Disastrous transient spike and electrical overstress such as electrostatic discharge, inducctive load switching or lightning can destroy sensitive electronics in a glimpse. This sudden release of damaging energy may be generated from a variety of sources both internal and external to the circuit. Fulfilling protection against these damages is not an afterthought—it is an essential requirement deploying Transient Voltage Suppressors(TVS) at the frontline defense.
TVS diodes are devices manufactured with large PN junction area to provide high surge current handling capability and low dynamic impedance in avalanche mode. This technology enables these devices to absorb large amounts of energy in a short duration of time without sustaining damage. Within the TVS, destructive voltage spike is limited and reduced to a safe point within the clamping voltage level while the transient current is diverted to ground through the device. This conducting of avalanche energy shields the protected electronics from being damaged at affordable cost.
Typical TVS diodes feature peak pulse power ratings of 400W, 500W, 600W, 1.5KW, 3KW and 5KW. Higher power devices of 15KW, 20KW and 30KW are most frequently used for telecom power buses and lightning protection. The key electrical parameters are:
The voltage where the TVS turns into a low resistance path and breaks down into avalanche mode. The breakdwon voltage is usually measured at a test current(IT) as low as 1 milliamp and specified with minimum and maximum voltage range.
This parameter is also referred to the working voltage where the TVS works at its maximum DC operating voltage. This voltage is always at least 10 percent lower than the minimum breakdown voltage. At this voltage, the TVS will be in a nonconducting mode.
The leakage current is measured at the above working voltage. Devices with breakdown voltage below 10V feature leakage current as high as 1 milliamp while the ones with higher breakdown voltages usually exhibit very low leakage current of 1 microamp.
The maximum permissible current that the TVS is guaranteed to endure without sustaining damage. This parameter is usually measured at 10/1000uS exponential waveform at which the pulse would have a 10uS rise time and decay to 50 percent of the peak value in 1 millisecond.
The maximum voltage that can flow across the TVS when the maximum peak pulse current is conducting through it. This is the maximum voltage that the protected component can be exposed to. The clamping voltage is approximately 33 percent above breakdown voltage.
By determining the maximum circuit operating voltage and selecting the TVS with a reverse stand-off voltage equal or higher than the circuit operating voltage, this should insure the TVS becomes nonconductive while the breakdown voltage, leakage current and capacitance cause no effect on normal circuit performance. Further defining the transient conditions in the circuit such as surge wave shape and pulse duration, and selecting the clamping voltage less than the voltage which can cause circuit damage, the safeguard is solidly built and the TVS is now capable of diverting the damaging current away.
The losses due to transient spikes cost tremendous amount of spendings and time. Deploying protection with the TVS efficiently eliminates the threats of destructive transient voltages. Don’t leave circuit protection to chance. Request a sample for your application at www.wontop.com.
