P89LPC9321 NXP Semiconductors, P89LPC9321 Datasheet - Page 23

• Manufacturer Part Number: P89LPC9321
• Description: The P89LPC9321 is a single-chip microcontroller, available in low cost packages, basedon a high performance processor architecture that executes instructions in two to fourclocks, six times the rate of standard 80C51 devices
• Manufacturer: NXP Semiconductors

NXP Semiconductors
P89LPC9321
Product data sheet
Fig 6.
Block diagram of oscillator control
(7.3728 MHz/14.7456 MHz ± 1 %)
WITH CLOCK DOUBLER
7.10 CCLK wake-up delay
7.12 Low power select
7.11 CCLK modification: DIVM register
XTAL1
XTAL2
RC OSCILLATOR
(400 kHz ± 5 %)
The P89LPC9321 has an internal wake-up timer that delays the clock until it stabilizes
depending on the clock source used. If the clock source is any of the three crystal
selections (low, medium and high frequencies) the delay is 1024 OSCCLK cycles plus
60 μs to 100 μs. If the clock source is the internal RC oscillator, the delay is 200 μs to
300 μs. If the clock source is watchdog oscillator or external clock, the delay is
32 OSCCLK cycles.
The OSCCLK frequency can be divided down up to 510 times by configuring a dividing
register, DIVM, to generate CCLK. This feature makes it possible to temporarily run the
CPU at a lower rate, reducing power consumption. By dividing the clock, the CPU can
retain the ability to respond to events that would not exit Idle mode by executing its normal
program at a lower rate. This can also allow bypassing the oscillator start-up time in cases
where Power-down mode would otherwise be used. The value of DIVM may be changed
by the program at any time without interrupting code execution.
The P89LPC9321 is designed to run at 18 MHz (CCLK) maximum. However, if CCLK is
8 MHz or slower, the CLKLP SFR bit (AUXR1.7) can be set to logic 1 to lower the power
consumption further. On any reset, CLKLP is logic 0 allowing highest performance
access. This bit can then be set in software if CCLK is running at 8 MHz or slower.
OSCILLATOR
WATCHDOG
MEDIUM FREQUENCY
HIGH FREQUENCY
LOW FREQUENCY
TIMER 0 AND
RCCLK
TIMER 1
All information provided in this document is subject to legal disclaimers.
Rev. 2 — 16 November 2010
8-bit microcontroller with accelerated two-clock 80C51 core
I
2
C-BUS
OSCCLK
PCLK
DIVM
SPI
CCLK
PCLK
÷2
UART
P89LPC9321
WDT
RTC
CPU
32 × PLL
CCU
002aae108
© NXP B.V. 2010. All rights reserved.
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