SM320F2808-EP Datasheet, PDF (47/118 Pages) Texas Instruments – Digital Signal Processors

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Time−base (TB)
TBPRD shadow (16)
TBPRD active (16)
CTR=PRD
TBCTL[CNTLDE]
Counter
up/down
(16 bit)
TBCNT
active (16)
CTR=ZERO
CTR_Dir
16
TBPHSHR (8)
8
TBPHS active (24)
Phase
control
Counter compare (CC)
CTR=CMPA
CMPAHR (8)
16
8
CMPA active (24)
CMPA shadow (24)
Action
qualifier
(AQ)
EPWMA
SM320F2808-EP, SM320F2806-EP
SM320F2801-EP
Digital Signal Processors
SGLS316A – MARCH 2006 – REVISED FEBRUARY 2007
CTR=ZERO
CTR=CMPB
Disabled
Sync
in/out
select
Mux
TBCTL[SYNCOSEL]
TBCTL[SWFSYNC]
(software forced sync)
EPWMxSYNCO
EPWMxSYNCI
CTR = PRD
CTR = ZERO
CTR = CMPA
CTR = CMPB
CTR_Dir
Event
trigger
and
interrupt
(ET)
EPWMxINT
EPWMxSOCA
EPWMxSOCB
HiRes PWM (HRPWM)
EPWMxAO
CTR=CMPB
16
CMPB active (16)
CMPB shadow (16)
EPWMB
Dead
band
(DB)
PWM
chopper
(PC)
CTR = ZERO
Trip
zone
(TZ)
EPWMxBO
EPWMxTZINT
TZ1 to TZ6
Figure 4-4. ePWM Sub-modules Showing Critical Internal Signal Interconects
4.3 Hi-Resolution PWM (HRPWM)
The HRPWM module offers PWM resolution (time granularity) which is significantly better than what can
be achieved using conventionally derived digital PWM methods. The key points for the HRPWM module
are:
• Significantly extends the time resolution capabilities of conventionally derived digital PWM
• Typically used when effective PWM resolution falls below ~ 9-10 bits. This occurs at PWM frequencies
greater than ~200 KHz when using a CPU/System clock of 100 MHz.
• This capability can be utilized in both duty cycle and phase-shift control methods.
• Finer time granularity control or edge positioning is controlled via extensions to the Compare A and
Phase registers of the ePWM module.
• HRPWM capabilities are offered only on the A signal path of an ePWM module (i.e., on the EPWMxA
output). EPWMxB output has conventional PWM capabilities.
Only PWM channels ePWM 1A, 2A, 3A, 4A support HRPWM features. The remaining ePWM
channels do not support the HRPWM features.
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Peripherals
47