Chapter 12 Pulse Width Modulator with Fault Protection (PMF15B6CV4)MC9S12ZVMB Family Reference Manual Rev. 1.3438 NXP SemiconductorsSampled results will be DT0 = 0 and DT1 = 1. Thus, the best time to change one PWM value register toanother is just before the current zero crossing.Figure 12-57. Output Voltage Waveforms12.4.6.2 Current-Sensing CorrectionA current sense input, IS, for a PWM pair selects either the odd or the even PWM value registers to use inthe next PWM cycle. The selection is based on user-provided current sense circuitry driving the related ISinput high for negative current and low for positive current.Previously shown, the current direction can be determined by the output voltage during deadtime. Thus, asimple external voltage sensor can be used when current status is completed during deadtime, ISENS = 10.Deadtime does not exist at the 100 percent and zero percent duty cycle boundaries. Therefore, the secondautomatic mode must be used for correction, ISENS = 11, where current status is sampled at the half cycleTable 12-43. Top/Bottom Current Sense CorrectionPin Logic State Output ControlIS0 0 PMFVAL0 controls PWM0/PWM1 pair1 PMFVAL1 controls PWM0/PWM1 pairIS1 0 PMFVAL2 controls PWM2/PWM3 pair1 PMFVAL3 controls PWM2/PWM3 pairIS2 0 PMFVAL4 controls PWM4/PWM5 pair1 PMFVAL5 controls PWM4/PWM5 pairDEADTIMEPWM TO TOPPOSITIVENEGATIVEPWM TO BOTTOMLOAD VOLTAGE WITHLOAD VOLTAGE WITHTRANSISTORTRANSISTORHIGH POSITIVE CURRENTLOW POSITIVE CURRENTCURRENTCURRENTLOAD VOLTAGE WITHHIGH NEGATIVE CURRENTLOAD VOLTAGE WITHNEGATIVE CURRENTT B T BT = DEADTIME INTERVAL BEFORE ASSERTION OF TOP PWMB = DEADTIME INTERVAL BEFORE ASSERTION OF BOTTOM PWMV+
