The TPIC8101 is a dual-channel signal processing IC for detection of premature detonation in combustion engine. The two sensor channels are selectable through the SPI bus. The knock sensor typically provides an electrical signal to the amplifier inputs. The sensed signal is processed through a programmable band-pass filter to extract the frequency of interest (engine knock or ping signals). The band-pass filter eliminates any engine background noise associated with combustion. The engine background noise is typically low in amplitude compared to the predetonation noise.
The detected signal is full-wave rectified and integrated by use of the INT/HOLD signal. The digital output from the integration stage is either converted to an analog signal, passed through an output buffer, or be read directly by the SPI.
This analog buffered output may be interfaced to an A/D converter and read by the microprocessor. The digital output may be directly interfaced to the microprocessor.
The data from the A/D enables the system to analyze the amount of retard timing for the next spark ignition timing cycle. With the microprocessor closed-loop system, advancing and retarding the spark timing optimizes the load/RPM conditions for a particular engine (data stored in RAM).