Name: DRV8834 Low-Voltage Stepper Motor Driver Carrier
Brand: Pololu
SKU: 2134
Price: 7.95 USD
Availability: InStock

This is a breakout board for TI’s DRV8834 microstepping bipolar stepper motor driver. It has a pinout and interface that are nearly identical to those of our A4988 carriers, so it can be used as a drop-in replacement for those boards in many applications. The DRV8834 operates from 2.5–10.8 V, allowing stepper motors to be powered with voltages that are too low for other drivers, and can deliver up to approximately 1.5 A per phase continuously without a heat sink or forced air flow (up to 2 A peak). It features adjustable current limiting, overcurrent and overtemperature protection, and six microstep resolutions (down to 1/32-step). This board ships with 0.1″ male header pins included but not soldered in.

Pictures

Overview

This product is a carrier board or breakout board for TI’s DRV8834 low-voltage stepper motor driver; we therefore recommend careful reading of the DRV8834 datasheet before using this product. This stepper motor driver lets you control one bipolar stepper motor at up to 2 A output current per coil (see the Power Dissipation Considerations section below for more information). Here are some of the driver’s key features:

This product ships with all surface-mount components—including the DRV8834 driver IC—installed as shown in the product picture.

Some unipolar stepper motors (e.g. those with six or eight leads) can be controlled by this driver as bipolar stepper motors. For more information, please see the frequently asked questions. Unipolar motors with five leads cannot be used with this driver.

Included hardware

The DRV8834 stepper motor driver carrier ships with one 1×16-pin breakaway 0.1″ male header strip (for a version of this carrier with header pins already installed, see item #2874). The headers can be soldered in for use with solderless breadboards or 0.1″ female connectors. You can also solder your motor leads and other connections directly to the board.

Using the driver

Power connections

The driver requires a motor supply voltage of 2.5-10.8 V to be connected across VMOT and GND. This supply should have appropriate decoupling capacitors close to the board, and it should be capable of delivering the expected stepper motor current.

Warning: This carrier board uses low-ESR ceramic capacitors, which makes it susceptible to destructive LC voltage spikes, especially when using power leads longer than a few inches. Under the right conditions, these spikes can exceed the 11.8 V maximum voltage rating for the DRV8834 and permanently damage the board, even when the motor supply voltage is as low as 9 V. One way to protect the driver from such spikes is to put a large (at least 47 µF) electrolytic capacitor across motor power (VMOT) and ground somewhere close to the board.

Motor connections

Four, six, and eight-wire stepper motors can be driven by the DRV8834 if they are properly connected; a FAQ answer explains the proper wirings in detail.

Warning: Connecting or disconnecting a stepper motor while the driver is powered can destroy the driver. (More generally, rewiring anything while it is powered is asking for trouble.)

Step (and microstep) size

Stepper motors typically have a step size specification (e.g. 1.8° or 200 steps per revolution), which applies to full steps. A microstepping driver such as the DRV8834 allows higher resolutions by allowing intermediate step locations, which are achieved by energizing the coils with intermediate current levels. For instance, driving a motor in quarter-step mode will give the 200-step-per-revolution motor 800 microsteps per revolution by using four different current levels.

The resolution (step size) selector inputs (M0 and M1) enable selection from the six step resolutions according to the table below. M0 is floating by default, while M1 has an internal 200 kΩ pull-down resistor, so leaving these two microstep selection pins disconnected results in 1/4-step mode. For the microstep modes to function correctly, the current limit must be set low enough (see below) so that current limiting gets engaged. Otherwise, the intermediate current levels will not be correctly maintained, and the motor will skip microsteps.

Control inputs

Each pulse to the STEP input corresponds to one microstep of the stepper motor in the direction selected by the DIR pin. These inputs are both pulled low by default through internal 200 kΩ pull-down resistors. If you just want rotation in a single direction, you can leave DIR disconnected.

