LM4940

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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 RF, sets the closed-loop gain. Input resistance RIN and input

1.

RIN

capacitance CIN form a high pass filter.

The filter's cutoff frequency is fC = 1/(2πRINCIN).

This is the input coupling capacitor. It blocks DC voltage at the amplifier's inverting input. CIN and RIN create a

2.

CIN

highpass filter. The filter's cutoff frequency is fC = 1/(2πRINCIN). Refer to the SELECTING EXTERNAL

COMPONENTS section for an explanation of determining CIN's value.

3.

RF

This is the feedback resistance that, along with Ri, sets closed-loop gain.

The supply bypass capacitor. Refer to the POWER SUPPLY BYPASSING section for information about properly

4.

CS

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.

CBYPASS

COMPONENTS for information about properly placing, and selecting the value of, this capacitor.

This is the output coupling capacitor. It blocks the nominal VDD/2 voltage present at the output and prevents it

6.

COUT

from reaching the load. COUT and RL form a high pass filter whose cutoff frequency is fC = 1/(2πRLCOUT). Refer to

the SELECTING EXTERNAL COMPONENTS section for an explanation of determining COUT's value.

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