STMicroelectronics L7986ATR

Overview

L7986ATR from STMicroelectronics is a 3 A synchronous step-down DC-DC switching regulator with integrated P-channel high-side MOSFET, operating from 4.5 V to 38 V input and delivering adjustable output down to 0.6 V. It features 250 kHz–1 MHz programmable switching frequency, internal soft-start, enable control, and voltage feed-forward for line transient immunity. Used in LCD TV power rails, FPGA core supplies, and industrial DC-DC modules.

For engineers reviewing the L7986ATR datasheet, L7986ATR pinout, L7986ATR application, or L7986ATR equivalent, key selection criteria include its 3.7 A current limit, VFDFPN3x3-10L/HSOP8 thermal performance (R_thJA = 60 °C/W and 40 °C/W), zero-load operation capability, and synchronization support for multi-phase designs.

Technical Context

The L7986ATR implements voltage-mode PWM control with a fixed-frequency sawtooth oscillator whose slope is dynamically adjusted via voltage feed-forward (input-dependent) and frequency feed-forward (FSW-resistor dependent) to maintain constant loop gain across input and frequency variations. Its error amplifier drives COMP for external Type II or Type III compensation networks.

Functional blocks include UVLO (4.5 V turn-on, 0.4 V hysteresis), peak-current limiting (3.7–4.7 A), hysteretic thermal shutdown (150 °C, 30 °C hysteresis), and master/slave synchronization via the SYNCH pin-enabling phase-shifted parallel operation without external timing controllers.

Key Specifications

Pinout & Package

Available in VFDFPN3×3–10L (3 mm × 3 mm × 1.0 mm, exposed thermal pad) and HSOP8 (exposed pad). Both packages support high-power density layouts with low junction-to-ambient thermal resistance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM5164QPWPRQ1 and MP2451DT-LF-Z, the L7986ATR uniquely delivers 3 A integrated power in a thermally optimized VFDFPN/HSOP package while maintaining automotive-grade input range (4.5–38 V) and zero-load operation-making it optimal for mid-power industrial and display power rails.

Availability

L7986ATR is available at Aetrix Electronics and suitable for FPGA core supplies, industrial PLC power rails, and LCD TV backlight biasing requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for L7986ATR 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 analog, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.

The L7986 series belongs to ST's high-voltage buck regulator product line, engineered for robustness in wide-input industrial and automotive environments-emphasizing thermal resilience, input transient tolerance, and seamless multi-device synchronization.

FAQ

What package variants does the L7986ATR ship in?

The L7986ATR is offered in two thermally enhanced packages: VFDFPN3×3–10L (3 mm × 3 mm × 1.0 mm with exposed pad, R_thJA = 60 °C/W) and HSOP8 (with exposed pad, R_thJA = 40 °C/W). Both require soldering the exposed pad to a thermal copper plane for rated 3 A operation. The "TR" suffix denotes tape-and-reel packaging for automated assembly.

How does the SYNCH pin enable multi-phase operation?

When two L7986ATR devices have their SYNCH pins connected, the unit with the higher switching frequency automatically acts as master, synchronizing the slave device with a 180° phase shift. This interleaving reduces input capacitor RMS current and output voltage ripple-critical for high-current applications like FPGA power delivery where dual-phase 1.8 V/3 A rails are needed.

Can the L7986ATR operate with no load?

Yes-the L7986ATR supports true zero-load operation without bursting or regulation loss. Its voltage-mode architecture and internal biasing allow continuous PWM operation down to 0 A output current while maintaining ±1.2% output accuracy at 0.6 V reference. This enables reliable powering of standby circuits and real-time clocks in always-on systems.

What is the minimum output voltage achievable with the L7986ATR?

The L7986ATR regulates down to 0.6 V, set by its internal bandgap reference. This value is guaranteed over temperature (−40 °C to +125 °C) and input voltage (4.5–38 V) with ±1.2% tolerance (0.582–0.618 V). Output voltages below 0.6 V are not supported; for sub-0.6 V rails, an external reference or post-regulator is required.