Maxim Integrated MAX31782 - Manual (Page 111)

MaximIntegrated 12-9
MAX31782 User’s Guide
Revision 0; 8/11
12.1.5.2Up/DownCountPWMOutputMode
The Timer B can also operate in an up/down count configuration when in PWM output mode by setting DCEN = 1 . The
timer counts upward until it reaches the value in the reload register (TB0R) . On the next cycle, it reverses the count
direction and starts counting down . When the TB0V counter reaches 0000h, it again reverses direction and begins
counting up .
When operating in an up/down count configuration and either set or reset mode, the PWM effectively allows 17-bit
resolution . In set mode the duty cycle is always less than 50%, and in reset mode the duty cycle is always greater than
50% . The toggle mode provides a center-aligned 16-bit PWM with twice the period of the up counting PWM output
mode .
Figure 12-7 illustrates the PWM waveforms when the Timer B is operating in up/down count PWM output mode .
The up/down count PWM output period and duty cycle are calculated as follows:
PERIOD = 2 × TB0R × TIMER B CLOCK PERIOD
Duty Cycle in Set Mode =
TB0R TB0C
2 TB0R
+
×
Duty Cycle in Reset Mode =
TB0C
2 TB0R ×
Duty Cycle in Toggle Mode =
TB0R TB0C
TB0R
−
Figure 12-7. TBB Pin Waveform in Up/Down Count PWM Output Mode
TB0C > TB0R
TB0C < TB0R
0000h
TB0V
SET MODE
RESET MODE
TOGGLE MODE
SET MODE
RESET MODE
TOGGLE MODE
TB0R
TB0C < TB0R
TB0C > TB0R