EVAL_AD5522EBDZ Use Question

Hi, keswel416. 

Thanks for your interest in AD5522. This is to inform you that we have received this question. Let me discuss this matter with the team and I'll get back to you as soon as I can.

Best regards,
Mac

Hi, keswel416. 

Thanks for your patience. I needed to validate my idea of testing a transistor using a PMU like the AD5522.

You have two options:

1. To use two AD5522 channels: one that supplies the drain voltage of 0.1V and another that sweep gate voltage from -5V to +5V with both channels' DUTGND held common and connected to the source. You will have to use the channel that forces voltage to the drain for your drain current measurement.

2. Concept still very similar to the first method but a separate source sweeping voltage to the gate.

Please let me know if you have questions.

Best regards,
Mac

Thank you very much for your reply, my friend. After two days of debugging, I have now successfully implemented the test of the I-V characteristic curve of the resistor using the AD5522 evaluation board, and the results obtained are very satisfactory. However, during this process, I also discovered some operational issues and several questions:

1. What is the role of the ADG1209 chip on the entire evaluation board?

2. Can the four PMU channels simultaneously apply different signals, such as PMU1 providing a scanning voltage that changes over time, while PMU2 simultaneously provides a certain fixed voltage? These two channels are applied simultaneously, and then the signal of one of the channels is measured synchronously, which is the method you mentioned in your new reply. Could you please elaborate in more detail?

3. The old problem: Can a three-terminal or multi-terminal chip be tested for parameter curves using only one evaluation board, such as a MOSFET? If so, how should it be achieved? How should the pins of the tested chip be connected to the evaluation board? I don't know if you can provide an access photo or illustration?

If these questions can be answered, I will be extremely grateful. Thank you!

Hi, keswel416. 

Please see these responses:

1. The ADG1209 is on the evaluation board to let you choose your desired feedforward capacitor. It is controlled using the evaluation software. You may check the product datasheet and the eval board schematic for reference.

2. Yes, each channel can force different voltage levels at the same time but it is not straight-forward if you are using the evaluation board and the evaluation software. You will have to use the Write PMU Reg and the Write DAC Reg functions by manually writing the command codes into the part, which may take quite some time because you wish to sweep voltage from one of the channels. Here's a snip of the Write PMU Reg fields in case you have trouble finding it in the software (it's located in the second window), and in case you want to give this a try: 

I personally won't keep doing this if I am planning to test several parts because this approach will be too time consuming, but if you're not going to design your own system and rely on the evaluation board and software for testing a part or two before designing your system, then this is your only way of doing that.

3. I believe it can be done but I haven't tried it myself yet. I think that this can be pretty tricky to do. Please see the illustration below that shows the connections from AD5522 to an N-channel MOSFET:

In this illustration, you will need to force out 0.1V from channel 0 and sweep voltage using channel 1.

You may need to use a breadboard to test this out.

Best regards,
Mac

Thank you very much for your patient reply, my friend. You have helped me solve many problems.

1.That is to say, if I want to use the existing single-board evaluation board and the accompanying software to meet the testing requirements, it is relatively difficult. I can only try to do it through the register method, but it may take a lot of time, right?

2.If I later consider designing my own testing system with the AD5522 as the core chip to meet the testing requirements of the ID-VG curve of my MOSFET, what adjustments should I make based on the existing official evaluation board circuit design (AD5522 + AD7685)? Do I need to replace the single ADC with multiple ADCs to meet my testing requirements? I have very limited experience in this area. Could you give me some guidance in this regard?

Once again, thank you very much, my friend!