AK4118A Datasheet, PDF (25/56 Pages) Asahi Kasei Microsystems – High Feature 192kHz 24bit Digital Audio I/F Transceiver

■ Biphase Signal Input/Output Circuit
[AK4118A]
75Ω
Coax
0.1uF
RX
75Ω
AK4118A
Figure 20. Consumer Input Circuit (Coaxial Input)
Note: In case of coaxial input, if a coupling level to this input from the next RX input line
pattern exceeds 50mV, there is a possibility to occur an incorrect operation is occured.
In this case, it is possible to lower the coupling level by adding this decoupling
capacitor.
Optical
Fiber
Optical Receiver
O/E
470
RX
AK4118A
Figure 21. Consumer Input Circuit (Optical Input)
For coaxial input, as the input level of RX line is small in Serial Mode, cross-talking among RX input lines have to be
avoided. For example, inserting the shield pattern among them is effective. In Parallel Mode, four channel inputs
(RX0/1/2/3) are available and RX4-7 change to other pins for audio format control. Those pins must be fixed to “H” or
“L”.
The AK4118A includes the TX output buffer. The output level meets 0.5V+/-20% using the external resistors. The T1 in
the Figure 22 is a transformer of 1:1.
R1
TX
R2
75Ω cable
DVSS
T1
Figure 22. TX External Resistor Network
Vdd R1 R2
3.3V 240Ω 150Ω
3.0V 220Ω 150Ω
Note: When the AK4118A is in the power-down mode (PDN pin= “L”), power supply current can be suppressed by using
AC couple capacitor as following figure since the TX1 pin output becomes uncertain at power-down mode.
0.1uF R1
TX1
DVSS
R2
75Ω cable
Vdd R1 R2
T1
3.3V 240Ω 150Ω
3.0V 220Ω 150Ω
MS1130-E-02
- 25 -
2009/12