Nxp Semiconductors LPC2917 User Manual
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LPC2917_19_1
© NXP B.V. 2007. All rights reserved.
Preliminary data sheet
Rev. 1.01 — 15 November 2007
37 of 68
NXP Semiconductors
LPC2917/19
ARM9 microcontroller with CAN and LIN
8.7.5.4
ADC clock description
The ADC modules are clocked from two different sources; CLK_MSCSS_ADCx_VPB and
CLK_ADCx (x = 1 or 2), see
CLK_ADCx (x = 1 or 2), see
. Note that each ADC has its own CLK_ADCx
and CLK_MSCSS_ADCx_VPB branch clocks for power management. If an ADC is
unused both its CLK_MSCSS_ADCx_VPB and CLK_ADCx can be switched off.
unused both its CLK_MSCSS_ADCx_VPB and CLK_ADCx can be switched off.
The frequency of all the CLK_MSCSS_ADCx_VPB clocks is identical to
CLK_MSCSS_VPB since they are derived from the same base clock
BASE_MSCSS_CLK. Likewise the frequency of all the CLK_ADCx clocks is identical
since they are derived from the same base clock BASE_ADC_CLK.
CLK_MSCSS_VPB since they are derived from the same base clock
BASE_MSCSS_CLK. Likewise the frequency of all the CLK_ADCx clocks is identical
since they are derived from the same base clock BASE_ADC_CLK.
The register interface towards the system bus is clocked by CLK_MSCSS_ADCx_VPB.
Control logic for the analog section of the ADC is clocked by CLK_ADCx, see also
Control logic for the analog section of the ADC is clocked by CLK_ADCx, see also
.
8.7.6 PWM
8.7.6.1
Overview
The MSCSS in the LPC2917/19 includes four PWM modules with the following features.
•
Six pulse-width modulated output signals
•
Double edge features (rising and falling edges programmed individually)
•
Optional interrupt generation on match (each edge)
•
Different operation modes: continuous or run-once
•
16-bit PWM counter and 16-bit prescale counter allow a large range of PWM periods
•
A protective mode (TRAP) holding the output in a software-controllable state and with
optional interrupt generation on a trap event
optional interrupt generation on a trap event
•
Three capture registers and capture trigger pins with optional interrupt generation on
a capture event
a capture event
•
Interrupt generation on match event, capture event, PWM counter overflow or trap
event
event
•
A burst mode mixing the external carrier signal with internally generated PWM
•
Programmable sync-delay output to trigger other PWM modules (master/slave
behavior)
behavior)
8.7.6.2
Description
The ability to provide flexible waveforms allows PWM blocks to be used in multiple
applications; e.g. automotive 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.
applications; e.g. automotive 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:
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: