ZHCSHN9A February 2018 – April 2018 LMK05028
PRODUCTION DATA.
The TCXO input has amplitude and frequency monitors to help qualify the input before it can be used to lock the TCXO-DPLLs.
The TCXO amplitude detector determines if the input meets the minimum input slew rate threshold. The input slew rate detector clears its LOS flag when the slew rate is faster than 0.2 V/ns on the clock edge selected by the registers (rising edge, falling edge, or both edges). If the input clock does not meet the slew rate threshold on the selected clock edge(s), the amplitude monitor will set the LOS flag and disqualify the input.
The TCXO frequency detector clears its LOS_FDET flag when the input frequency is detected within the range of about 10 MHz to 90 MHz. Above 90 MHz, the frequency detector should be bypassed for proper operation.
The TCXO monitors can be bypassed through registers, so the input will always considered valid by the PLL control state machines. The TCXO's LOS status flags can be observed through the status pins and the status bits. The TCXO LOS signal from the status pin is the logic-OR combination of both its amplitude and frequency monitor flags.