LPC2925 NXP Semiconductors, LPC2925 Datasheet - Page 37

• Manufacturer Part Number: LPC2925
• Description: (LPC2921 - LPC2925) ARM9 microcontroller
• Manufacturer: NXP Semiconductors

NXP Semiconductors
LPC2921_2923_2925_0
Preliminary data sheet
Fig 7.
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APB system bus
IRQ capt_match
PWM block diagram
6.14.5.1 Functional description
IRQ pwm
The ability to provide flexible waveforms allows PWM blocks to be used in multiple
applications; e.g. dimmer/lamp control and fan control. Pulse-width modulation is the
preferred method for regulating power since no additional heat is generated, and it is
energy-efficient when compared with linear-regulating voltage control networks.
The PWM delivers the waveforms/pulses of the desired duty cycles and cycle periods. A
very basic application of these pulses can be in controlling the amount of power
transferred to a load. Since the duty cycle of the pulses can be controlled, the desired
amount of power can be transferred for a controlled duration. Two examples of such
applications are:
The PWM block diagram in
functionality is split into two major parts, a APB domain and a PWM domain, both of which
run on clocks derived from the BASE_MSCSS_CLK. This split into two domains affects
behavior from a system-level perspective. The actual PWM and prescale counters are
located in the PWM domain but system control takes place in the APB domain.
•
•
Dimmer controller: The flexibility of providing waves of a desired duty cycle and cycle
period allows the PWM to control the amount of power to be transferred to the load.
The PWM functions as a dimmer controller in this application
Motor controller: The PWM provides multi-phase outputs, and these outputs can be
controlled to have a certain pattern sequence. In this way the force/torque of the
motor can be adjusted as desired. This makes the PWM function as a motor drive.
REGISTERS
CONTROL
PWM
&
Rev. 00.01 — 24 October 2008
PWM counter value
capture data
config data
APB DOMAIN
update
Figure 7
IRQ's
shows the basic architecture of each PWM. PWM
PWM DOMAIN
ARM9 microcontroller with CAN and LIN
LPC2921/2923/2925
sync_in
sync_out
REGISTERS
COUNTER,
PRESCALE
COUNTER
SHADOW
PWM,
transfer_enable_in
transfer_enable_out
&
© NXP B.V. 2008. All rights reserved.
match outputs
capture inputs
trap input
carrier inputs
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