Maxim-integrated MAX31782 Manual do Utilizador descarregar pdf (Página 85)

Maxim Integrated 9-4

MAX31782 User’s Guide

Revision 0; 8/11

Figure 9-2. PWM Output Waveform in Normal PWM Output Mode

9.1.3 Normal PWM Output Operation

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

it reaches the reload value, PWMRn. At this point, PWMVn reloads with 0000h, the TFB flag is set (which can generate

an interrupt if enabled), and counting continues. Figure 9-2 illustrates the PWM waveforms when the PWM is operating

with DCEN = 0. The period of the PWM waveform is set by the value in the PWMRn register. The set and reset modes

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

PWM PERIOD = (PWMRn + 1) × PWM.n CLOCK PERIOD

Duty Cycle in Set Mode =

PWMRn PWMCn

PWMRn 1

−

Duty Cycle in Reset Mode =

PWMCn

PWMRn 1+

The toggle mode generates a 50% duty-cycle waveform if the PWMCn register remains fixed. The period of the wave-

form is:

PERIOD = 2 × (PWMRn + 1) × PWM.n CLOCK PERIOD

PWMCn > PWMRn

PWMCn < PWMRn

0000

PWMVn

SET MODE

RESET MODE

TOGGLE MODE

SET MODE

RESET MODE

TOGGLE MODE

PWMRn

PWMCn < PWMRn

PWMCn > PWMRn

1 2 ... 80 81 82 83 84 85 86 87 88 89 90 ... 222 223

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Maxim-integrated MAX31782 Manual do Utilizador Página 85