UJA1069TW24/5V0/C, NXP Semiconductors, UJA1069TW24/5V0/C, Datasheet - Page 10

• Manufacturer Part Number: UJA1069TW24/5V0/C,
• Description: IC LIN FAIL-SAFE 24HTSSOP
• Manufacturer: NXP Semiconductors

Specifications of UJA1069TW24/5V0/C,

• Applications: *
• Interface: *
• Voltage - Supply: *
• Package / Case: 24-TSSOP Exposed Pad, 24-eTSSOP, 24-HTSSOP
• Mounting Type: Surface Mount
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 935285413512

NXP Semiconductors
UJA1069_4
Product data sheet
6.2.5 Standby mode
Interrupts from SBC to the host microcontroller are also monitored. A system reset is
performed if the host microcontroller does not respond within t
mode does not activate the LIN transceiver automatically. The LIN Mode Control (LMC) bit
must be used to activate the LIN medium if required, allowing local cyclic wake-up
scenarios to be implemented without affecting the LIN-bus.
In Standby mode the system is set into a state with reduced current consumption. The
watchdog will, however, continue to monitor the microcontroller (Time-out mode) since it is
powered via pin V1.
In the event that the host microcontroller can provide a low-power mode with reduced
current consumption in its Standby mode or Stop mode, the watchdog can be switched off
entirely in Standby mode of the SBC. The SBC monitors the microcontroller supply current
to ensure that there is no unobserved phase with disabled watchdog and running
microcontroller. The watchdog will remain active until the supply current drops below
I
Should the current increase to I
application specific hardware, the watchdog will start operating again with the previously
used time-out period. If the watchdog is not triggered correctly, a system reset will occur
and the SBC will enter Start-up mode.
If Standby mode is entered from Normal mode with the selected watchdog OFF option,
the watchdog will use the maximum time-out as defined for Standby mode until the supply
current drops below the current detection threshold; the watchdog is now OFF. If the
current increases again, the watchdog is immediately activated, again using the maximum
watchdog time-out period. If the watchdog OFF option is selected during Standby mode,
the last used watchdog period will define the time for the supply current to fall below the
current detection threshold. This allows the user to align the current supervisor function to
the application needs.
Generally, the microcontroller can be activated from Standby mode via a system reset or
via an interrupt without reset. This allows implementation of differentiated start-up
behavior from Standby mode, depending on the application needs:
When an interrupt event occurs the application software has to read the Interrupt register
within t
entered. If the application has read out the Interrupt register within the specified time, it
can decide whether to switch into Normal mode via an SPI access or to stay in Standby
mode.
thL(V1)
•
•
If the watchdog is still running during Standby mode, the watchdog can be used for
cyclic wake-up behavior of the system. A dedicated Watchdog Time-out Interrupt
Enable (WTIE) bit enables the microcontroller to decide whether to receive an
interrupt or a hardware reset upon overflow. The interrupt option will be cleared in
hardware automatically with each watchdog overflow to ensure that a failing main
routine is detected while the interrupt service still operates. So the application
software must set the interrupt behavior each time before a standby cycle is entered.
Any wake-up via the LIN-bus together with a local wake-up event will force a system
reset event or an interrupt to the microcontroller. So it is possible to exit Standby mode
without any system reset if required.
. Below this current limit the watchdog is disabled.
RSTN(INT)
. Otherwise a fail-safe system reset is forced and Start-up mode will be
Rev. 04 — 28 October 2009
thH(V1)
, e.g. as result of a microcontroller wake-up from
LIN fail-safe system basis chip
RSTN(INT)
UJA1069
. Entering Normal
© NXP B.V. 2009. All rights reserved.
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