The chip has two different inputs for controlling its power states: SLEEP and ENBL. For details about these power states, see the datasheet. Please note that the driver pulls the SLEEP pin low through an internal 500 kΩ pull-down resistor, and it pulls the ENBL pin low through an internal 200 kΩ pull-down resistor. The default SLEEP state prevents the driver from operating; this pin must be high to enable the driver (it can be connected directly to a logic “high” voltage between 2.5 and 5.5 V, or it can be dynamically controlled by connecting it to a digital output of an MCU). The default state of the ENBL pin is to enable the driver, so this pin can be left disconnected.

The DRV8834 also features a FAULT output that drives low whenever the H-bridge FETs are disabled as the result of over-current protection or thermal shutdown, or while the undervoltage lockout is disabling the chip. The carrier board connects this pin to the SLEEP pin through a 10k resistor that acts as a FAULT pull-up whenever SLEEP is externally held high, so no external pull-up is necessary on the FAULT pin. Note that the carrier includes a 1.5k protection resistor in series with the FAULT pin that makes it is safe to connect this pin directly to a logic voltage supply, as might happen if you use this board in a system designed for the pin-compatible A4988 carrier. In such a system, the 10k resistor between SLEEP and FAULT would then act as a pull-up for SLEEP, making the DRV8834 carrier more of a direct replacement for the A4988 in such systems (the A4988 has an internal pull-up on its SLEEP pin). To keep faults from pulling down the SLEEP pin, any external pull-up resistor you add to the SLEEP pin input should not exceed 4.7k.

Optional pin jumpers

The CONFIG pin on the DRV8834 can be used to select between its default indexer mode, which is intended for controlling stepper motors, and an alternate phase/enable mode that can be used to drive two brushed DC motors. It is not made available by default (to avoid conflicts when using the DRV8834 carrier as a drop-in replacement for our other stepper motor driver carriers), but it can be connected to the pin labeled “(CFG)” by bridging the surface mount jumper indicated in the picture below. A second jumper can be bridged to make the current limit reference voltage available on the pin labeled “(REF)”.

Current limiting

To achieve high step rates, the motor supply is typically higher than would be permissible without active current limiting. For instance, a typical stepper motor might have a maximum current rating of 1 A with a 5 Ω coil resistance, which would indicate a maximum motor supply of 5 V. Using such a motor with 9 V would allow higher step rates, but the current must actively be limited to under 1 A to prevent damage to the motor.

The DRV8834 supports such active current limiting, and the trimmer potentiometer on the board can be used to set the current limit. You will typically want to set the driver’s current limit to be at or below the current rating of your stepper motor. One way to set the current limit is to put the driver into full-step mode and to measure the current running through a single motor coil without clocking the STEP input. The measured current will be 0.7 times the current limit (since both coils are always on and limited to approximately 70% of the current limit setting in full-step mode).

Another way to set the current limit is to measure the voltage on the “ref” pin and to calculate the resulting current limit (the current sense resistors are 0.100 Ω). The ref pin voltage is accessible on a via that is circled on the bottom silkscreen of the circuit board, or on the pin labeled “(REF)” if the appropriate surface mount jumper is connected (see above). The current limit in amps relates to the reference voltage in volts as follows:

So, for example, if you have a stepper motor rated for 1 A, you can set the current limit to 1 A by setting the reference voltage to 0.5 V.

Note: The coil current can be very different from the power supply current, so you should not use the current measured at the power supply to set the current limit. The appropriate place to put your current meter is in series with one of your stepper motor coils.

Power dissipation considerations

The DRV8834 driver IC has a maximum continuous current rating of 1.5 A per coil, and in our tests, this carrier board was capable of supplying the rated current for many minutes without requiring additional cooling. The DRV8834 can support peak currents of up to 2.2 A per coil, but its overcurrent protection might kick in at currents as low as 2 A, and the actual current you can deliver depends on how well you can keep the IC cool. The carrier’s printed circuit board is designed to draw heat out of the IC, but to supply more than approximately 1.5 A per coil, a heat sink or other cooling method is required.

This product can get hot enough to burn you long before the chip overheats. Take care when handling this product and other components connected to it.

