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MSP430G2744: ESR of external crystal oscillator

Brian Zoro
Intellectual 2780 points
Part Number: MSP430G2744
Other Parts Discussed in Thread: MSP430F2132

Dear all,

our customer would like to use MSP430 on their Project ("Gateways to gassensor").
For this they would need to have a very stabile Baud rate over the entire temperature range.
This is why they consider using a 16MHz-crystall with a max ESR of 80Ohm

According to the data sheet (msp430g2744.pdf), crystals up to 16MHz can be used if XTS = 1 and LFXT1Sx = 2.
In chapter 5.23 "Typical Characteristics - LFXT1 Oscillator in HF Mode (XTS = 1)", Figure 5-16 shows the max. ESR for the respective frequency. With "LFXT1Sx = 2" only values up to 8 MHz are available.
They compared this figure with that of the MSP430F2132 and saw that the characteristics are almost identical, but the names are different.
 "LFXT1Sx = 3" is specified, although it is an external signal source and not a crystal.

So I wanted to ask how high the max ESR of the crystal can be? or whether they can use this or not.

Thanks in advance.
Regards,
Brian

  • 0
    TI__Mastermind 32870 points

    Please wait for some time. I will reply before tomorrow.

  • 0
    TI__Mastermind 32870 points

    You can see that the chart in the datasheet of mspg2744 is same as the one in MSP430F2132. But the figure is different. You must know that the CS mode is same for MSPG2744 and MSP430F2132, I advice you to refer to the chart not the figure.

    The reason is that the chart is tested in ATE, however the figure only show a typical value and not tested in the ATE test. That means the data in the chart is more reliable. 

    See from the chart the typical ESR is 300R for 16MHz with XTS = 1, LFXT1Sx = 2. For the crystal your customer chooses, it is has a lower ESR than 300R, it means it will cost less time before it vibrate to a certain frequency. It is good. 

    The conclusion is that your customer can use it.

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