I have completed assembly and testing of K8055 - USB expirment interface board.
I want to connect an MPX2010 pressure transduce to analogue input A2. Data sheet for MPX2010 is available from
alldatasheet.com/datasheet-p … 010DP.html
I have tried using 820ohm resistor to give 15x gain but this does not seem to be enough.
What would you recommend?
many thanks
[quote]I have tried using 820ohm resistor to give 15x gain but this does not seem to be enough.[/quote]The differential output voltage of the MPX2010 is 25mV.
When connected to the K8055 analog input the MPX2010 is used in a “single–ended” connection. In this case the voltage span is only 12.5mV.
You need to set a very high gain to get the full 5V span to the amplifier output.
The gain should be 5V/12.5mV = 400.
This is not a very practical solution. The offset voltage of the operational amplifier and the offset voltage of the MPX2010 sensor are amplified too.
As an alternative solution you may use an external differential amplifier to convert the differential output of the MPX2010 sensor to a high level ground-referenced (single–ended) voltage.
Connect this voltage to the analog input of the K8055.
The classic three–op amp instrumentation amplifier can be used.
Here are some example circuits:
cache.freescale.com/files/sensor … AN1324.pdf
cache.freescale.com/files/sensor … AN1668.pdf
Dear Vel255
Many thanks for your suggestion.
The cache.freescale.com/files/sensor … AN1324.pdf seems to be right on target for me.
I’ll have to try and source the part
Very much appreciated
Many thanks
Dear VEL255
I am unable to get either the An1324 or AN1688 as both have been discontinued. While considering building from scratch I realised there exists a pressure sensor that may connect direct to the K8055:
freescale.com/files/sensors/ … PX5050.pdf
The MPX5050 has output 0.5v-4.5V. I presume this could connect direct.
Could you confirm I am correct before I get one
Many thanks
The output voltage of this sensor is OK to connect directly to the K8055.