LPC2220 PHILIPS [NXP Semiconductors], LPC2220 Datasheet - Page 27

• Manufacturer Part Number: LPC2220
• Description: 16/32-bit ARM microcontrollers; flashless with 64 kB, with 10-bit ADC and external memory interface
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
9397 750 14061
Product data sheet
6.20.1 Crystal oscillator
6.20.2 PLL
6.20 System control
On-chip integrated oscillator operates with external crystal in range of 1 MHz to 30 MHz
and with external oscillator up to 50 MHz. The oscillator output frequency is called f
the ARM processor clock frequency is referred to as CCLK for purposes of rate equations,
etc. f
Section 6.20.2 “PLL”
The PLL accepts an input clock frequency in the range of 10 MHz to 25 MHz. The input
frequency is multiplied up into the range of 10 MHz to 60/75 MHz (LPC2210/2220) with a
Current Controlled Oscillator (CCO). The multiplier can be an integer value from 1 to 32
(in practice, the multiplier value cannot be higher than 6 on this family of microcontrollers
due to the upper frequency limit of the CPU). The CCO operates in the range of 156 MHz
to 320 MHz, so there is an additional divider in the loop to keep the CCO within its
frequency range while the PLL is providing the desired output frequency. The output
divider may be set to divide by 2, 4, 8, or 16 to produce the output clock. Since the
minimum output divider value is 2, it is insured that the PLL output has a 50 % duty cycle.
The PLL is turned off and bypassed following a chip Reset and may be enabled by
software. The program must configure and activate the PLL, wait for the PLL to Lock, then
connect to the PLL as a clock source. The PLL settling time is 100 s.
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The match registers also allow:
– Continuous operation with optional interrupt generation on match.
– Stop timer on match with optional interrupt generation.
– Reset timer on match with optional interrupt generation.
Supports single edge controlled and/or double edge controlled PWM outputs. Single
edge controlled PWM outputs all go HIGH at the beginning of each cycle unless the
output is a constant LOW. Double edge controlled PWM outputs can have either edge
occur at any position within a cycle. This allows for both positive going and negative
going pulses.
Pulse period and width can be any number of timer counts. This allows complete
flexibility in the trade-off between resolution and repetition rate. All PWM outputs will
occur at the same repetition rate.
Double edge controlled PWM outputs can be programmed to be either positive going
or negative going pulses.
Match register updates are synchronized with pulse outputs to prevent generation of
erroneous pulses. Software must ‘release’ new match values before they can become
effective.
May be used as a standard timer if the PWM mode is not enabled.
A 32-bit Timer/Counter with a programmable 32-bit Prescaler.
osc
and CCLK are the same value unless the PLL is running and connected. Refer to
for additional information.
16/32-bit ARM microcontrollers with external memory interface
Rev. 02— 30 May 2005
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
LPC2210/2220
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