LM3S2110-IQN20-A0 Luminary Micro, Inc., LM3S2110-IQN20-A0 Datasheet - Page 401

• Manufacturer Part Number: LM3S2110-IQN20-A0
• Description: Microcontroller
• Manufacturer: Luminary Micro, Inc.

16
16.1
16.2
16.2.1
November 29, 2007
Pulse Width Modulator (PWM)
Pulse width modulation (PWM) is a powerful technique for digitally encoding analog signal levels.
High-resolution counters are used to generate a square wave, and the duty cycle of the square
wave is modulated to encode an analog signal. Typical applications include switching power supplies
and motor control.
The Stellaris
generator block contains one timer (16-bit down or up/down counter), two PWM comparators, a
PWM signal generator, a dead-band generator, and an interrupt selector. The control block determines
the polarity of the PWM signals, and which signals are passed through to the pins.
The PWM generator block produces two PWM signals that can either be independent signals (other
than being based on the same timer and therefore having the same frequency) or a single pair of
complementary signals with dead-band delays inserted. The output of the PWM generation block
is managed by the output control block before being passed to the device pins.
The Stellaris
such as those required by a simple charge pump. It can also generate paired PWM signals with
dead-band delays, such as those required by a half-H bridge driver.
Block Diagram
Figure 16-1 on page 401 provides a block diagram of a Stellaris
controller contains one generator block (PWM0) and generates two independent PWM signals or
one paired PWM signal with dead-band delays inserted.
Figure 16-1. PWM Module Block Diagram
Functional Description
PWM Timer
The timer runs in one of two modes: Count-Down mode or Count-Up/Down mode. In Count-Down
mode, the timer counts from the load value to zero, goes back to the load value, and continues
counting down. In Count-Up/Down mode, the timer counts from zero up to the load value, back
down to zero, back up to the load value, and so on. Generally, Count-Down mode is used for
PWM Clock
®
®
PWM module provides a great deal of flexibility. It can generate simple PWM signals,
PWM module consists of one PWM generator block and a control block. The PWM
PWMnCOUNT
PWMnLOAD
16
Timer
Comparator A
Comparator B
PWMnCMPA
PWMnCMPB
zero
load
dir
cmpA
cmpB
Preliminary
Trigger Generate
Interrupt and
PWMnINTEN
PWMnGENA
PWMnGENB
Generator
PWMnRIS
PWMnISC
PWM
pwma
pwmb
PWM Generator Block
®
PWM module. The LM3S2110
PWMnDBRISE
PWMnDBCTL
PWMnDBFALL
Dead-Band
Generator
LM3S2110 Microcontroller
Fault
Interrupt
PWM Output
PWMENABLE
PWMINVERT
PWMFAULT
Control
401