We are using Wilink7 1281(module from murata) in our project. We understand that 3 clocks (slow, fast and TCXO) is required by 1281.
#1. What is the role of Fast clock (Fref) ??
#2. If external 26MHz TCXO is fed to 1281, does we still require Fref or is it optional ??
#3. If Fref is mandatory, can we use a clock buffer to feed both TCXO and Fref clock input ?
#4. If TXCO uses in-built LDO of 1281, then which pin VIO or VDD_1v8_IN should be left NC. Datasheet indicates if 1.8 volt is present internal LDO will not work.
Are we right or missing something ?
Thanks for such valuable forum
1. TCXO is the main system fast clock and can be the only fast clock supplied.
2. FREF clock is required in addition to TCXO only if FREF is < 0.5 ppm and can be used to calibrate TCXO (2-6 ppm).
3. TCXO can be one of the following frequencies: 19.2, 26, 33.6, 38.4, 52 MHz.
4. Fref clock can only be one of 4 frequencies: 19.2, 26, 38.4, 52 MHz.
5. The TCXO clock is supplied by the TCXO_LDO_OUT.
6. If you don't use the TCXO_LDO_OUT, it can be left N.C.
7. TCXO_LDO_OUT voltage is selectable between 1.83, 2.5 or 2.83V. The voltage is chosen by the TCXO_VOL_SEL pin.
8. The TCXO_LDO_OUT voltage is chosen as follow: TCXO_VOL_SEL=GND==>TCXO_LDO_OUT=1.83V, TCXO_VOL_SEL=floating==>TCXO_LDO_OUT=2.5V, TCXO_VOL_SEL=VIO==> TCXO_LDO_OUT=2.83V
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