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2W × 2 Class AB Audio Power Amplifier
PT2303
FUNCTION DESCRIPTION
POWER SUPPLY
The operating voltage of PT2303 is from 3V to 5V, In general operation 5V is recommended, it can
deliver higher power output. When the supply voltage less then 3V the IC can work properly, but the
distortion will rise. After the supply voltage exceed 6V the temperature of package outside will rising
quickly due to higher stand-by current consumption.
SHUTDOWN
When the supply still powered the chip, pull-up the shutdown pin to VDD level will take chip into the
shutdown mode. After the shutdown mode is active, the total current consumption is less than 0.5µA
and the all of input or output pins no voltage output. When shutdown pin set to GND, the IC is back to
the normal operation.
Shutdown Pin
VDD
GND
Output State
Shutdown ON
Normal
VOLTAGE GAIN ADJUST
The output stage structure of the PT2303 is Bridge Tied Loaded (BTL), the close loop voltage gain can
be get from following formula.
Gain = 20log ( Rf
÷
Ri ) + 6dB
The close loop gain can be adjusted by external resistance, in general purpose the 6dB gain setting is
recommended, please reference to the application circuit. If the amplitude of input voltage in lower
level (ex. < 2Vpp), it can raise the voltage gain to get enough power output. Recommended of the
minimum series resistance (Ri) is 10KΩ to ensure IC have appropriate input impedance. Please refer
to following table.
External Resistance
Ri
Rf
Gain= 0dB
20KΩ
10KΩ
Gain= 6dB
20KΩ
20KΩ
Gain=12dB
10KΩ
20KΩ
PT2303 V1.2
-4-
December, 2007
PTC [ PRINCETON TECHNOLOGY CORP ]
