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PGA2310: Channel Inquiry

Art Mecina
Genius 16505 points
Part Number: PGA2310

Hello Guys,

Good day.

We have a customer who wants to confirm the following:

1) Is it okay to leave one channel of the PGA2310 unconnected when only one is used? Or will it cause any problems?

2) Can I used the remaining unused channel for another signal, for example from an microphone?

3) When two PGA2310 are daisy chained together, will the data which is meant for the last IC in the chain, cause any change on the first IC of the chain? Or will the first IC just pass the data to the second IC?

Thanks to confirm!

Art

  • 0
    Genius 3945 points

    I'm not a TI employee but I've used the 2310 in several designs.

    1. Yes, you can leave it unconnected. I would set the output level to minimum, though.

    2. Sure, the two channels are unrelated. Of course, you should probably put a preamp on a microphone before connecting it to the PGA2310. You'll have better noise performance. You don't want to put the preamp after the PGA2310. You always want the high-gain stage first in the signal chain.

    3. The data meant for the last device in the chain will not affect a previous device. However -- when daisy-chaining the serial port you must always send all channels' settings every time you want to make a change. That means if you have two PGA2310s in series, you have to send 32 bits of control setting every time. To change device 0, you have to send device 0 and device 1 settings each time, even if device 1 settings have not changed. And the chip select has to be true for the entire 32 bit time.

  • 0
    TI__Expert 6380 points

    Hi Art,

    1) Yes for the unused output pins, but I would recommend for you to connect the unused input pins to the stable node such as GND, in order to minimize the risk for any noise coupling.

    2) Yes, each ch can be configured in different gain settings, as you can see in the fig.10 of the data sheet.

    3) As Andy pointed out, you must write all devices when you update the gain settling for the specific device. Please refer it to the subsection 7.3.4 Daisy-Chaining Multiple PGA2310 Devices in the data sheet.

    Thank you and Best regards,
    Iwata Etsuji 

  • 0 in reply to Iwata Etsuji
    TI__Genius 16505 points

    Thanks Guys!

    Art