Hi, I'm using AD637BR with a circuit that controls the chip select pin. I implemented a 2 pole filter using the internal buffer (pins 1 and 16) that follows the RMSOUT (pin 11).
I found out that, when chip is enabled, everything works fine but when chip is disabled by driving low pin 5, I get -1,5V at buffout (pin16) and +68mV at RMSOUT pin 11.
Voltage at pin 11 can be driven to 0V by placing a pulldown resistor in it but this doesn't change buffout output.
Placing a pulldown of 10K in buffout gives me -1.53V, while 750R give me about -0.4V and 330R take it to 0.2V. No pulldown resistor make this pin float to -7.5V.
Apparently disabling the chip disables the RMS circuit but the buffer does not change to high Z output, it changes to a strange state. Its not a buffer, its not high Z, and it drives current. For my application I need to drive Voltage output at buffout to 0V. Is there any way to do this? A low resistance pull down wont work for this.
By the way, datasheet does not explain this and should be reviewed.