YMF795 Datasheet, PDF (22/45 Pages) YAMAHA CORPORATION – APL-2 Automobile sound Player-2

YMF795
AP3
This is the bit to power off the inverted amplifier side of the speaker output section.
Turning the inverted amplifier side power on after turning the VREF circuit and a non-inverted amplifier power on
can reduce pop noise.
AP4
This is the bit to power off the DAC and the HP Volume section.
Cautions for transition to the power-down
1. Be sure to shift a state to the power-down after the sound generation stops.
2. Power-down of the digital and analog section can be made at the same time.
Be sure to mute FM Volume and HP Volume in advance for the reduction of noise during power-down transition.
The registers to which the digital section cannot access during the power-down are as follows.
Index
$00h
$10-2Fh
$30h
$31h
$34h
Register functions
Musical score data
Timbre data
Timbre allocation
Tempo data
IRQ Control
Cautions for cancellation of the power-down
1. The time of 64×CLK_I is necessary from the setting of DP=0 until the digital section returns to the normal
operation. Be sure to access the registers after waiting for the time.
2. Perform the return procedure in this order when the whole analog section was powered off or the analog power
supply is OFF.
• Set AP1 to “0.” VREF goes up at the maximum of 50ms.
Do not set AP2 to AP4 to “0” until VREF goes up.
• Set AP2 to “0.”
• Set AP3 and AP4 to “0” after at least 10µs.
• Here, analog section is made available.
Consumption current can be reduced more, by setting AP4 to “1” when only speaker amplifier section is
used, and by setting AP2 and AP3 to “1” when only headphone is used without speaker amplifier.
Analog power supply OFF mode
Analog power supply can be powered off only when sound generation is being stopped.
Be sure to set AP1 to AP4 to “1” before powering off the analog power supply.
Or, pop noise may occur.
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