L6984TR - 36V, 400mA Sync Step-Down Converter | STMicroelectronics
Teilenummer: L6984TR ✓ Aktiv| Menge | Stückpreis | Gesamt |
|---|---|---|
| 1 | $1.85 | $1,85 |
| 10 | $1.62 | $16,20 |
| 100 | $1.31 | $131,00 |
| 500 | $1.15 | $575,00 |
| 1.000 | $0.98 | $980,00 |
L6984TR Übersicht
A switching DC-DC converter (buck regulator) is a power management IC that steps a higher DC input voltage down to a lower regulated DC output voltage using a controlled switching element, an inductor, and an output capacitor. Synchronous buck converters integrate a low-side rectifier MOSFET (replacing the traditional Schottky diode) to improve efficiency, especially at light loads. The L6984TR belongs to ST's L698x family of step-down regulators within the broader power management IC hierarchy, designed for distributed point-of-load applications where small PCB area and high efficiency at low current are required.
Key features of the L6984TR include a wide 4.5 V-36 V input range, integrated high-side and low-side MOSFETs, an internal reference of 0.9 V with ±2% accuracy, a fixed 3.3 V VOUT option, Low Consumption Mode (LCM) that maintains efficiency at light load with controlled output ripple, and internal compensation. The synchronous rectification architecture minimizes external component count while preserving high efficiency across the 0.4 A load profile.
Internally, the L6984TR uses a peak-current-mode control topology with an embedded compensation network, allowing the device to operate with a small 4.7 µH-22 µH inductor and low-value ceramic output capacitors. The internal N-MOSFET pair is sized for 400 mA continuous load, and the LCM function automatically skips pulses at light load to keep quiescent current low and reduce output ripple below audible bands.
Typical applications include 24 V industrial sensor rails, automotive body and accessory supplies, distributed 5 V/3.3 V point-of-load conversion in PLC modules, smart metering, and low-power IoT edge nodes. The wide input range also covers 12 V battery and 24 V bus transient environments.
When designing with the L6984TR, choose the inductor value based on the switching frequency (typically 250 kHz-1 GHz depending on variant) and ripple target. Place the input ceramic capacitor close to the VIN pin and connect the exposed pad (EP) to a sufficiently large copper island to dissipate up to ~1 W continuous.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet. Source pricing reflects up-to-date distributor listings as of 2026-10-08.
Drop-in-Alternativen für L6984TR – gleiches Gehäuse, Pin-kompatibel. Bauteile mit anderem Gehäuse, die eine PCB-Überarbeitung erfordern, sind ausgeschlossen.
Schnellvergleichstool – Wählen Sie Alternativbauteile für den Direktvergleich:
L6985TR
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
L6984TR-CUT
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
L6984
✅ Drop-In📋 Referenzalternative (nicht im Katalog)
L6984TR Grenzwerte & elektrische Eigenschaften
| Topologie | Synchronous Buck (Step-Down) |
| Eingangsspannungsbereich | 4.5 V to 36 V |
| Output Voltage (Adjustable) | 0.9 V to 28 V |
| Output Voltage (Fixed) | 3.3 V |
| Maximaler Ausgangsstrom | 400 mA |
| Reference Voltage Accuracy | ±2% (typical) |
| Internal MOSFETs | High-side + Low-side N-MOSFET (integrated) |
| Control Mode | Peak Current Mode |
| Light-Load Operation | Low Consumption Mode (LCM) |
| Betriebstemperaturbereich | -40°C to +125°C |
| Gehäuse | 10-VFDFN Exposed Pad |
| Montageart | Surface Mount |
| RoHS-Status | Compliant |
| Integrated Compensation | Yes (internal) |
L6984TR Pin-Konfiguration
| Pin 1 | BOOT — Bootstrap capacitor connection for high-side gate driver |
| Pin 2 | VIN — Input voltage supply (4.5V to 36V) |
| Pin 3 | VIN — Input voltage supply (4.5V to 36V) |
| Pin 4 | EN — Enable input (active high) |
| Pin 5 | FB — Feedback input for adjustable output (VREF=0.9V) |
| Pin 6 | VOUT — Regulated output voltage sense |
| Pin 7 | SW — Switch node - connect to inductor |
| Pin 8 | PGND — Power ground |
| Pin 9 | AGND — Analog ground |
| Pin 10 | EP — Exposed pad - thermal dissipation (connect to PGND) |
Typische Anwendungen
L6984TR ist geeignet für 6 Anwendungs: 24V Industrial Sensor Power Rails, Automotive Body Electronics Power, Distributed Point-of-Load Conversion, Smart Metering and Energy Harvesting, Low-Power IoT Edge Nodes, 12V/24V Industrial Test Equipment.
24V Industrial Sensor Power Rails
The L6984TR's 4.5V-36V input window and 400mA load capability fit industrial 24V sensor rails. With its synchronous buck topology and integrated MOSFETs, the device steps 24V bus voltage down to 3.3V or 5V for PLC analog front-ends, 4-20 mA loop transmitters, and smart-meter modules. Peak efficiency above 90% is achieved across the typical 50-300 mA sensor load profile, and the LCM light-load mode keeps standby current low for always-on remote sensors. Using the fixed 3.3V variant removes the external feedback divider, reducing BOM cost and PCB area on dense PLC carrier boards.
Empfohlen
Automotive Body Electronics Power
The L6984TR is well matched to 12V automotive body modules thanks to its 36V transient rating (load-dump tolerant) and -40°C to +125°C operating range. It delivers clean 3.3V rails for body control microcontrollers, RKE receivers, seat-control ECUs, and lighting subsystems. The Low Consumption Mode (LCM) is specifically designed for car-parking duty cycles where the regulator stays active for days - skipping pulses at light load keeps efficiency above 80% while preventing audible output ripple on infotainment-rail sensitive loads.
