AK4205EN Datasheet, PDF (14/25 Pages) Asahi Kasei Microsystems – Ultra Low Noise and Distortion Headphone Amp with Analog Switch

[AK4205]
9.3 Analog Switch & Mute Circuits
The AK4205 has an analog switch circuit with ultra-low on-resistance. It is able to achieve a 124 dB
S/N(A-weighted) and -118dB THD+N when combined with a headphone amplifier that has ultra-low
noise and distortion.
When the MUTEN pin = “H” and the SEL pin = “L”, the signals input to the AUXA and AUXB pins are
output from the SWOUTA and SWOUTB pins, respectively. At this time, the SWINA and SWINB pins are
pulled down to SWVSS by 4Ω (typ) resistance of SWA and SWB switches. When the MUTEN pin = “H”
and the SEL pin = “H”, input signals to the SWINA and SWINB pins are output from the SWOUTA and
SWOUTB pins, respectively. Soft mute transition is executed when changing the path (SEL pin = “L” →
“H” or “H” → “L”) or when releasing a mute (MUTEN pin = “L” → “H”) to reduce pop noises. These
transition times depend on the time constant of a capacitor that is connected to the CAPSS pin. Turn-off
time will be 29ms (typ.) and Turn-on time will be 59ms (typ.) if the capacitor value Css = 0.1 μF
Setting of the SEL pin is ignored and the SWOUTA and the SWOUTB pins become mute state
immediately by setting the MUTEN pin to “L”.
MUTEN pin
L
H
Table 1. Modes Control (x: Do not care)
SEL pin
Mode
x
Mute State (SWOUTA/B pins output Hi-Z)
L
AUX Mode (AUXA/B pins are enabled)
H
Hi-Fi Mode (SWINA/B pins are enabled)
SWINA pin
SWA
SWINB pin SWVSS
AUXA pin
0V
SWB
SWVSS
“H”
“L”
SEL pin
“H”
“L”
Analog
Switch
SWOUTA pin
0V
CAPSS pin
0.1μF
(Css)
0V
SWOUTB pin
SEL pin
“L”
0V
“H”
AUXB pin
MUTEN pin
AUX Mode (SEL pin = “L”)
SWINA pin
0V
SWA
SWINB pin
0V
SWVSS
SWB
SWVSS
AUXA pin
“H”
“L”
SEL pin
“H”
“L”
Analog
Switch
SWOUTA pin
0V
CAPSS pin
0.1μF
(Css)
0V
SWOUTB pin
SEL pin
“H”
AUXB pin
“H”
MUTEN pin
Hi-Fi Mode (SEL pin = “H”)
Figure 11. AUX Mode and Hi-Fi- Mode
016012367-E-00
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2016/12