lv4985vh Sanyo Semiconductor Corporation, lv4985vh Datasheet - Page 10

• Manufacturer Part Number: lv4985vh
• Description: Bi-cmos Ic For Portable Electronic Device Use 1.2w ? 2ch Btl Power Amplifier
• Manufacturer: Sanyo Semiconductor Corporation

9. Electronic volume control (pin 10 control)
10. Thermal protection circuit
11. Short-circuit between pins
12. Load Short-circuit
13. Maximum rating
By changing voltage applied to the pin 10, the voltage gain of the built-in VCA(variable control amplifier) is varied.
Since the ripple component of applied voltage is generated, a stabilized power source must be used.
When controlling the amplifier using the PWM signal from the CPU, use a resistor and capacitor for DC conversion as
shown in Figure 4 and adjust the voltage gain by changing the pulse width of PWM signal. In this case, the frequency
of PWM signal used must be higher than audio frequency band.
The IC has a built-in thermal protection circuit that can reduce the risk of breakdown or degradation when the IC
becomes abnormally hot for some reason. When the internal chip junction temperature Tj rises to approximately 170°C,
this protective circuit operates to cut off the power supply to the power amplifier block and stop signal output.
Operation recovers automatically when the chip temperature drops to approximately 130°C.
Note that this circuit cannot always prevent breakdown or degradation, so sufficient care should be taken for using the
IC. When the chip becomes abnormally hot, immediately turn off the power and determine the cause.
Turning on the power supply with the short-circuit between terminals leads to the deterioration and destruction of IC.
When fixing the IC to the substrate, please check that the solder is not short-circuited between the terminals before
turning on the power.
Leaving the IC in the load short-circuit for many hours leads to the deterioration and destruction of the IC.
The load must not be short-circuited absolutely.
When the rated value used is just below to the absolute maximum ratings value, there is a possibility to exceed the
maximum rating value with slight extrusion variable. Also, it can be a destructive accident.
Please use within the absolute maximum ratings with sufficient variation margin of supply voltage.
In addition, the package of this IC has low thermal radiation characteristics, so secure sufficient thermal radiation by
providing a copper foil land on the printed circuit board near the heat sink.
PWM output
CPU
PWM signal
LV4985VH
Fig. 4
R7
C8
Discharge resistor
R8
10
VOL
LV4985VH
No.A1568-10/15