LA42031

No.A0394-4/7

External Components

C1

: The input coupling capacitors, for which 4.7

μF or less is recommended. LA42031 employs the zero-bias type

input circuit, with the input pin potential being nearly zero (about 0.01V). Accordingly, the polarity must be

determined according to the DC potential of a circuit connected to the previous stage of LA42031.

C2

: Capacitor for starting time of the ripple filter and amplifier, for which 47

μF is recommended.

C3, R1

: Capacitor and resistor for mute. C3 is necessary even when the mute function is not used.

C4

: Power capacitor.

C5, C6

: Capacitor and resistor for oscillation prevention. For C5, C6, the polyester film capacitor with superior

R2, R3

temperature characteristics (Mylar capacitor) is recommended. Use R2, R3 of 2.2

Ω 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 C3. Determine the constant after careful review because it is related

to the pop sound at mute ON/OFF.

C3 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-static

diodo and that decrease of the VCC pin 7 potential below that of

pin 6 causes the current to flow through the diode.

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

μA or less

RSTB =

Applied voltage (VSTB) -2VBE (About 1.4V)

500

μA

-15k

Ω

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

C3

10

μF

R1

2k

Ω

2k

Ω

VCC

VM

20k

Ω

5

RSTB

1.5k

Ω

15k

Ω

VCC

2VBE

VS

30k

Ω