
LA42102
No.A0494-4/8
External Components
C1, C2
: Input coupling capacitors, for which 4.7
F or less is recommended. LA42102 employs the zero-bias type
input circuit, with the input pin potential being nearly zero. Accordingly, the polarity must be determined
according to the DC potential of a circuit connected to the previous stage of LA42102.
C3
: Capacitor for starting time of the ripple filter and amplifier, for which 47
F is recommended.
C4, R1
: Capacitor and resistor for mute. C4 is necessary even when the mute function is not used.
C5
: Power capacitor.
C6 to C9 : Capacitor and resistor for oscillation prevention. For C6 to C9, the polyester film capacitor with superior
R2 to R5
temperature characteristics (Mylar capacitor) is recommended. Use R2 to R5 of 2.2
along with the
capacitor.
1. Mute function (pin 6)
With the pin 6 voltage of 1.7V (minimum) or more, the mute function is turned ON.
Set the VM application voltage so that the pin 6 voltage becomes. 1.7V or more.
The mute time constant is determined by R1 and C4. Determine the constant after careful review because it is related
to the pop sound at mute ON/OFF.
C4 is necessary even when the mute function is not used because it is related to the pop sound when the amplifier is
turned ON.
Note that the MUTE pin (pin 6) incorporates the
anti-electrostatic diode, allowing the current to flow through the
diode when the potential of VCC 7 pin decreases below that of
pin 6.
2. Standby function (pin 5)
The amplifier is turned ON when the voltage of 2.5V (minimum) or more is applied to pin 5.
Pin 5 control voltage
Pin 5 voltage
Amplifier
Standby
0 to 0.5
OFF
ON
2.5 to 15
ON
OFF
To suppress the inrush current to pin 5 when the VSTB
application voltage is high, insert the control resistor (RSTB).
Example : Tosuppress the pin 5 inrush current to 500
A or less
RSTB =
Applied voltage (VSTB) -2VBE (About 1.4V)
500
A
-15k
Note that the standby pin (pin 5) incorporates the anti-electrostatic diode, allowing the cu orrent to flow through the
diode when the potential of VCC pin 7 decreases below that of pin 5.
Mute
Standby
+
6
C4
10
F
R1
2k
2k
VCC
VM
20k
5
RSTB
1.5k
15k
VCC
2VBE
VS
30k