Maxim-integrated MAX31782 Manual do Utilizador descarregar pdf (Página 110)

Maxim Integrated 12-8

MAX31782 User’s Guide

Revision 0; 8/11

12.1.5.1 Up Count PWM Output Mode

When operating in PWM output mode and configured for up count (DCEN = 0), the value in TB0V is incremented until it

reaches the reload value, TB0R. At this point, TB0V is reloaded with 0000h, the TFB flag is set (which can generate an

interrupt if enabled), and counting continues. Figure 12-6 illustrates the PWM waveforms when the Timer B is operating

in up count PWM output mode. The period of the PWM waveform is set by the value in the TB0R register. The set and

reset modes provide similar functionality. The formulas for period and duty cycle are:

PWM PERIOD = (TB0R + 1) × TIMER B CLOCK PERIOD

Duty Cycle in Set Mode =

TB0R TB0C

TB0R 1

−

Duty Cycle in Reset Mode =

TB0C

TB0R 1+

The toggle mode generates a 50% duty-cycle waveform if the TB0C register remains fixed with the Timer B running.

The period of the waveform is:

PERIOD = 2 × (TB0R + 1) × TIMER B CLOCK PERIOD

Figure 12-6. TBB Pin Waveform in Up Count PWM Output Mode

TB0C > TB0R

TB0C < TB0R

0000

TB0V

SET MODE

RESET MODE

TOGGLE MODE

SET MODE

RESET MODE

TOGGLE MODE

TB0R

TB0C < TB0R

TB0C > TB0R

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Maxim-integrated MAX31782 Manual do Utilizador Página 110