ZHCSFZ9C February 2017 – February 2018 TVS3300
If the TVS3300 is in place to protect the device, during a surge event the voltage will rise to the breakdown of the diode at 35.8 V, and then the TVS3300 will turn on, shunting the surge current to ground. With the low dynamic resistance of the TVS3300, large amounts of surge current will have minimal impact on the clamping voltage. The dynamic resistance of the TVS3300 is around 40 mΩ, which means 24 A of surge current will cause a voltage raise of 24 A × 40 mΩ = 0.96 V. Because the device turns on at 35.8 V, this means the XTR115 input will be exposed to a maximum of 35.8 V + 0.96 V = 36.76 V during surge pulses, well within the absolute maximum input voltage. This ensures robust protection of your circuit.
The small size of the device also improves fault protection by lowering the effect of fault current coupling onto neighboring traces. The small form factor of the TVS3300 allows the device to be placed extremely close to the input connector, lowering the length of the path fault current will take through the system compared to larger protection solutions.
Finally, the low leakage of the TVS3300 will have low input power losses. At 33 V, the device will see typical 19 nA leakage for a constant power dissipation of less than 100 µW, a small quantity that will minimally effect overall efficiency metrics and heating concerns.