Datasheet

LM4940
www.ti.com SNAS219C –OCTOBER 2003–REVISED MAY 2013
EXTERNAL COMPONENTS DESCRIPTION
Refer to Figure 1.
Components Functional Description
This is the inverting input resistance that, along with R
F
, sets the closed-loop gain. Input resistance R
IN
and input
1. R
IN
capacitance C
IN
form a high pass filter.
The filter's cutoff frequency is f
C
= 1/(2πR
IN
C
IN
).
This is the input coupling capacitor. It blocks DC voltage at the amplifier's inverting input. C
IN
and R
IN
create a
2. C
IN
highpass filter. The filter's cutoff frequency is f
C
= 1/(2πR
IN
C
IN
). Refer to the SELECTING EXTERNAL
COMPONENTS section for an explanation of determining C
IN
's value.
3. R
F
This is the feedback resistance that, along with R
i
, sets closed-loop gain.
The supply bypass capacitor. Refer to the POWER SUPPLY BYPASSING section for information about properly
4. C
S
placing, and selecting the value of, this capacitor.
This capacitor filters the half-supply voltage present on the BYPASS pin. Refer to the SELECTING EXTERNAL
5. C
BYPASS
COMPONENTS for information about properly placing, and selecting the value of, this capacitor.
This is the output coupling capacitor. It blocks the nominal V
DD
/2 voltage present at the output and prevents it
6. C
OUT
from reaching the load. C
OUT
and R
L
form a high pass filter whose cutoff frequency is f
C
= 1/(2πR
L
C
OUT
). Refer to
the SELECTING EXTERNAL COMPONENTS section for an explanation of determining C
OUT
's value.
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