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2W × 2 Class AB Audio Power Amplifier
PT2303
If the amplitude of input signal exceed the VDD-GND range, or voltage gain setup too high, the input
stage is very easy overload and distorted. Please make sure the amplitude of audio source (Vin) and
setting the best gain value, in general use the gain setup to +6dB is recommended. Please refer to
following table.
Operating Voltage
VDD=3V
Gain= 0dB
Vin <5Vpp
Vin <8Vpp
Gain= 6dB
Vin <2.5Vpp
Vin<4Vpp
Gain=12dB
Vin <1.25Vpp
Vin<2Vpp
VDD=5V
SE/BTL MODE SWITCHING
PT2303 have two output modes, SE (Single-Ended) or BTL (Bridge-Tied Load). When driving a 4Ω
speaker load suggestion set to the BTL mode for get the more power output. And driving a 32Ω
headphone load, it can be set to SE mode and turn-off the un-work amplifier to decrease stand-by
power consumption. Switching between the SE/BTL modes is controlled by the HP-IN pin, please refer
to following table:
HP-IN
VDD
Output Mode
SE
GND
BTL
OVER TEMPERATURE PROTECTION
The PT2303 has a built-in over temperature protection circuit, it will turn off all output when the chip
temperature over 130℃, the chip will return to normal operation automatically after the temperature
cool down to 100℃.
POP AND CLICK SURPRESS
A power amplifier uses single supply voltage may almost have inrush noise on output in the
power-on/off period. It is because of the output DC potential needs time to stable on 1/2VDD, the
period relative with the capacitance (CB) on the Vref pin. Larger CB value will extend the stable time,
and also can suppress the noise happened in power-on. In supply voltage=5V and CB=2.2µF, stable
time is about 300mS. The value of CB also relative with the value of the DC blocking capacitor
connected in input terminal. In general condition the time constant of DC blocking capacitor should be
less than CB stable time. The recommended value of DC blocking capacitor is 1µF, and the capacitor
of output terminal connected to 32Ω headphone is 220µF. Smaller capacitance can shorten the charge
time to suppress the pop noise, both the input and output capacitance will limited the low frequency
extend range.
PT2303 V1.2
- 5 -
December, 2007
PTC [ PRINCETON TECHNOLOGY CORP ]
