AD7730: Load cell

Document created by analog-archivist Employee on Feb 23, 2016
Version 1Show Document
  • View in full screen mode

We are currently researching the subject of weighing using strain gauges and
the AD7730 ("almost all in one") seems to be quite suitable for that job.
Our question is: Since a 10V excitation seems popular in the market for this
application, we would like to have an idea of how to work with a 10V excitation
and the AD7730 (or an AD similar chip).

 

If you are working with a standard 2mV/V load cell and a 10V excitation
current, this will give you a Full Scale input range of 20mV at the AD7730.

If you were using a 5V excitation current with the same load cell, your full
scale would be 10mV, and therefore you would be effectively loosing one bit of
resolution.

The problem is that the AD7730 is designed for a power supply of 5V (+4.75 to
+5.25) and will not tolerate a power supply of 10V (it will destroy). Therefore
if you want to use the 10V excitation, you cannot apply it directly at the
power supply pins of the converter. You will need a Voltage Regulator to
provide the +5V signal. Check the ADP3335ARM-5 for this purpose:

Attachments

    Outcomes