MSP430F449: transconductance gain of XT1 and XT2

Hugh Yang

Part Number: MSP430F449

Dears,

When my customer used F449, the crystal oscillator cannot start up under certain circumstances. It is necessary to know the transconductance gain of the XT1/XT2 circuit inside the chip to calculate the margin.

Siyan

7 months ago

0 Dennis Lehman 7 months ago

TI__Guru 61121 points

Hi Hugh,

Under what circumstances does the oscillator fail to start? Low voltage, high temperature, .etc?

Typically, startup issues have to do with improper selection of capacitor values necessary to meet the crystal's required parallel capacitance.

Have your customer take a look at this application report -> MSP430 32-kHz Crystal Oscillators (Rev. D) (ti.com) , specifically section 2.1.

If the information does not help customer, let me know.

0 Hugh Yang 7 months ago in reply to Dennis Lehman

TI__Intellectual 780 points

Hi Dennis,

The problem happened accidentally. Temperature is key variation.

Have your customer take a look at this application report -> MSP430 32-kHz Crystal Oscillators (Rev. D) (ti.com) , specifically section 2.1.

Customer already read this AP. But it's only for 32k low frequency, in other word XT1. They still don't know how to choose the XT2 crystal.

Hugh

0 Dennis Lehman 7 months ago in reply to Hugh Yang

TI__Guru 61121 points

Hi Hugh,

Let me run this by the design team.

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MSP430F449: transconductance gain of XT1 and XT2