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Variation in internal VCO LDO voltage level

Question asked by s.kannan on Mar 30, 2018
Latest reply on Apr 4, 2018 by srimoyi

We are using AD9364 in the custom board. We are trying to configure FIR filter coefficients through No-OS drivers with the API ad9361_trx_load_enable_fir(). We are facing Calibration Timeout error( reference clock is 40MHz-which is well within the allowable range). Since we are getting Calibration timeout error, we probed the Rx_VCO_LDO_OUT- PIN G2 to see the response of the LDO across the program.

When we try to configure the Rx FIR Coefficients, we are witnessing the LDO voltage dropped to 1.08V from 1.2V (difference of 120mV). So, my questions are,

1) Are the internal LDO's expected to show the above variation?

2) How much can the input supply of the LDO change, So as to keep the supply going to the LDO’s unchanged ?

3) Is my LDO running into unstable mode?