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User’s Guide

DRV8251/AEVM User's Guide

ABSTRACTThis document is provided with the DRV82X1 family customer evaluation modules (EVM) as a supplement tothe DRV8251, DRV8251A, DRV8231 and DRV8231A data sheets. This user's guide describes the hardware
implementation of the EVM.
Hot surface. Contact may cause burns. Do not exceed limitations of the DRV devices:
4.5-V to 48-V operating supply voltage range • RDS(on), voltage, and current sense/regulation
variants (external shunt resistor and integrated current mirror) – DRV8251: 4.5-V to 48-V, 450-mΩ,shunt – DRV8251A: 4.5-V to 48-V, 450-mΩ, mirror – DRV8231: 4.5-V to 33-V, 600-mΩ, shunt –DRV8231A: 4.5-V to 33-V, 600-mΩ, mirror • Keep the peak current below 1.6 A RMS to avoidtemperatures above 130°C (at 25°C ambient temperature).

Table of Contents
1 PCB (Top and Assembly View).............................................................................................................................................. 22 Introduction.............................................................................................................................................................................33 Power Connectors and Coding............................................................................................................................................. 33.1 Programming EVM.............................................................................................................................................................34 Component Description......................................................................................................................................................... 55 Operation of the EVM............................................................................................................................................................. 65.1 H-Bridge Control................................................................................................................................................................ 7
5.2 Current Sensing and Current Regulation Details............................................................................................................... 76 Removing and Installing Supported Motor Drivers.............................................................................................................97 Revision History......................................................................................................................................................................9TrademarkseZ-FET™ is a trademark of Texas Instruments.
All trademarks are the property of their respective owners.

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1 PCB (Top and Assembly View)

Figure 1-1. PCB Assembly View

Figure 1-2. PCB Top 3-D View

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Introduction

2 Introduction
The MD039 is a complete solution for evaluating the DRV8251/DRV8251A/DRV231/DRV8231A H bridge motordrivers. It includes the necessary shunt resistors for the current regulation in the non a variants and the internal
FETs needed for the current mirroring circuit in the A variants.
The EVM includes and MSP430 microcontroller that is preprogrammed tot ake input from three dedicatedanalog potentiometers for PWM (POT1) (POT2) speedcontrol as well as VREF (POT3) for current regulation andmonitoring. The jumper for STALL_ACT allows for the selection of differetn stall detection features depending on
the desired application.
The supply voltage can be externally powered to 48 V for the DRV8251x series and up to 33 V for
the DRV8231X series. To expand beyond the included firmware capability, the MSP430 MCU can bereprogrammed through the eZ-FET™ emulation circuit found in most MSP430 Launchpads. We recommend
the MSP-EXP430FR5969. Note that a four pin angled male header is required and must be soldered to J21of this Launchpad from V+ pin to GND pin. We recommend a pin header with pin dimensions similar to850-10-050-20-001000 (Digikey part number). The U1 MCU must be removed from the Launchpad.

3 Power Connectors and Coding
The DRV8251/AEVM uses a single header for power entry to the EVM board. Only a single power supply rail
is necessary since an onboard 3.3-V regulator provides power to the MSP430. The minimum recommended VM
voltage for the EVM is 4.5 V and the maximum depends on the specific device installed (see reference section).
For complete voltage range information of the driver itself, refer to the device.
As previously mentioned, the MSP430 comes preprogrammed to control basic DC motor operation. If changing
the firmware via the external eZ-FET™ emulation tool, do not supply power to the VM connector on the EVM.
The eZ-FET™ board provides the necessary power during programming when connected to the J6 connector.
Note that a four-pin angled male header is required and must be soldered to J21 of this Launchpad from V+ pinto GND pin shown in image below. We recommend a pin header with pin dimensions similar to the Digikey partnumber 850-10-050-20-001000. The U1 MCU must be removed from the Launchpad.

3.1 Programming EVM
This section outlines the procedure for programming the EVM with a custom firmware. Out of the box, theDRV8251/DRV8251A EVMs will come programmed so no programming is required from the user. However, theinformation in this section only applies if the user wants to flash a custom program to the MSP430FR2100 MCU.
If you are interested in viewing the source firmware files, go to the tool product page and download the firmware
files.
To flash a custom firmware you will need the following components:
1.
2.
3.
4.

