[AK4685]
■ Analog Outputs
(Differential Mode)
The analog outputs are fully differential outputs when the SGL pin = “L”, and the output range is 2.56 x (AVDD2)/5
Vpp centered around analog common voltage (VCOM pin). The differential outputs are summed externally. The
summing gain between L/ROUT+ and L/ROUT- is VL/ROUT = (L/ROUT+)-(L/ROUT-). If the summing gain is 1.09, the
output range is 5.59Vpp (typ@VDD=5V). The bias voltage of the external summing circuit is supplied externally. The
output voltage (VAOUT) is positive full scale for 7FFFFFH (@24-bits) and negative full scale for 800000H (@24-bits).
The ideal VAOUT is 0V for 000000H(@24-bits).
The internal switched-capacitor filters attenuate the noise generated by the delta-sigma modulator beyond the audio
passband. Figure 12 and Figure 13 show examples of an external LPF circuit summing the differential outputs with an
op-amp.
7.5k
8.2k
L/ROUT-
L/ROUT+
R1
R1
270p
Vop
2200p
8.2k
Analog
Out
7.5k
Vop
270p
1k
0.1u
BIAS
47u
When R1=300Ω
fc=93.1kHz, Q=0.717, g=-0.1dB at 40kHz
1k
Figure 12. External 2nd order LPF Circuit Example (using op-amp with single power supply)
7.5k
8.2k
L/ROUT-
L/ROUT+
R1
R1
270p
+Vop
2200p
8.2k
Analog
Out
7.5k
-Vop
270p
When R1=300Ω
fc=93.1kHz, Q=0.717, g=-0.1dB at 40kHz
Figure 13. External 2nd order LPF Circuit Example (using op-amp with dual power supplies)
(Single-ended Mode)
The analog outputs are single-ended when the SGL pin = “H” and the signals are output from the L/ROUT+
pins. In this case, the L/ROUT- pins should be opened. The output range is 2.8 x (AVDD2)/5 Vpp (typ)
centered around the analog common voltage (VCOM pin).
MS1106-E-00
2009/08
- 28 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
