STMicroelectronics L5986TR

Overview

L5986TR from STMicroelectronics is a 2.5 A synchronous step-down switching regulator with integrated P-channel MOSFET, designed for mid-power DC-DC conversion in space-constrained systems. It operates from 2.9 V to 18 V input, delivers adjustable output down to 0.6 V, features 250 kHz–1 MHz programmable switching frequency, internal soft-start, and 100% duty-cycle low-dropout capability - deployed in LCD TV power rails, FPGA core supplies, and XDSL line cards.

For engineers reviewing the L5986TR datasheet, L5986TR pinout, L5986TR application, or L5986TR equivalent, key selection criteria include input voltage range (2.9–18 V), output current capability (2.5 A), thermal resistance (40 °C/W in HSOP8), synchronization support via SYNCH pin, and zero-load operation - all critical for industrial embedded power design and consumer DC-DC module integration.

Technical Context

The L5986TR implements voltage-mode PWM control with feedforward compensation: input voltage and switching frequency both modulate sawtooth slope to maintain constant PWM gain across operating conditions. Its error amplifier provides 100 dB open-loop gain and 4.5 MHz GBWP, supporting stable Type II/III compensation networks for LC-filtered outputs.

Overcurrent protection uses blanking-time–gated peak-current sensing (200 ns mask) with hiccup-mode recovery under sustained overload and pulse-skipping during soft-start. Thermal shutdown activates at 150 °C with 30 °C hysteresis, and inhibit logic (INH pin) enables <30 µA standby current when pulled high (>1.9 V).

Key Specifications

Pinout & Package

Available in HSOP8 package with exposed thermal pad (40 °C/W R_thJA) and VFQFPN 3 × 3 mm –8L (60 °C/W). Pinout validated per STMicroelectronics DocID14971 Rev 5, Section 1.2.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MP2315DJ-LF-Z and TPS54202DRCT, the L5986TR offers superior thermal performance in HSOP8 (40 °C/W), wider input range starting at 2.9 V, and true 100% duty-cycle operation - making it optimal for low-input, high-ambient, or dropout-critical industrial and automotive applications.

Availability

L5986TR is available at Aetrix Electronics and suitable for LCD TV power rails, FPGA core supplies, and XDSL line card DC-DC modules requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for L5986TR 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, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The L5986TR belongs to ST's high-efficiency monolithic DC-DC regulator product line, engineered specifically for compact, thermally demanding mid-power applications where integration, reliability, and wide input range are critical - including set-top boxes, networking equipment, and automotive infotainment systems.

FAQ

What is the maximum achievable output current for L5986TR under continuous operation?

The L5986TR delivers up to 2.5 A DC output current under typical thermal conditions (T_A ≤ 85 °C, HSOP8 on 4-layer PCB with 2 oz copper and thermal vias). This assumes 12 V input to 3.3 V output at 250 kHz, ≥90% efficiency, and proper layout per ST Application Note AN2711. Current drops to ~2.0 A at 105 °C ambient due to thermal derating.

Can L5986TR operate with a 3.3 V input supply?

Yes - the L5986TR supports input voltages as low as 2.9 V, making it fully compatible with regulated 3.3 V intermediate buses. At 3.3 V input, it can regulate down to 0.6 V (e.g., 1.0 V for low-power logic) with duty cycle approaching 100%, provided output current is reduced to limit conduction loss and junction temperature rise.

How does the SYNCH pin function when two L5986TR devices are used in parallel?

When SYNCH pins of two L5986TRs are connected, the device with higher oscillator frequency becomes master and the other slave. The slave switches at the master's frequency with 180° phase shift, reducing input capacitor RMS current by up to 30%. No external clock source is needed - synchronization occurs automatically via pin coupling.

Is external compensation required for stable operation?

Yes - the COMP and FB pins require an external Type II or Type III compensation network selected based on output capacitor ESR and inductor value. ST recommends Type III for low-ESR ceramic outputs and Type II for higher-ESR polymer caps. Design guidance, including component values and stability margins, is provided in Section 6.4 of the official datasheet (DocID14971 Rev 5).