Please note that measuring the current draw at the power supply will generally not provide an accurate measure of the coil current. Since the input voltage to the driver can be significantly higher than the coil voltage, the measured current on the power supply can be quite a bit lower than the coil current (the driver and coil basically act like a switching step-down power supply). Also, if the supply voltage is very high compared to what the motor needs to achieve the set current, the duty cycle will be very low, which also leads to significant differences between average and RMS currents. Additionally, please note that the coil current is a function of the set current limit, but it does not necessarily equal the current limit setting. The actual current through each coil changes with each microstep. See the DRV8834 datasheet for more information.

Schematic diagram

Key differences between the DRV8834 and A4988

The DRV8834 carrier was designed to be as similar to our A4988 stepper motor driver carriers as possible, and it can be used as a drop-in replacement for the A4988 carrier in many applications because it shares the same size, pinout, and general control interface. There are a few differences between the two modules that should be noted, however:

In summary, the DRV8834 carrier is similar enough to our A4988 carriers that the minimum connection diagram for the A4988 is a valid alternate way to connect the DRV8834 to a microcontroller as well:

Frequently-asked questions

I want to control a 3.9 V, 600 mA bipolar stepper motor. Do I need to use a low-voltage stepper motor driver like this one, since your other stepper motor drivers have minimum operating voltages above 3.9 V?

No, a low-voltage stepper motor driver is not your only option. To avoid damaging your stepper motor, you want to avoid exceeding the rated current, which is 600 mA in this instance. All of our stepper motor drivers let you limit the maximum current, so as long as you set the limit below the rated current, you will be within spec for your motor, even if the voltage exceeds the rated voltage. (For example, driving a 3.9 V motor with a DRV8825, and using a supply voltage higher than the DRV8825’s minimum of 8.2 V, will not damage the motor as long as the current limit is set appropriately.)

The voltage rating is just the voltage at which each coil draws the rated current, so the coils of your stepper motor will draw 600 mA at 3.9 V. By using a higher voltage along with active current limiting, the current is able to ramp up faster, which lets you achieve higher step rates than you could using the rated voltage.

However, if you still want to use a lower motor supply voltage for other reasons, our DRV8834 or STSPIN-220 low-voltage stepper motor drivers are appropriate choices.

Do I really need to set the current limit on my stepper motor driver before using it, and if so, how do I do it?

Yes, you do! Setting the current limit on your stepper motor driver carrier before connecting your motor is essential to making sure that it runs properly. An appropriate current limit also ensures that your motor is not allowed to draw more current than it or your driver can handle, since that is likely to damage one or both of them.

Setting the current limit on our A4988, DRV8825, DRV8824, DRV8834, DRV8880, STSPINx20, and TB67SxFTG stepper motor driver carriers is done by adjusting the on-board potentiometer. We strongly recommend using a multimeter to measure the VREF voltage while setting the current limit so you can be sure you set it to an appropriate value (just turning the pot randomly until things seem to work is not a good approach). The following video has more details on setting the current limit:

My DRV8834 stepper motor driver is overheating, but my power supply shows it’s drawing significantly less than 1.5 A per coil. What gives?

Measuring the current draw at the power supply does not necessarily provide an accurate measure of the coil current. Since the input voltage to the driver can be significantly higher than the coil voltage, the measured current on the power supply can be quite a bit lower than the coil current (the driver and coil basically act like a switching step-down power supply). Also, if the supply voltage is very high compared to what the motor needs to achieve the set current, the duty cycle will be very low, which also leads to significant differences between average and RMS currents: RMS current is what is relevant for power dissipation in the chip but many power supplies won’t show that. You should base your assessment of the coil current on the set current limit or by measuring the actual coil currents.

Please note that while the DRV8834 driver IC is rated for up to 2.2 A (peak) per coil, its overcurrent protection might kick in at as low as 2 A, and the chip by itself will overheat at lower currents. We have found that it generally requires a heat sink to deliver more than approximately 1.5 A per coil, but this number depends on factors such as ambient temperature and air flow. For example, sealing three DRV8834 driver carriers in close proximity in a small box will cause them to overheat at lower currents than a unit by itself in open air.

