68HC08AZ32

The following paragraphs should be added to the end of the Reaction Time Calculation section on page 118 of the data book: When defining a limit in software for the maximum lock time, the value must allow for variation due to all of the factors mentioned in this section, especially due to the Cf capacitor and application specific influences.

The calculated lock time is only an indication and 68HC08AZ32 is the customer's responsibility to allow enough of a guard band for their application. Prior to finalising any software and while determining the maximum lock time, take into account all device to device differences. Typically, applications of 68HC08AZ32 set the maximum lock time as an order of magnitude higher than the measured value. This is considered sufficient for all such device to device variation.

Motorola recommends measuring the lock time of the application system by utilising dedicated software, running in Flash, EEPROM or RAM. This should toggle a port pin when the PLL is first configured and switched on, then again when 68HC08AZ32 goes from acquisition to lock mode and finally again when the PLL lock bit is set. The resultant waveform can be captured on an oscilloscope and used to determine the typical lock time for the micro controller and the associated external application circuit.