A4988 Characteristics, Application and Basic Principle

A4988 is an efficient and commonly used stepper motor driver chip, widely used in 3D printing and CNC machine tools and other fields. We will discuss in depth the characteristics, usage and basic principles of the A4988 chip to help readers better understand and apply this chip.

Ⅰ. Introduction to A4988

The A4988 is a DMOS microstepping driver with converter and overcurrent protection. The product can operate bipolar stepper motors in full, half, 14, 1/8 and 116 step modes with output drive performance up to 35V. The A4988 includes a fixed off-time current regulator that can operate in slow or mixed decay modes. The converter is the key to the ease of implementation of the A4988. As long as a pulse is input into the "step" input, the motor can be driven to produce microsteps. It eliminates the need for phase sequence tables, high frequency control lines or complex interface programming. The A4988 interface is ideal for applications where complex microprocessors are not available or are overloaded.

It is characterized by simple operation, low power consumption, and extremely low cost of use. Therefore, it is widely used in precision instruments such as 3D printers, CNC machine tools, robotic arms, and robots.

Ⅱ. The Pin-out Diagram

Ⅲ. The pin circuit diagram of A4988

Ⅳ. Replacement and Equivalent of A4988

The TMI8421 is a fully integrated microstepping motor driver that supports a full-scale drive current up to 2A. It employs a simple STEP/DIR control interface to manage direction and step rate, supporting up to 1/16th level of microstepping for smooth motion planning. You can Pin to Pin to replace the A4988 chip.

Ⅴ. Characteristics of A4988

• Simple step and direction control interface

• Built-in overheating protection and undervoltage protection functions.

• Configurable current control for more current.

• Built-in driver MOS tube, power reaches 35V/2A.

• It has high temperature thermal shutdown, reverse voltage protection, high current protection functions.

• It can drive most stepper motors including NEMA 17 and NEMA 23.

• It is packaged in a QFN package with better thermal conductivity, which can improve heat dissipation efficiency.

• It supports five microstep resolutions of 1/1, 1/2, 1/4, 1/8 and 1/16.

• It can control the direction of movement and the number of steps of the stepper motor with a single pulse.

Ⅵ. Typical application diagram of A4988

Ⅶ. How to use A4988？

1. Control mode

The A4988 driver supports pulse and direction control modes, which can be controlled by the output signal from the controller board. When the frequency of the pulse signal is different, the speed of the motor will also be different.

(1) Sleep mode: Set the level of the Sleep pin to 0, enter the sleep mode, and the driver outputs the standby mode. Sleep pin is set to 1, the driver is in normal working state;

(2) Forward and reverse mode: DIR pin is set to 0 or 1 in forward mode, and set to 1 or 0 in reverse mode;

(3) Reset mode: It is easy to consume energy in the reset mode and generate a large inrush current. Directly set the RESETQ pin to 1, and set the RESET pin to 0 to reset when it does not affect the system work. Once the driver chip is reset, the system will return to the original A4988 IO port control state;

(4) Enable mode: Enable mode controls whether the system starts to work, the ENBALBE pin is set to 0 to start working, and set to 1 to stop working;

(5) Subdivision mode: Control subdivision coefficient through MS1, MS2, MS3, A4988 subdivision is 1/16 subdivision is the minimum. By calculating the angle value, we can obtain that the minimum subdivision angle is 1/16 of the full step angle.

2. Adjust the current

Adjusting the current can be achieved by rotating the potentiometer. There is also a calculation formula next to the potentiometer, we can adjust the output current according to our needs. It should be noted that when we adjust the current, we must first power off the motor, and then power on after the adjustment is completed.

3. Connection method

The A4988 driver needs to be interfaced with the controller board and the stepper motor. The connection method is as follows:

• Connect the 5V pin of the controller board to the VDD pin of the A4988;

• Connect the DIR pin of the controller board to the DIR pin of the A4988;

• Connect the GND pin of the controller board to the GND pin of the A4988;

• Connect the STEP pin of the controller board to the STEP pin of the A4988;

• Connect the wires of the two phases of the motor to the A1 and A2 pins of the A4988, and the wires of the other two phases to the B1 and B2 pins of the A4988.

4. Precautions

We need to pay attention to the following points when using the A4988 driver.

• Guarantee the stability of the power supply voltage and avoid the voltage being too high or too low;

• To avoid overheating of the driver, methods such as heat sink or forced air cooling can be used;

• Do not rotate the potentiometer at will, otherwise it may cause the motor to burn out;

• The output signal frequency of the controller board should match the microstep setting of the A4988 driver.

Ⅷ. A4988 Stepper Motor Driver Carrier

Ⅸ. The basic principle of A4988

The A4988 driver is a driver that uses stepper motor micro-stepping technology. It can achieve high-precision step control, thereby improving the smoothness and accuracy of the motor's operation. In addition, it also has a variety of protection functions, such as overvoltage, undervoltage, overtemperature protection, etc., to ensure that the motor operates within a safe range.

By adjusting the potentiometer, we can easily adjust the output current of the A4988 driver. In addition, the A4988 driver also supports pulse and direction control modes. It can control the motor rotation direction and step length through pulse signals to achieve more flexible and precise control.

Ⅹ. Advantages and disadvantages of A4988

The A4988 stepper driver is an excellent stepper driver with the advantages of low cost, high performance, simplicity and ease of use, and strong reliability. It is mainly used in small equipment, such as printers, scanners, industrial control systems, etc.

However, the A4988 stepper driver also has some disadvantages. First of all, due to its low driving power, it can only control some smaller motors and cannot meet the application needs of large motors. Secondly, because it uses analog control, the control accuracy is relatively low. In addition, the current of the A4988 stepper driver is small. For motors that require larger current drive, current amplification is required. At the same time, its noise is relatively large and may cause interference to surrounding circuits.

Frequently Asked Questions

1. What is the replacement for A4988?

The DRV8825 is a good alternative for the a4988 or tmc2208. However, a better and newer alternative is the DRV8425 which has similar functionality as the a4988 and tmv2208.

2. What is the use of A4988?

The A4988 is a complete microstepping motor driver with built-in translator for easy operation. It is designed to operate bipolar stepper motors in full-, half-, quarter-, eighth-, and sixteenth-step modes, with an output drive capacity of up to 35 V and ±2 A.

3. Which is better DRV8825 or A4988?

The DRV8825 has a higher maximum supply voltage than the A4988 (45 V vs 35 V), which means the DRV8825 can be used more safely at higher voltages and is less susceptible to damage from LC voltage spikes.

4. What is the current limit for A4988?

The A4988 driver IC has a maximum current rating of 2 A per coil, but the actual current you can deliver depends on how well you can keep the IC cool.