STMicroelectronics L4978D Industrial-Grade Adjustable Synchronous Buck Regulator Overview
The STMicroelectronics L4978D is a high-performance, industrial-qualified adjustable synchronous buck regulator engineered for B2B applications demanding flexible voltage output and robust power management-including Industrial Automation (PLC power cores, motor control units), Energy and Power (solar inverter auxiliary circuits), and Internet of Things (IoT) environmental monitors. Designed to convert a 4.5V?C40V input range to an adjustable 0.8V?C30V output (with 3.0A continuous current capacity), it delivers low-ripple power to voltage-sensitive components like industrial microcontrollers, solar charge controllers, and IoT wireless transceivers. Integrating synchronous rectification (for maximum efficiency), overcurrent protection, short-circuit protection, thermal shutdown, and under-voltage lockout into a durable TO220 through-hole package (compatible with standard heatsinks), it operates reliably across -40??C to +150??C-making it ideal for engineers prioritizing voltage flexibility, high current, and thermal resilience in harsh industrial or outdoor power systems.
As a flagship power management product from STMicroelectronics-a global leader in industrial semiconductors with 35+ years of expertise in buck regulators-it meets strict quality standards: RoHS 2 compliance, ISO 9001 certification, IEC 61000-6-2 industrial EMC compliance, and 3,000+ hours of durability testing (including high-temperature cycling and voltage spike stress). Senior engineers at a top energy solutions firm endorse it, noting: ??The L4978D??s adjustable output replaces 3 fixed regulators in our solar systems, cutting component count by 60% while maintaining 93% efficiency-critical for remote solar deployments.?? For more industrial-grade power ICs, visit ICメーカー.
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Technical Parameters of STMicroelectronics L4978D
| パラメータ | 仕様 |
|---|---|
| 機能 | Adjustable synchronous buck regulator (0.8V?C30V output range) |
| 入力電圧範囲 | 4.5V to 40V |
| 調整可能な出力電圧範囲 | 0.8V to 30V (??2% accuracy at 25??C, full load) |
| 最大連続出力電流 | 3.0A |
| ピーク出力電流 | 4.0A (short-duration, ??100ms) |
| Efficiency (Typical) | 93% (at 12V input, 5V output, 2.0A load) |
| スイッチング周波数 | 300kHz (fixed, no external clock needed) |
| パッケージタイプ | TO220 through-hole package (compatible with heatsinks; thermal resistance: 60??C/W without heatsink, 22??C/W with standard heatsink) |
| パッケージ寸法 | 10.0mm x 6.7mm x 4.5mm |
| 動作温度範囲 | -40～+150 |
| 静止電流 | 8.2mA (typical, no-load condition); 0.2mA (shutdown mode) |
| 出力リップル | 18mV頁 (typical, 5V output, 1.5A load, 1kHz bandwidth) |
| 統合された保護機能 | Overcurrent protection (6.0A typical), short-circuit protection (hiccup mode), thermal shutdown (160??C typical), under-voltage lockout (UVLO: 3.8V typical), reverse polarity protection (up to 40V) |
| コンプライアンス | RoHS 2 compliant, ISO 9001 certified, IEC 61000-6-2 (industrial EMC) |
Key Technical Features of L4978D Buck Regulator
- 0.8V?C30V adjustable output: Replaces multiple fixed regulators, simplifying designs. An automation engineer reported: ??Cuts 2 extra ICs from our PLC-PCB space saved by 40%, assembly time reduced by 25%.??
- 93% high efficiency: Minimizes power loss in industrial systems. A plant manager noted: ??Slash our 24V PLC energy use by 28%-saves $1,500 annually per factory floor.??
- TO220 heatsink compatibility: Lowers thermal resistance to 22??C/W, preventing overheating. A solar tech shared: ??With a heatsink, it stays at 92??C in 85??C solar inverters-standard TO220 units hit 148??C and shut down.??
- 40V load-dump protection: Withstands industrial voltage spikes (common during machinery startup). An energy firm confirmed: ??Handles 38V spikes from 24V solar supplies-old 30V regulators failed 14% of the time.??
- 0.2mA shutdown current: Extends battery life in IoT devices. An IoT firm explained: ??In standby, uses 0.2mA-extends 12V monitor battery life by 42%, cutting replacement costs by 35%.??
Advantages of L4978D vs. Typical Buck Regulators
Compared to fixed-output buck ICs, low-efficiency linear regulators, and non-heatsink-compatible packages, the L4978D delivers three critical benefits for B2B industrial and energy designs-backed by real customer feedback:
1. Adjustable output replaces fixed regulators: Most industrial systems need 2?C3 fixed-output regulators (e.g., 3.3V for MCUs, 5V for sensors, 12V for motors), increasing component count and PCB space. The L4978D??s 0.8V?C30V range replaces all three. An industrial automation firm said: ??Our PLC used 3 fixed buck regulators ($4 total) and 15% of PCB space-this model costs $3 and uses 5% of space. With 10,000 PLCs annually, we save $10,000 in component costs and $8,000 in PCB manufacturing. Fewer parts also reduce assembly errors by 22%, cutting rework time by 18 hours weekly.??
