L7985TR - 2A Step-Down Switching Regulator | STMicroelectronics
MPN: L7985TR ✓ نشطL7985TR نظرة عامة
A step-down switching regulator, also known as a buck converter, 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 a switch to transfer energy in a controlled manner, achieving high efficiency. The L7985TR belongs to the family of voltage regulators, which are essential components in power management systems, converting unregulated power sources into stable, usable voltages for electronic circuits.
Key features of the L7985TR include a 250 kHz fixed switching frequency, an internal power MOSFET, and a current-mode control architecture. The device offers a typical efficiency of over 85% at full load, reducing power loss and heat generation. It also includes a built-in soft-start function to limit inrush current during startup, and a thermal shutdown protection to prevent damage from overheating. The output voltage is adjustable from 0.6V to the input voltage, providing flexibility for various design requirements.
The L7985TR utilizes a current-mode control scheme, which provides fast transient response and simplifies loop compensation. The internal power switch is rated for a peak current of 3A, ensuring reliable operation under load transients. The device also features a low quiescent current of 2.5 mA, which is beneficial for battery-powered applications. The HSOP-8 package has a thermal resistance of 40°C/W, allowing for efficient heat dissipation in moderate power applications.
Typical applications for the L7985TR include point-of-load converters, distributed power systems, industrial control systems, and automotive power supplies. Its wide input voltage range and high efficiency make it ideal for converting 12V or 24V bus voltages to lower logic rails. The device is also suitable for LED lighting applications, where constant current regulation is required.
When designing with the L7985TR, it is important to select the appropriate inductor and output capacitor values to ensure stable operation. The datasheet provides a detailed design procedure and recommended component values for various output voltages and currents. Additionally, proper PCB layout is critical to minimize parasitic inductance and ensure reliable performance.
بدائل مباشرة لـ L7985TR — نفس الحزمة، متوافق دبوس بدبوس. تُستثنى القطع ذات الحزم المختلفة التي تتطلب تعديل PCB.
الطرازات في هذه السلسلة
طرازات من نفس السلسلة متوافقة تمامًا مع L7985TR (نفس عامل الشكل والبصمة) — يختلف في Input Voltage Range, Maximum Output Current, Output Voltage Range, Package, Switching Frequency.
L7985
✅ بديل مباشر📋 بديل مرجعي (غير موجود في الكتالوج)
L7986TR
✅ بديل مباشر ⚠️ مواصفات غير مُتحقق منهاتواصل لمعرفة السعر
عرض ورقة البيانات ←L7987
✅ بديل مباشر ⚠️ مواصفات غير مُتحقق منهاتواصل لمعرفة السعر
عرض ورقة البيانات ←TPS5420
✅ بديل مباشر ⚠️ مواصفات غير مُتحقق منها📋 بديل مرجعي (غير موجود في الكتالوج)
NCP3063
✅ بديل مباشر ⚠️ مواصفات غير مُتحقق منها📋 بديل مرجعي (غير موجود في الكتالوج)
L7985TR الحدود القصوى والخصائص الكهربائية
| نوع الخرج | Adjustable |
| نطاق جهد الخرج | 0.6 V to 38 V |
| أقصى تيار خرج | 2 A |
| نطاق جهد الدخل | 4.5 V to 38 V |
| تردد التبديل | 250 kHz |
| الكفاءة | >85% at full load |
| تيار السكون | 2.5 mA |
| Internal Power MOSFET | Yes, 3A peak current |
| Control Architecture | Current-mode |
| بدء التشغيل الناعم | Built-in |
| الإيقاف الحراري | Yes |
| درجة حرارة التشغيل | -40°C to +150°C |
| العلبة | HSOP-8 |
| نوع التركيب | Surface Mount |
| حالة RoHS | Compliant |
تكوين أطراف L7985TR
| دبوس 1 | BOOT — Bootstrap capacitor connection for high-side driver |
| دبوس 2 | IN — Input supply voltage |
| دبوس 3 | SW — Switch node output |
| دبوس 4 | GND — Ground |
| دبوس 5 | FB — Feedback voltage sense |
| دبوس 6 | COMP — Compensation network connection |
| دبوس 7 | EN — Enable input (active high) |
| دبوس 8 | VCC — Internal supply voltage (decouple with capacitor) |
التطبيقات النموذجية
L7985TR مناسب لـ 6 التطبيقs: Point-of-Load Converters, Industrial Control Systems, Automotive Power Supplies, LED Lighting, Distributed Power Systems, Battery-Powered Devices.
Point-of-Load Converters
The L7985TR is ideal for point-of-load (POL) converters that step down a higher voltage bus to a lower logic rail. Its wide input range (4.5V to 38V) and 2A output current make it suitable for powering FPGAs, microcontrollers, and other digital ICs. The high efficiency reduces heat generation, allowing for compact designs without heatsinks. In a typical POL application, the L7985TR is placed close to the load, with input and output capacitors to filter noise. The adjustable output voltage allows for precise regulation, and the current-mode control provides fast transient response to sudden load changes. Compared to linear regulators, the switching topology minimizes power loss, especially when the input-to-output voltage difference is large.
موصى به
Industrial Control Systems
In industrial control systems, the L7985TR can convert a 24V DC bus to lower voltages for sensors, actuators, and control logic. Its wide input voltage range and robust thermal performance make it suitable for harsh environments. The device's thermal shutdown protection ensures safe operation under overload conditions. The fixed 250 kHz switching frequency allows for simple EMI filtering, which is important in industrial settings with strict electromagnetic compatibility requirements. The L7985TR's current-mode control provides stable operation with ceramic output capacitors, reducing the need for bulky electrolytic capacitors. This makes the design compact and reliable for long-term operation in factory automation and process control equipment.
