External Components Description

(

Figures 1, 2)

Components

Functional Description

1.

R

IN

Acts as a volume control by setting the voltage level allowed to the amplifier’s input terminals.

2.

R

A

Provides DC voltage biasing for the single supply operation and bias current for the positive input terminal.

3.

C

A

Provides bias filtering.

4.

C

Provides AC coupling at the input and output of the amplifier for single supply operation.

5.

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 under-voltage

circuitry is off. This phenomenon occurs when the supply voltages are below 1.5V.

6.

C

C

(Note 15)

Reduces the gain (bandwidth of the amplifier) at high frequencies to avoid quasi-saturation oscillations of

the output transistor. The capacitor also suppresses external electromagnetic switching noise created from

fluorescent lamps.

7.

Ri

Inverting input resistance to provide AC Gain in conjunction with R

8.

Ci

(Note 15)

Feedback capacitor. Ensures unity gain at DC. Also a low frequency pole (highpass roll-off) at:

f

9.

R

f1

Feedback resistance to provide AC Gain in conjunction with Ri.

10.

R

f2

(Note 15)

At higher frequencies feedback resistance works with C

and Ri. A high frequency pole (lowpass roll-off) exists at:

f

11.

C

f

(Note 15)

Compensation capacitor that works with R

DS011775-6

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