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Original question:

PGA2320 more output current

PGA2320: PGA2320 more output current

Briquel Florian
Intellectual 280 points
Part Number: PGA2320
Other Parts Discussed in Thread: LT1054

Hello,

I just would like to know if it's possible to supply analog part of PGA2320 with a 30VDC single voltage instead of +/-15VDC ?

Of course digital part will be supply with something like 3.3 or 5VDC.

regards

Florian

  • 0
    TI__Genius 15210 points

    Hi Florian,

    You could do this, but you'd have to elevate the digital and analog grounds to 15V and level shift your digital interface up to that new ground level as well. If you don't have a negative rail in your design, you might consider the LT1054 as a power supply option for that rail. 

  • 0 in reply to Alex Davis
    Intellectual 280 points

    Hi Alexander,

    Thanks for reply. My main concern is to keep a good (low) noise floor level and also thd. The target application is an very high end audio amplifier.

    I want a digital control for volume, then I'm very interested in PGA23xx components.

    The easy way is indeed to generate a dual power supply for the PGA23xx but this is the only part where I need such a symetrical supply, and this symetrical power supply seems to be complex, the PSRR of PGA23xx is about 100dB and I need the PGA23xx generate no more than 110dB of THD+N (that's why I use this high end component), so I have to use a very low noise LDO for the positif rail and a voltage inverter like LT1054 followed by a low noise LDO for negatif rail, that's complex.

    The other solution is to integrate PGA2320xx directly in my amp design but then I need it to support 0-24V main rail voltage, if I choose this solution can I use a kind of level shifter to adapt CMOS level to 12V - 12+3.3V level ? Maybe a smart way will be to use some optical or magnetic coupler to shift level and gain a strong isolation between digital and analog circuitery ?

    Best Regards,

    Florian

  • 0 in reply to Briquel Florian
    TI__Genius 15210 points

    Hi Florian,

    As long as you elevate the ground potential and digital interface, this should work. If your analog inputs and outputs sit at a different DC level, you'll need to add capacitors to block that DC offset. I'd recommend adding an op amp to provide a buffered mid-supply voltage for the PGA ground terminals. Your level shifting could then use optocouplers or any other isolation system. 

    Keep in mind that while adding a voltage inverter and low-noise LDO will add some complexity, this might end up being less complex than running the PGA in a single-supply configuration.