ACO160
Deluxe Audio-Controlled Oscillator
1 999 SW 1st Ave. #1617, Miami, FL 33130
ACO160 Audio Controlled Oscillator
•Direct audio to analog
square/sawtooth/sine oscillator output
•1V/octave pitch CV output (with
calibrated post-amplifier)
•Rail-to-rail output zero-ripple envelope
follower
•Modulation CV input with +/-2 octave
range and semitone resolution
•Hard sync input for internal audio
oscillators
•Gate output with user-configurable
threshold
•“Track” input enables freezing of pitch
when input is weak
•Fully balanced audio signal path
•Support for MIDI out with additional uC
•7mm x 7mm 32-pin LQFP
•25mA max current consumption from
4.5-5.5v supply
•One-cycle latency
•25Hz-5.2kHz frequency tracking range
Applications
•Audio-controlled modular and semi-
modular synthesizers
•Pitch-to-CV converters
•Harmonizers
•Guitar and other instrument
effects/stompboxes
Description
The ACO160 audio-controlled oscillator is an
ultra-low latency, low-power frequency-tracking
oscillator suitable for audio-controlled music
synthesizer applications. It contains a
fundamental frequency detector based on dual
switched-capacitor peak detectors with
frequency-dependent decay time for ultra-wide
detection range, ultrasonic analog oscillator and
frequency tracking engine that forces the
analog oscillator to run at 8192 times the
frequency of the incoming audio signal detected
at the input. This ultrasonic analog oscillator is
then divided back down to audio range using
programmable dividers that are controlled by
the harmony CV input and which cover a +/-2
octave range with semitone precision over the
entire range.
Additionally, the ACO160 features an integrated
switched-capacitor envelope follower which
exhibits zero ripple, even for the lowest
frequency signals the chip can detect (down to
25Hz). An integrated gate generation
comparator has the envelope signal wired to its
positive input and allows the user to set the
voltage on the negative input. This voltage
functions as the gate threshold and generates a
rail-to-rail gate CV output.
The ACO160 consumes only 25mA max from a
4.5-5.5V power supply, making it ideal for
battery-powered applications. Together with
other signal conditioning blocks such as a VCA,
VCF, PWM, the ACO100 can provide a complete
low-power analog audio-controlled synthesizer
solution.
For digital synth applications, the internal 16-bit
frequency detected by the chip is transmitted
via an SPI interface for easy processing by a
micro-controller. Together with the envelope
and gate outputs, it is easy to convert this
information into MIDI commands for controlling
digital synths with short enough latency to
satisfy even the most demanding real-time
applications.
Ordering Information
