STMicroelectronics L7986TA

Overview

L7986TA from STMicroelectronics is a 3 A synchronous step-down DC-DC switching regulator with integrated P-channel MOSFET, designed for high-input-voltage industrial and automotive power rails. It operates from 4.5 V to 38 V input, delivers adjustable output down to 0.6 V, features 250 kHz–1 MHz programmable switching frequency, internal soft-start, and supports 100% duty cycle for low-dropout operation - deployed in car infotainment systems and FPGA power supplies.

For engineers reviewing the L7986TA datasheet, L7986TA pinout, L7986TA application, or L7986TA equivalent, key selection criteria include input voltage range (4.5–38 V), guaranteed 3 A load capability, thermal shutdown at 150 °C, HSOP8 exposed-pad package for 40 °C/W R_thJA, and voltage-mode control with feed-forward compensation.

Technical Context

The L7986TA implements voltage-mode PWM control with a fixed-frequency sawtooth oscillator whose slope is dynamically adjusted via voltage and frequency feed-forward to maintain constant loop gain across input voltage and switching frequency variations. Its internal error amplifier has 100 dB DC gain, 4.5 MHz GBWP, and drives an external Type II or Type III compensation network on the COMP pin.

Overcurrent protection uses pulse-by-pulse current limiting with 200 ns blanking time and adaptive pulse-skipping (up to 7 skipped cycles) to reduce effective switching frequency to 1/8 of nominal during overload - ensuring stable 3.7 A current limit even under short-circuit conditions when F_SW ≤ 706 kHz.

Key Specifications

Pinout & Package

HSOP8 package with exposed thermal pad (R_thJA = 40 °C/W on demo board); 8-pin surface-mount outline optimized for high-current thermal dissipation and compact layout.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM5164QDDARQ1 and MP2451DT-LF-Z, the L7986TA uniquely combines 3 A capability, 4.5–38 V input, programmable frequency, and integrated P-MOSFET in HSOP8 - making it optimal for thermally demanding automotive and industrial buck regulators where BOM count and thermal management are critical.

Availability

L7986TA is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial FPGA power supplies, and networking DC-DC modules requiring stable component supply, long-lifecycle support, and AEC-Q100-aligned reliability.

Supply support for L7986TA 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, specializing in power management, microcontrollers, and automotive-grade ICs with ISO/TS 16949-certified manufacturing.

The L7986TA belongs to ST's high-voltage buck regulator product line, engineered for robust operation in harsh environments - targeting automotive body electronics, industrial automation, and telecom infrastructure where wide input range and thermal resilience are mandatory.

FAQ

What is the minimum recommended output capacitor for stable operation at 3 A load?

The datasheet specifies ≥22 µF ceramic output capacitance with low ESR (e.g., X7R 1206) for stability across all operating conditions. At 3 A, total output capacitance should be ≥47 µF to limit peak-to-peak ripple to <1% of V_OUT, especially when using Type II compensation. The ESR must remain below 10 mΩ to prevent phase margin degradation.

Can the L7986TA operate with input voltage below 4.5 V?

No - the absolute minimum operating input voltage is 4.5 V per the datasheet's V_CCON threshold and guaranteed electrical characteristics. Below this, UVLO prevents startup and regulation is not assured. For sub-4.5 V applications, consider ST's L5983 or L6986 series with lower VIN capability.

How does the SYNCH pin behave when left unconnected?

When floating, the SYNCH pin outputs a 180° phase-shifted version of the internal oscillator signal. This enables natural interleaving when two L7986TAs are synchronized by connecting their SYNCH pins - one acts as master (higher frequency), the other as slave, achieving half-cycle phase offset to reduce input RMS current.

Is the L7986TA qualified for automotive applications?

Yes - the L7986TA is specified over −40 °C to +125 °C junction temperature, features AEC-Q100 stress-tested reliability (documented in ST's qualification reports), and is widely used in car audio and infotainment systems. It meets automotive EMC requirements when implemented with proper layout and filtering per AN4405 guidelines.