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2. 93% efficiency outperforms linear regulators: Linear regulators for industrial voltages have only 25%?C40% efficiency (wasting 60%?C75% power as heat), driving up energy bills and cooling needs. The L4978D??s 93% efficiency eliminates this waste. A solar energy firm confirmed: ??Our 24V solar monitor used a linear regulator that wasted 70% of power-this buck regulator cuts waste to 7%. With 500 monitors (each drawing 1.5A), we save 1,095W daily. Annual energy costs dropped by $396 (at $0.10/kWh) for grid backup, and the cooler operation extends monitor life by 2 years-saving $12,000 in replacements.??
3. Heatsink compatibility prevents downtime vs. standard TO220: Standard TO220 buck regulators (without heatsink support) overheat in 85??C factories or solar inverters, triggering thermal shutdowns that halt production or disrupt power. The L4978D??s TO220 design works with off-the-shelf heatsinks. A manufacturing plant shared: ??Our old TO220 regulator caused 3.5 hours of daily motor control downtime in 85??C conditions. This model with a $2 heatsink stays at 92??C, no shutdowns. Motor uptime rose to 99.3% from 97.6%, and we moved 175 more units daily-adding $210,000 in annual revenue.??
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Typical Applications of STMicroelectronics L4978D
The L4978D excels in flexible, high-efficiency industrial and energy power designs-proven in these key B2B use cases:
- Industrial Automation (PLC Power Cores): Adjusts 24V factory power to 3.3V/5V MCU cores. An industrial firm confirmed: ??Adjustable output replaces 2 ICs, 93% efficiency cuts energy use-PLC uptime hit 99.3%.??
- Energy and Power (Solar Inverter Auxiliary Circuits): Converts 36V solar power to 12V inverter control IC. An energy firm noted: ??40V protection handles spikes, heatsink prevents overheating-inverter downtime down 40%.??
- Internet of Things (IoT) Environmental Monitors: Steps down 12V battery power to 3.3V sensor arrays. An IoT firm reported: ??Low shutdown current extends battery life by 42%, low ripple ensures data accuracy-monitor failures down 38%.??
- Industrial Automation (Motor Control Units): Regulates 12V power to 5V motor driver IC. A factory tech firm shared: ??3.0A current handles startup loads, thermal protection prevents damage-motor failure rates down 45%.??
- Energy and Power (Battery Charging Systems): Adjusts 24V supply to 7.2V/12V battery packs. A logistics firm confirmed: ??Adjustable output charges 2 battery types, high efficiency saves energy-charging time cut by 20%.??
Frequently Asked Questions (FAQ) About L4978D
Why is 0.8V?C30V adjustable output useful for industrial PLCs?
Industrial PLCs power multiple components (3.3V MCUs, 5V sensors, 12V relays) that need different voltages-fixed regulators require 2?C3 ICs, increasing cost and PCB space. The L4978D??s adjustable range replaces all. An automation engineer said: ??Our PLC used 3 fixed regulators ($4) and 15% PCB space-this model costs $3 and uses 5%. With 10,000 PLCs, we save $10,000. Fewer parts also reduce assembly errors by 22%, cutting rework time by 18 hours weekly and improving on-time delivery by 15%.??
Can the L4978D handle 40V input spikes in solar inverter systems?
Yes. Its 4.5V?C40V input range is engineered to withstand 40V spikes-common in solar inverters when clouds clear and panel voltage surges. Most low-cost buck ICs max at 30V and fail here. A solar engineer confirmed: ??Our 24V solar system spikes to 38V-old 30V regulators failed 14% of the time, causing 2.8 hours of daily inverter downtime. This regulator maintains stable output, no shutdowns. Inverter uptime rose to 99.5%, and we generated 8% more solar energy annually-adding $140,000 in revenue for our clients.??
What value does TO220 heatsink compatibility add for factory motor controls?
Factory motor controls operate in 85??C+ environments, and standard TO220 buck regulators (without heatsinks) overheat to 148??C, triggering shutdowns that halt production. The L4978D??s heatsink support lowers thermal resistance to 22??C/W. A plant manager said: ??Our old TO220 regulator caused 3.5 hours of daily motor downtime. This model with a $2 heatsink stays at 92??C, no shutdowns. Motor uptime rose to 99.3%, and we moved 175 more units daily-adding $210,000 in annual revenue. It also extends motor control board life by 1.5 years, cutting maintenance costs by 30%.??
Why is 93% efficiency critical for solar IoT monitors?
Solar IoT monitors rely on battery backup when sunlight is low-low-efficiency regulators drain batteries fast, requiring frequent field replacements. The L4978D??s 93% efficiency minimizes this drain. An IoT sustainability firm noted: ??Our old 35% efficiency linear regulator lasted 6 months on battery-this model lasts 8.5 months. Battery replacements dropped by 42%, saving $80,000 in annual field service costs. The stable 3.3V output also reduces sensor data errors by 92%, improving the accuracy of our clients?? environmental reports and boosting retention by 28%.??
How does low shutdown current benefit battery-powered IoT monitors?
Battery-powered IoT monitors spend 80% of time in standby-high shutdown current drains batteries quickly, increasing replacement frequency and costs. The L4978D??s 0.2mA shutdown current uses 97% less power than 7mA buck regulators. A logistics monitor firm confirmed: ??Our old 7mA regulator lasted 5 months-this model uses 0.2mA, extending life to 7.1 months. We replace 42% fewer batteries, saving $65,000 in annual service costs. Clients also report 35% fewer data gaps (from dead batteries), which has improved our Net Promoter Score by 22 points.??