SPRUIY4B February 2023 – May 2024 TMS320F2800152-Q1 , TMS320F2800153-Q1 , TMS320F2800154-Q1 , TMS320F2800155 , TMS320F2800155-Q1 , TMS320F2800156-Q1 , TMS320F2800157 , TMS320F2800157-Q1
Figure 14-78 shows a block diagram of the HRPWM. This module extends the time resolution capabilities of the conventionally derived digital pulse width modulator (PWM). HRPWM is typically used when PWM resolution falls below approximately 9-10 bits. The key features of HRPWM are:
The ePWM peripheral is used to perform a function mathematically equivalent to a digital-to-analog converter (DAC). As shown in Figure 14-79, the effective resolution for conventionally generated PWM is a function of PWM frequency (or period) and system clock frequency.
If the required PWM operating frequency does not offer sufficient resolution in PWM mode, consider using HRPWM. As an example of improved performance offered by HRPWM, Table 14-15 shows resolution in bits for various PWM frequencies. These values assume a MEP step size of 180ps. See the device data sheet for typical and maximum performance specifications for the MEP.
PWM Frequency (kHz) |
Regular
Resolution (PWM) 100MHz EPWMCLK |
High Resolution (HRPWM) | ||
---|---|---|---|---|
Bits | % | Bits | % | |
20 | 12.3 | 0.02 | 18.1 | 0.000 |
50 | 11 | 0.05 | 16.8 | 0.001 |
100 | 10 | 0.1 | 15.8 | 0.002 |
150 | 9.4 | 0.15 | 15.2 | 0.003 |
200 | 9 | 0.2 | 14.8 | 0.004 |
250 | 8.6 | 0.25 | 14.4 | 0.005 |
500 | 7.6 | 0.5 | 13.4 | 0.009 |
1000 | 6.6 | 1 | 12.4 | 0.018 |
1500 | 6.1 | 1.5 | 11.9 | 0.027 |
2000 | 5.6 | 2 | 11.4 | 0.036 |
Although each application can differ, typical low-frequency PWM operation (below 250kHz) does not require HRPWM. HRPWM capability is most useful for high-frequency PWM requirements of power conversion topologies such as: