LR6311 Datasheet, PDF (6/13 Pages) Leshan Radio Company – 3 Watt Mono Filter-Free Class-D Audio Power Amplifier

Leshan Radio Co ., Ltd
3>. A 33uH inductor should be used in series with R_L for efficiency
measurement
4>. The 30 kHz LPF (shown in figure 5) is required even if the analyzer has
an internal LPF
Component Recommended
Due to the weak noise immunity of the single-ended input application, the
differential input application should be used whenever possible. The typical
component values are listed in the table:
R_I
C_I
C_S
150 k
3.3 nF
1 uF
(1) C_I should have a tolerance of ±10% or better to reduce impedance
mismatch.
(2) Use 1% tolerance resistors or better to keep the performance optimized,
and place the R_I close to the device to limit noise injection on the high-
impedance nodes.
Input Resistors (R_I) & Capacitors (C_I)
The input resistors (R_I) set the total voltage gain of the amplifier according to Eq1
Gain = ^{2 ×150kΩ}
R_I
^V 
^V 
Eq1
The input resistor matching directly affects the CMRR, PSRR, and the second
harmonic distortion cancellation.
If a differential signal source is used, and the signal is biased from 0.5V ~ V_DD-
0.8V (shown in Figure2), the input capacitor (C_I) is not required.
If the input signal is not biased within the recommended common-mode input
range in differential input application (shown in Figure3), or in a single-ended input
application (shown in Figure4), the input coupling capacitors are required.
If the input coupling capacitors are used, the R_I and C_I form a high-pass filter
(HPF). The corner frequency (f_C) of the HPF can be calculated by Eq2
f_C
=
2π
1
⋅ R_I
⋅ C_I
(Hz )
Eq2
Decoupling Capacitor (C_S)
A good low equivalent-series-resistance (ESR) ceramic capacitor (C_S), used as
power supply decoupling capacitor (C_S), is required for high power supply rejection
(PSRR), high efficiency and low total harmonic distortion (THD). Typically C_S is
1µF, placed as close as possible to the device VDD pin.
6/13