Datasheet

Product data sheet Rev. 3.1 — 1 September 2014 71 of 138

NXP Semiconductors

LPC408x/7x

32-bit ARM Cortex-M4 microcontroller

• RTC power supply is isolated from the rest of the chip.

7.35 Event monitor/recorder

The event monitor/recorder allows recording of tampering events in sealed product

enclosures. Sensors report any attempt to open the enclosure, or to tamper with the

device in any other way. The event monitor/recorder stores records of such events when

the device is powered only by the backup battery.

7.35.1 Features

• Supports three digital event inputs in the VBAT power domain.

• An event is defined as a level change at the digital event inputs.

• For each event channel, two timestamps mark the first and the last occurrence of an

event. Each channel also has a dedicated counter tracking the total number of events.

Timestamp values are taken from the RTC.

• Runs in VBAT power domain, independent of system power supply. The

event/recorder/monitor can therefore operate in Deep power-down mode.

• Very low power consumption.

• Interrupt available if system is running.

• A qualified event can be used as a wake-up trigger.

• State of event interrupts accessible by software through GPIO.

7.36 Clocking and power control

7.36.1 Crystal oscillators

The LPC408x/7x include four independent oscillators. These are the main oscillator, the

IRC oscillator, the watchdog oscillator, and the RTC oscillator.

Following reset, the LPC408x/7x will operate from the Internal RC oscillator until switched

by software. This allows systems to operate without any external crystal and the boot

loader code to operate at a known frequency.

See Figure 10

for an overview of the LPC408x/7x clock generation.