Given by LM331 input instruction is input clock instruction DIR f0 and direction, the two instructions hitches in PMM8713 logic combination the common fault of temporal logic signal. PMM8713 phase driver output side (PIN10 ~ PIN13)The drive current of more than 20 mA, can direct drive mini stepper motor. R1, C1 for initialization circuit automatically when the phone is switched on. Tens of milliseconds R end early on electricity as the low level, thus A ~ D the automatic reset to initial state. If an external stepper motor power is larger, PMM8713 output drive side drive ability is not enough, when a power amplifier drive circuit design, and then driving a stepper motor. PMM8713 each phase the output conduction sequence logic signal is sent to the power driver section into the internal power switch base (Or the grid)Drive signal. Stepper motor drive mode according to the phase winding through the electric current is a one-way or two-way can be divided into single polarity and bipolar drive, usually, three-phase stepper electric hunger driven by single polarity. According to the analysis of power driver circuit and voltage and current drive. This design adopts the series resistance voltage driving mode. Concatenated in the phase winding resistance and power of resistance, on the one hand, reduced the winding circuit time constant, the low frequency at the same time and still work to limit the current. Using the above principle, an automatic gate valve controller was designed by the gate of the upper and lower position limit switch control, using the corresponding circuit change the action of the limit switch is shown in figure 5 LM348 compare the size of the voltage of the input voltage, so as to control stepping motor running or shut down. Its working principle; LM348 in-phase input for reference voltage, the reverse input to compare the voltage input, when comparing the voltage at the input voltage is less than the reference voltage, LM348 1 pin output high level, make the BD237 conduction, so that the stepper motor can realize forward or reverse; When compare the voltage at the input voltage is higher than the reference voltage, 1 pin on LM348 output low level, BD237 cut-off, stepper motor stalling. Driver circuit as shown in figure 4. External resistance Rt and capacitance Ct, internal timing comparator, zero transistors, R -S a trigger when a single stable circuit. When the input Vi + input voltage is greater than the ViAt the input voltage, f0 output logic low level. At the same time, for capacitance CL charging current source IR. Vcc power supply and the resistance Rt of capacitive Ct to recharge. When the capacitor charging voltage at the ends of the Ct is more than two-thirds of Vcc, output, f0 output logic high level. F0 signal output clock end to PMM8713 chips, the frequency after PMM8713 treatment, the output frequency of A, B, C foot drive signal to control the power transistor conduction time, to control the speed of the stepper motor. Direction control circuit made up of LM348 four general operational amplifier circuit. Direction of external control signal by comparing LM348 and voltage reference voltage circuit. When Vdi is greater than the reference voltage VH, U3A output is positive, and PMM8713 feet, 4 output control output is pulse sequence. When Vdi is less than the benchmark voltage VH, output is negative, and PMM8713 feet, 4 control output output negative phase pulse sequence, corresponding phase output driver output forward and reverse pulse sequence, thus to control the step motor and reversing. the main products: stepper motor, brushless motor, servo motor, stepping motor drive, brake motor, linear motor and other kinds of models of the stepper motor, welcome to inquire. Telephone:
