[AK4492]
the audio passband. Figure 74 shows examples of external LPF circuit summing the differential outputs by
a single op-amp. Load resistances of the analog output of the AK4492 are 1360 ohm for AOUT+ and 453
ohm for AOUT-, and the external LPF circuit can be driven regardless of the HLOAD pin or HLOAD bit
setting. The HLOAD pin/bit should be set to “H/1” when driving the LPF circuit if the AOUT- load resistance
is 300 ~ 400 ohm. The analog output will be 5.6 Vpp (typ.) after a single conversion with this circuit by
setting the GAIN pin = “L” or GC[2] bit = “0”. It will be 7.5 Vpp if setting the GAIN pin = “H” or GC[2] bit = “1”.
A resistor that has 0.1% or less absolute error must be used for external LPFs.
AK4492
680
680
680
3.3n
AOUT-
30
30
22n
+Vop
7
2
3
6
Analog
Out
AOUT+
4
OPA1611
-Vop
680
3.3n
Figure 74. External LPF Circuit Example 1 (fc = 90 kHz(typ), Q = 0.705(typ))
Table 43. Frequency Response of External LPF Circuit Example 1
Gain(1 kHz,typ)
0 dB
20 kHz
40 kHz
80 kHz
-0.04 dB
-0.22 dB
-2.08 dB
Frequency
Response
(ref:1 kHz,typ)
016011073-E-00
2016/12
- 96 -
AKM [ ASAHI KASEI MICROSYSTEMS ]
