L7986TR - 3A 61V Step-Down Switching Regulator | STMicroelectronics
MPN: L7986TR β Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.85 | $2.85 |
| 10 | $2.56 | $25.60 |
| 100 | $2.28 | $228.00 |
| 500 | $2.05 | $1,025.00 |
| 1,000 | $1.85 | $1,850.00 |
L7986TR Overview
A step-down (buck) switching regulator is a type of DC-DC converter that efficiently reduces a higher input voltage to a lower output voltage. Unlike linear regulators, which dissipate excess power as heat, switching regulators use an inductor and switch to transfer energy in pulses, achieving efficiencies often above 90%. This makes them essential in power management systems where thermal budget and battery life are critical, such as in industrial control, automotive electronics, and distributed power architectures.
Key features of the L7986TR include a 250 kHz fixed switching frequency, an internal power MOSFET, and a high-voltage capability up to 61V. The device offers a low dropout operation and a wide output voltage range from 0.6V to VIN, making it versatile for various rail requirements. It also includes built-in protection features such as thermal shutdown, current limiting, and an enable pin for power sequencing.
The L7986TR uses a current-mode control architecture, providing fast transient response and stable operation with a wide range of output capacitors. The internal compensation simplifies design, reducing external component count. The HSOP-8 package with exposed pad enhances thermal performance, allowing the device to deliver full 3A output current without excessive junction temperature rise when properly laid out.
Typical applications include industrial 24V bus systems, automotive power supplies, and point-of-load converters. The wide input range and high efficiency make it suitable for pre-regulation in multi-rail systems, where it can step down a high-voltage bus to an intermediate rail for downstream linear regulators or low-voltage switching converters.
When designing with the L7986TR, ensure proper input and output capacitor selection and adequate PCB copper area for thermal dissipation. The enable pin allows for controlled startup sequencing in multi-rail systems, which is critical for processor-based designs.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the ST datasheet, providing a comprehensive resource for engineers evaluating the L7986TR.
Drop-in alternatives for L7986TR β same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with L7986TR (same form factor and footprint) β differing in Package, Efficiency, Input Voltage Range, Quiescent Current, Operating Temperature.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
L7986ATR
β Drop-Inπ Reference alternative (not in catalog)
L7986
β Drop-Inπ Reference alternative (not in catalog)
L7986TR-1.8
β Drop-Inπ Reference alternative (not in catalog)
L7986TR Maximum Ratings & Electrical Characteristics
| Function | Step-Down (Buck) Switching Regulator |
| Input Voltage Range | 4.5 V to 61 V |
| Output Voltage Range | 0.6 V to VIN |
| Maximum Output Current | 3 A |
| Switching Frequency | 250 kHz |
| Output Type | Adjustable |
| Synchronous Rectifier | No |
| Internal Power MOSFET | Yes |
| Enable Pin | Yes |
| Thermal Shutdown | Yes |
| Current Limiting | Yes |
| Operating Temperature Range | -40C to +150C |
| Package | HSOP-8 |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
L7986TR Pin Configuration
| Pin 1 | IN β Input supply voltage |
| Pin 2 | GND β Ground |
| Pin 3 | EN β Enable (active high) |
| Pin 4 | COMP β Compensation network |
| Pin 5 | FB β Feedback voltage |
| Pin 6 | OUT β Switching output |
| Pin 7 | OUT β Switching output |
| Pin 8 | VCC β Internal supply bypass |
| Pin 9 | EP β Exposed pad (thermal and ground) |
Typical Applications
L7986TR is suitable for 6 applications: Industrial 24V Bus Power Supply, Automotive Power Supply, Point-of-Load Converter, Telecom and Networking Equipment, Battery-Powered Systems, LED Lighting Power Supply.
Industrial 24V Bus Power Supply
The L7986TR is ideal for industrial 24V bus systems, stepping down to 5V or 3.3V rails for logic, sensors, and communication interfaces. Its input range up to 61V handles transients, and the 3A output supports multiple loads. The high efficiency reduces thermal stress in enclosed cabinets. In a typical industrial PLC, the L7986TR converts 24V to 5V for the microcontroller and I/O drivers, with a 10uH inductor and 100uF output capacitor for stable operation. The enable pin allows sequencing with other rails, and the thermal shutdown protects against overload. Compared to linear regulators, the switching topology dissipates less power, enabling higher current without large heatsinks.
