AK4620A Datasheet, PDF (38/42 Pages) Asahi Kasei Microsystems – 24 BIT 192KHZ AUDIO CODEC WITH IPGA

ASAHI KASEI
[AK4620A]
5. Analog Outputs
The analog outputs are fully differential and 2.8Vpp (typ. VREF = 5V), centered around VCOM. The differential outputs
are summed externally: Vout = (AOUT+)-(AOUT-) between AOUT+ and AOUT-. If the summing gain is 1, the output
range is 5.6Vpp (typ. VREF = 5V). The bias voltage of the external summing circuit is supplied externally. The input data
format is 2’s complement. The output voltage is a positive full scale for 7FFFFFH(@24bit) and a negative full scale for
800000H(@24bit). The ideal AOUT is 0V for 000000H(@24bit).
The internal switched-capacitor filter and the external LPF attenuate the noise generated by the delta-sigma modulator
beyond the audio passband. Figure 18 shows an example of external LPF circuit summing the differential outputs by an
op-amp. Figure 19 shows an example of differential outputs and LPF circuit example by three op-amps.
AK4620A
AOUT-
AOUT+
4.7k
2.2n
4.7k
4.7k
4.7k
200
330p
+Vop
200
330p ^-Vop
Analog
Out
Figure 18. External LPF Circuit Example 1 for PCM (fc = 136kHz, Q=0.694)
Frequency Response
Gain
20kHz
−0.01dB
40kHz
−0.06dB
80kHz
−0.59dB
Table 18. Filter Response of External LPF Circuit Example 1 for PCM
MS0368-E-00
- 38 -
2004/12