AK4205EN Datasheet, PDF (13/25 Pages) Asahi Kasei Microsystems – Ultra Low Noise and Distortion Headphone Amp with Analog Switch

[AK4205]
9. Functional Descriptions
9.1 System Reset
Power supplies must be applied when the RSTN pin = “L”. Set the RSTN pin to “H” to release
power-down after lapse of 1ms or longer from SWVDD power-up. The charge pump circuit starts to
operate after the RSTN pin is set to “H”, and then the positive and negative voltage for analog switch are
generated.
9.2 Charge Pump Circuit
The positive and negative powers are generated by built-in charge pump circuit from SWVDD voltage
when RSTN pin = “H”. These generated powers are used for the analog switch. Input and output signals
for the analog switch are single-ended and centered around on VSS (0V). The AK4205 has built-in
capacitors for charge pump circuit; therefore no external capacitors are necessary.
The power-up time of the charge pump circuit is typ. 100μs (max. 500μs). The operating frequency of the
charge pump circuit is depended on internal oscillator (typ. 4.5MHz). RVDD, PVDDA/B and PVEEA/B
must be supplied after power-up the charge pump circuit.
SWINA pin
0V
SWINB pin SWVSS
0V
SWVSS
AUXA pin
Hi-Fi
BG
-3.3V _Charge
Pump
Analog
Switch
+6.6V _Charge
Pump
AUX
-3.3V _Charge
Pump
SWOUTA pin
0V
Headphone
SWVDD pin
+3.3V
SWVSS pin
AUXB pin
Figure 10. Charge Pump Circuit
SWOUTB pin
0V
Headphone
016012367-E-00
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2016/12