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Are there provisions in switching clock division ratio selection bit?

Latest Updated:08/05/2009

Question:

(CPU, Clock)
Are there any precautions about switching the clock division ratio selection bits? [2009/08/05]

Answer:

Please change the values of the clock division ratio selection bits at the same time using a single instruction.

Example using the 7546 Group:
When changing from on-chip oscillator (10) to middle-speed mode (01), if you switch the clock division ratio selection bits one at a time, you will transition through other states such as high-speed mode (00) or double-speed mode (11). Recommended operating voltage differs by frequency, so care is required.

(#107430)

Suitable Products
3803H
3803L
3850A
3858
38D2
38D5
7544
7545
7546
7547
7548
7549