SLLSFU1A December 2023 – July 2024 MCF8315C
PRODMIX
The MCF8315C uses 12-bit timers to estimate the time during the current ramp up and ramp down during IPD, when the motor start-up is configured as IPD (MTR_STARTUP is set to 10b). During IPD, the algorithm checks for a successful current ramp-up to IPD_CURR_THR, starting with an IPD clock of 10MHz; if unsuccessful (timer overflow before current reaches IPD_CURR_THR), IPD is repeated with lower frequency clocks of 1MHz, 100kHz, and 10kHz sequentially. If the IPD timer overflows (current does not reach IPD_CURR_THR) with all the four clock frequencies, then the IPD_T1_FAULT gets triggered. Similarly the algorithm checks for a successful current decay to zero during IPD current ramp down using all the mentioned IPD clock frequencies. If the IPD timer overflows (current does not ramp down to zero) in all the four attempts, then the IPD_T2_FAULT gets triggered. The user can enable IPD timeout (IPD timer overflow) by setting IPD_TIMEOUT_FAULT_EN to 1b.
IPD gives incorrect results if the next IPD pulse is commanded before the complete decay of current due to present IPD pulse. The MCF8315C can generate a fault called IPD_FREQ_FAULT during such a scenario by setting IPD_FREQ_FAULT_EN to 1b. The IPD_FREQ_FAULT maybe triggered if the IPD frequency is too high for the IPD current limit and the IPD release mode or if the motor inductance is too high for the IPD frequency, IPD current limit and IPD release mode.
On the occurrence of any IPD fault, MCF8315C stops the IPD based start-up process and FETs are in Hi-Z. MCF8315C automatically retries IPD based start-up after tLCK_RETRY elapses.