SPRUIU1C July 2020 – February 2024 DRA821U , DRA821U-Q1
Figure 12-2649 shows the high-resolution PWM (HRPWM) submodule in the EPWM system. Some devices include the high-resolution PWM submodule, see EPWM Integration to determine which EPWM instances include this feature.
The high-resolution pulse-width modulator (HRPWM) extends the time resolution capabilities of the conventionally derived digital pulse-width modulator (PWM). HRPWM is typically used when PWM resolution falls below ~9-10 bits.
The key features of HRPWM are:
The EPWM peripheral is used to perform a function that is mathematically equivalent to a digital-to-analog converter (DAC). As shown in Figure 12-2650, the effective resolution for conventionally generated PWM is a function of PWM frequency (or period) and system clock frequency.
Use HRPWM when the required PWM operating frequency does not offer sufficient resolution in PWM mode. As an example of improved performance offered by HRPWM, Table 12-5076 shows resolution in bits for various PWM frequencies. Table 12-5076 values assume a MEP step size of 180 ps. See the device-specific Datasheet for typical and maximum performance specifications for the MEP.
PWM Frequency (kHz) | Regular Resolution (PWM) | High Resolution (HRPWM) | |||
---|---|---|---|---|---|
Bits | % | Bits | % | ||
20 | 12.3 | 0.0 | 18.1 | 0.000 | |
50 | 11.0 | 0.0 | 16.8 | 0.001 | |
100 | 10.0 | 0.1 | 15.8 | 0.002 | |
150 | 9.4 | 0.2 | 15.2 | 0.003 | |
200 | 9.0 | 0.2 | 14.8 | 0.004 | |
250 | 8.6 | 0.3 | 14.4 | 0.005 | |
500 | 7.6 | 0.5 | 13.8 | 0.007 | |
1000 | 6.6 | 1.0 | 12.4 | 0.018 | |
1500 | 6.1 | 1.5 | 11.9 | 0.027 | |
2000 | 5.6 | 2.0 | 11.4 | 0.036 |
Although each application may differ, typical low-frequency PWM operation (below 250 kHz) may not require HRPWM. HRPWM capability is most useful for high-frequency PWM requirements of power conversion topologies such as: