BU26154MUV_15 Datasheet, PDF (29/90 Pages) Rohm – Monaural Audio CODEC with Touch Panel Interface

BU26154MUV
Datasheet
Analog block
VMID is used as analog circuit reference voltage for both recording path and playback path. Therefore, both case for
recording and playback, VMID need to do power up. At the power up, the wait time in proportion to the capacitor value is
needed to charge external capacitor connected with VMID pin. If recording and playback start before completion of charge,
it may generate noise. The following is a sequence of recommendation. Refer to the Analog Reference Power Management
Register for the function of VMIDCON.
.
VMID Power UP/DOWN Sequence (External capacitor 1uF)
Power Up
vmid ( 0V )
1/2 Regout Level
Power Down
Power Down Charge Time
Record or Playback Power Down
VMIDCON
0x0
0x1
0x2
0x0
Min 5ms _{Min 5ms}
Figure 33
Playback Path
The LSI can be executed sound output from 4 paths bellow. The output can be selected by Speaker Amplifier Output
Control Resister and Analog Reference Power Management Register.
Digital Input (SAI) → DAC → D-class Speaker Amplifier
Digital Input (SAI) → DAC → AB-class Speaker Amplifier
Digital Input (SAI) → DAC → Headphone Amplifier
Analog Microphone Input (MIN pin) → ADC → DAC → Headphone Amplifier
<attention>
No guaranty of record path sound quality during speaker amplifier active.
Speaker amplifier
The speaker amplifier of BU26154 can choose operation mode among one of D-class operation or the AB-class operation.
It can prevent interference with FM radio influence by making AB-class operation.
It performs the change of the enable / disable setting of the speaker amplifier and the AB-class/D-class operation in
Speaker Amplifier Power Management Register.
Headphones amplifier
The headphones amplifier of BU26154 operates in a ground reference. Therefore the LSI can delete the condenser for the
AC coupling to get outside. In addition, the LSI can suppress a POP noise when you want to suppress a POP noise by
connecting the optional resistance of the chart below outside.
Left
Headpphone Amplifier
BU26154
option
HPL
HPR
Right
Headpphone Amplifier
Figure 34
option
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