موصى به
Automotive Power Supplies
The L7985TR is well-suited for automotive power supplies, where input voltage can vary from 9V to 16V (or higher during load dump). Its input range of 4.5V to 38V provides ample margin for such transients. The device's operating temperature range of -40°C to +150°C meets automotive requirements. In a typical automotive application, the L7985TR steps down the battery voltage to power infotainment systems, sensors, or ECUs. The high efficiency reduces power dissipation, which is critical in the confined spaces of a vehicle. The built-in soft-start prevents inrush current during startup, protecting the battery and other components. The thermal shutdown feature ensures the device survives extreme conditions.
موصى به
LED Lighting
The L7985TR can be used in LED lighting applications as a constant current source. By configuring the feedback network, the device regulates the output current to drive LEDs with consistent brightness. The adjustable output voltage allows for series LED strings of varying lengths. The high efficiency minimizes heat generation, which is beneficial for LED luminaires where thermal management is challenging. The current-mode control ensures stable current regulation even with input voltage variations. In a typical LED driver circuit, the L7985TR is used with an inductor and a sense resistor to set the output current. The device's wide input range makes it suitable for both low-voltage (12V) and high-voltage (24V) lighting systems.
موصى به
Distributed Power Systems
In distributed power systems, the L7985TR is used to generate multiple voltage rails from a single input source. Its adjustable output voltage and 2A current capability make it versatile for various loads. The device's high efficiency reduces overall power loss in the system, improving energy efficiency. The compact HSOP-8 package allows for high power density on the PCB. In a typical distributed power architecture, the L7985TR is used as a secondary stage, converting an intermediate bus voltage (e.g., 12V) to lower logic rails (e.g., 3.3V, 5V). The current-mode control provides excellent line and load regulation, ensuring stable voltages for sensitive electronics.
موصى به
Battery-Powered Devices
The L7985TR is suitable for battery-powered devices where efficiency is critical to extend battery life. Its low quiescent current of 2.5 mA helps minimize standby power consumption. The wide input voltage range allows the device to operate from a variety of battery configurations, such as 2-cell Li-ion (7.4V) or 4-cell NiMH (4.8V). The high efficiency ensures that most of the battery energy is converted to useful output, reducing heat and prolonging runtime. In a typical battery-powered application, the L7985TR steps down the battery voltage to power a microcontroller, sensors, or wireless transceiver. The soft-start feature prevents inrush current that could otherwise stress the battery.
موصى به
ملخص المنتجات الموصى بها
بيانات مرجعية هندسية لـ L7985TR — المقارنة وإرشادات التصميم ومعلومات الامتثال.
دليل الاختيار
المقارنة مع البدائل
| المعامل | هذا المنتج | L7985 | L7986 | L7987 | TPS5420 | NCP3063 |
|---|---|---|---|---|---|---|
| Package | HSOP-8 | HSOP-8 | HSOP-8 | HSOP-8 | HSOP-8 | HSOP-8 |
| Brand | STMicroelectronics | STMicroelectronics | STMicroelectronics | STMicroelectronics | Texas Instruments | onsemi |
| Input Voltage Range | 4.5V to 38V | 4.5V to 38V | 4.5V to 38V | 4.5V to 38V | 5.5V to 36V | 3V to 40V |
| Output Current | 2A | 2A | 3A | 1A | 2A | 1.5A |
| Switching Frequency | 250 kHz | 250 kHz | 250 kHz | 250 kHz | 500 kHz | 150 kHz |
| Output Voltage Range | 0.6V to 38V | 0.6V to 38V | 0.6V to 38V | 0.6V to 38V | 1.22V to 36V | 1.25V to 40V |
| Quiescent Current | 2.5 mA | 2.5 mA | 2.5 mA | 2.5 mA | 2 mA | 2.5 mA |
| Enable Pin | Yes | Yes | Yes | Yes | Yes | No |
أبرز الفروقات
- Wide input voltage range up to 38V (مقابلTPS5420)
- Higher output current than L7987 (مقابلL7987)
- Enable pin for power sequencing (مقابلNCP3063)
ملاحظات التصميم
For optimal performance, place the input capacitor (10uF) and output capacitor (22uF) as close as possible to the L7985TR pins. Use a solid ground plane to minimize parasitic inductance. The bootstrap capacitor (100nF) should be placed between BOOT and SW pins with minimal trace length. Refer to the ST application note AN2823 for layout guidelines.
The HSOP-8 package has a thermal resistance of 40°C/W (theta_JA). At 2A output with a 12V to 5V conversion, power dissipation is approximately 14W, which would cause a junction temperature rise of 560°C. This is not feasible without a heatsink. For such high power, consider using a larger package or reducing the output current. For typical applications with lower power dissipation (e.g., 12V to 5V at 1A, dissipation ~7W), a copper pour of at least 1 square inch is recommended.
Do not operate the L7985TR without a proper compensation network on the COMP pin. Use the values recommended in the datasheet for the desired output voltage and current. Also, ensure the EN pin is not left floating; tie it to VIN for always-on operation or use a logic signal for control. Incorrect inductor selection can cause instability or excessive ripple.
معلومات الامتثال
RoHS compliant per STMicroelectronics product page. Not AEC-Q100 qualified, but suitable for automotive applications per datasheet.
