SBAU171D May 2010 – January 2016 ADS1198 , ADS1298
The ADS1298 has an on-chip oscillator circuit that generates a 2.048MHz clock (nominal). This clock can vary by ±5% over temperature. For applications that require higher accuracy, the ADS1298 also accepts an external clock signal. The ADS1298ECG-FE provides an option to test both internal and external clock configurations. For the external signal, circuitry is available to generate the external clock from an on-board oscillator or from an externally connected source.
The external oscillator included on the EVM is powered from DVDD, the same supply as the ADS1298. Care must be taken to ensure that the externally supplied clock oscillator can operate either with +1.8V or +3.0V, depending on the DVDD supply configuration. Table 9 shows the jumper settings for the three options for the ADS1298 clocks.
ADS1298 Clock | Internal Clock | External OSC Clock | External Clock |
---|---|---|---|
JP18 | Not Installed | 2-3 | 1-2 |
JP19 | Don't Care | 1-2 (Disable) | Don't Care |
2-3 (Enable) |
A 2.048MHz oscillator installed on the EVM for +3V DVDD operation is FXO-HC735-2.048MHz. If operation at +1.8V DVDD is desired, the oscillator will need to be replaced. SiT8002AC-34-18E-2.048 is a possible oscillator for +1.8V DVDD operation. The EVM is shipped with the external oscillator enabled.