5.9 Motor Line Diagnostics

While the motor is not in operation, the Back-EMF module can be used for motor line diagnostics. GDU must be in GDU Standby mode. Motor line (SHx) short to GND, short to VDH and open load can be evaluated, see Motor Line Diagnostics Setup. The MLDCR register is used to control the motor line diagnostics. As soon as the diagnostics are activated, the outputs of the diagnostics comparators will continuously update the MLDRR register. Enabling the motor line diagnostics disables the NIHX and ILx PWM input pins.

Figure 5-8. Motor Line Diagnostics Setup
Figure 5-9. Motor Line Diagnostics diagram

Motor Line Short to GND and Supply Test and Motor Line Open Connection Test show the motor clamp short to GND, short to VBUS or open-load failure detection.

Figure 5-10. Motor Line Short to GND and Short to VDH Test
Figure 5-11. Motor Line Open Load Test

A sufficient delay time is required before evaluating the MLDRR register, to account for parasitic board and power MOSFET capacitances, as well as the limited current capability of the diagnostic current sources.

Motor line diagnostics can be activated when VS is within the valid operating range, the ATA6847 is in Normal mode and the GDU is in GDU Standby mode.