ISD5008 View Datasheet(PDF) - Unspecified

Part Name

Description

Manufacturer

ISD5008

SINGLE-CHIP, VOICE RECORD / PLAYBACK DEVICE 4-, 5-, 6- AND 8-SECOND DURATION

Unspecified 

ISD5008 Product

5 OPERATIONAL MODES DESCRIPTION

The ISD5008 can operate in many different

modes. It’s flexibility allows the user to configure

the chip such that almost any input can mixed

with any other input and then be directed to any

output. The variable settings for the ANA and AUX

input amplifiers plus the microphone AGC and

speaker volume controls make it possible to use

the device with most existing cell phone or cord-

less phone chip sets with no external level adjust-

ment. Several modes will be found in most

applications, however. Please refer to the ISD5008

block diagram to better understand the following

modes. In all cases, we are assuming that the

chip has been powered up with the PU bit in the

SPI control register and that a time period of TPUD

has elapsed after that bit was set:

5.1 FEED THROUGH MODE

This mode enables the ISD5008 to connect to a

base band cell phone or cordless phone chip set

without affecting the audio source or destination.

There are two paths involved, the transmit path

and the receive path. The transmit path connects

the ISD chip’s microphone source through to the

microphone input on the base band chip set. The

receive path connects the base band chip set’s

speaker output through to the speaker driver on

the ISD chip. This allows the ISD chip to substitute

for those functions and incidentally gain access to

the audio to and from the base band chip set.

Figure 15 shows one possible connection to such

a chip set.

Figure 16 shows the part of the ISD5008 block dia-

gram that is used in Feed Through Mode. The rest

of the chip will be powered down to conserve

power. The bold lines highlight the audio paths.

Note that the Microphone to ANA OUT +/– path is

differential.

Figure 16: Basic Feed-Thru Mode

Microphone

MIC+

MIC–

6 dB

FTHRU

INP

VOL

FILTO

SUM1

SUM2

ANA OUT

MUX

Chip Set

ANA OUT+

ANA OUT–

1

(AOPD)

3 (AOS2,AOS1,AOS0)

Chip Set

ANA IN

VOL

ANA IN

AMP

1 (AIPD)

ANA IN AMP

FILTO

2 (AIG1,AIG0)

SUM2

OUTPUT

MUX

Speaker

SP+

SP–

2

(OPS1,OPS0)

2

(OPA1, OPA0)

ISD

21

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