A2323
AUDIO AMPLIFIER
AiT Semiconductor Inc.
www.ait-ic.com
2.65W CLASS-D AUDIO POWER AMPLIFIER
Application Information
Power decoupling capacitor
Excellent power decoupling capacitor can increase power amplifier efficiency and transient characteristic, low
ESR (equivalent-series-resistance) ceramic capacitors X5R or X7R are recommended. Usually
recommended connecting 1uF and 33pF two decupling capacitors to bypass VDD to ground, decupling
capacitor 0.1uF can grantees power amplifier low frequency transient response, but smaller capacitor 33pF
filter out power source radiated RF jamming signal, because capacitor 33pF resonant frequency at RF
frequency range, for 900MHz or 1.8GHz RF frequency jamming provide better filter characteristic. Meanwhile
the decoupling capacitor layout should near the chip VDD layout as near as possible to achieved best filtering
effect.
Input resistance
The A2323 is a full differential structure, designed by differential input and single-ended input, under both
input condition, the input resistance remain the same; through input resistance design can calculate the gain
of the amplifier, equation is below:
2x150kΩ
Gain=
Rin
All explanation stated that increasing the chip PSRR, CMRR, and THD characteristic by better matching
between two input resistors, so recommended designing with 5% accuracy resistor or better resistor. While
PCB layout, resistor should near power amplifier layout, it can prevent noise injecting into high resistance
point.
Input capacitor
Between Input resistance and input capacitance become a high pass filter, the equation of cut off frequency
as below:
1
ƒc =
2πx RinCin
The smaller CIN Capacitor helping filter out 217 Hz input coupling noise, and smaller capacitor decreased
power amplifier power up Pop-Click sound. Better matching between two input capacitor increase chip total
performance and suppressed Pop-Click sound, design 10 % accuracy resistor or better accuracy resistor is
recommended.
REV3.0
- MAY 2013 RELEASED, APR 2016 UPDATED -
- 15 -
AITSEMI [ AiT Semiconductor ]
