TLH7894 – 11

FIGURE 8B Waveform for Anti-Pop Circuit

Component

External Component Function

Normal Range

of Value

R1

Used in conjunction with varying impedance of pin 5 forming a resistor divider

500X –20 kX

network to reduce input level in automatic level control circuit

C2

Forms a noise reduction system by varying bandwidth as a function of the

001 mF – 05 mF

changing impedance on pin 5 With a small input signal the bandwidth is

reduced by R1 and C2 As the input level increases so does the bandwidth

C1 C3

Coupling capacitors Because these are part of the source impedance it is

05 mF–10 mF

important to use the larger values to keep low frequency source impedance at

a minimum

C4

Radio frequency interference roll-off capacitor

100 pF – 300 pF

R2

Playback response equalization C5 and R3 form a pole in the amplifier

50X – 200X

response at 50 Hz C5 and R4 form a zero in the response at 13 kHz for

R3

47 kX – 33 MX

120 ms equalization and 23 kHz for 70 ms equalization

R4

2kX – 200 kX

C5

R5

Microphone preamplifier gain equalization

50X – 200X

R6

5kX – 200 kX

R7

DC feedback path Provides a low impedance path to the negative input in

0 – 2 kX

order to sink the 50 mA negative input amplifier current C6 R9 R7 and C7

R8

200X –5 kX

provide isolation from the output so that adequate gain can be obtained at 20

R9

1kX –30 kX

Hz This 2-pole technique also provides fast turn-ON settling time

C6

200 mF – 1000 mF

C7

0 – 100 mF

C8

Preamplifier output to monitor amplifier input coupling

005 mF–1 mF

C9

ALC coupling capacitor Note that ALC input impedance is 2 kX

01 mF–5 mF

R10

These components bias the monitor amplifier output to half supply since the

10 kX – 100 kX

amplifier is unity gain at DC This allows for maximum output swing on a

R11

10 kX – 100 kX

varying supply

R12

10 kX – 100 kX

C10

1 mF – 100 mF

10