Login/Register
Hint: separate multiple terms with commas
Date
E.g., 06/17/2022
Date
E.g., 06/17/2022
Global
Global
China (简体中文)
Japan (日本語)
Korea (한국어)
Taiwan (繁體中文)
TI training & videos >
Applications & designs
Live training
Products
Tools & software
Toggle navigation
Hint: separate multiple terms with commas
Date
E.g., 06/17/2022
Date
E.g., 06/17/2022
Global
China (简体中文)
Japan (日本語)
Korea (한국어)
Taiwan (繁體中文)
Email
Designing wide input DC/DC converters for thermostat applications
Hello. I am Robert Blattner. I'm an application engineer in TI's Buck converter and controllers product line. I'm here to talk about wide VIN converters servicing thermostats. Shown on the left is a generic schematic for a thermostat used in building automation. It shows a large number of circuits, which are powered off the combined power from a 24 volt AC line, a USB input, and a backup battery. The circuits perform functions such as measuring temperature, displaying information such as temperature and HVAC settings, as well as often including an alarm. In this video, we will be concerned with the main DC to DC converter, which is normally powered by the 24 volt AC line, but in some designs can also be powered off the battery as well. For 24 volt AC operation, the main DC to DC converter must work with up to 60 volt input. In designs with this converter powered off the battery, at times, unloaded operating current is critical. Typically, the main converter outputs 5 volts or 3.3 volts. Summarizing a thermostat's needs from its main DC to DC converter. Key electrical specifications are-- maximum operating voltage of at least 60 volts, maximum output current of at least a half an amp, low unloaded power consumption. Other needs include-- small total BOM size, operating with maximum ambient temperature of the entire thermostat of at least 70 degrees, and a total solution must be inexpensive. COT architecture is a good fit with a thermostat's main DC to DC converter. COT architecture intrinsically handles a wide range of input voltages, has very little internal circuitry, so low IQ and high, light load efficiency can easily be achieved. COTs also have high performance. They operate with small output capacitors, so the total solution size is small. The LM5166 comes in a 3mm by 3mm package, allowing, again, a small total solution size, and the LM5166 has a PFM mode to further improve light load efficiency. When working with COT converters, some aspects of design warrant close attention. COT converters may need external ripple injection, if low GSR capacitors are used. Since COT converters tend to lock to external signals, watch for ringing in circuitry connected to both the input and the output. An example would be LC filters connected to either input or output. COT converters also do not operate at a constant frequency, so attention to EMI requirements is essential. There are also reference designs available on TI's website. An example is TIDA-01358. This design includes the front end of a thermostat's power system. A block diagram is included in the lower left on this slide. This design converts a combination of battery power, USB power, and 24 volt AC into 3.3 volts, which powers the rest of the thermostat. This design features the LM5166 wide VIN buck, as well as the BQ24072 for battery control and the TLV62080 to produce the 3.3 volts. More information on this design is available online. Also available online is an EVM for the LM5166. The version shown here has a 5 volt output. This EVM is very small. It is only a little over 30mm by 25mm in total size. This EVM makes an excellent