Code Composer Studio (CCS)DRV8251/DRV8251AEVM
MSP430FR5969 LaunchPad
Mini USB to USB cable

Follow these steps in order to flash a custom firmware to the EVM MCU
1. Open Code Composer Studio. If you are new to CCS, visit this link to view the user's manual. Alternative,
you can visit dev.ti.com/tirex to view code examples for any of the TI MCUs.
2. Connect the power supply cables to the EVM, connect USB cable to the LaunchPad (LP) and the computer,connect the launch pad to the EVM via the J21 connector on the LP and J6 on the EVM, make sure that
there are jumpers on "TST", "RST", "V+", and "GND" on J13 on the LP. Your set-up should look as thepicture below:

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Figure 3-1. MSP-EXP430FR5969 connected to EVM
3. Once the code is ready to be flashed to the MCU, click on the "Debug" icon on the top left of the window.

a.
Figure 3-2. CCS Debug Icon
4. If there are no compiling or linking issues, a "Play" button will appear on the top left window. Click on it torun the program. If you get any errors in the code or any other error messages, please submit a post on
e2e.ti.com for assistance.
5. Congrats! Your EVM is now programmed with your custom code. You may now disconnect the EVM from theLP.

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Component Description

4 Component Description

Figure 4-1. Render With Components Labelled
Table 4-1. Component Reference
Connector/Component

Function

J1

Main poer supply connector

J3

Motor connection

J4Signal header test points

J6Header for launchpad connection

VREF

Potentiometer for VREF Adjustment

3.3 V

3.3-V LDO Test point

IN1 PWM

Potentiometer for VREF Adjustment

GND

Main ground

Explanation of Components:
1. Pot1 controls the PWM signal that goes into IN1, by turning it clockwise you increase the duty cycle from 0%
to 100%.
2. Pot 2 controls the PWM signal that goes into IN2, by turning it clockwise you increase the duty cycle from0% to 100%.
3. The potentiometer labelled VREF controls the setting for VREF. When turning it clockwise it increases
gradually until it reaches its limit adjusting VREF for 3.3 V
a. VREF is responsible for current regulation threshold, by lowering the value in VREF turning it
counterclockwise you will lower the current regulation threshold.
4. IN1 and IN2 test points will display the PWM signals coming from the microcontroller. Be sure to refer to thestickers in the board to correctly identify IN1 and IN2 test points.
5. Vsense/Ipropi test point provides a voltage that is dependent on the current going through the load for
current regulation.
a. Said curent, and current regulation can be calculated by the equations in the current sensing and current
regulation section.

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5 Operation of the EVM
Quickstart guide
1. Move POT1, POT2, and VREF all the way counter-clockwise
2. Connect power supply to connector J1. J1 is positive terminal and GND negative terminal as shown in
Figure 5-1.

Figure 5-1. Power Connected
3. Set power supply to desired voltage dependent on load, do not exceed the maximum limits of the device see
section above for max limits, for 8231 series it is 33 V
4. Enable power supply
5. The status LED D1 (Bottom left green led) will turn on
6. Disable power and connect load in J3 as shown in Figure 5-2:

Figure 5-2. Power and Load Connected
7. Re-enable power
8. Turn VREF potentiometer all the way clockwise.
a. This will make Itrip the maximum value possible.

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Operation of the EVM

9. Turn “POT1” (labeled as “IN1_PWM” on silkscreen) clock-wise. The motor should start spinning and its
speed should increase as the POT is turn more clockwise.
10. Slowly turn VREF counter clockwise while probing the VREF test point, this should allow you to set VREF tothe desired value for current regulation. If not current regulation is desired then leave VREF fully clockwise.
11. Turn “IN1_PWM” POT all the way counter-clockwise. Motor should come to a complete stop.
12. Turn “IN2_PWM” POT clock-wise. Motor should begin to spin the opposite direction of step 9

5.1 H-Bridge Control
Table 5-1. H-Bridge Control
IN1IN2

OUT1

OUT200High-Z

High-ZDESCRIPTION01LHReverse (current OUT2 → OUT1)

10HLForward (current OUT1 → OUT2)11LLBrake; low-side slow decay

Coast; H-bridge disabled to High-Z (sleep entered after 1 ms)

