Motor Circuit DiagramsPower Supplies

3 Amp PWM DC Motor Controller Schematic Circuit Diagram

Motion Control Circuit Overview

This circuit serves the purpose of controlling motion, a common requirement in robotics applications. It provides an affordable solution for PWM (Pulse Width Modulation) DC motor control. Compatible with PMDC motors operating between 12 V to 30 V and a maximum current of 3 Amps. The direction of the motor can be easily managed using a slide switch, while motor speed control is achieved through a standard potentiometer. At its core, this circuit incorporates ICs such as LMD18200 and SG3525, which play essential roles in its operation. The SG3525 functions as a pulsewidth modulator control circuit, while the LMD18200 acts as an H-Bridge, enabling bi-directional motor movement.

SG3525: Frequency and Duty Cycle Control

The SG3525 component within the circuit offers precise control over both frequency and duty cycle. The oscillator frequency is determined by components connected to pins 5 and 6. By adjusting preset P2, users can modify the frequency within a range of 1.16 kHz to 35 kHz. It is generally advisable to maintain a frequency above 20 kHz to avoid audible motor noise, although this may not always be feasible depending on the specific motor in use. Additionally, potentiometer P1 enables the fine-tuning of the duty cycle, allowing it to be adjusted from 10% to 100%. In cases where a 100% duty cycle is required, the internal transistors are appropriately configured. Pins 11 and 14 are used to ground the internal driver transistors during alternate oscillator cycles. Furthermore, pin 16 of the IC functions as the REF V terminal, providing a 5 V output.

3 Amp PWM DC Motor Controller Schematic Circuit Diagram

3 Amp PWM DC Motor Controller Schematic Circuit Diagram Components List

Supply and Direction Control Circuitry

In this section, resistor R1 provides the supply voltage to an open collector-transistor, generating TEL-level PWM output. The direction of the motor, either clockwise (cw) or counterclockwise (ccw), is determined by slide switch SI connected to the Direction control input (pin 3) of the LMD18200. Additionally, resistor R4, linked to thermal flag pin T (pin 9), remains unused in this context but could be employed to signal a warning if the chip temperature reaches 145 degrees Celsius. The IC has an automatic shutdown feature triggered at 170 degrees Celsius for protection.

LMD18200 Features and Power Supply Section

Pin 8 of the LMD18200 functions as the current sense input and is grounded through resistor R6. The Brake input (pin 4) is permanently connected to ground. Bootstrap capacitors C2 and C4 at the motor output facilitate operation. H-Bridge outputs, represented by pins 2 and 10, power the DC motor. The power supply section utilizes capacitors C5 to C9 to minimize noise on the two supply rails. The logic supply voltage is regulated by the L7805ACV voltage regulator, accepting unstabilized DC voltage between 7.5 V to 18 V through connector K2. Connector K3 caters to the motor power, with the required capacity contingent on the specific motor used. For heavy-duty motors consuming more than 1 A, reinforcing copper tracks with 1.5 mm2 solid copper wire between K2/K3 might be necessary.

Interface and PCB Design

To interface the driver with a 0-5 V source, potentiometer P1 can be removed, and the analog voltage applied to pin 2 of the IC. The PCB layout, featured in Figure 2, is meticulously designed for versatility, fitting various applications within a robot. Since most robotic motions necessitate motor usage, this driver board proves indispensable. The compact design utilizes only leaded components, avoiding surface-mount devices (SMDs). Detailed copper track layout and component mounting instructions can be accessed through the free download available on our website (file no.


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