (0–3.3 V).

Overcurrent protection uses pulse-by-pulse current limiting with 200 ns blanking time and adaptive pulse-skipping (up to 7 skipped cycles), reducing effective switching frequency to 1/8th nominal under overload to sustain ~3.7 A current limit. Thermal shutdown activates at 150 °C with 30 °C hysteresis, restarting at ~120 °C.

Key Specifications

Pinout & Package

Supplied in HSOP8 package with exposed thermal pad (R_th(JA) = 40 °C/W), enabling high-power density in automotive environments where board space and thermal management are constrained.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM5164QPWPRQ1 and MPQ4436AGL-AEC1, the A7986ATR uniquely combines AEC-Q100 qualification, 150 °C junction rating, voltage feed-forward, and 3 A capability in HSOP8 - making it optimal for thermally constrained, safety-critical automotive buck stages where transient immunity and long-term reliability are non-negotiable.

Availability

A7986ATR is available at Aetrix Electronics and suitable for automotive front lighting, ADAS power rails, and body control modules requiring stable component supply across extended temperature and voltage ranges.

Supply support for A7986ATR 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 specializing in automotive, industrial, and power management solutions, with deep expertise in AEC-Q100-compliant analog and power ICs.

The A7986A belongs to ST's automotive-grade DC-DC converter product line, engineered specifically for harsh-automotive environments - emphasizing input transient robustness, thermal resilience, and functional safety readiness.

FAQ

What is the maximum allowable input voltage for continuous operation?

The A7986ATR supports continuous operation up to 38 V input, with absolute maximum rating of 45 V. Operation beyond 38 V is limited to transient conditions such as load dump (per ISO 7637-2 Pulse 5a), and must remain within the 45 V absolute maximum for ≤200 ms to avoid permanent damage.

How does the SYNCH pin enable multi-phase operation?

When two A7986ATR devices have their SYNCH pins connected, the higher-frequency unit acts as master and the lower as slave, producing complementary 180° phase-shifted switching waveforms. This interleaving cuts RMS input capacitor current by ~30%, reducing size and heating in multi-rail automotive systems.

Can the A7986ATR regulate output voltages below 0.6 V?

No - the internal 0.6 V reference is fixed and non-adjustable. Output voltage is set via external resistor divider from V_OUT to FB; minimum regulated output equals the reference voltage (0.6 V). Sub-0.6 V regulation requires external circuitry or a different controller.

What thermal derating applies above 60 °C ambient?

Derating begins at T_A = 60 °C per the datasheet's "Power dissipation at T_A < 60 °C" specification. With R_th(JA) = 40 °C/W, maximum allowable power dissipation decreases linearly: P_D(max) = 2 W × (1 − (T_A − 60)/90). At 105 °C ambient, max P_D drops to ~1.0 W, limiting practical output current to ~1.5 A depending on V_IN/V_OUT.