Return to Answer

A long elevator sensor cable looks like a great antenna, so low impedance and filters are needed to attenuate RF and surge impulse noise but not so low that it conducts 100A!

Both modes have been supported by TVS's due to very high dynamic range (<<1uA to >10A), fast response time and low resistance. Note that these waveforms are not power waveforms. They are either voltage or current waveforms. To measure peak pulse power, the voltage and the current must both be measured and the peaks multiplied together to get the peak pulse power.

A long elevator sensor-cable looks like a great antenna, so low impedance and filters are needed to attenuate RF and surge impulse noise but not too low that it conducts 100A!

Both modes have been supported by TVS's due to very high dynamic range (<<1uA to >10A), fast response time and low resistance. Note that these waveforms are not power waveforms. They are either voltage or current waveforms. To measure peak pulse power, the voltage and the current must both be measured and the peaks multiplied together to get the peak pulse power.

But the CA type TVS is a dual zener-line back-back diode. The TVS acts a brute force 600W absorbing bipolar zener. But this can lead to crosstalk with leakage crosstalk current. A complete analysis is not possible without geometric layout. Basically, a good design not might still cause glitches.

Ref Peak pulse power ratings are measured by using laboratory-generated pulses that are designed to simulate pulses on cables caused by nearby lightning strikes. These waveforms are called double exponential waveforms. A standard waveform used in telephone circuits is a 10 x 1000 μs waveform meaning 10 μs rise time and 1000 μs tail decay time to 50% V. AC powered industry uses shorter transients (with lower impedance) which are often tested with 8 x 20 us surge impulses. Often power transformers can pass thru thus voltage if the level exceeds the supply protection or is capacitively coupled or the impulse might be induced via the building lightning rod current travelling down (hopefully) not too near the elevator shaft.

But the CA type TVS is a special dual zener back-back diode. The TVS acts a brute force 600W absorbing bipolar zener. But this can lead to crosstalk with leakage crosstalk current. A complete analysis is not possible without geometric layout. Basically, a good design but might still cause glitches.

Ref Peak pulse power ratings are measured by using laboratory-generated pulses that are designed to simulate pulses on cables caused by nearby lightning strikes. These waveforms are called double exponential waveforms. A standard waveform used in telephone circuits is a 10 x 1000 μs waveform meaning 10 μs rise time and 1000 μs tail decay time to 50% V. AC powered industry uses shorter transients (with lower impedance) which are often tested with 8 x 20 us surge impulses. Often power transformers can pass thru this voltage if the level exceeds the supply protection or is capacitively coupled or the impulse might be induced via the building lightning rod current travelling down (hopefully) not too near the elevator shaft.

A long elevator sensor cable looks like a great antenna, so low impedance and filters are needed to attenuate RF and surge impulse noise but not so low that it conducts 100A!

But the CA type TVS is a dual zener-line back-back diode. The TVS acts a brute force 600W absorbing bipolar zener. But this can lead to crosstalk with leakage crosstalk current. A complete analysis is not possible without geometric layout. Basically, a good design not might still cause glitches.

This is one attempt to similate repeated injected impulse voltage dumped from 10nF cap thru a spark gap. The Opto was defined as a Current controlled current source with gain =CTR=0.3

But the CA type TVS is a dual zener-line back-back diode. The TVS acts a brute force 600W absorbing bipolar zener. But this can lead to crosstalk with leakage crosstalk current. A complete analysis is not possible without geometric layout. Basically, a good design not might still cause glitches.

This is one attempt to simulate repeated injected impulse voltage dumped from 10nF cap thru a spark gap. The Opto was defined as a Current controlled current source with gain =CTR=0.3

This best attenuation is the 100nF cap which ought to be increased to >=1uF ceramic with a film cap to shunt piezo effects.

HERE is my old explanation of how CMOS ESD protection works. A large cap after the 1st 10K would help in this case doing similar with HV WW resistors and film caps in 2 stages with Sch. diodes so the series R to diode R ratio is about 10k:100R for a chip ESD diode and 10k:5R for a discrete 250mW Schottky diode. This "can" provide robust protection with low current 2 stage clamps, and shnt cap with ferrite beads, if done right.