®
LY8221
Rev. 1.3
3.0W Stereo & 3D Enhancement Class D Audio Power Amplifier (SOP16)
In the table 2 shows the external components. Rin in connect with Cin to create a high-pass filter.
Table 2. Typical Component Values
Reference
Description
Note
Ri
Ci
150KΩ
0.22uF
1% tolerance resistors
80%/–20%
Ci = 1 / ( 2πRi fc)
Ci = 1 / ( 2π x 150KΩ x 4.8Hz)=0.221uF，Use 0.22uF
Decoupling Capacitor (CS)
The LY8221 is a high-performance class-D audio amplifier that requires adequate power supply decoupling to
ensure the efficiency is high and total harmonic distortion (THD) is low. For higher frequency transients,
spikes, or digital hash on the line, a good low equivalent-series-resistance (ESR) ceramic capacitor, typically
1.0uF, placed as close as possible to the device VDD lead works best. Placing this decoupling capacitor close
to the LY8221 is very important for the efficiency of the class-D amplifier, because any resistance or
inductance in the trace between the device and the capacitor can cause a loss in efficiency. For filtering
lower-frequency noise signals, a 10.0uF or greater capacitor placed near the audio power amplifier would also
help, but it is not required in most applications because of the high PSRR of this device.
Over-Heat Protection
The LY8221 has a built-in over-heat protection circuit, it will turn off all power output when the chip
temperature over 150℃, the chip will return to normal operation automatically after the temperature cool down
to 120℃.
3D Enhance
The LY8221 has a built-in 3D enhance effect that widens the perceived soundstage from the stereo audio
signal. The 3D enhance improves the apparent stereo channel separation whenever the left and right
speakers are too close, due to system size constraints or equipment limitations.
Activating the 3D effect by applying VDD to pin 1 (3D Control) and external RC network (Shown in figure 1) is
required to enable the 3D effect. The amount of the 3D effect is set by the R3 and C3. Decreasing the value of
R3 will increase the 3D effect. Increasing the value of the capacitors C3 will decrease the low cutoff frequency
at which the 3D effect starts to occur.The amount of perceived 3D is also dependent on many other factors
such as speaker placement and the distance to the listener. Therefore,it is recommended that the user try
various values of R3 and C3 to get a feel for how the 3D effect works in the application.
PCB Layout
All the external components must place very close to the LY8221. The input resistors need to be very close to
the LY8221 input pins so noise does not couple on the high impedance nodes between the input resistors and
the input amplifier of the LY8221. Then place the decoupling capacitor Cs, close to the LY8221 is important
for the efficiency of the class-D amplifier. Any resistance or inductance in the trace between the device and
the capacitor can cause a loss in efficiency.
Making the high current traces going to VDD, GND, VO+ and VO- pins of the LY8221 should be as wide as
possible to minimize trace resistance. If these traces are too thin, the LY8221's performance and output
power will decrease. The input traces do not need to be wide, but do need to run side-by-side to enable
common-mode noise cancellation.
Lyontek Inc. reserves the rights to change the specifications and products without notice.
5F, No. 2, lndustry E . Rd. IX, Science-Based Industrial Park, Hsinchu 300, Taiwan
TEL: 886-3-6668838
FAX: 886-3-6668836
13