testbed for designing thermostats, as it can usually be wired into a prototype design. Summarizing the advantages of the LM5166 in thermostats. The LM5166 operates with input voltage range of 3 volts to 65 volts. This part has a small package and a physically small BOM due to its COT architecture and synchronous rectifier. Unloaded current consumption is only 10 micro amps, due to its COT architecture and PFM mode. This part also has a total BOM cost that is very low. For more information on thermostats, the LM5166, and some available reference designs, please search out the following keywords on TI's websites. In order to find more about thermostats, go to Applications, then click Industrial, then click Building Automation, and finally you will see Thermostats. You can click on Thermostats. Thank you for watching this video today on the LM5166 in thermostats. This is Robert Blattner from the Buck converters and controllers product line. 你好。 我是Robert Blattner。 我是TI降压转换器和控制器产品线的 应用工程师。 我在这里谈论维修恒温器的宽VIN 转换器。 左侧显示的是用于楼宇自动化的 恒温器的通用示意图。 它显示了大量电路,这些电路 由24伏交流电源线,USB输入电源和 备用电池组合供电。 这些电路执行诸如测量温度, 显示诸如温度和HVAC设置之类的信息 以及通常包括警报的功能。 在本视频中,我们将关注主要的DC-DC 转换器,它通常由24伏交流电源 供电,但在某些设计中也可以关闭 电池。 对于24伏交流电操作,主直流到直流转换器 必须使用高达60伏的输入。 在使用此转换器关闭电池的设计中, 有时,卸载的工作电流至关重要。 通常,主转换器输出5伏或3.3伏。 从主直流到直流转换器总结恒温器的 需求。 关键电气规格是 - 最大工作电压至少为60伏, 最大输出电流至少为半安培, 低负载功耗。 其他需求包括 - 小的总BOM尺寸, 在至少70度的整个恒温器的最高环境温度下 运行,并且总体解决方案 必须是便宜的。 COT架构非常适合恒温器的主DC-DC 转换器。 COT架构本质上处理各种 输入电压,内部电路非常少, 因此可以轻松实现低IQ和高负载 效率。 COT也具有很高的性能。 它们采用小输出电容器工作, 因此整体解决方案尺寸很小。 LM5166采用3mm x 3mm封装,同样 具有较小的总体解决方案尺寸, LM5166具有PFM模式,可进一步 提高轻载效率。 在使用COT转换器时, 设计的某些方面需要密切关注。 如果使用低GSR电容, COT转换器可能需要外部纹波注入。 由于COT转换器倾向于锁定外部信号, 因此请注意连接到输入和输出的 电路中的振铃。 一个例子是连接到 输入或输出的LC滤波器。 COT转换器也不能 以恒定频率工作,因此必须注意EMI 要求。 TI网站上还提供了参考设计。 一个例子是TIDA-01358。 该设计包括 恒温器电源系统的前端。 此幻灯片的左下角包含一个框图。 这种设计将电池电源, USB电源和24伏交流电的组合转换为 3.3伏特,为恒温器的其余部分供电。 该设计采用LM5166宽VIN降压, 以及用于电池控制的BQ24072和用于 产生3.3伏特的TLV62080。 有关此设计的更多信息可在线上获得。 也可在线获得LM5166的EVM。 此处显示的版本具有5伏输出。 这个EVM非常小。 总尺寸仅略大于30mm×25mm。 这款EVM是设计恒温器的 绝佳测试平台,因为它通常 可以连接到原型设计中。 总结LM5166在恒温器中的优势。 LM5166的输入电压范围为 3伏至65伏。 由于采用COT架构和同步整流器, 该器件具有小型封装和物理尺寸小的BOM。 由于其COT架构和PFM模式, 空载电流消耗仅为10微安。 该部件的总BOM成本也非常低。 有关恒温器,LM5166 以及一些可用参考设计的更多信息, 请在TI网站上搜索以下关键字。 要了解有关恒温器的更多信息, 请转到Applications,然后单击Industrial, 然后单击Building Automation,最后 你将看到Thermostats。 你可以点击Thermostats。 感谢你今天观看 关于LM5166恒温器的视频。 我是Robert Blattner,来自降压转换器和 控制器产品线部门。
Description
April 5, 2019
What to look for when selecting a wide input DC/DC converter for thermostat applications
Additional information
Learn more about TI's portfolio of wide input power solutions
Deep dive into thermostat applications
Take a look at the TIDA-01358 reference design
Learn more about LM5166
Related courses and events
06:08
Shunt resistor layout
13:12
Level 1 and 2 AC Charging (Pile) Station Design Considerations
03:17
TI-RSLK Module 10 - Lab video 10.1 – Demonstrate running the line sensor/black box recorder
14:32
Understanding signal to noise ratio and noise spectral density in high speed data converters
03:06
How To Display Video & Control Light Using TI DLP® Technology
arrow-top
close
delete
download
menu
search
sortingArrows
zoom-in
zoom-out
arrow-down
arrow-up
arrowCircle-left
arrowCircle-right
blockDiagram
calculator
calendar
chatBubble-double
chatBubble-person
chatBubble-single
checkmark-circle
chevron-down
chevron-left
chevron-right
chevron-up
chip
clipboard
close-circle
crossReference
dash
document-generic
document-pdfAcrobat
document-web
evaluationModule
globe
historyClock
info-circle
list
lock
mail
myTI
onlineDataSheet
person
phone
question-circle
referenceDesign
shoppingCart
star
tools
videos
warning
wiki