SPRUJ17H March 2022 – October 2024 AM2631 , AM2631-Q1 , AM2632 , AM2632-Q1 , AM2634 , AM2634-Q1
Figure 7-233 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 AM263x platform does not support high-resolution output swapping on the EPWMxA and EPWMxB output or use of the OUT_SWAP register bit.
The ePWM peripheral is used to perform a function mathematically equivalent to a digital-to-analog converter (DAC). As shown in Figure 7-234, 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 7-166 shows resolution in bits for various PWM frequencies. These values assume a MEP step size of 180 ps. See the device data sheet for typical and maximum performance specifications for the MEP.
PWM Frequency (kHz) |
Regular Resolution (PWM) 100 MHz 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 250 kHz) does not require HRPWM. HRPWM capability is most useful for high-frequency PWM requirements of power conversion topologies such as: