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ISD
Software Changes for the ISD5008/ISD5116 ChipCorder Products
Avoiding High Speaker Output Offset Voltage
and High Operating Current in the ISD5008 Device
Users of the ISD5008 may sometimes find the device in a mode such that it draws
considerably more ICC current than the datasheet specifies. They also may find that
the Speaker + and Speaker – outputs have more offset in a static condition than spec-
ified in the datasheet. Unfortunately, the present datasheet doesn’t make clear some-
thing very important: The Playback/Record bit (C6 of the command byte; opcode)
should only be set LOW during a Record operation. At all other times, this bit must
be set to HIGH!
The 10/1999 datasheet is being modified to change the following Opcodes on page 14:
Please note that in each case, the Opcode leaves the P/R bit HIGH.
Proper AGC and AutoMute™ Operation in the ISD5008/ISD5116 Devices
Another fact that was not discussed in much detail in the datasheets is the relationship
between the microphone AGC amplifier and the AutoMute function. They are directly
related from the fact that they both use the 4.7 uF capacitor fastened to the ACAP pin.
In record mode the 4.7 uF capacitor determines the time constant of the AGC opera-
tion. In playback mode the capacitor determines the time constant of the AutoMute,
which attenuates noise in the “quiet” time between words in a message. The bit that
controls this pin, and the function, is the AGPD bit, which is D0 of the CFG1 byte. When
the ISD5008/ISD5116 is recording from the microphone, this bit should be set LOW.
At all other times, this bit must be HIGH because, if not, it will prevent the AutoMute
circuit from working during playback and will waste current when the AGC amp is not
used in record.
Opcode Old Opcode Revised Opcode
POWERUP 0010 0000 0110 0000 Power up the Device
LOADCFG0 00X0 0010 <D15–D0> 01X0 0010 <D15–D0> Load Config. Reg. 0
LOADCFG1 00X0 0100 <D15–D0> 01X0 0100 <D15–D0> Load Config. Reg. 1
STOP 0X11 0000 0111 0000 Stops current operation
STOPWRDN 0X01 0000 0101 0000 Stop current operation
and powers down
RINT 0X11 0000 0111 0000 Read Interrupt Status
