TB67S579FTG Stepper Motor Driver Compact Carrier

Overview

This product is a carrier board or breakout board for Toshiba’s TB67S579FTG bipolar stepper motor driver; we therefore recommend careful reading of the TB67S579FTG datasheet (5MB pdf) before using this product. This stepper motor driver lets you control one bipolar stepper motor at up to approximately 1.1 A per phase continuously (2 A peak) without a heat sink or forced air flow (depending on supply voltage; see the Power Dissipation Considerations section below for more information.)

Here are some of the board’s key features:

• Simple step and direction control interface
• Seven different step modes: full-step, non-circular half-step, circular half-step, 1/4-step, 1/8-step, 1/16-step, and 1/32-step
• Adjustable current control lets you set the maximum current output with a potentiometer, which lets you use voltages above your stepper motor’s rated voltage to achieve higher step rates
• Advanced Dynamic Mixed Decay (ADMD) dynamically switches between slow and fast decay modes by monitoring the state of current decay (not according to fixed timing)
• Automatic Wave Generation System (AWGS) can be enabled to generate a pseudo-sine wave sequence of 1/32 microsteps from a full step clock input
• 4.5 V to 34 V (40 V absolute max) supply voltage range
• Can deliver approximately 1.1 A per phase continuously without additional cooling (depending on supply voltage), up to 2 A peak
• Built-in regulator (no external logic voltage supply needed)
• Can interface directly with 3.3 V and 5 V systems
• Under-voltage lockout and protection against over-current and over-temperature
• Active-low fault output activates for over-temperature, over-current, open-load condition, or motor stall conditions
• Compact size (0.6″ × 0.8″)
• 4-layer, 2 oz copper PCB for improved heat dissipation
• Exposed solderable ground pad below the driver IC on the bottom of the PCB

This product ships with all surface-mount components—including the TB67S579FTG driver IC—installed as shown in the product picture.

We also have a variety of other stepper motor driver options in this same form factor with different operating profiles and features.

We manufacture these boards in-house at our Las Vegas facility, so we can make these drivers with customized components to better meet the needs of your project, such as by setting custom fixed current limits or jumper settings. If you are interested in customization, please contact us for a quote.

Details for item #5247

This version of the TB67S579FTG Stepper Motor Driver Carrier does not have header pins soldered or included; 0.1″ headers are available separately, as is a version of this carrier with header pins already soldered.

TB67S579FTG Stepper Motor Driver Compact Carrier.

TB67S579FTG Stepper Motor Driver Compact Carrier, top view.

TB67S579FTG Stepper Motor Driver Compact Carrier, bottom view.

Using the driver

Minimal wiring diagram for connecting a microcontroller to a TB67S579FTG Stepper Motor Driver Compact Carrier (full-step mode).

The 16 connections are labeled on the back side of the PCB and are arranged as two rows of eight through-holes with a 0.1″ (2.54 mm) spacing along the long edges of the board for compatibility with solderless breadboards, connectors, and other prototyping arrangements that use a 0.1″ grid. You can solder wires or 0.1″ header pins directly to the board. Note: header pins are not included with this product, but 1×8 straight male headers are available separately, and we also have a version of this driver available with header pins already soldered in.

Power connections

The driver requires a motor supply voltage of 4.5 V to 34 V to be connected across VIN and GND. This supply 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 40 V absolute maximum voltage rating for the TB67S579FTG and permanently damage the board, even when the motor supply voltage is much lower. 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; this will also help keep the supply voltage more stable as the driver’s current draw changes.

Motor connections

Four, six, and eight-wire stepper motors can be driven by the TB67S579FTG 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 TB67S579FTG 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 (DMODE0, DMODE1, and DMODE2) enable selection from the seven step resolutions according to the table below. These three pins have internal 100 kΩ pull-down resistors, so the driver defaults to full-step mode when these inputs are left disconnected. 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.

DMODE0	DMODE1	DMODE2	Microstep Resolution
Low	Low	Low	Full step
Low	Low	High	Non-circular half step (“A”)
Low	High	Low	Circular half step (“b”)
Low	High	High	1/4 step
High	Low	Low	1/8 step
High	Low	High	1/16 step
High	High	Low	1/32 step
High	High	High	1/32 step

Control inputs and status outputs

The rising edge of each pulse to the STEP (CLK) input corresponds to one microstep of the stepper motor in the direction selected by the DIR (CW/CCW) pin. These inputs are both pulled low by default through internal 100 kΩ pull-down resistors. If you just want rotation in a single direction, you can leave DIR disconnected.

