CXA1946BQ/BR
VCT
GAINX2
GAINX1
GAINX34
INAOX
INX4
50k
50k
50k
50k
INX3
INX2
INX1
Fig. 2. Input Selector (2)
2. Volume
The volume circuit consists of two sections, an 8dB/step section and a 1dB/step section, as shown in Fig. 3.
This circuit also serves as a balance control because the volume for channel 1 and channel 2 can be set
independently.
To mute the output signal, send –∞dB data.
The input impedance is 9.5kΩ (typ.) for VRIN1 and VRIN2.
The output impedance for VOUT1 and VOUT2 is low impedance (roughly 0Ω). The volume step width and
gain are not affected by the load impedance.
3. Loudness
The configuration of the loudness circuit is shown in Fig. 3. CLDHCX and CLDLCX are connected externally,
and the loudness frequency characteristics are determined by these constants. The relationships between
CLDHCX/CLDLCX and the frequency characteristics are as follows:
1/fL = 2πCLDLCXR1
1/fH = 2πCLDHCXR2
The loudness characteristics are not affected by the load impedance of VOUT1 and VOUT2.
Loudness is turned on and off by serial data bit D5.
fH
VRINX (input impedance 9.5kΩ)
20k
fL
CLDHCX
0.0022µ
20k
Loudness frequency
characteristics
Total 40k
4.98k
OFF
R2
8.92k
VOUTX
ON
LOUD
LDHCX
R1
6.18k
25.7k
CLDLCX
0.047µ
LDLCX
Loudness
Volume
Fig. 3. Volume and Loudness
– 18 –
SONY [ SONY CORPORATION ]
