SLVSEE9D April 2020 – April 2021 DRV8889-Q1
PRODUCTION DATA
If the winding current in any coil drops below the open load current threshold (IOL) and the ITRIP level set by the indexer, and if this condition persists for more than the open load detection time (tOL), an open-load condition is detected. The EN_OL bit must be '1' to enable open load detection. When an open load fault is detected, the OL and FAULT bits are latched high in the SPI register and the nFAULT pin is driven low. If the OL_A bit is high, it indicates an open load fault in winding A, between AOUT1 and AOUT2. Similarly, an open load fault between BOUT1 and BOUT2 causes the OL_B bit to go high. Normal operation resumes and the nFAULT line is released when the open load condition is removed and a clear faults command has been issued either through the CLR_FLT bit or an nSLEEP reset pulse. The fault also clears when the device is power cycled or comes out of sleep mode.
If the motor is held at a position corresponding to 0°, 90°, 180° or 270° electrical angles, for more than the open load detection time, open load fault will be flagged, as one of the coil current is zero. This situation does not arise in full-step mode, because the coil currents are never zero.