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MSP430I2041: TIDM-SERVER-PWR-MON (tidu454a) : Rosc pin vs accuracy

Part Number: MSP430I2041

TI,

How do we obtain such a low level of %error when using internal Rosc mode for DCO?  

tidu454a, page 13, schematic shows 'Rosc' floating?  For internal resistor DCO mode, it should be tied to AVSS.  For external mode, there should be an external resistor to AVSS.

I duplicated the schematic but added an accurate, external resistor but they did not get the same accuracy of < 1% error?

Regards,

Marc

  • Hello Marc,

    I see on the schematic that ROSC is open and confirmed that it's open on the EVM. If the ROSC external resistor is not used, Table 1-3 in the User’s Guide actually recommends that the ROSC pin gets connected to AVSS (GND). I would recommend that you use a high precision, high tolerant 20kOhm external resistor in the design (both populated on hardware and enabled in software) to achieve the highest accuracy. This resistor is described in Section 4.2.1.2 in the User’s Guide. To select the external ROSC resistor, use the DCOF bit.

    Regards,

    James

    MSP Customer Applications

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