LPC802 datasheet(23/83 Pages) NXP

23 / 83 page

LPC802

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Product data sheet

Rev. 1.6 — 27 April 2018

23 of 83

NXP Semiconductors

LPC802

32-bit ARM Cortex-M0+ microcontroller

• Optional warning interrupt can be generated at a programmable time prior to

watchdog time-out.

• Enabled by software but requires a hardware reset or a watchdog reset/interrupt to be

disabled.

• Incorrect feed sequence causes reset or interrupt if enabled.

• Flag to indicate watchdog reset.

• Programmable 24-bit timer with internal prescaler.

• Selectable time period from (Tcy(WDCLK)  256  4) to (Tcy(WDCLK)  224  4) in

multiples of Tcy(WDCLK)  4.

• The WatchDog Clock (WDCLK) is generated by the dedicated watchdog oscillator

(WDOSC).

9.18 Self-Wake-up Timer (WKT)

The self-wake-up timer is a 32-bit, loadable down counter. Writing any non-zero value to

this timer automatically enables the counter and launches a count-down sequence. When

the counter is used as a wake-up timer, this write can occur prior to entering a reduced

power mode.

9.18.1 Features

• 32-bit loadable down counter. Counter starts automatically when a count value is

loaded. Time-out generates an interrupt/wake up request.

• The WKT supports three clock sources: an external clock on the WKTCLKIN pin, the

low-power oscillator, and the FRO. The low-power oscillator can be used as the clock

source in sleep, deep-sleep, and power-down modes.

• The WKT can be used for waking up the part from any reduced power mode or for

general-purpose timing.

9.19 Analog comparator (ACMP)

The analog comparator with selectable hysteresis can compare voltage levels on external

pins and internal voltages.

After power-up and after switching the input channels of the comparator, the output of the

voltage ladder must be allowed to settle to its stable value before it can be used as a

comparator reference input. Settling times are given in Table 27.

The analog comparator output is a movable function and is assigned to a pin through the

switch matrix. The comparator inputs and the voltage reference are enabled through the

switch matrix.

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