AK4385ET AKM [Asahi Kasei Microsystems], AK4385ET Datasheet - Page 19

• Manufacturer Part Number: AK4385ET
• Description: 108dB 192kHz 24-Bit 2ch ?? DAC
• Manufacturer: AKM [Asahi Kasei Microsystems]

ASAHI KASEI
1. Grounding and Power Supply Decoupling
VDD and VSS are supplied from analog supply and should be separated from system digital supply. Decoupling
capacitor, especially 0.1µF ceramic capacitor for high frequency should be placed as near to VDD as possible. The
differential Voltage between VDD and VSS pins set the analog output range.
2. Analog Outputs
The analog outputs are full-differential outputs and 0.55 x VDD Vpp (typ) centered around the internal common voltage
(about AVDD/2). The differential outputs are summed externally, V
AOUT-. If the summing gain is 1, the output range is 5.5Vpp (typ @VREFH=5V). The bias voltage of the external
summing circuit is supplied externally. The input data format is 2’s complement. The output voltage (V
full scale for 7FFFFF (@24bit) and a negative full scale for 800000H (@24bit). The ideal V
(@24bit).
The internal switched-capacitor filter and external low pass filter attenuate the noise generated by the delta-sigma
modulator beyond the audio passband. DC offset on AOUT+/- is eliminated without AC coupling since the analog
outputs are differential. Figure 10 and 11 show the example of external op-amp circuit summing the differential outputs.
MS0246-E-01
Figure 10. External 2
Figure 11. External 2
AOUT+
AOUT-
AOUT+
AOUT-
BIAS
47u
nd
nd
0.1u
order LPF Circuit Example (using op-amp with single power supply)
order LPF Circuit Example (using op-amp with dual power supplies)
Vop
1k
1k
4.7k
4.7k
4.7k
4.7k
3300p
4.7k
3300p
4.7k
When R1=200Ω
When R1=180Ω
- 19 -
fc=93.2kHz, Q=0.712, g=-0.1dB at 40kHz
fc=98.2kHz, Q=0.681, g=-0.2dB at 40kHz
When R1=200Ω
When R1=180Ω
R1
R1
fc=93.2kHz, Q=0.712, g=-0.1dB at 40kHz
fc=98.2kHz, Q=0.681, g=-0.2dB at 40kHz
470p
R1
R1
470p
4.7k
AOUT
4.7k
+Vop
-Vop
470p
=(AOUT+)-(AOUT-) between AOUT+ and
Vop
470p
Analog
Out
Analog
Out
AOUT
is 0V for 000000H
AOUT
) is a positive
[AK4385]
2006/01