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???
10/30/05 01:13
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#103125 - ESD protection is no HV protection!
Responding to: ???'s previous message
Jeff said:
Ultimately, the resistor network is the only thing I can even think of.

Ok, if you want to use a resistive voltage divider, then take care that resistors can only withstand a characteristic maximum voltage. For a 0207-resistor this maximum voltage is typically 350V. So, when choosing a maximum voltage of 300V per resistor, you will need a resistor network containing 15kV / 300V = 50 resistors!

Maximum power dissipation of 0207-resistor is about 0.4W, so that the minimum resistance of each resistor of this resistor array will be R = 300V^2 / 0.4W = 225kOhm. So, you might want to use resistors in the MOhm-range to keep the loading low.

In most cases you will need an OPamp as buffer. Then, using protection diodes at input of OPamp (from input to power supply rails) will be useful.

Some chips have some level of HV protection, around 15kv I believe; but I doubt the Maxim 8051s do...

This is no protection against static HV as in your application, but only against ESD (electrostatic discharge) events, which lasts for only some nanoseconds!

Kai

List of 17 messages in thread
TopicAuthorDate
8051 ds420 in close proximity to HV            01/01/70 00:00      
   Smoking!            01/01/70 00:00      
      Static fields            01/01/70 00:00      
         analog opto isolator            01/01/70 00:00      
   marx            01/01/70 00:00      
      Re Marx            01/01/70 00:00      
   Measure low voltage primary side xmfer            01/01/70 00:00      
      seems to be a good solution            01/01/70 00:00      
   Be warned...            01/01/70 00:00      
      high voltages            01/01/70 00:00      
         ESD protection is no HV protection!            01/01/70 00:00      
         One hand rule            01/01/70 00:00      
            tesla coil            01/01/70 00:00      
               two notres            01/01/70 00:00      
                  resistors            01/01/70 00:00      
                     Special HV resistor is needed            01/01/70 00:00      
                        HV resistors            01/01/70 00:00      

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