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ADS58C48 EVM clock input

Other Parts Discussed in Thread: ADS58C48

Hi

I just want to know if the clock signal input of ADS58C48 EVM can take directly a sine wave or I have to add an circuit  before clock  input

thanks

  • Hi,

    We routinely use a sine wave for the sample clock and in fact sine wave is one of the options listed for sample clock input on page 4 of the datasheet.  Characterization of the device is generally done with a sine wave clock, since a narrow passband filter is usually needed to get a clock that is as free of phase noise as possible adn the filter also removes harmonics - so a sine wave is really the most common clock input to the ADC.

    Regards,

    Richard P.

  • Hi

    thanks richard for your answer.

    So, ADS58C48 data output format is by default  set into 2's if I want to set its into SOB by cliking the switch on in ADS58C48 EVM software control, this setting will stay or I have to configure everytime

    thanks

  • Hi,

    Any settings you write to the register space through the SPI interface will persist until the device is either reset (by the reset pin or the reset bit in the register space) or until the device is power cycled.   Everytime you power up the device or reset the device you will need to set the desired mode of operation again.

    Regards,

    Richard P.

  • Hi Richard

     

    I wonder how  ADC retrieves data serial from a serial interface controlled by a FPGA and process it, since the output MOSI interface is connected to SDATA.

    thanks

  • Hi,

    I see from your reference to the MOSI signal that you are thinking of an 'industry standard' 4-wire serial interface. ( as in  http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus   "Sometimes SPI is called a "four-wire" serial bus, contrasting with three-, two-, and one-wire serial buses." )  The serial interface on our devices are not set to conform to any such standard - the format of our interface is what it is as described in the data sheet for a particular device.

    Many of our older data converters used a 3-wire interface where only writes to the device are permitted.  We've added read-back to our newer devices, but sometimes still in a 3-wire format where the SDATA pin becomes bidirectional, and sometimes in a 4-wire interface where the data to be read back from the ADC is on the fourth wire.  The ADS58C48 can support readback using the 4th wire, but only after a 3-wire write is performed to register 0 to enable the SDOUT readback signal.   Then a 3-wire write is needed to register 0 again to turn off readback before writes can be done to other registers.

    in any event, the datasheet description of our serial interface for any particular device is what you need to look at - it will be the controlling document for the specifics of the interface for that device,  The data sheet description of our serial interface will describe the protocol such as number of addresss bits, number of data bits, polarity of the SCLK, how readback is supported and if it is supported.   We do not have a MOSI pin or MISO pin, although our SDATA pin has similar funciton as the MOSI signal in conveying data from the master to the ADC and the readback signal SDOUT has similar function as the MOSI signal in conveying data from the ADC to the master.

    Regards,

    Richard P.

  • Hi Richard

    thanks you so much for explanation 

    I'll start to read attentively datasheet

    thanks

  • Hi

    Sorry but one question again, ads58c48 internal register are eeprom?

    thanks

  • No,

    they are simply flip flops.  Hence they are volatile, and that is why the settings do not persist after the device is reset or power cycled. 

     

    Regards,

    Richard P.