Voice recorder IC series has proprietary message management system

The ISD1700 devices also support an optional “vAlert” (voiceAlert) feature that can be used as a new message indicator. With vAlert, the IC strobes an external LED to indicate that a new message is present. Four special sound effect locations are reserved for audio confirmation of commands, such as “Start Record”, “Stop Record,” and “Erase.”

Recordings are stored in on-chip Flash memory cells, providing zero-power message storage using Winbond’s patented Multi-Level Storage (MLS) technology. Audio data is stored directly in solid-state memory without digital compression, providing superior quality voice and music reproduction. The ISD1700 devices automatically enter power down mode for power conservation when an operation is completed.

The ISD1700 series incorporates user-selectable message duration from 26 to 480 seconds, depending on the specific device. The sampling frequency of each device can be adjusted from 4 to 12kHz with an external resistor, providing design flexibility in duration versus recording quality. Operating voltage is from 2.4 to 5.5V.

The devices are designed for operation in either stand-alone or microcontroller (SPI) mode. In the SPI mode, the user has full control via the serial interface in operating the device. This includes random access to any location inside the memory array by specifying the start and end address of operations.
The ISD1700 devices include an on-chip oscillator (with external resistor control), microphone preamplifier with Automatic Gain Control (AGC), an auxiliary analogue input, anti-aliasing filter, Multi-Level Storage (MLS) array, smoothing filter, volume control, Pulse Width Modulation (PWM) Class D speaker driver, and current output.