isd5008 Winbond Electronics Corp America, isd5008 Datasheet - Page 25

• Manufacturer Part Number: isd5008
• Description: Single-chip, Voice Record / Playback Device 4-, 5-, 6- And 8-second Duration
• Manufacturer: Winbond Electronics Corp America

5
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 T
has elapsed after that bit was set:
ISD
OPERATIONAL MODES DESCRIPTION
Chip Set
ANA IN
Microphone
MIC+
MIC–
Figure 16: Basic Feed-Thru Mode
2 (AIG1,AIG0)
ANA IN
AMP
1 (AIPD)
PUD
6 dB
ANA IN AMP
VOL
FILTO
SUM2
5.1
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.
FTHRU
INP
VOL
FILTO
SUM1
SUM2
FEED THROUGH MODE
(OPS1,OPS0)
2
OUTPUT
MUX
3 (AOS2,AOS1,AOS0)
ANA OUT
MUX
(OPA1, OPA0)
2
(AOPD)
1
Speaker
Chip Set
SP+
SP–
ANA OUT+
ANA OUT–
ISD5008 Product
21