External Components Description
Components
Functional Description
1R
B
Prevents currents from entering the amplifier’s non-inverting input which may be passed through to the
load upon power down of the system due to the low input impedance of the circuitry when the
undervoltage circuitry is off. This phenomenon occurs when the supply voltages are below 1.5V.
2R
i
Inverting input resistance to provide AC gain in conjunction with R
f.
3R
f
Feedback resistance to provide AC gain in conjunction with R
i.
4C
i
(Note 14)
Feedback capacitor which ensures unity gain at DC. Also creates a highpass filter with R
i at fC =
1/(2
πR
iCi).
5C
S
Provides power supply filtering and bypassing. Refer to the Supply Bypassing application section for
proper placement and selection of bypass capacitors.
6R
V
(Note 14)
Acts as a volume control by setting the input voltage level.
7R
IN
(Note 14)
Sets the amplifier’s input terminals DC bias point when C
IN is present in the circuit. Also works with CIN to
create a highpass filter at f
C = 1/(2πRINCIN). Refer to Figure 4.
8C
IN
(Note 14)
Input capacitor which blocks the input signal’s DC offsets from being passed onto the amplifier’s inputs.
9R
SN
(Note 14)
Works with C
SN to stabilize the output stage by creating a pole that reduces high frequency instabilities.
10
C
SN
(Note 14)
Works with R
SN to stabilize the output stage by creating a pole that reduces high frequency instabilities.
The pole is set at f
C = 1/(2πRSNCSN). Refer to Figure 4.
11
L (Note 14)
Provides high impedance at high frequencies so that R may decouple a highly capacitive load and reduce
the Q of the series resonant circuit. Also provides a low impedance at low frequencies to short out R and
pass audio signals to the load. Refer to
Figure 4.
12
R (Note 14)
13
R
A
Provides DC voltage biasing for the transistor Q1 in single supply operation.
14
C
A
Provides bias filtering for single supply operation.
15
R
INP
(Note 14)
Limits the voltage difference between the amplifier’s inputs for single supply operation. Refer to the Clicks
and Pops application section for a more detailed explanation of the function of R
INP.
16
R
BI
Provides input bias current for single supply operation. Refer to the Clicks and Pops application section
for a more detailed explanation of the function of R
BI.
17
R
E
Establishes a fixed DC current for the transistor Q1 in single supply operation. This resistor stabilizes the
half-supply point along with C
A.
18
R
M
Mute resistance set up to allow 0.5mA to be drawn from pin 6 or 11 to turn the muting function off.
→ R
M is calculated using: RM ≤ (|VEE| 2.6V)/l where l ≥ 0.5mA. Refer to the Mute Attenuation vs Mute
Current curves in the Typical Performance Characteristics section.
19
C
M
Mute capacitance set up to create a large time constant for turn-on and turn-off muting.
20
S
1
Mute switch that mutes the music going into the amplifier when opened.
Note 14: Optional components dependent upon specific design requirements.
Typical Performance Characteristics
THD+N vs Frequency
DS100928-55
THD+N vs Frequency
DS100928-56
THD+N vs Output Power
DS100928-58
LM4766
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