LA4815VH

No.A1374-9/15

11. Signal mixing methods

The following methods can be used to mix a beep, key tone or other signal into the audio signal. Note that when input

to Pin 4 is selected, amplification of signals input from Pin 4 changes according to impedance Z4 connected to Pin 13.

11-1. Mixing method using resistors in the Pin 13 input front end

Figure 10

11-2. Method using input to Pin 4

• First signal system (Signal-1) voltage gain : Vg1

Vg1 = 20log (Vout/Vin1) = 20log (4 × (125 + Z4) (500 + (125 × Z4/(125 + Z4)))/(25 × Z4))

* Z4 = R1 + ro

• Second signal system (Signal-2) voltage gain : Vg2

Vg2 = 20log (Vout/Vin2) = 20log (10000/(125 + R1))

* fc2 = 1/(2

π × Cin2 × (R1 + 125))

Figure 11

12. Short-circuit between pins

Turning on the power supply with some pins short-circuited may cause deterioration or breakdown. Therefore, when

mounting the IC on a board, check to make sure that no short-circuit is formed between pins by solder or other foreign

substances before turning on the power supply.

13. Load short circuit

Leaving the IC for a long time in the condition with a load short circuit may cause deterioration or breakdown.

Therefore, never short-circuit the load.

14. Maximum ratings

When used under conditions near the maximum ratings, even a slight fluctuation in the conditions may cause the

maximum ratings to be exceeded, possibly resulting in a breakdown or other accidents. Therefore, always provide

enough margin for fluctuations in the supply voltage and other conditions, and use within a range not exceeding the

maximum ratings.

Vbias

100k

Ω

+

-

+

-

Pre-Amp

Rg2

Rg1

Signal-2

Signal-1

other IC

ro

R1

Vin2

ro

LA4815VH

Cin

Cin2

Vin1

Vout

+

125

Ω

10k

Ω

PWR - Amp

500

Ω

OUT

OUT1

OUT2

IN

GAIN2

13

4

1

Vbias

100k

Ω

+

-

Pre-Amp

Rg2

Rg1

Signal-2

Signal-1

other IC

ro

Rg3

Vout2

Vout1

ro

LA4815VH

Cin

Vin

IN

OUT1

OUT2

13

Pin 13 input impedance : Zin = 100k

Ω