Test Points
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SLVUBG7C – August 2018 – Revised December 2019
Copyright © 2018–2019, Texas Instruments Incorporated
DRV8876/74 Evaluation Module
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+ pin to GND pin. We recommend a pin header with pin dimensions like 850-10-050-20-
001000. The U1 MCU must be removed from the Launchpad.
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Test Points
The inputs and control signals between the MCU and the DRV8876/74 connect to the J4 header pins to
use as test points for EN/IN1, PH/IN2, nSLEEP, nFAULT, VREF, and IPROPI signals. The resistors next
to the headers (R2, R3, R4, R6, R10, and R11) can be removed to test the DRV8876/74 with external
signals rather than the signals from the MCU. The MCU provides logic output signals to the EN/IN1,
PH/IN2, and nSLEEP pins between 0 V and 3.3 V. The nFAULT signal pulls low during a fault condition
from the DRV8876/74. When nFAULT is low, the Fault LED, D2, will turn on. The VREF potentiometer
sets a reference voltage between 0 V and 3.3 V. The IPROPI signal voltage will be proportional to the
current out of the IPROPI pin. On the EVM, the R
IPROPI
resistor (R8) is 1.5 k
Ω
. For more information on
IPROPI, refer to the
and
datasheets.
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PMODE Jumper and Speed-Adjustment Potentiometers
The PMODE header and jumper allow the user to select from the input modes of PH/EN (GND), PWM
(3.3 V), and independent half-bridge control (Hi-Z). PMODE must be selected prior to powering the EVM.
The inputs to the DRV8876/74 are EN/IN1 and PH/IN2. The function of these inputs are IN1 and IN2 when
the PMODE is 3.3 V (PWM mode) or Hi-Z (independent half-bridge mode). When PMODE is connected to
ground (PH/EN control mode) the input function is a phase/enable (PH/EN) interface.
The MSP430 produces PWM signals for the EN/IN1 and PH/IN2 pins with duty cycles proportional to the
voltage from the PWM potentiometers. The tables below show how to configure the potentiometers for
each PMODE configuration.
NOTE:
When switching between modes, completely power down the board before changing the
PMODE jumper. Once powered down, turn both potentiometers completely counterclockwise
so motor does not start turning immediately when the board is powered. After moving the
PMODE jumper and setting the potentiometers, power up the board again to use the new
mode.