The inputs can be set to static voltages for 100% duty-cycle drive, or they can be pulse-width modulated (PWM)
for variable motor speed. When using PWM, switching between driving and braking typically works best. For
example, to drive a motor forward with 50% of its max RPM, IN1 = 1 and IN2 = 0 during the driving period, andIN1 = 1 and IN2 = 1 during the other period. Alternatively, the coast mode (IN1 = 0, IN2 = 0) for fast current
decay is also available. The input pins can be powered before VM is applied.
VMVM

1 Reverse drive

1 Forward drive

2 Slow decay (brake)

2 Slow decay (brake)
1OUT1

1

3 High-Z (coast)
OUT1

OUT2

3 High-Z (coast)
OUT2

2233

FORWARD

REVERSE

Figure 5-3. H-Bridge Current Paths

5.2 Current Sensing and Current Regulation Details
The current sensing and current regulation will depend on the device used:
DRV8251AEVM and DRV8231AEVM:
An internal current mirror architetcture on the IPROPI pin implements current sensing and regulation. Thiseliminates the need for a large power shunt resistor, saving board area and reducing system cost. The
IPROPI current-sense output allows a microcontroller to detect motor stall or changes in load conditions.
VREF determines the threshold of current regulation during start-up and stall events without interaction of amicrocontroller.

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The motor current can be monitor by the IPROPI pin voltage. The IPROPI voltage is the voltage proportional tothe motor current. A more detailed explanation on how current regulation and sensing can be found on section
8.4.3 of the datasheet.
DRV8251EVM and DRV8231EVM:
Features integrated current regulation. This is implemented by comparing the analog input VREF and thevoltage on the ISEN pin, which is proportional to motor current through an external sense resistor. The ability
to limit current to a known level can significantly reduce the system power requirements and bulk capacitanceneeded to maintain stable voltage, especially for motor startup and stall conditions.
Current regulation for both variants will be dependent on Itrip, a set threshold which once exceeded will cause
the device to enter current regulation. This threshold can be adjusted by the VREF potentiometer and follows thefollowing equations:Figure 5-4. Current Regulation Equations
For more information be sure to refer to the datasheet of the device installed on the EVM.

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Removing and Installing Supported Motor Drivers

6 Removing and Installing Supported Motor Drivers
The EVM can support the DRV8251/DRV8251A/DRV8231/DRV8231A devices. Below are step-by-step
instructions on how to remove and place different drivers on the EVM:
1. Disconnect power from the EVM.
2. Carefully de-solder the device from the PCB. Make sure to follow proper soldering and ESD protection
procedures to prevent damage to the EVM.
3. Carefully solder the new device to the EVM. Visit ti.com or any authorized third party vendor to purchase thedesired driver.
4. The EVM uses a combination of resistors to identify the device that is populated on the board.
5. The firmware will function slightly different depending on the device that is on the board. After installing thenew device, make sure to populate the appropriate resistors.
The Table 6-1 shows the changes that need to be implemented when switching from one device to the other.
Table 6-1. Procedure For Soldering New Device and Passives to EVM
New device being installed
8251 switching to 8251A

Soldering procedures••••

8251A switching to 8251

••••
•
••
•

Solder the device to footprint U2. Make sure pin 1 of device aligns with the dot on thePCB
Depopulate C6, R5, R7, R8, R13, R14 and U2Populate R4 and R7 with 0 ohm resistor.
Populate R5 with 1.5 kOhm resistor
Solder the device to footprint U2. Make sure pin 1 of device aligns with the dot on thePCB
Depopulate R4, R5, and R7
Populate R5 and R14 with 0 ohm resistor
Populate R7 with 0.15 ohm resistor
Populate C6 with 0.1 uF cap
Populate R8 with 1k ohm resistor
Populate R13 with 4.02 k ohm resistor
Populate U4 with TLV9001IDCKRBe mindful of warnings in voltage differences.

This hardware can be used to test and validate the 8231 series as it is pin to pin compatible with the DRV8251
series. The steps of switching between DRV8231 and DRV8231A are identical as those between the DRV8251
to 8251A and vice versa.Be mindful of warnings in voltage differences.

7 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
DATENovember 2021

REVISION*NOTES
Initial Release

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