Blown HCPL-7520's
I recently changed my high side power supply from a cheap 5V volt adapter which was actually 6V and so I had to use a 5V 100mA voltage regulator to keep it at 5V, to a computer power supply which gave a clean 5V output. Two hcpl's blew soon after.
In an attempt to find out why, I blew my last one and im still a bit in the dark as to the reason.
The first setup I had using the cheap variable voltage power adapter and voltage regulator survived for much longer. I used it off and on for about 3 weeks. The signal off the power adapter was quite noisy and so I though that the computer powersupply might be cleaner and it wouldn't need a voltage regulator since its output was 5V.
With the intent to see if the 5V 100mA voltage regulator was needed. I connected up the circuit with my remaining hcpl-7520 to monitor the voltage waveform. I used the computer power supply modified to run at 6V with the voltage reduced to 5V with the 5V 100mA voltage regulator to supply power to the high side. It all worked fine. I turned the setup off for the night
Coming back to it in the morning it no longer worked... a result that suggests that the voltage regulator makes no difference.
Im going to put a few more hcpl's on order and try again with the old power adapter.
Exploring another possibility I dont think the problem is due to exeeding maximum input voltages. The chip can take a maximum positive voltage of 5.5V and a maximum negative voltage of -2V. At 2V either side this would correspond to when monitoring current 80A the powerstrip has a 13A fuse, when monitoring voltage 4402V well above anything close to mains voltage.