PT2308P
2-Channel 300mW Class AB Power Amplifier
DESCRIPTION
PT2308P is a 2 channel Class AB stereo speaker
driver utilizing CMOS technology designed by AB
push-pull, the original sound will be low distortion
amplify and low consumption. The power of PT2308P
will be reach 300mW on THD=10% and deliver 8Ω
load.
FEATURES
•
Wild operating temperature large
•
Excellent Power Signal-to-Noise Repel Rate
(PSRR)
•
Low static state current consumption
•
Output power (THD=10％)
- Load is 16Ω/190mW
- Load is 8Ω/300mW
•
Low harmonics distortion (THD=0.03%)
•
Large output amplitude
APPLICATIONS
•
•
•
•
Walkman
Portable audio
HI-FI audio system
CD-ROM
BLOCK DIAGRAM
Tel: 886-66296288
‧
Fax: 886-29174598
‧
http://www.princeton.com.tw
‧
2F, 233-1, Baociao Road, Sindian, Taipei 23145, Taiwan
PT2308P
APPLICATION CIRCUIT
VIN 1
2.2uF
15K
15K
220uF
RL
VOUT 1
4
3
2
1
VSS
GND
VREF
(typ. 1/2VDD)
PT2308P
VDD
5
6
7
8
100uF
VDD
VIN 2
2.2uF
15K
15K
220uF
RL
VOUT 2
V1.1
2
July, 2009
PT2308P
ORDER INFORMATION
Valid Part Number
PT2308P-S
Package Type
8 Pins, SOP, 150mil
Top Code
PT2308P-S
PIN CONFIGURATION
PIN DESCRIPTION
Pin Name
OUT1
IN1-
IN1+
VSS
IN2+
IN2-
OUT2
VDD
I/O
O
I
I
-
I
I
O
-
Description
Output pin 1
Inverting input pin 1
Non-inverting input pin 1
Negative power supply
Non-inverting input pin 2
Inverting input pin 2
Output pin 2
Positive power supply
Pin No.
1
2
3
4
5
6
7
8
V1.1
3
July, 2009
PT2308P
BASIC APPLICATION DESCRIPTION
PT2308P is a low power amplifier which operates with a 5V input voltage, it can be used to drive regular earphones or
low power speakers with a load resistance of 8ohm or higher. The operation mechanics is much like the typical OPAMP.
(The picture below shows the basic application circuit of PT2308P as an inverted amplifier).
R2
Vin
Ci
R1
Co
Vout
VREF
Show in one side
R3
RL
PT2308P Typical Application Circuit
1. Gain Settings
The inverted amplifier’s amplification is equal to the ratio between R2 and R1 (Av= -(R2÷R1)). Please take note that
the maximum supply voltage for the PT2308P is 5V, voltage gain setting should depend on the input level amplitude;
too much voltage gain may increase the chance of causing clipping at the output.
2. VREF
Because the PT2308P operates with a single power source, to ensure the best output performance, the suggested
value for VREF is 1/2 VDD.
3. Input Coupling Capacitor Ci
In typical applications, this input coupling capacitor transfers signals between the input and PT2308P, it allows block
DC bias of the PT2308P flowing into input signal, and thus the user must be aware of the voltage tolerance and the
polarity of this Cap.
Referring to the diagram above, Ci and R1 forms a 1
st
order high-pass filter; the lower-cutoff frequency is determined
by the equation:
f
c(highpass)
=1/2πR1Ci
The diagram below shows the frequency response when: Ci=10µF/1µF/0.47µF/0.22µF/0.1µF
V1.1
4
July, 2009
PT2308P
4. Output Coupling Capacitor Co
Single power single-ended (SE) configuration generates a DC bias at the output of the amplifier; a coupling capacitor
must be placed at the output to block the DC bias from being sent to the load and connect a RL at the signal output
terminal. The low cut-off frequency may be needs to adjust to correspond to different load (speaker or earphone)
specifications. Similar to the input coupling capacitor, the output coupling capacitor and impedance of the load form a
1
st
order high-pass filter, the low cut-off frequency is determined by the equation:
f
c(highpass)
=1/2πR
L
Co
The diagram below shows the frequency response when: Co=1000µF/470µF/220µF/100µF.
5. Discharging Resistor (R3)
When the PT2308P is powered ON, the output coupling capacitor Co will start charging. When there is no load
connected at Vout, there will be a DC voltage present. At this time, if a load is suddenly connected (usually earphone
or speaker for general applications), the charged Co will then discharge through Vout to the load, causing a very loud
popping sound, thus, it is recommended to connect a R3 to regulate the discharge of Co.
The time it takes to discharge is T=CoR3.
The recommended resistance value for R3 is between 1KΩ
~
10KΩ, to prevent loading effect from the amplifier. If the
load (ex. Speaker) is permanently connected then R3 can be neglected.
V1.1
5
July, 2009
京公网安备 11010802033920号
EEWORLD
