LMX2572: CE pin behavior

Hello Vic,

vic zap said:

1. Is it required to wait 100us every time the CE pin goes from LOW to HIGH or is this required only once upon power applying? Does CE physically control internal LDOs (turn it on/off)?

Yes, when the devices are power down, some internal LDOs will be shut down as well. It takes time for them to wake up after coming out of power down state. in cases when these LDOs are not up and stable before the last calibration data is applied, you may not get the same performance as it was before power down. As a result, we will need to calibrate it again.

vic zap said:

2. What time is required after CE goes HIGH for the SPI to become ready for operation? Maybe it's always ready, while the power is applied, irrespective to CE?

SPI should be ready immediately when CE goes high. However although registers can be written to the calibration should take place only after the wait time. In LMX2572 we introduced the LDO_DLY register to adjust the LDOs wake up time in order to make sure the LDOs is up before calibration data is applied.

Thanks,

Vibhu