TDA1185A single-phase AC commutator motor controller

TDA1185A provides trigger pulses to the controlled triac and can be used to control
  single-phase AC commutator motors. It does not require the use of a tachogenerator, and the internal positive feedback
  function keeps the motor speed constant. Typical applications are the control of handheld power tools, vacuum cleaners,
  blenders , dimmers and other small appliances.
    This chip generates a ramp voltage signal that is synchronized with the power grid every half cycle, which is related to
  an external set voltage representing the desired conduction angle. A comparison is made to determine the conduction angle.
  The resulting trigger pulse is negative (sinking eight currents), so the thyristor is
  driven in its most efficient quadrants two and three.
    When TDA1185A is used to control an AC motor, the speed will decrease as the load torque increases
  . At this time, the load current is detected through the sampling resistor connected in series in the main circuit, and the conduction
  angle is increased to increase the speed. The increased firing angle is proportional to the load current. In this low-cost system, which does not use
  a tachogenerator, the motor speed varies by approximately 5%. If the circuit is accurately
  designed and tuned, the speed change will be reduced by about 2% from no load to full load.
  The working principle is explained below.
  1. Connect pin 14 of the DC power supply to the same end of the AC power supply as the ground of the chip. The negative power
supply (-Vcc) is at pin 1 and is obtained from
the other end of the power supply through an 18kn (2W) resistor, a
rectifier diode and a 100VF filter capacitor
. Pin 1 is internally connected with a Zener diode to maintain one
V at -8.6V (typical value).
    The mutual trigger pulse generator and the sawtooth wave
generator have a ≈- circuit protection circuit in the trigger pulse generator to protect the 2-pin output circuit and can provide a minimum sink current of 60mA. The pulse width is proportional to R,oC,. If the triac fails or the motor brush jumps and is disconnected , the pulse will be repeated every 420ps.