An Overview of L297 Stepper Motor Controller
04 December 2023
Ⅰ. What is a stepper motor driver?
Ⅲ. What are the features of L297 stepper motor controller?
Ⅳ. Pin configuration of L297 stepper motor controller
Ⅴ. Structure and working principle of L297 stepper motor controller
Ⅵ. Specifications of L297 stepper motor controller
Ⅶ. What are the applications of L297 stepper motor controller?
A stepper driver is a power amplifier that drives a stepper motor, which can receive control signals from (e.g., PLC or microcontroller, etc.) and control the stepper motor to turn through the corresponding angle or number of steps. When a pulse signal is input, the rotor of the stepper motor will rotate by an angle or a step forward accordingly. Its output angular displacement or line displacement is proportional to the number of pulses input, while the rotational speed is also proportional to the pulse frequency. In simple terms, stepper motor can be understood as a special kind of pulse motor.
L297 is a controller designed for stepper motors by SGS Semiconductor of Italy. By connecting with external circuits, it is able to realize precise control and drive of stepper motor. L297 chip has integrated logic control circuit and power output circuit inside, which enables it to connect with external stepper motor and its power supply. It is capable of generating 4-phase control signals for computer-controlled bi-phase bipolar and 4-phase single-phase stepper motors. Users can choose single four-beat, double four-beat or four-phase eight-beat to control the stepper motor according to their needs.
Replacements and equivalents:
• A4988
• DRV8711
• L298
• L6208
• TB6600
• It has over-current and over-temperature protection to protect the stepper motor from damage.
• L297 provides directional control which allows the user to control the direction of rotation of the stepper motor.
• The L297 can realize different driving methods such as full stepping, half stepping and micro stepping. This allows the user to select the appropriate stepping method according to the specific application scenario, thus balancing performance and power consumption to achieve better usage.
• An on-chip PWM chopper circuit regulates the current in the stepper motor windings in switching mode.
• L297 usually contains a current detection circuit for monitoring the stepper motor current, which helps to protect the motor from overload and avoid the current exceeding the rated value.
The L297 has a total of 20 pins with the following names and descriptions.
Pin 1 (SYNC): It is the chopper output. If multiple 297s are synchronized for control, all SYNC terminals should be connected together and the Chopper shares a common set of oscillating elements. If we use an external clock source, the clock signal is received on this pin.
Pin 2 (GND): It is the ground terminal.
Pin 3 (HOME): It is the open collector output. When L297 is in initial state (ABCD=0101), this terminal is indicated. When this pin is active, the transistor is open.
Pin 4 (A): It is the A-phase drive signal.
Pin 5 (INH1): It is the drive pole for controlling the A phase and B phase. When this pin is low, the A-phase and B-phase drive control is disabled; when the coil stage is powered down, the bipolar bridge uses this signal to make the load power supply attenuate quickly. If the input to the CONTROL terminal is low, it regulates the load current with a chopper.
Pin 6 (B): It is the B phase drive signal.
Pin 7 (C): It is the C phase drive signal.
Pin 8 (INH2): It is the drive stage to control the C phase and D phase, and it serves the same function as INH1.
Pin 9 (D): It is the D-phase drive signal.
Pin 10 (ENABLE): It is the enable input of L297. When it is low, INH1, INH2, A, B, C, D are all low. It is used to block motor drive when the system is reset.
Pin 11 (CONTROL): It is the chopper function control terminal and is responsible for regulating the conditions for function triggering. At low level, it causes INH1 and INH2 to function, while at high level, it causes A, B, C and D to function.
Pin 12 (Vcc): It is the +5V power input.
Pin 13 (SENS2): It is the phase C and D winding current detection voltage feedback input.
Pin 14 (SENS1): It is the phase A, phase B winding current detection voltage feedback input.
Pin 15 (Vref ): It is the chopper reference voltage input. The voltage added to this pin determines the peak value of the winding current.
