16/32-bit ARM microcontroller with external memory interface
The RTC runs at 32768 Hz using a very low power oscillator. The RTC counts seconds
and can generate alarm interrupts that can wake up the device from Stop mode. The
RTCCLK can also clock the 397x PLL, the Millisecond Timer, the ADC, the Keyboard
Scanner and the PWMs. The RTC up-counter value represents a number of seconds
elapsed since second 0, which is an application determined time. The RTC counter will
reach maximum value after about 136 years. The RTC down-counter is initiated with all
Two 32-bit Match registers are readable and writable by the processor. A match will result
in an interrupt provided that the interrupt is enabled. The ONSW output pin can also be
triggered by a match event, and cause an external power supply to turn on all of the
operating voltages, as a way to startup after power has been removed.
The RTC block is implemented in a separate voltage domain. The block is supplied via a
separate supply pin from a battery or other power source.
The RTC block also contains 32 words (128 B) of very low voltage SRAM. This SRAM is
able to hold its contents down to the minimum RTC operating voltage.
• Measures the passage of time in seconds.
• 32-bit up and down seconds counters.
• Ultra low power design to support battery powered systems.
• Dedicated 32 kHz oscillator.
• An output pin is included to assist in waking up when the chip has had power removed
to all functions except the RTC.
• Two 32-bit match registers with interrupt option.
• 32 words (128 B) of very low voltage SRAM.
• The RTC and battery RAM power have an independent power domain and dedicated
supply pins, which can be powered from a battery or power supply.
6.22 Pulse width modulators
The LPC3180 provides two PWMs. They are clocked separately by either the main
peripheral clock or the 32 kHz RTC clock. Both PWMs have a duty cycle programmable in
• Clocked by the main peripheral clock or the 32 kHz RTC clock.
• Programmable 4-bit prescaler.
• Duty cycle programmable in 255 steps.
• Output frequency up to 50 kHz when using a 13 MHz peripheral clock.
Preliminary data sheet
Rev. 02 — 15 February 2007
© NXP B.V. 2007. All rights reserved.
24 of 36