UJA1076 datasheet(24/47 Pages) NXP

24 / 47 page

UJA1076_2

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Product data sheet

Rev. 02 — 27 May 2010

24 of 47

NXP Semiconductors

UJA1076

High-speed CAN core system basis chip

6.9 Interrupt output

Pin INTN is an active-LOW, open-drain interrupt output. It is driven LOW when at least

one interrupt is pending. An interrupt can be cleared by writing 1 to the corresponding bit

in the Int_Status register (Table 7). Clearing bit CWI in Standby mode only clears the

interrupt status bit and not the pending wake-up. The pending wake-up is cleared on

entering Normal mode and when the corresponding standby control bit (STBCC) is 0.

On devices that contain a watchdog, the Cyclic Interrupt (CI) is enabled when the

watchdog switches to Timeout mode while the SBC is in Standby mode or Normal mode

(provided WDOFF = LOW). A CI is generated if the watchdog overflows in Timeout mode.

The CI is provided to alert the microcontroller when the watchdog overflows in Timeout

mode. The CI will wake up the microcontroller from a

μC standby mode. After polling the

Int_Status register, the microcontroller will be aware that the application is in cyclic wake

up mode. It can then perform some checks on CAN before returning to the

μC standby

mode.

6.10 Temperature protection

The temperature of the SBC chip is monitored in Normal and Standby modes. If the

temperature is too high, the SBC will go to Overtemp mode, where the RSTN pin is driven

LOW and limp home is activated. In addition, the voltage regulators and the CAN

transmitter are switched off (see also Section 6.1.6 “Overtemp mode”). When the

temperature falls below the temperature shutdown threshold, the SBC will go to Standby

mode. The temperature shutdown threshold is between 165

°C and 200 °C.

UJA1076 Datasheet(PDF) 24 Page - NXP Semiconductors