Pin 16 (OSC ): This pin corner is the frequency input of the chopper. The RC network is connected to this pin to determine the frequency of the chopper. When multiple L297s are operated synchronously, one of the devices connects the RC network while the rest of the devices ground this pin. Pin I (SYNC) of each device should be connected together, which effectively avoids clutter introduction problems.
Pin 17 (CW/CCW): It is the direction control terminal. The actual direction of rotation of the stepper motor is determined by the method of connection of the windings. When the level state of this pin is changed, the stepper motor rotates in the reverse direction.
Pin 18 (CLOCK): It is the stepper clock input. When a negative pulse is input to this pin, the stepper motor steps forward by one increment. This stepping is generated by triggering on the rising edge of the signal.
Pin 19 (HALF/FULL): This is the half/full step selector. When a high level is input to this pin, it is half-step mode (four-phase eight-beat), and when a low level is input, it is full-step mode. If full-step mode is selected and the converter is in odd state, it will get single-phase operation (single four-beat).
Pin 20 (RESET): It is the reset input. When a negative pulse is input to this pin, the converter restores the initial state (ABCD=0101).
1. Internal structure of L297
The L297 driver has a counter that works like a shift register. Whenever the clock input receives a rising edge, the counter increments or decrements by one unit. By comparing it to preset stepper motor requirements, the counter determines the phase required by the stepper motor at its current position. In addition, the L297 also contains some electronic components such as capacitors, resistors and transistors, as well as a battery backup power supply to save system calibration values and other basic parameters. These electronic components work together to ensure the normal operation of the device.
2. How does the L297 stepper motor controller work?
The L297 operates on the premise that stepper motors must undergo distinct phases to accomplish a full rotation. By receiving clock and direction signals from an external system, the L297 governs internal counters and circuits, thereby ensuring precise positioning of the stepper motor during each phase.
• Precision instruments: L297 can provide a high degree of control over the movement of stepper motors, so it is used in instruments that require precise control, such as precision processing equipment, laboratory instruments, etc.
• CNC machine tools: Computer numerically controlled (CNC) machine tools often use stepper motors to control the position of the tool. The L297 module generates appropriate control signals to ensure that CNC machine tools can accurately move tools and perform complex cutting tasks.
• Printers and Scanners: L297 stepper motors are often used in office equipment such as printers and scanners to control paper feed and scan head movement.
• Medical Equipment: In some medical equipment, L297 stepper motors are also used to achieve precise position control, such as X-ray scanners and MRI machines.
• Automation systems: L297 can be used in various automation systems, such as positioning on assembly lines, packaging machinery and mechanical control on assembly lines.
• Stepper motor driver: L297 can achieve high-precision position and speed control when driving a stepper motor. By using L297 we can easily generate pulse sequences for controlling stepper motors.
• Telescopes and astronomical observation equipment: In some astronomical observation equipment that require accurate positioning and tracking of targets, stepper motors are used with the L297 to ensure precise positioning and movement.
Frequently Asked Questions
1. What is L297?
The L297 integrates all the control circuitry required to control bipolar and unipolar stepper motors. Used with a dual bridge driver such as the L298N forms a complete microprocessor-to-bipolar stepper motor interface. Unipolar stepper motor can be driven with an L297 plus a quad darlington array.
2. What is the relationship between the L297 and the L298?
The L298 is a dual full-bridge driver IC commonly used for driving DC motors and stepper motors. The L297 and L298 are often used together in a circuit. The L297 generates control signals for the L298, allowing it to drive a stepper motor.
3. How does motor driver work?
We use motor drivers to give high power to the motor by using a small voltage signal from a microcontroller or a control system. If the microprocessor transmits a HIGH input to the motor driver, The driver will rotate the motor in one direction keeping the one pin as HIGH and one pin as LOW.
4. How does the L297 work with stepper motors?
The L297 generates the necessary control signals for a stepper motor by converting step and direction inputs into the appropriate waveforms required to drive the motor coils. It synchronizes the motor movement based on these inputs.
