LV4904V SANYO [Sanyo Semicon Device], LV4904V Datasheet - Page 13

• Manufacturer Part Number: LV4904V
• Description: Digital Input Class-D Power Amplifier
• Manufacturer: SANYO [Sanyo Semicon Device]

4. Protection Circuits
4.1 Under voltage protection circuit
The LV4904V is provided with under voltage protection circuit, overcurrent protection circuit and thermal protection
circuit.
In order to prevent unstable operation at low voltages, the under voltage protection circuit monitors the PVD pin
voltage, and once the attack voltage (PVD=7V typ.) has been exceeded, it turns on the amplifier. Furthermore, the
recovery voltage (6V typ.) is set so that unstable operation is also prevented when the PVD pin voltage has dropped for
some reason during operation. Since hysteresis of 1V or so is provided between the attack voltage and recovery voltage,
unstable operation near the threshold voltage where the under voltage protection circuit is continuously set to ON and
OFF is prevented. Figure 4.1 shows the operating model of the under voltage protection circuit.
The circuit is designed to turn the amplifier OFF in the same sequence as when Mute is set to ON so that this can be
used as a measure to prevent pop noise when the primary power for PVD has been turned off.
SANYO Semiconductors’ demonstration board is designed so that the above processes are carried out by the charge
stored in the power supply capacitor (470 µF) that has been added to the primary power supply line.
However, bear in mind that, in the actual products into which this IC has been incorporated, the primary power supply
is connected to other blocks as well, so the time constant for the fall may differ.
Figure 4.1 Under voltage protection circuit operation
Internal
Control
Signal
LV4904V
PVD Pin Voltage
Recovery Voltage
No.A1963-13/25