Recommended
Automotive Power Supply
The L7986TR is suitable for automotive power supplies, converting battery voltage (12V or 24V) to lower rails for infotainment, body control, and ADAS. Its wide input range handles load dump transients up to 61V, and the -40C to +150C temperature range meets automotive requirements. In a typical automotive ECU, the L7986TR steps down 12V to 5V for the microcontroller, with a 10uH inductor and 47uF output capacitor. The enable pin allows power sequencing with the ignition signal. The AEC-Q100 qualified L7986ATR variant is recommended for production vehicles. The high efficiency reduces battery drain, and the thermal shutdown protects against faults.
Recommended
Point-of-Load Converter
The L7986TR can be used as a point-of-load (POL) converter to generate low-voltage rails from a higher intermediate bus. Its 3A output is suitable for powering FPGAs, DSPs, and ASICs. The adjustable output down to 0.6V allows core voltages for modern digital ICs. In a typical POL application, the L7986TR converts 12V to 1.8V for an FPGA core, with a 6.8uH inductor and 100uF ceramic capacitors. The current-mode control provides fast transient response, essential for digital loads with dynamic current demands. The enable pin allows sequencing with other rails, and the small HSOP-8 package saves board space.
Recommended
Telecom and Networking Equipment
The L7986TR is used in telecom and networking equipment to convert -48V or 24V buses to local rails. Its input range up to 61V covers -48V telecom standards, and the 3A output powers line cards and switches. In a typical router, the L7986TR converts 24V to 5V for the switch fabric, with a 10uH inductor and 100uF output capacitor. The high efficiency reduces heat in dense racks, and the enable pin allows power sequencing. The wide temperature range ensures reliable operation in uncontrolled environments.
Recommended
Battery-Powered Systems
The L7986TR can be used in battery-powered systems to efficiently step down battery voltage to system rails. Its high efficiency extends battery life, and the wide input range accommodates battery voltage variation. In a typical portable instrument, the L7986TR converts a 12V battery to 5V for the microcontroller and sensors, with a 10uH inductor and 47uF output capacitor. The low quiescent current in shutdown mode (via enable pin) helps preserve battery life. The thermal shutdown protects the regulator during fault conditions.
Recommended
LED Lighting Power Supply
The L7986TR can be used in LED lighting applications to step down a high-voltage bus to a constant voltage rail for LED drivers. Its 3A output can power multiple LED strings, and the wide input range supports various AC/DC adapters. In a typical LED driver, the L7986TR converts 24V to 12V for the LED constant-current driver, with a 10uH inductor and 100uF output capacitor. The high efficiency reduces heat in lighting fixtures, and the enable pin allows dimming control. The thermal shutdown protects the regulator in high-temperature environments.
Recommended
Recommended Products Summary
Engineering reference data for L7986TR β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | L7986ATR | L7986 | L7986TR-1.8 |
|---|---|---|---|---|
| Package | HSOP-8 | HSOP-8 - same | HSOP-8 - same | HSOP-8 - same |
| Input Voltage Range | 4.5V to 61V | 4.5V to 61V | 4.5V to 61V | 4.5V to 61V |
| Output Current | 3A | 3A | 3A | 3A |
| Output Voltage | Adjustable (0.6V to VIN) | Adjustable (0.6V to VIN) | Adjustable (0.6V to VIN) | Fixed 1.8V |
| Switching Frequency | 250 kHz | 250 kHz | 250 kHz | 250 kHz |
| Automotive Grade | No | Yes (AEC-Q100) | No | No |
| Packaging | Tape & Reel | Tape & Reel | Tube | Tape & Reel |
| Enable Pin | Yes | Yes | Yes | Yes |
Key Differentiators
- Wide input voltage range up to 61V (vs L7986ATR)
- Adjustable output down to 0.6V (vs L7986TR-1.8)
- Tape and reel packaging (vs L7986)
Design Notes
For optimal thermal performance, solder the exposed pad (EP) of the HSOP-8 package to a large copper area on the PCB. Use multiple vias to connect the pad to the ground plane. Ensure the input capacitor is placed close to the IN pin to minimize parasitic inductance.
Select an inductor with a saturation current rating higher than the peak switch current. For 3A output, a 10uH inductor with a saturation current of at least 4A is recommended. Use a low ESR output capacitor (e.g., 100uF ceramic) to minimize output ripple.
Do not exceed the absolute maximum input voltage of 61V. Ensure the feedback resistor divider uses 1% tolerance resistors to maintain output voltage accuracy. The compensation network (COMP pin) must be designed according to the datasheet guidelines to ensure stability across load and line conditions.
Compliance Information
RoHS compliant per STMicroelectronics product page. Not AEC-Q100 qualified - choose L7986ATR for automotive.
