MC33AR6000(LIN2112 is nick name) have advanced Excitation current feedback and protection. But different current value is been used in different condition.
1. Current measurements:
Excitation control is a MOS ON/OFF PWM. During MOS ON, current raise, during MOS OFF, current decrease, as motor parasitic inductance. Current measurement only happens during MOS ON. IC catch sample current value Sn in every 10-15us, . When MOS OFF, current measurement value Iexc=ΣSn/n.
2. Iexc current feedback by LIN
MC33AR600 can report Iexc value by LIN. The report value Iexc_LIN= ΣIexcx/X, X is number of excitation cycles happens during two LIN current command.
3. Current limitation
current limitation is compare Iexc to Iexc_limit threshold.
Be careful, Iexc is an average value. Iexc>Iexc_limit trigger limitation on next excitation cycle. So current limitation dose not mean limitation action happen once current real time value reach the limitation threshold.
EXC current measurement:
1. sampling Iexc every 10-15μs when MOS ON. (S0,S1,...Sn)
2. calculate average value of the sampes in one period. ( D=(S0+S1+S2+..Sn)/n)
3.report D to digital core. D = Iexc.
4. calculate average of D value in Ffilter_Iexc (selected by OTP) period. Reprot to ECU by LIN. (Iexc_LIN=(D0+D1+...Dx)/X
EXC current limitation:
1. once detect Iexc(D)>Ilimit, the duty cycle(DC) in next period is minimum duty cycle(celected by OTP).
2. once Iexc<Ilimit , the next duty cycle back to normal regulation DC. -- other words, the current limit function is refreshed by regulation requency(200Hz).