la4815m Sanyo Semiconductor Corporation, la4815m Datasheet - Page 7

• Manufacturer Part Number: la4815m
• Description: Monaural Power Amplifier
• Manufacturer: Sanyo Semiconductor Corporation

3. Mute control pin (Pin 7)
4. Mute control timing
The internal power amplifier circuit can be disabled and audio mute is turned on by controlling the voltage applied to
Pin 7. Control can be performed directly using the CPU output port, but digital noise from the CPU may worsen the
LA4815M noise floor. Therefore, inserting a series resistor, Rm1 (1 to 2.2kΩ) as shown in Fig. 6, is recommended.
In addition, the Pin 7 DC voltage is dependent on the supply voltage, so a reverse current flows to the CPU power
supply line when the Pin 7 voltage is higher than the CPU supply voltage. In these cases, connect a resistor, Rm2 (see
Fig. 7) between Pin 7 and GND to lower the Pin 7 DC voltage as shown in Fig. 6.
Note that when not using the mute function, Pin 7 must be left open.
Reverse current prevention resistor value : Rm2 (reference value) ← When V7 is set to approximately 2.5V
When performing mute control, exercise control at the timing shown in Fig. 8.
• Mute ON : Low
• Mute OFF : High or open
During power-on : Twu = 0 to 50ms
During power-off : Twd = 100 to 200ms
* Pins 6 and 7 can also rise simultaneously.
V DD
V SS
CPU
(MUTE)
(V CC )
Pin 6
Pin 7
* For reverse
current prevention
1000
100
Rm1
1kΩ
10
7
5
3
2
7
5
3
2
7
Rm2
Twu
9
Supply voltage, V CC – V
7
LA4815M
LA4815M
Figure 6
Rm2 – V CC
Figure 7
Figure 8
10kΩ
30kΩ
11
40kΩ
30kΩ
13
Twd
15
V CC
GND
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