AK4528_04 Datasheet, PDF (26/29 Pages) Asahi Kasei Microsystems – High Performance 24Bit 96kHz Audio CODEC

ASAHI KASEI
[AK4528]
4. Analog Outputs
The analog outputs are full differential outputs and nominally 0.54 x VREF Vpp centered in the internal common voltage
(about VA/2). The differential outputs are summed externally, Vout=(AOUT+) − (AOUT−) between AOUT+ and
AOUT−. If the summing gain is 1, the output range is 5.4Vpp (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.
Differential outputs can eliminate any DC offset on analog outputs without using capacitors. Figure 13 to Figure 15 show
the example of external op-amp circuit summing the differential outputs.
AOUT-
4.7k
4.7k
R1
470p
3300p
Vop
AOUT+
4.7k
Vop
4.7k
R1
-
+
470p
Analog
Out
1k
BIAS 0.1µ
+
47µ
1k
When R1=200ohm
fc=93.2kHz, Q=0.712, g=-0.1dB at 40kHz
When R1=180ohm
fc=98.2kHz, Q=0.681, g=-0.2dB at 40kHz
Figure 13. External 2nd order LPF Example (using single supply op-amp)
MS0011-E-01
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2004/01