LY8005_13 Datasheet, PDF (15/21 Pages) Lyontek Inc. – 3.3 W Mono Filterless Class D Audio power Amplifier

®
Rev. 2.2
LY8005
3.3 W Mono Filterless Class D Audio power Amplifier
Input Resistors (Ri)
The input resistors (RI) set the gain of the amplifier according to equation Equation 1.
150 kΩ
Pre-Amplifier Gain = -----------
Ri
150 kΩ
Total Gain = 2 x -------------- …………………………………………………………….(1)
Ri
150 kΩ
AVD = 20 x log [2 x ( ----------- )]
Ri
Resistor matching is very important in fully differential amplifiers. The balance of the output on the reference
voltage depends on matched ratios of the resistors. CMRR, PSRR, and cancellation of the second harmonic
distortion diminish if resistor mismatch occurs. Therefore, it is recommended to use 1% tolerance resistors or
better to keep the performance optimized. Matching is more important than overall tolerance.
Resistor arrays with 1% matching can be used with a tolerance greater than 1%.
Place the input resistors very close to the LY8005 to limit noise injection on the high-impedance nodes.
For optimal performance the gain should be set to 2 V/V or lower. Lower gain allows the LY8005 to operate at
its best, and keeps a high voltage at the input making the inputs less susceptible to noise.
For example
Rf (KΩ)
Ri (KΩ)
Pre AMP. Gain
Total Gain
AVD (db)
Table 2. Typical Total Gain and AVD Values
150
150
150
150
150
75
50
37.5
1
2
3
4
2
4
6
8
6.02
12.04
15.56
18.06
150
25
6
12
21.58
150
18.75
8
16
24.08
Decoupling Capacitor (CS)
The LY8005 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 μF, placed as close as possible to the device VDD lead works best. Placing this decoupling capacitor close to
the LY8005 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 μF 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.
Lyontek Inc. reserves the rights to change the specifications and products without notice.
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