ISD1110P, using analog in input from PC line out

Discussion in 'General Electronics Chat' started by xnihilo, Dec 1, 2008.

  1. xnihilo

    Thread Starter Active Member

    Nov 20, 2008
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    0
    Hi there,

    I'm going to use a ISD1110P chipcorder for a project. I will record 5 sample of 2s length. I will not be using an electret microphone. Instead, I will be using the ANALOG IN pin of the ISD.

    I have a couple questions, maybe you could help me to sort that out.

    When not in use, ANA-In is connected to ANA-OUT through a resistor and a capacitor.
    I will not be using ANA-OUT, what should I do with the ANA-OUT pin, leave it floating?

    As I will not be using Microphone as an input, What should I do with the following pins: MIC, MIC REF and AGC? leave them floating?

    It will be very kind if someone could give some advice about that.

    Thank you in andvance for any clue.
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    You can leave them floating but its better to tie MIC, MIC REF and AGC to ground via a 10K resistor for each one to minimize noise pick up which might cause internal interference.
     
  3. xnihilo

    Thread Starter Active Member

    Nov 20, 2008
    33
    0
    Oh, I see. Okay, thank you for this information.
    By the way did you already work with such products as Chipcorder, they seem pretty cool but I'm afraid the sound quality might not be very nice.
    I was thinking of using a pic to get a recorded sample from an SPI EEPROM and send it to a 16 bits DAC then to a LM386 or TPA701 aplifier, as Norm Carlberg did. Unfortunately, TPA701 and the DAc are very expensive and hard to find here... Maybe I could use a 8bits DAC instead but I never used that kind of components, there will be a lot of datasheets reading to do... And a lot of forums reading too I guess :)
     
  4. mik3

    Senior Member

    Feb 4, 2008
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    I haven't used them yet but I don't think they are bad.
     
  5. xnihilo

    Thread Starter Active Member

    Nov 20, 2008
    33
    0
    You say:
    "You can leave them floating but its better to tie MIC, MIC REF and AGC to ground via a 10K resistor for each one to minimize noise pick up which might cause internal interference.",

    I read at http://www.isd.com/products/isd_products/chipcorder/faq/FAQs.pdf
    the following at page 8:
    "These pins should be left floating. Do not connect them to ground"

    You can't even ground SP+ and SP- or you may destroy the chip.
     
  6. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    If you connect this pins directly to ground (with wire), especially ANA OUT, you will destroy the chip. If you connect them via resistors I can't see something which can destroy the chip. If you leave them floating it will be fine, don't worry.
     
  7. xnihilo

    Thread Starter Active Member

    Nov 20, 2008
    33
    0
    Okay, thank you very much.
     
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