Many thanks X, now I understand your first post clearly - I will use pin 1 from one module for both enable inputs and hope it works. If not, I could use a turn on delay with about 15 seconds or so on the enable inputs.Hope your surgery went well.
You have it right mostly. It is open collector logic which means that you need to provide the reference voltage that needs to be pulled down when enabled. That’s provided by 1200AS P101 pin 1. Pin 10 is indeed the Enable and needs to be pulled low to enable. That means low relative to the AuxGND on pin 2 P101.
So I normally connect
P101 pin 1 to J401 pin 1
P101 pin 2 to J401 pin 3
P101 pin 10 to J401 pin 2
If you don’t connect P101 pin 1, you won’t have any source of voltage to “pull down” when the optoisolator is active.
It might work your way if we had used a logic gate with internal open collector topology - then it can pull down parallel circuits to internal ground.
Here the pull down is the external (on 1200As GND defined at pin 2 or pin 10 of P101).
Anyhow, you might try your way and see what happens. You would still need to connect P101 pin 2 to J401 pin 3 in addition, to have a place to GND pin 10 P101.
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Paste, hot plate on the bottom and hot air on the top.Uff da! Good luck on the soldering. (Better you than me)
I'll be interested in following the development of this new DAC.On the bench tonight is a test board for a new DAC that we are developing. This is the USB bridge using a ComTrue chip. I ordered some 5 samples of a QFN48 and it arrived in a “waffle iron” style chip carrier that holds 490 chips. Crazy. Now I have to solder those things on - 0.4mm pitch solder pads.
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How do you verify if there is no short between the legs. Can't be seen from top. I guess it will either work or notPaste, hot plate on the bottom and hot air on the top.
Neither. We use a sample rate converter to turn all digital signals into pulse density modulation (PDM) which is similar to DSD. The PDM signal is then fed to a discrete 32 tap FIR filter in conjunction with an output signal transformer to reconstruct the signal. The output signal will be intrinsically balanced and galvanically isolated from the input.X,
Discrete R2R or DAC chip based?