Datasheet

LM4766
SNAS031F –SEPTEMBER 1998–REVISED MARCH 2013 www.ti.com
External Components Description
Components Functional Description
1 R
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.
2 R
i
Inverting input resistance to provide AC gain in conjunction with R
f
.
3 R
f
Feedback resistance to provide AC gain in conjunction with R
i
.
4 C
i
(1)
Feedback capacitor which ensures unity gain at DC. Also creates a highpass filter with R
i
at f
C
= 1/(2πR
i
C
i
).
5 C
S
Provides power supply filtering and bypassing. Refer to the SUPPLY BYPASSING section for proper placement
and selection of bypass capacitors.
6 R
V
(1)
Acts as a volume control by setting the input voltage level.
7 R
IN
(1)
Sets the amplifier's input terminals DC bias point when C
IN
is present in the circuit. Also works with C
IN
to create a
highpass filter at f
C
= 1/(2πR
IN
C
IN
). Refer to Figure 7.
8 C
IN
(1)
Input capacitor which blocks the input signal's DC offsets from being passed onto the amplifier's inputs.
9 R
SN
(1)
Works with C
SN
to stabilize the output stage by creating a pole that reduces high frequency instabilities.
10 C
SN
(1)
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/(2πR
SN
C
SN
). Refer to Figure 7.
11 L
(1)
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
12 R
(1)
to the load. Refer to Figure 7.
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
(1)
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: R
M
≤ (|V
EE
| − 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.
(1) Optional components dependent upon specific design requirements.
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