[FAQ] How is Internal Surge Protection achieved in ISO1228?

The Internal Surge Protection is functional only in sink mode. The internal ESD structures can take current up to 1A and Voltage clamp at around 42V. Hence, if RTHR is surge proof resistor then surge protection is achieved without any additional Protection Components.

The ISO1228’s internal surge protection circuitry will pass surge tests if V_SURGE / R_THR < 1A. External surge protection devices are needed if the peak surge current is in excess of 1A in one channel at a time. A common TVS diode used is TVS3300.