External Clock ADS1232

Hi Mohan,

Welcome to the forum!  No external clock source is required for the ADS1232.  If you set the pin 3 (CLKIN/XTAL1) of the ADS1232 low the device will use the internal oscillator as the clock source.  However if you wish to use a different clock source you may do so.  This can include a clock output from a microcontroller.  The clock input frequency range is specified in the electrical characteristics table on page 4 of the datasheet.  You can apply a clock in the range of 200kHz to 8MHz.

When applying an external clock, you need to realize that the data rate and digital filtering characteristics given in the datasheet only apply to the nominal frequency of 4.9152MHz.  Any other clock frequency will vary the timing as a ratio of the nominal clock timings to the actual clock frequency.  In simple terms the data rate is faster with a faster clock and slower with a slower clock.  As the filter notches occur at multiples of the data rate, these will also scale accordingly (see the section on page 16 of the datasheet called Frequency Response).

When using a micro to apply the clock, I suggest that a weak pull-down (around 47k Ohm) be added to the CLKIN pin to prevent any issues with glitching or floating inputs on startup of the microcontroller.  This also allows for debug and experimentation by still being able to use the internal clock source or the external clock source.  More information regarding the Clock Sources can be found on page 15 of the datasheet.

Best regards,

Bob B