la4820m Sanyo Semiconductor Corporation, la4820m Datasheet - Page 14

• Manufacturer Part Number: la4820m
• Description: Monaural Speaker/stereo Headphone Power Amplifier
• Manufacturer: Sanyo Semiconductor Corporation

c An equivalent circuit for the mute circuit is shown on the previous page. If the power supply is turned on, the external capacitor
c The mute-on/off time during normal operation is as shown below.
2. Common amplifier control switch
c When the headphone output is connected to other equipment, in an application set in which the common amplifier output (jack
c An equivalent circuit for the switching circuit is shown below.
c PWRC-off condition
3. HzP/SP switch
c This circuit uses a headphone jack with a switch to detect the headphone plug-in/out and automatically switch between the HzP
c Smoothing is applied by using an external capacitor and resistor in order to prevent switching shock noise.
c Open HzP condition
is charged by the internal constant current; once the voltage reaches 0.75 V (the switching level), mute turns off and the pin 2
DC voltage stabilizes at approximately 1.2 V. To turn mute on, short through a resistor to pull down pin 2. In this way,
smoothing is applied by using an external capacitor and resistor to prevent switching noise when mute is turned on/off.
common pin) may be connected to GND causing overcurrent to flow from the common amplifier, it is necessary to turn off the
common amplifier. In such an application, it is recommended to use the common capacitor scheme shown in Sample Application
Circuit 2 where pin 11 is grounded to turn off the common amplifier.
amplifier and the MONO amplifier. When the HzP amplifier is operating, the MONO amplifier is turned off, and when the
MONO amplifier is operating, the HzP amplifier is turned off.
V
S14
% 0.2 V
Mute-off time 6 8 ms
When 270 k
Mute off
V
and 0.033 µF are used:
S11
% 0.4 V
Pin 2 charging
LA4820M
Mute-on time 6 9 ms
Mute on
to
Pin 2 discharging
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