![Asahi KASEI AK4458 Скачать руководство пользователя страница 81](http://html1.mh-extra.com/html/asahi-kasei/ak4458/ak4458_general-description-manual_2980215081.webp)
[AK4458]
014011794-E-01
2015/08
- 81 -
3. Analog Outputs
The analog outputs are full differential outputs and 2.8Vpp (typ, VREFH1/2/3/4
VREFL1/2/3/4 = 5V)
centered around VREFH2. The differential outputs are summed externally, V
AOUT
= (AOUT+)
(AOUT
)
between AOUT+ and AOUT
. If the summing gain is 1, the output range is 5.6Vpp (typ, VREFH1/2/3/4
VREFL1/2/3/4 = 5V). The bias voltage of the external summing circuit is supplied externally. PCM input data
format is 2's complement. The output voltage (V
AOUT
) is a positive full scale for 7FFFFFH (@24bit) and a
negative full scale for 800000H (@24bit). The ideal V
AOUT
is 0V for 000000H(@24bit).
The output level is determined by the 1-bit signal duty ratio in DSD input mode. The output level is positive full
scale when the duty is 100% (all “1”) and the output level is negative full scale when the duty is 0% (all “0”). In
ideal case, a 0V voltage is output when the input signal duty is 50%.
The internal switched - capacitor filters attenuate the noise generated by the delta -sigma modulator beyond the
audio pass band.
Figure 75
shows an example of differential outputs and LPF circuit example by a single
op-amp.
3.9k
4.7k
150
3.9k
150
4.7k
470p
+Vop
470p
-Vop
AOUT-
AOUT+
3.9n
Analog
Out
AK4458
NJM2043
Figure 75 External LPF Circuit Example 1 for PCM (fc = 99.0kHz, Q=0.680)
R1
3.3k
3.9k
3.9k
4.3k
4.7k
5.6k
R2
3.3k
4.7k
5.6k
6.8k
8.2k
12.0k
GAIN(dB)
0
1.620665 3.142468 3.980809
4.83432
6.619864
DC Load (MAX)
3.8k
4.0k
3.5k
3.6k
3.6k
3.8k
Table 32. External LPF Circuit Example 1 for PCM
Frequency Response
Gain
20kHz
0.036dB
40kHz
0.225dB
80kHz
1.855dB
Table 33. Frequency Response of External LPF Circuit Example 1 for PCM