Analog Output: This pin provides the preamplifier output to the
user. The voltage gain of the preamplifier is determined by the
voltage level at the AGC pin.
Overflow: This signal pulses LOW at the end of memory array,
indicating the device has been filled and the message has
overflowed. The OVF output then follows the CE input until a
PD pulse has reset the device. This pin can be used to cascade
several ISD2500 devices together to increase record/playback
Chip Enable: The CE input pin is taken LOW to enable all
playback and record operations. The address pins and
playback/record pin (P/ R ) are latched by the falling edge of CE .
CE has additional functionality in the M6 (Push-Button)
Operational Mode as described in the Operational Mode section.
Power Down: When neither record nor playback operation, the PD
pin should be pulled HIGH to place the part in standby mode (see
ISB specification). When overflow ( OVF ) pulses LOW for an
overflow condition, PD should be brought HIGH to reset the
address pointer back to the beginning of the memory array. The PD
pin has additional functionality in the M6 (Push-Button) Operation
Mode as described in the Operational Mode section.
End-Of-Message: A nonvolatile marker is automatically inserted at
the end of each recorded message. It remains there until the
message is recorded over. The EOM output pulses LOW for a
period of TEOM at the end of each message.
In addition, the ISD2500 series has an internal VCC detect circuit to
maintain message integrity should VCC fall below 3.5V. In this case,
EOM goes LOW and the device is fixed in Playback-only mode.
When the device is configured in Operational Mode M6 (Push-
Button Mode), this pin provides an active-HIGH signal, indicating
the device is currently recording or playing. This signal can
conveniently drive an LED for visual indicator of a record or
playback operation in process.