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ML22594 is a high-quality speech synthesis LSI with built-in 6Mbits Mask ROM and compatible with up to 128Mbits external memory. It ensures operation between -40 to +105°C(automotive-grade) with built-in speaker amplifier.
Customers development and stock control can be made easy by using usage which stores a common voice data in built-in ROM, and stores a difference voice extension data based on a product in external ROM.
Max. 5240 seconds long time playback is possible when 128Mbits external ROM is connected. (at sampling frequency 8.0kHz on HQ-ADPCM)

An HQ-ADPCM, high-pass interpolation filter and 16-bit D/A converter that enables high sound quality are integrated.
And functions necessary for voice output, such as 4-channel mixing, repeat playback, edit function, are all integrated into a single chip.
In addition, sound data can be easily created by utility software "Speech LSI Utility".

Playback Time

Max. ROM capacity Fs=8kHz Fs=16kHz Fs=32kHz
128Mbit(External ROM) 5240 2620 1310
6Mbit(Built-in ROM) 243 121 60




Parameter Specification
Speech synthesis method HQ-ADPCM*
non-linear PCM
8 / 16bit straight PCM
(Can be set method for each phrase)
Speech ROM capacity Built-in 6Mbits ROM, External 128Mbits ROM ( Max )
Sampling frequency
at Fosc=4.096MHz
12.0 / 24.0 / 48.0kHz
8.0 / 16.0 / 32.0kHz
6.4 / 12.8 / 25.6kHz
Analog output 1.0W Speaker amplifier / Low-pass filter / Built-in 16-bit D/A converter
Interface Clock synchronous serial interface
Max. No. of phrases 1024 ( Built-in ROM : 512, External ROM : 512 )
Short detection
Edit ROM function
Repeat function
Volume control 32 levels
Channel mixing function 4 channels
Operating power supply voltage +4.5V to +5.5V
Operating temperature -40°C to +105°C
Package 30pin plastic SSOP

*HQ-ADPCM is a high sound quality audio compression technology of "Ky's".
"Ky's" is a registered trademark of National University Corporate Kyushu Institute of Technology.