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Original question:

AFE4300: channel 2 input pin broken

AFE4300: Damaged IOUT on AFE4300

Austen Fogarty
Prodigy 40 points

Part Number: AFE4300

Hi,

We are analysing failures of the AFE4300 in a clients product. There have now been 15 boards with the damaged AFE, these boards have been installed in health stations for several months before failure. It appears the IOUT0 pin is being damaged and the IOUT1 pin is outputting a reduced amplitude signal. The AFE4300 is only being used for the body composition measurement functionality.

Below are the scope captures for 3 different scenarios. 1. Working AFE, 2. Health application reading low values, 3. Health application reading near zero values. We are seeing approximately 50% failure with low values and 50% with near zero values. 

 Working_AFE_50kHz_IOUT0

Working_AFE_50kHz_IOUT0.png

Working_AFE_50kHz_IOUT1

Working_AFE_50kHz_IOUT1.png

Low_Value_AFE_50kHz_IOUT0

Low_Value_AFE_50kHz_IOUT0.png

Low_Value_AFE_50kHz_IOUT1

Low_Value_AFE_50kHz_IOUT1.png

Extra_Low_Value_AFE_50kHz_IOUT0

Extra_Low_Value_AFE_50kHz_IOUT0.png

Extra_Low_Value_AFE_50kHz_IOUT1

Extra_Low_Value_AFE_50kHz_IOUT1.png

Below are schematics relating to the output. The inputs are buffered by opamps before going to the AFE. ISO_GND is isolated from the main supply using NXE2S1205MC-R7 and digital isolators for the signals. 

AFE4300 Output Schematic.png

AFE4300 Schematic.png

I would greatly appreciate some assistance in understanding the cause of the damage to AFEs and how we can resolve this.

Many Thanks,

Austen