LMD18200 is used in speed regulation

Input control signals include direction (DIRECTION, pin 3), brake (BRAKE,
pin 4) and PWM (pin 5). PWM control can be used in two ways.
    Mode 1: The PWM signal is input from pin 3, and pin 5 is connected to high level. A so% duty cycle
PWM signal corresponds to zero drive, and the average load current is zero. The PWM signal with a duty cycle greater than 50% corresponds to the forward current, and the load current flows
from pin 2 to pin 10 .
A PWM signal with a duty cycle less than 50% corresponds to a negative current
flowing from pin 10 to pin 2.
  Mode 2: Pin 3 inputs the symbol signal, logic 1 represents forward direction, logic O represents reverse
direction. Pin 5 inputs a PWM signal, and its duty cycle is proportional to the load current.
  I, MD18201 has similar functions. The difference is that there is no internal current detection ,
which can be replaced by a current detection resistor connected in series to ground on pin 7, and pin 8 is changed to logic ground.
    Figures 11 17 and 11 18 show
the schematic diagram of the integrated circuit applied to DC motor torque regulation and speed regulation. PWM control adopts mode 1. The LM3525A in the picture
is a general-purpose PWM controller. In the torque adjustment diagram, pin 8 leads to the current detection
signal to provide torque feedback. In the speed adjustment diagram, a DC tachometer generator is used to provide
speed feedback. Its speed sensitivity is 1V/(r/min).