Reference Guide
SPRUG04A – October 2008 – Revised July 2009
TMS320x2833x, 2823x Enhanced Pulse Width Modulator
(ePWM) Module
The enhanced pulse width modulator (ePWM) peripheral is a key element in controlling many of the power
electronic systems found in both commercial and industrial equipments. These systems include digital
motor control, switch mode power supply control, uninterruptible power supplies (UPS), and other forms of
power conversion. The ePWM peripheral performs a digital to analog (DAC) function, where the duty cycle
is equivalent to a DAC analog value; it is sometimes referred to as a Power DAC.
This reference guide is applicable for ePWM type 0 . See the TMS320x28xx, 28xxx DSP Peripheral
Reference Guide (
) for a list of all devices with an ePWM module of the same type, to determine
the differences between the types, and for a list of device-specific differences within a type.
1
Introduction
An effective PWM peripheral must be able to generate complex pulse width waveforms with minimal CPU
overhead or intervention. It needs to be highly programmable and very flexible while being easy to
understand and use. The ePWM unit described here addresses these requirements by allocating all
needed timing and control resources on a per PWM channel basis. Cross coupling or sharing of resources
has been avoided; instead, the ePWM is built up from smaller single channel modules with separate
resources that can operate together as required to form a system. This modular approach results in an
orthogonal architecture and provides a more transparent view of the peripheral structure, helping users to
understand its operation quickly.
In this document the letter x within a signal or module name is used to indicate a generic ePWM instance
on a device. For example output signals EPWMxA and EPWMxB refer to the output signals from the
ePWMx instance. Thus, EPWM1A and EPWM1B belong to ePWM1 and likewise EPWM4A and EPWM4B
belong to ePWM4.
1.1
Submodule Overview
The ePWM module represents one complete PWM channel composed of two PWM outputs: EPWMxA
and EPWMxB. Multiple ePWM modules are instanced within a device as shown in
. Each ePWM
instance is identical with one exception. Some instances include a hardware extension that allows more
precise control of the PWM outputs. This extension is the high-resolution pulse width modulator (HRPWM)
and is described in the TMS320x2833x, 2823x High-Resolution Pulse Width Modulator (HRPWM)
Reference Guide (
) . See the device-specific data manual to determine which ePWM instances
include this feature. Each ePWM module is indicated by a numerical value starting with 1. For example
ePWM1 is the first instance and ePWM3 is the 3rd instance in the system and ePWMx indicates any
instance.
The ePWM modules are chained together via a clock synchronization scheme that allows them to operate
as a single system when required. Additionally, this synchronization scheme can be extended to the
capture peripheral modules (eCAP). The number of modules is device-dependent and based on target
application needs. Modules can also operate stand-alone.
Each ePWM module supports the following features:
•
Dedicated 16-bit time-base counter with period and frequency control
•
Two PWM outputs (EPWMxA and EPWMxB) that can be used in the following configurations:
–
Two independent PWM outputs with single-edge operation
–
Two independent PWM outputs with dual-edge symmetric operation
11
SPRUG04A – October 2008 – Revised July 2009
TMS320x2833x, 2823x Enhanced Pulse Width Modulator (ePWM) Module
© 2008–2009, Texas Instruments Incorporated
