Texas Instruments C2000

ePWM
7 - 20 C2000 Microcontroller Workshop - Control Peripherals
PWM Computation Example
Symmetric PWM Computation Example
 Determine TBPRD and CMPA for 90 kHz, 25% duty
symmetric PWM from a 90 MHz time base clock
CMPA = (100% - duty cycle)*TBPRD = 0.75*500 = 375
TBPRD =
f
TBCLK
f
PWM
2
2
11
90 kHz
90 MHz
..
= 500=
Counter
Compare
Period
PWM Pin
f
TBCLK
= 90 MHz
CA
↑
CA
↓
.
.
f
PWM
= 90 kHz
(T
PWM
= 11.1 µs)
(T
TBCLK
= 11.1 ns)
Asymmetric PWM Computation Example
 Determine TBPRD and CMPA for 90 kHz, 25% duty
asymmetric PWM from a 90 MHz time base clock
CMPA = (100% - duty cycle)*(TBPRD+1) - 1 = 0.75*(999+1) - 1 = 749
TBPRD =
f
TBCLK
f
PWM
90 kHz
90 MHz
- 1 = 999- 1 =
Counter
Compare
Period
PWM Pin
P
↓
CA
↑
f
TBCLK
= 90 MHz
.
.
f
PWM
= 90 kHz
(T
PWM
= 11.1 µs)
(T
TBCLK
= 11.1 ns)