OM11043 NXP Semiconductors, OM11043 Datasheet - Page 33

• Manufacturer Part Number: OM11043
• Description: DEVELOPMENT BOARD LPC1768 MBED
• Manufacturer: NXP Semiconductors
• Series: mbedr
• Type: MCUr

Specifications of OM11043

• Contents: Board and software
• Development Tool Type: Hardware / Software - Eval/Demo Board
• Kit Contents: Board Cable Docs
• Mcu Supported Families: LPC1000
• Tool / Board Applications: General Purpose MCU, MPU, DSP, DSC
• Silicon Manufacturer: NXP
• Core Architecture: ARM
• Core Sub-architecture: Cortex - M3
• Silicon Core Number: LPC17xx
• Silicon Family Name: LPC17xx
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: LPC1768
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 568-4916

NXP Semiconductors
LPC1769_68_67_66_65_64_63
Product data sheet
7.28.1 Features
7.29.1 Crystal oscillators
7.28 RTC and backup registers
7.29 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. The RTC on the LPC17xx is designed to have extremely low power
consumption, i.e. less than 1 μA. The RTC will typically run from the main chip power
supply, conserving battery power while the rest of the device is powered up. When
operating from a battery, the RTC will continue working down to 2.1 V. Battery power can
be provided from a standard 3 V Lithium button cell.
An ultra-low power 32 kHz oscillator will provide a 1 Hz clock to the time counting portion
of the RTC, moving most of the power consumption out of the time counting function.
The RTC includes a calibration mechanism to allow fine-tuning the count rate in a way
that will provide less than 1 second per day error when operated at a constant voltage and
temperature. A clock output function (see
rate easy and accurate.
The RTC contains a small set of backup registers (20 bytes) for holding data while the
main part of the LPC17xx is powered off.
The RTC includes an alarm function that can wake up the LPC17xx from all reduced
power modes with a time resolution of 1 s.
The LPC17xx include three independent oscillators. These are the main oscillator, the IRC
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 main PLL and ultimately the CPU.
Following reset, the LPC17xx 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.
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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.
Includes lock/safe feature.
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 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.
Backup registers (20 bytes) powered by VBAT.
RTC power supply is isolated from the rest of the chip.
All information provided in this document is subject to legal disclaimers.
Rev. 6.01 — 11 March 2011
LPC1769/68/67/66/65/64/63
Section
32-bit ARM Cortex-M3 microcontroller
7.29.4) makes measuring the oscillator
© NXP B.V. 2011. All rights reserved.
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