Search FAQs on the left to see if your question has been answered. Click on the dropdown to view all of the documents associated with the product. If you can't find your question, click on Ask a Question

Problem with AD737

I need to measure pulse current so I bought a few AD737 RMS to DC converters. I
have a few questions about how to connect the IC. First: My power supply will
be at 5 V. So what`s the max input voltage?? Second: I`ll measure the current
through a current transformer. I`ve attacked the schematics. I`m sure I`m doing
something wrong, but ... Can you give me a working schematics for measuring
current with current trasformer or just help me to fix this? My application is
working on 25kHz(the current I have to measure is on


I do have a couple of comments:

1. Pin-8 'COM' has to be connected to the half supply, same as pin 1.

2. By-pass caps are needed on the VCC, even if the 5V source is a battery or a
regulator of some sort.

3. By-pass caps also needed on the LM324 pin-7 and pin-5.

The AD737 bandwidth drops with input level, if the internal resistance of the
current transformer is 50 Ohm this could mean low currents are expected.
Consult the AD737 data sheet fig. 8; keep ein >10mV for accuracy.