Product Data Sheets

ISD1000A Series

1–18

APPLICATION EXAMPLE – PASSIVE COMPONENT FUNCTIONS

Part

Function

Comments

R1

Microphone power supply

decoupling

Reduces power supply noise

R2

Release time constant

Sets release time for AGC

R3, R4

Microphone biasing resistors

Provides biasing for microphone operation

R5

Series limiting resistor

Reduces level at high supply voltages

C1, C5

Microphone DC–blocking capacitor

Low-frequency cutoff

Decouples microphone bias from chip. Provides

single-pole low-frequency cutoff and common-mode

noise rejection

C2

Attack/Release time constant

Sets attack/release time for AGC

C3

Low-frequency cutoff capacitor

Provides additional pole for low-frequency cutoff

C4

Microphone power supply

decoupling

Reduces power supply noise

C6, C7, C8

Power supply capacitors

Filter and bypass of power supply

06.DataBook_1000A Dsht Page 18 Friday, September 27, 1996 10:44 AM