M51728 DC motor speed phase-locked controller - typical application circuit

M51728 is a DC motor precision speed control
phase-locked loop (PLL) integrated circuit produced by Mitsubishi Electric Corporation of Japan. The frequency of the oscillator built into the chip is compared with the frequency of the external tachometer
in the phase comparator, and a pulse signal with appropriate pulse width is output, which is fed to the DC motor
after external amplification and correction to maintain a constant speed.     There are two packaging methods. M51728L is an 8-pin single-in-line plastic package; M51728FP is an 8-pin dual-in-line plastic package.     The power supply (pin 2) is obtained from the external DC power supply Vs through the step-down resistor Rs and the filter capacitor Ce. Vs=9-18V, 13V is recommended. There is a voltage stabilizing diode inside to make the voltage at pin 2 Vcc-6 9V (typical value). Due to the internal voltage adjustment of the chip, the voltage Vs.h output at pin 4 is 27V (typical value).