TPS2595: TVS selection

Hi JH,

The reason for choosing SMBJ16A in EVM was that it has Reverse Stand off Voltage VR =16volts. VR should be less than equal to maximum operating input voltage .

Reverse stand-off voltage is the maximum voltage that can be applied to the protector without actually activating the TVS. The device VR should be equal to, or higher than the peak operating voltage of the circuit being protected.

This is to ensure that the protection device does not clip the normal circuit operating or signal voltage.

EVM is designed for general use case where input can vary from 12 to 18v . In EVM there is test case for Overvoltage clamp where input is varied from 12 to 16 . But if  SMBJ12A(VR=12) was chosen it would cause the TVS to conduct when voltage cross 12v and  and we would not able to test overvoltage clamp feature. So  SMBJ16A  was chosen to allow input of 16v at IC input.

But you are right the Vclamp of SMBJ16A is 26v and is greater than 20v and can damage the device. Yes you can use SMBJ12A(V_RWM:12V, Max Clamping Voltage: 19.9V) for 12v operating voltage range.

Thanks

Kunal Goel

Sorry correction in first line of earlier post:

VR should be less  greater than equal to maximum operating input voltage .