Empfohlen
Distributed Point-of-Load Conversion
On multi-rail embedded boards, the L6984TR provides local 3.3V/5V point-of-load conversion directly from 12V or 24V backplanes. Its integrated compensation network eliminates the need for an external RC network, simplifying routing - the four boards (FPGA, MCU, sensors, memory) each get a small L6984TR footprint instead of a shared centralized converter. The 400mA load capability covers typical MCU + memory sub-systems. Synchronous rectification holds efficiency above 85% even at 50 mA loads thanks to LCM mode.
Empfohlen
Smart Metering and Energy Harvesting
The L6984TR's wide VIN and LCM mode make it a good fit for smart electricity meters, gas meters, and water meters powered by 24V utility rails or energy-harvested sources. The 400mA capability supports bursts for wireless transmission while LCM keeps idle current below audible ripple. The fixed 3.3V variant directly powers sub-GHz radio SoCs and metering MCUs without external feedback components. Battery-backed metering systems also benefit from the low quiescent current at light load.
Empfohlen
Low-Power IoT Edge Nodes
Battery- or bus-powered IoT edge nodes drawing under 400mA can use the L6984TR as their primary DC-DC converter. The synchronous buck topology and LCM mode deliver above 85% efficiency at light load, extending battery life on LoRaWAN, NB-IoT, and Zigbee sensor nodes. With a 4.5V-36V VIN range, the L6984TR can also be fed from solar panels, USB-C 5V/9V/15V/20V PD rails, or 12V lead-acid backups - the same board supports multiple deployment scenarios.
Empfohlen
12V/24V Industrial Test Equipment
Bench-top and portable industrial test equipment running on 12V/24V DC inputs benefits from the L6984TR's wide VIN range and small 10-VFDFN footprint. It can power analog signal-conditioning chains (op-amps, ADCs) from the 24V bench supply without an upstream regulator. The synchronous architecture eliminates the need for an external Schottky diode, reducing PCB area. The LCM mode keeps the regulator cool during long standby intervals common in lab environments.
Empfohlen
Zusammenfassung der empfohlenen Produkte
Technische Referenzdaten für L6984TR – Vergleich, Designhinweise und Compliance-Informationen.
Auswahlhilfe
Vergleich mit Alternativen
| Parameter | Dieses Produkt | L6985TR | L6984TR-CUT | L6984 |
|---|---|---|---|---|
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics |
| Package | 10-VFDFN Exposed Pad | 10-VFDFN Exposed Pad - same | 10-VFDFN Exposed Pad - same | 10-VFDFN Exposed Pad - same |
| Input Voltage Range | 4.5 V to 36 V | 4.5 V to 36 V - same | 4.5 V to 36 V - same | 4.5 V to 36 V - same |
| Output Current | 400 mA | 500 mA | 400 mA - same | 400 mA - same |
| Output Voltage (Adjustable) | 0.9 V to 28 V | 0.9 V to 28 V - same | 0.9 V to 28 V - same | 0.9 V to 28 V - same |
| Fixed Output Option | 3.3 V | 3.3 V - same | 3.3 V - same | 3.3 V - same |
| Light-Load Mode | Low Consumption Mode (LCM) | Low Consumption Mode - same | Low Consumption Mode - same | Low Consumption Mode - same |
| Packaging Format | Tape & Reel (3000 pcs) | Tape & Reel | Cut Tape | Tray |
Wichtigste Unterscheidungsmerkmale
- Higher output current in same package (vs. L6985TR)
- Lower per-unit cost at high volume (vs. L6984 (tray))
- Same silicon, multiple package delivery options (vs. L6984TR-CUT)
Designhinweise
Place the input ceramic capacitor (recommended 4.7 µF X7R) as close as possible to the VIN and PGND pins to suppress high di/dt switching currents. Keep the SW node copper area small to minimize radiated EMI, but ensure the exposed pad (EP) is soldered to a copper island of at least 50 mm² for thermal dissipation. Estimated: at VIN=24V, VOUT=3.3V, IOUT=400mA, the L6984TR dissipates approximately (24-3.3)×0.4 = 8.3W? — no, 24-3.3=20.7V × 0.4A = ~8.3W, but synchronous buck efficiency is ~85%, so internal dissipation ≈ 1.5W, requiring at least 50 mm² of 1-oz copper on EP. A 4-layer board with thermal vias to inner ground planes is recommended for continuous 400 mA operation.
Select the inductor based on ripple target: a 4.7 µH inductor gives ~30% peak-to-peak ripple at 400 mA and 250 kHz typical switching, while a 10 µH inductor cuts ripple to ~15%. Choose a shielded ferrite-core inductor with saturation rating above 1 A to handle transients. According to ST datasheet, low DCR (<50 mΩ) inductors maximize efficiency. Verify the inductor's self-resonant frequency is well above the switching frequency to avoid ringing.
Common pitfalls when designing with the L6984TR: (1) Do not exceed 36 V on VIN - load-dump transients on 12V automotive can spike to 40V+, so consider a TVS clamp. (2) The BOOT capacitor must be a 100 nF X7R ceramic placed close to BOOT and SW pins - omitting it disables the high-side MOSFET. (3) The fixed 3.3V variant requires no feedback resistors; do not install R1/R2 on the FB pin. (4) The EN pin must be tied high (or driven by MCU GPIO) - leaving it floating can prevent startup. (5) The exposed pad (EP) must be soldered for thermal dissipation - cold-solder joints will trigger thermal shutdown at full load.
Compliance-Informationen
RoHS compliant per STMicroelectronics product page. AEC-Q100 qualified for automotive applications per ST datasheet. Halogen-free and lead-free packaging per ST environmental compliance data.
