Dear All,
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
Rishi
Hi Rishi:
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
Arild