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I am getting started on a project using an Analog Devices AD1938.
I purchased the Development board (EVAL-AD1938AZ) and I’m trying to get some form of communication going between the development board and my pc.
Question #1: Powering the board.
The datasheet for the development board says that I need ±12Vdc and ground.
I connected the 3 posts from my power supply to the 3 posts on the dev board and set the voltage on the supply to 12Vdc. Is that all I need to do in order to power the dev board? Are there any quick ways to make sure I hooked everything up correctly?
Question #2: Working with SigmaStudio and AD1938:
Where should I go for some tutorials on using SigmaStudio specifically with the AD1938?
Thanks for any input.
This is all new territory for me.
Basically to hook up the evaluation kit with the information in the User guide. I am not aware of any way to test the board to make sure it is hooked up correctly. Basically it just would most likley not work.
That “ground” terminal on that sort of supply is connected to the device chassis, the third prong on the AC power plug, and (if your building is wired properly) the dirtball spaceship. It has no direct connection to either output terminal of the supply, thus cannot sink/source current from either.
The “and ground” part of “±12V and ground” means a midpoint between two points 24V apart, capable of providing a path for current flow through either of the remaining two terminals. The board itself doesn’t care a bit which (if any) of the three are connected to the dirtball spaceship.
In the lab, such a source is usually created by using two single-output bench supplies connected in series, or the two (isolated) outputs of a dual-output bench supply connected in series.
See also this post for further illustration of the topic.
I did try doing the method of using 2 single output power supplies.
Here is what I did:
Set both power supplies to 12Vdc.
Connect the “+” post of supply 1 to the “+” post of the dev board.
Connect the “-” post of supply 2 to the “-” post of the dev board.
Connect the “-” post of supply 1 to the “+” of supply 2.
Connect the “ground” post of the dev board to “-” post of supply 1.
When I did this, I got a CC (Constant Current) indicator on my power supply and I figured that wasn’t a good thing, so I disconnected it.
For reference I am using a BK-Precision 1761 DC Power Supply.
Is that the configuration you were thinking of @rick_1976 ?
That might mean you’ve set the current limit below what the board requires, or it might mean that there’s an errant connection or fault somewhere. Config sounds reasonable if I’m reading correctly.
Please be careful with the connection on that B&K Precision 1761 power supply. There are hidden internal connections that are designed to make wiring the circuit easier. However, a mistake can result in the supply entering the current limit mode you described.
Specifically, we need to properly configure the independent / track and the series / parallel switches in the middle of the device. I suspect you had the power supply in parallel mode. The wire connection + to – would short out the device.
Recommend:
Remove the flat plate jumper(s) between the black to green and the black to red terminals. If you are in a school, chances are good these metal plates were long ago discarded.
Disconnect all wires from the power supply.
Connect a jumper wire from B pos to A neg. Note that this wire is redundant provided the power supply is in the series mode. However, it serves as a reminder that the supplies are internally tied together.
Set the power supply to independent mode using the selector switch.
Set each supply to 12 VDC.
Verify that you have +/- 12 VDC relative to ground where “ground” is the jumper wire you just installed.
At this point you may want to explore the “track” mode. As I recall, it allows side A to control side B: here a single control adjusts the complementary + and – outputs.
Once you have mastered these setting, you are ready to reconnect your demo board.
Thanks for the help @rick_1976 and @APDahlen, my team and I were able to get the power supply configured correctly and the dev board seems to be powered on now.
