lpc2364 NXP Semiconductors, lpc2364 Datasheet - Page 28

• Manufacturer Part Number: lpc2364
• Description: Single-chip 16-bit/32-bit Microcontrollers; Up To 512 Kb Flash With Isp/iap, Ethernet, Usb 2.0, Can, And 10-bit Adc/dac
• Manufacturer: NXP Semiconductors

NXP Semiconductors
LPC2364_66_68_3
Product data sheet
7.23.1 Features
7.24.1 Crystal oscillators
7.23 RTC and battery RAM
7.24 Clocking and power control
The RTC is a set of counters for measuring time when system power is on, and optionally
when it is off. It uses little power in Power-down mode. On the LPC2364/66/68, the RTC
can be clocked by a separate 32.768 kHz oscillator, or by a programmable prescale
divider based on the APB clock. Also, the RTC is powered by its own power supply pin,
VBAT, which can be connected to a battery or to the same 3.3 V supply used by the rest of
the device.
The VBAT pin supplies power only to the RTC and the Battery RAM. These two functions
require a minimum of power to operate, which can be supplied by an external battery.
The LPC2364/66/68 includes three independent oscillators. These are the Main
Oscillator, the Internal RC oscillator, and the RTC oscillator. Each oscillator can be used
for more than one purpose as required in a particular application. Any of the three clock
sources can be chosen by software to drive the PLL and ultimately the CPU.
Following reset, the LPC2364/66/68 will operate from the Internal RC oscillator until
switched by software. This allows systems to operate without any external crystal and the
bootloader code to operate at a known frequency.
•
•
•
•
•
•
•
•
•
•
Selectable time period from (T
multiples of T
The Watchdog Clock (WDCLK) source can be selected from the RTC clock, the
Internal RC oscillator (IRC), or the APB peripheral clock. This gives a wide range of
potential timing choices of Watchdog operation under different power reduction
conditions. It also provides the ability to run the WDT from an entirely internal source
that is not dependent on an external crystal and its associated components and
wiring, for increased reliability.
Measures the passage of time to maintain a calendar and clock.
Ultra low power design to support battery powered systems.
Provides Seconds, Minutes, Hours, Day of Month, Month, Year, Day of Week, and Day
of Year.
Dedicated 32 kHz oscillator or programmable prescaler from APB clock.
Dedicated power supply pin can be connected to a battery or to the main 3.3 V.
Periodic interrupts can be generated from increments of any field of the time registers,
and selected fractional second values.
2 kB data SRAM powered by VBAT.
RTC and Battery RAM power supply is isolated from the rest of the chip.
cy(WDCLK)
Rev. 03 — 20 December 2007
4.
cy(WDCLK)
256
4) to (T
LPC2364/66/68
cy(WDCLK)
Fast communication chip
© NXP B.V. 2007. All rights reserved.
2
32
4) in
28 of 50