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doubt about the ADS1254

Jose de Jesus Colin Robles
Prodigy 200 points

Other Parts Discussed in Thread: ADS1254

Hi everyone, I'm traing to develop a driver to handle the ADS1254 with the PIC18F4550.

I've got a doubt for connect the ADC, can the Digital part support 5V?, the suitable is 3.6 Volts. but while the 18F26j50 arrives from USA I need to test the converter. and I've got another doubts.

Do I need a decoupling resistor to ground between ADC'S SCLK pin and pic's SCLK pin ?

Do I need a decoupling capacitors between Digital V and Digital Ground, Analog V and Analog Ground?

best regards, and have a good day

  • 0
    TI__Mastermind 44820 points

    Hi Jose,

    The ADS1254 does not support 5V for DVdd. For testing, you can use a resistor divider to bring the voltage down to the proper level. An LDO would be a better final solution.

    No decoupling is needed for the SCLK. It is not a bad idea to prevent the SCLK signal from floating, or to add a small RC to reduce the edge rates on fast digital signals, but this is not required.

    Decoupling on AVdd and DVdd is recommended for best performance. The circuit can work without the decoupling, but you will probably see extra noise. AGND and DGND don't need decoupling because, by nature of the direct connection to ground, they are decoupled completely. However, these ground connections must be low impedance and AGND and DGND need to connected together.

    Regards,
    Chris

  • 0 in reply to Christopher Hall
    Prodigy 200 points

    Hi Christopher  ! thanks for your reply.

    Ok. the better way is wait till the PIC18F26J50 arrives, because the pic18f4550 doesn't  sense the falling edge of the ADC at 3.3 Volts :(

    thanks so much best regard