Product description: DRV8834 Low-Voltage stepper motor controller 10.8V 2A
The module based on the DRV8834 controller from Texas Instruments allows you to control a stepper motor with a maximum current consumption of up to 2A per coil, powered from 2.5 V to 10.8 V. We recommend that you read the driver's documentation before use.
Below are some of the main product features:
- The module features a simple interface for step and directional control.
- It can operate in six modes: full, half, 1/4-, 1/8-, 1/16- and 1/32- step.
- It provides control of the maximum motor current by means of a potentiometer, which allows for the use of a supply voltage higher than the rated motor voltage, so you can get a higher step speed.
- The motors can be supplied with voltages from 2.5 V to 10.8 V.
- Current consumption up to 2 A per coil (continuous 1.5 A).
- Thanks to the integrated voltage regulator, the user does not have to supply additional power to the logical part.
- The DRV8834 works with systems with both 3.3 V and 5 V logical part voltages.
- It has protection against too high a current, temperature and short-circuit and a start blocking system for too low a supply voltage.
- In order to increase the heat-retaining surface, the board is made in four-layer technology with a thicker copper cover.
- An exposed ground field on the underside allows for the soldering of cooling elements.
- The module is compatible with the A4988 controller in terms of size and outputs.
In our offer we also have controllers for stepper motors with different working parameters.
To control the bipolar stepper motor, connect the system as shown in the figure below. The controller also allows you to work with some unipolar motors - see the manual for details.
Controlling the controller
One pulse given per STEP pin causes one motor step in the direction chosen by giving the appropriate logical state (high or low) for the DIR output. The STEP and DIR pins are internally pulled to ground (GND) via a 200kΩ resistor. If the motor is to rotate in one direction only, the DIR pin can be left unconnected.
The system has two more inputs to control power consumption: SLEEP and ENBL, their description can be found in the documentation. Please note that both outputs are low by default. To start the system, the SLEEP output should be pulled up to the power supply voltage - give the logical one (voltage from 2.5 - 5.5 V). The SLEEP can also be connected to a microcontroller to dynamically control the system status.
The DRV8834 controller also has a lead marked as FAULT. The low state (logical zero) signals the occurrence of irregularities in the system operation, e.g. activation of one of the protections. On the board, the output has been connected to the SLEEP pin, so the high state on the SLEEP pin pulls up to VCC (pull-up) as well as FAULT. Thanks to the use of a serial resistor, the FAULT output can also be connected to the VCC, which makes the pin-compatible with the A4988 version.
Power supply for the DRV8834
The system can be supplied with voltage from 2.5V to 10.5V connected between VMOT (+) and GND (-) pins. The voltage should be filtered through an external capacitor placed as close to the controller board as possible. Its capacity depends on the maximum current drawn by the motor.
In some conditions even a relatively low power supply voltage may cause pins with a high amplitude exceeding the 45 V limit. Such situation leads to permanent damage to the system. One way to avoid this problem is to place the capacitor (at least 47 uF) as close as possible to the VMOT and GND pins of the controller module.
Connecting and disconnecting the motor while the controller is on can damage the system!
A micro-step controller such as the DRV8834 allows the motor to operate with a high resolution of up to 1/32 steps. Step size is selected using the M0 and M1 inputs - available modes are shown in the table below. By default, the M1 output is internally pulled to ground (via 200kΩ resistor). The M0 input is not connected (floating mode). Leaving both outputs disconnected means that the operating mode is selected with ¼ step.
Pin CONFIG allows you to change the operating mode of the controller. Switching to phase/enable mode allows to control two DC brush motors. To change the mode, the jumpers must also be made as shown in the figure below.
To maintain a high switching speed of the steps, a higher motor supply voltage than the nominal can be used. Only limit the maximum current flowing through the coils to the motor catalog value.
The module allows you to actively limit the current with a potentiometer. One way to introduce the limitation is to set the controller to full step mode and to measure the current flowing through one coil without giving a signal to the STEP input. The measured current is 70% of the set limit (both coils are always on and limited to 70% in full step mode).
Another way is to measure the voltage at the REF output (marked with a circle on the PCB) and to calculate the current limit (measuring resistors have a value of 0.1Ω). The current limit can be calculated from the formula:
Current Limit = VREF × 2
For example, if the motor can draw up to a maximum of 1A, the reference voltage on the VREF pin should be 0.5V.
The plate is designed to dissipate heat with a continuous current consumption of approximately 1.5A per coil. The circuit is capable of delivering a momentary current of up to 2.2A, but the temperature protection disconnects the circuit at about 2A. If the current is much higher, an external heat sink should be used, which can be mounted with a thermally conductive adhesive.
The system contains the necessary passive components for proper operation of the controller. The connection diagram is shown in the drawings below.
Main differences from the A4888 version
The DRV8834 is designed to be compatible with the A4988 version. The tiles have the same shape, size and layout. However, there are several differences between them:
- The pin used as the power supply voltage for the logical part of the A4988 has been replaced by the FAULT pin, because the DRV8834 does not require additional power supply. The FAULT has been connected by a protection resistor, so it can be successfully used in the system designed for the A4988 module, where this pin will be given the supply voltage of the logical part (2.2V to 5.5V).
- In the DRV8825 the SLEEP pin is not pulled to the power supply by default, it is connected to the FAULT output via a 10k resistor. In circuits designed for A4988, a 10k resistor pulls the SLEEP to the power supply through the supply voltage of the logical part connected to FAULT, setting it to high.
- The maximum current limiting potentiometer for motors is located elsewhere
- The DRV8834 allows you to operate in 1/32 step mode, while the A4988 operated to 1/16 step
- The time needed to make one pulse is 1.9 us, while the A4988 needed 1 us
- The DRV8834 allows you to work with lower power supply voltages - 2.5 V - 10.8 V range
- The DRV8834 can deliver higher current than A4988 without additional cooling (1.5A, instantaneous 2A)
- The tours have different names, but have the same function
Minimum driver connection - connections as in A4988 module.
DRV8834 motor controller specification
- Power supply voltage: 2.5 V - 10.8 V
- Continuous current on the coil: 1,5 A
- Maximal instantaneous current per coil: 2 A
- The supply voltage of the logical part: 2.5 V - 5.5 V
- The modes of operation: 1, 1/2, 1/4, 1/8, 1/16, and 1/32 steps
- Dimensions: 20 x 15 mm
- Weight: 1.6 g (without connectors)