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PGA2505: PGA2505, but not so expensive!?

Jay Shoemaker
Intellectual 650 points
Part Number: PGA2505
Other Parts Discussed in Thread: PCM1865, PGA2500
Hey TI, 

Does anyone know of a digitally controlled microphone preamp that doesn't cost ~$10 per channel like the PGA2505? Preferably one that is I2C controlled as opposed to SPI? I need a total of 4 channels. 

I'm finding it less costly to build a custom PCM1865 (4 channel ADC with +32db Mic Preamp Built In). The PGA1865 costs ~$2.10 a channel. So I've been actively working on that board (I have a few prototypes going). But I still find it hard to believe there is nothing similar to the PGA2505 that doesn't cost so much. I've looked fairly hard at this subject. 

Must Haves
- Balanced Input
- Gain from 0db -32db (or better)
- Digitally Controlled (Preferred I2C)
- For Dynamic PA Microphones such as "SM58". 

Any input on this subject would be appreciated. Thanks!

Jay
  • 0
    Genius 3945 points
    I needed a digitally-controlled mic preamp with 50 dB gain range in 1 dB steps. The gotcha was that it was for a bus-powered USB device with no negative rail. I ended up doing it with good +5 op-amps, 8:1 analog mux and another analog switch, with clever choice of gain-setting resistors. It works well. It was probably $5/channel, though.

    I realize that this is a TI support forum, but you might wish to look at THAT Corp's 6261, which has two channels for $12/e qty 1 (under $10/qty 100).
  • 0 in reply to Andy Peters
    TI__Guru 50696 points
    HI Jay,

    Unfortunately, the only programmable gain mic preamplifiers currently offered are the PGA2500 and PGA2505. The PGA2505 is the lowest cost option. The PGA2500 is the highest performance Gain range 0dB and10dB to 65dB in 1dB steps offering 114dB THD (typ) @gain=0dB.
    The PGA2505 offers 0dB and 9dB to 60dB in 3dB steps offering 110dB THD (typ) @gain=0dB.

    Thanks and Regards,
    Luis