TDA7272 principle block diagram and typical application circuit

The motor current flows through the sampling resistor R between pin 10 and ground . The speed information is led from pin 10 to pin 1 via capacitor CD, and CD and pin 1 input resistor
SOOfl form a high-pass filter. There is a 25mV bias voltage in pin 1, and each input passes
. A zero signal causes the input comparator to flip once. The comparator has a hysteresis loop of iOmV to suppress
the influence of noise. Then to the differentiator, the output of the differentiator is sent to the triggered monostable circuit. The output current
and duration D of the monostable circuit are set by external components Cr and RT. The output current of the monostable circuit represents the actual speed. It consists of external potentiometers RP1 and R on pins 17 and 20. The set speed is converted into a reference current representing the set speed through the internal circuit, which is compared with the monostable circuit current at the inverting input end of the error amplifier (pin 14).