How do I connect my stepper motor to the DRV8834 stepper motor driver carrier?

The answer to this question depends on the type of stepper motor you have. When working with stepper motors, you will typically encounter two types: unipolar stepper motors and bipolar stepper motors. Unipolar motors have two windings per phase, allowing the magnetic field to be reversed without having to reverse the direction of current in a coil, which makes unipolar motors easier to control than bipolar stepper motors. The drawback is that only half of the phase is carrying current at any given time, which decreases the torque you can get out of the stepper motor. However, if you have the appropriate control circuitry, you can increase the stepper motor torque by using the unipolar stepper motor as a bipolar stepper motor (note: this is only possible with 6- or 8-lead unipolar stepper motors, not with 5-lead unipolar stepper motors). Unipolar stepper motors typically have five, six, or eight leads.

Bipolar steppers have a single coil per phase and require more complicated control circuitry (typically an H-bridge for each phase). The DRV8834 has the circuitry necessary to control a bipolar stepper motor. Bipolar stepper motors typically have four leads, two for each coil.

Two-phase bipolar stepper motor with four leads.

The above diagram shows a standard bipolar stepper motor. To control this with the DRV8834, connect stepper leads A and C to board outputs A1 and A2, respectively, and stepper leads B and D to board outputs B1 and B2, respectively. Note that if you happen to swap which way the wires are connected for any coil, the stepper motor will turn in the opposite direction, and if you happen to pair up wires from different coils, the motor should be noticeably erratic when you try to step it, if it even moves at all. See the DRV8834 datasheet for more information.

If you have a six-lead unipolar stepper motor as shown in the diagram below:

Two-phase unipolar stepper motor with six leads.

you can connect it to the DRV8834 as a bipolar stepper motor by making the bipolar connections described in the section above and leaving stepper leads A’ and B’ disconnected. These leads are center taps to the two coils and are not used for bipolar operation.

If you have an eight-lead unipolar stepper motor as shown in the diagram below:

Two-phase unipolar stepper motor with eight leads.

you have several connection options. An eight-lead unipolar stepper motor has two coils per phase, and it gives you access to all of the coil leads (in a six-lead unipolar motor, lead A’ is internally connected to C’ and lead B’ is internally connected to D’). When operating this as a bipolar stepper, you have the option of using the two coils for each phase in parallel or in series. When using them in parallel, you decrease coil inductance, which can lead to increased performance if you have the ability to deliver more current. However, since the DRV8834 actively limits the output current per phase, you will only get half the phase current flowing through each of the two parallel coils. When using them in series, it’s like having a single coil per phase (like in four-lead bipolar steppers or six-lead unipolar steppers used as bipolar steppers). We recommend you use a series connection.

To connect the phase coils in parallel, connect stepper leads A and C’ to board output A1, stepper leads A’ and C to board output A2, stepper leads B and D’ to board output B1, and stepper leads B’ and D to board output B2.

To connect the phase coils in series, connect stepper lead A’ to C’ and stepper lead B’ to D’. Stepper leads A, C, B, and D should be connected to the stepper motor driver as normal for a bipolar stepper motor (see the bipolar stepper connections above).

M0	M1	Microstep Resolution
Low	Low	Full step
High	Low	Half step
Floating	Low	1/4 step
Low	High	1/8 step
High	High	1/16 step
Floating	High	1/32 step

Size:	0.6″ × 0.8″
Weight:	1.6 g¹

Minimum operating voltage:	2.5 V
Maximum operating voltage:	10.8 V
Continuous current per phase:	1.5 A²
Maximum current per phase:	2 A³
Minimum logic voltage:	2.5 V⁴
Maximum logic voltage:	5.5 V⁴
Microstep resolutions:	full, 1/2, 1/4, 1/8, 1/16, and 1/32
Reverse voltage protection?:	N
Header pins soldered?:	N

PCB dev codes:	md22a
Other PCB markings:	0J7097

DRV8834 Low-Voltage Stepper Motor Driver Carrier