YMF795 Datasheet, PDF (30/45 Pages) YAMAHA CORPORATION – APL-2 Automobile sound Player-2

YMF795
Precautions for the use of separate power supplies:
A LSI with multiple power supply inputs needs to pay attention to the followings for [Power supply connection] and
[Ground connection].
We explain it here by giving an analog circuit power supply and a digital circuit power supply as an example.
[Power supply connection]
When a power supply for analog circuits of this LSI and a power supply for digital circuits of this LSI can be separately
prepared (including a case where a power supply for the LSI's analog circuits is shared with analog circuits of the later
stage) please refer to “(1) Circuit diagram and wiring diagram when two power supplies are used:” On the contrary,
when multiple power supplies cannot be prepared, please refer to “(2) Circuit diagram and wiring diagram when one
power supply and one voltage regulator IC are used:”
And, when “(1) Circuit diagram and wiring diagram when two power supplies are used:” is selected, room for
improvement of analog performance becomes big, but you need to consider avoidance of time interval difference
between power supplies at the time of power-on (power-off).
[Ground connection]
The ground connection is common to “(1) Circuit diagram and wiring diagram when two power supplies are used:” and
“(2) Circuit diagram and wiring diagram when one power supply and one voltage regulator IC are used:” In each case,
grounds must not be separated.
(1) Circuit diagram and wiring diagram when two power supplies are used:
・Be sure to connect VSS pin to AVSS pin near the LSI. Excessive inductance between VSS pin and AVSS pin may
cause malfunctions and failures.
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