ISD2540 datasheet(31/42 Pages) WINBOND

31 / 42 page

ISD2532/40/48/64

TABLE 13: APPLICATION EXAMPLE – BASIC DEVICE CONTROL

Control Step

Function

Action

Power up chip and select Record/Playback Mode

1. PD = LOW, 2. P/ R = As desired

Set message address for record/playback

Set addresses A0-A8

Begin playback

P/ R = HIGH, CE = Pulse LOW

Begin record

P/ R = LOW, CE = LOW

End playback

Automatic

End record

PD or CE = HIGH

TABLE 14: APPLICATION EXAMPLE – PASSIVE COMPONENT FUNCTIONS

Parts

Function

Comments

Microphone power supply decoupling

Reduces power supply noise

Release time constant

Sets release time for AGC

R3, R5

Microphone biasing resistors

Provides biasing for microphone operation

Series limiting resistor

Reduces level to prevent distortion at

higher supply voltages

Series limiting resistor

Reduces level to high supply voltages

C1, C5

Microphone DC-blocking capacitor Low-

frequency cutoff

Decouples microphone bias from chip.

Provides single-pole low-frequency cutoff

and command mode noise rejection.

Attack/Release time constant

Sets attack/release time for AGC

Low-frequency cutoff capacitor

Provides additional pole for low-frequency

cutoff

Microphone power supply decoupling

Reduces power supply noise

C6, C7, C8

Power supply capacitors

Filter and bypass of power supply

Publication Release Date: June 2003

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