The driver has two different inputs for controlling its power states: SLEEP, which connects directly to the TB67S579FTG SLEEP_X pin, and ENABLE, which connects to the TB67S579FTG ENABLE pin through an inverter to match the pinout of many of our other stepper motor drivers in this form factor. For details about these power states, see the TB67S579FTG datasheet. SLEEP is pulled low through a 100 kΩ resistor, which prevents the driver from operating by default, so this pin must be set high to enable the driver (it can be connected directly to a logic “high” voltage between 2 V 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 ENABLE pin is to enable the driver, so this pin can be left disconnected.

Operation of the driver also requires the RESET (RESET_X) pin to be set high. The default state is low (100 kΩ pull-down), which resets the driver’s internal electric angle to an initial value of 45° and prevents the driver from responding to step inputs. Note that unlike the reset pin on many other stepper drivers, the RESET pin on the TB67S579FTG does not disable the motor outputs when it is asserted, and the driver will continue supplying current to the motor.

Schematic of nSLP and nFLT pins on the TB67S579FTG Stepper Motor Driver Compact Carrier.

The TB67S579FTG also features several open-drain fault outputs: LO0, LO1, and LO2. On the compact carrier, LO0 is connected to FAULT, and LO1 and LO2 are not accessible. LO0 drives low if any of four possible fault conditions are encountered: over-current, over-temperature, open load, and motor stall. Over-current and over-temperature errors disable the motor outputs and are latched, so the outputs will stay off and the error flags will stay asserted until the error is cleared by power cycling the board or toggling sleep mode. As shown in the schematic on the right, the carrier board connects this pin to the SLEEP pin through a 10 kΩ 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 1.5 kΩ 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 10 kΩ resistor between SLEEP and FAULT would then act as a pull-up for SLEEP, making the TB67S579FTG carrier more of a direct replacement for the A4988 in such systems (the A4988 has an internal pull-up on its SLEEP pin).

As a consequence of the connection between SLEEP and FAULT, active faults can pull the SLEEP pin low (below 2 V) if it is not externally pulled up strongly enough. We recommend any pull-up resistor used with SLEEP be 4.7 kΩ or stronger (or just connect SLEEP directly to VCC).

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 10 V would allow higher step rates, but the current must actively be limited to under 1 A to prevent damage to the motor.

The TB67S579FTG 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 equal to the current limit (since both coils are always on and limited to 100% of the current limit setting in full-step mode).

Another way to set the current limit is to measure the VREF voltage and calculate the resulting current limit. The VREF pin voltage is accessible via a small hole that is circled on the bottom silkscreen of the circuit board. The current limit in amps relates to the reference voltage in volts as follows:

``text(Current Limit) = text(VREF) * 0.556 A/V``

or, rearranged to solve for VREF:

``text(VREF) = text(Current Limit) / (0.556 A/V)``

So, the current limit in amps (A) is equal to 0.556 times the VREF voltage in volts (V), and if you a stepper motor rated for 1 A, for example, you can set the current limit to about 1 A by setting the reference voltage to about 1.8 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. If the driver is in full-step mode, both coils will always be on and limited to 100% of the current limit setting (unlike some other drivers that limit it to about 70% in full-step mode). If your driver is in one of the microstepping modes, the current through the coils will change with each step, ranging from 0% to 100% of the set limit. If Active Gain Control is active, it will also further reduce the actual motor current. See the driver’s datasheet for more information.

Advanced configuration jumpers

The TB67S579FTG has some advanced features that can be enabled through jumpers on the bottom side of the board:

Each of these pins on the driver IC are pulled low through internal 100 kΩ resistors, and they can be set high by shorting them to the opposite VREG pad with a solder blob, small wire, or 0 Ω 0402 SMT resistor. See the TB67S579FTG datasheet (5MB pdf) for more information about these features.

Power dissipation considerations

Thermal image showing the TB67S579FTG Stepper Motor Driver Compact Carrier heating up during operation.

The TB67S579FTG datasheet states that it can deliver maximum currents up to 2 A per coil, but 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 1.1 A per coil, a heat sink or other cooling method is required. The maximum current also decreases as the supply voltage increases: in our tests, the board could deliver about 1.3 A continuous per coil at 12 V and 1.1 A continuous per coil at 32 V.

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 as the actual current through each coil changes with each microstep.

Schematic diagram

Schematic diagram of the TB67S579FTG Stepper Motor Driver Compact Carrier.