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Relays have enabled low-voltage signals to control high-voltage systems since before the invention of the transistor. With very low on-resistance, the venerable electromechanical relay (EMR) still finds use today, but the newest solid-state relays (SSRs) offer considerable advantages with respect to lifetime reliability, switching speed, power consumption, and tolerance for shock and vibration.
SSR还提供了比光层（或光电继电器）的优势，该光层面临可实现的传输限制，并受到内部LED降解。SSR可以在各种汽车和工业应用中找到使用，包括当前的限制和绝缘抗性监测。
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- How to achieve higher-reliability isolation and a smaller solution size with solid-state relays
- 消除运动部件以通过新的固态继电器实现更高的系统可靠性
- TI drives isolation technology forward with new solid-state relays that provide industry-leading reliability
Gate Drivers and Switches
Texas Instruments的SSR阵容包括带有内部FET的开关以及与外部电源开关一起使用的栅极驱动程序, including MOSFETs, IGBTs, silicon-carbide (SiC) MOSFETs, and silicon-controlled rectifiers. They don’t experience mechanical degradation over their operating lifetimes, which can exceed EMR lifetimes by a factor of 10.
The switching times of these SSRs are in the microsecond range—orders of magnitude faster than those of EMRs. They can transfer both power and signals across their isolation barrier and don’t require separate isolated secondary bias supplies. And the devices can be driven by a microprocessor’s logic output, minimizing the need for external control circuitry.
请注意一个警告：像所有高速开关一样，SSR可以生成EMI。因此，在使用它们时，请遵循EMI设计的最佳实践，例如通过保持印刷电路板痕迹短，使当前循环最小化。
TI isolation products are available with basic or reinforced levels of isolation achieved through capacitive or magnetic isolation technology. The company’s isolation products employ polyimide or silicon dioxide as insulation material, which have typical dielectric strengths of 300 VRMS/µm and 500 VRMS/µm。相反，EMR和光层通常采用空气或环氧树脂作为绝缘材料，介电强度仅为1 VRMS/µm and 20 VRMS/µm.
汽车合格产品
TI的新SSR产品包括两个汽车合格设备：TPSI3050-Q1，一个具有积分10-V门电源的隔离开关驱动器，以及TPSI2140-Q1，1,400-V，50 ma隔离开关。两种设备都使用独特的方法整合了在单个隔离屏障上的功率和信号隔离，该方法可提高可靠性，同时与机电继电器和固态光层相比降低溶液的大小和成本。此外，两者都可以通过微秒中的单个隔离屏障断开并连接负载，与机电继电器的毫秒相关。
TPSI3050-Q1(Fig. 1)将电感增强隔离为5 kVRMS并且运行寿命比机电继电器长10倍。通过将隔离电源，数字隔离器和栅极驱动器集成在IC软件包中，它与机械 - 列层解决方案相比，将解决方案尺寸降低了90％。
The TPSI2140-Q1(Fig. 2)提供3.75 kV的电容基本隔离RMS，使其能够达到时间依赖性的电介质分解可靠性比固态光层高4倍以上。与传统的固态光层溶液相比，SSR通过集成信号FET和电阻，将溶液尺寸降低多达50％，从而消除了对芦苇继电器的需求。
The TPSI2140-Q1 can work with a battery-pack monitor such as the BQ79631-Q1 to detect insulation faults in 800-V battery-management systems. It enables the use of <1-MΩ resistors and can withstand over 300% more avalanche current than traditional photorelays.
The new automotive-qualified devices are the first in a new SSR portfolio that also will include ICs for high-voltage industrial applications.
设计资源
Texas Instruments提供了各种资源来帮助您设计其隔离产品除SSR外，其中包括独立的数字隔离器，孤立的界面IC，隔离ADC和孤立的放大器。资源包括PSPICE模型和评估板以及详细的应用说明和参考设计。
One application note, for example, demonstrates how to cascode two TPSI3050 isolated switch drivers to increase gate-drive voltage and minimize conduction losses in designs incorporating IGBTs and SiC MOSFETs. The TPSI3050’s floating secondary supply enables the cascode configuration(Fig. 3), which can provide a gate-drive voltage up to 20 V.
另一份申请说明显示了在电荷电路中使用的TPSI3050-Q1，以最大程度地减少汽车上充电器中的Inrush电流，以及工业电源和电力分布系统。TPSI3050启用的固态方法使不必要的笨重且容易出现故障的机电接触器。小于3 µs的响应时间可以使TPSI3050在过热或过热状态下快速关闭开关。
TI’s reference designs include design guides, schematics, BOMs, assembly drawings, Gerber files, PCB layout files, and a calculator to help determine critical component values. One reference design implements an analog front end (AFE) for insulation monitoring(Fig. 4)。它利用TPSI2140-Q1隔离开关和AMC3330增强隔离放大器，该放大器具有±1-V输入和集成的DC-DC转换器。
The AFE can monitor symmetrical or asymmetrical leakage current and measure insulation resistance from the positive or negative high-voltage supply to protective earth ground. It requires no external power supply on the hot side.
Other reference designs show the TPSI3050-Q1 isolated switch driver used in a zero-cross switching circuit and in an overtemperature and overcurrent protection application. For each reference design, TI fabricated a fully assembled board for test and performance validation.
结论
Systems using increasingly high voltages in automotive and industrial applications require reliable isolation to ensure the safety of personnel and equipment. TI’s new isolated switch and switch-driver ICs complement TI’s full lineup of isolation products to provide optimal performance and design flexibility. TI provides full support for its isolation portfolio, extending from simulation models to reference designs.
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