AK4621 AKM [Asahi Kasei Microsystems], AK4621 Datasheet - Page 37

• Manufacturer Part Number: AK4621
• Description: 24-Bit 192kHz Stereo Audio CODEC
• Manufacturer: AKM [Asahi Kasei Microsystems]

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.
example of differential outputs and LPF circuit example by three op-amps.
MS1258-E-01
Figure 19
shows an example of external LPF circuit summing the differential outputs by an op-amp.
AK4621
Figure 19. External LPF Circuit Example 1 (fc = 136kHz, Q=0.694)
Table 19. Frequency Response of External LPF Circuit Example 1
AOUT+
AOUT-
Frequency Response
20kHz
40kHz
80kHz
4.7k
4.7k
- 37 -
4.7k
2.2n
200
200
−0.01dB
−0.06dB
−0.59dB
330p
Gain
4.7k
+Vop
330p
-Vop
Analog
Out
Figure 20
[AK4621]
shows an
2011/01