SLLSFZ8 November 2025 MCF8329HS-Q1
PRODUCTION DATA
MCF8329HS-Q1 provides the option of dry run detection when pumps are operating with insufficient fluid. Dry run is a dangerous operating condition that can damage pumps - timely detection and preventive action is necessary to protect pumps. Dry run is characterized by the motor operating continuously at a lower current/power than when operating with sufficient fluid. Dry run detection is enabled when DRY_RUN_MODE ≠ 00b. The threshold speed for dry run detection is configured by DRY_RUN_SPEED_THR - even when enabled, dry run detection is active only when motor speed is higher than DRY_RUN_SPEED_THR. The q-axis current threshold (IDRY_RUN) for detecting dry run can either be fixed across motor speed (DRY_RUN_ILIM_MODE = 0b) or variable (DRY_RUN_ILIM_MODE = 1b). IDRY_RUN is fixed to DRY_RUN_ILIM when DRY_RUN_ILIM_MODE = 0b. When DRY_RUN_ILIM_MODE = 1b, IDRY_RUN varies with motor speed as shown in Figure 7-49. The Iq current must be lower than IDRY_RUN for a deglitch time interval set by DRY_RUN_TDEG before dry run fault is triggered as shown in Figure 7-48 .
On detection of dry run condition, action is taken based on DRY_RUN_MODE. If DRY_RUN_MODE is set to 11b, all external FETs are turned off (PWMs are pulled low), nFAULT is pulled low, CONTROLLER_FAULT, DRY_RUN bits are set to 1b until a clear fault command is issued by external MCU through the CLR_FLT bit. If DRY_RUN_MODE is set to 10b, all external FETs are turned off (PWMs are pulled low), nFAULT is pulled low - normal operation resumes automatically (gate driver operation and the nFAULT pin is released) after the tLCK_RETRY (configured by LCK_RETRY) time lapses. The CONTROLLER_FAULT and DRY_RUN bits are reset to 0b after the tLCK_RETRY period expires.
MCF8329HS-Q1 provides the option to vary IDRY_RUN as a function of motor speed to detect dry run in pumps that can operate at multiple speeds (or flow rates) during normal operation. User must set DRY_RUN_ILIM to the expected Iq current at 100% speed and DRY_RUN_ILIM_FIFTY_PERCENT_SPEED to the expected Iq current at 50% speed. MCF8329HS-Q1 will use DRY_RUN_ILIM as IDRY_RUN when motor is at 100% speed and DRY_RUN_ILIM_FIFTY_PERCENT_SPEED as IDRY_RUN when motor is at 50% speed. When motor is operating at other speeds, MCF8329HS-Q1 extrapolates IDRY_RUN as shown in Figure 7-49.