UJA1161 All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet Rev. 2 — 17 April 2014 6 of 27
NXP Semiconductors
UJA1161
Self-supplied high-speed CAN transceiver with Standby mode
6.1.1.2 Standby mode
Standby mode is the UJA1161’s power saving mode, offering reduced current
consumption. The transceiver is unable to transmit or receive data in Standby mode.
The receiver monitors bus activity for a wake-up request in Standby mode. The bus pins
are biased at GND level (via R
i(cm)
) when the bus is inactive for t > t
to(silence)
and at
approximately 2.5 V when there is activity on the bus (autonomous biasing). CAN
wake-up occurs via a standard wake-up pattern (see Section 6.3.2
). Pin RXD is forced
LOW when a bus wake-up event is detected.
The UJA1161 switches to Standby mode:
• from Normal mode if pin STBN goes LOW
• from Normal mode if an undervoltage is detected on VIO
6.1.1.3 Off mode
The UJA1161 switches to Off mode from any mode when V
BAT
< V
th(det)poff
. Only power-on
detection is enabled; all other modules are inactive. The UJA1161 starts to boot up when
the battery voltage rises above the power-on detection threshold V
th(det)pon
(triggering an
initialization process) and switches to Standby mode after t
startup
. Pin RXD is driven LOW
when the UJA1161 switches from Off mode to Standby mode, to indicate a power-on
event has occurred.
In Off mode, the CAN pins disengage from the bus (zero load; high-ohmic).
6.1.1.4 Overtemp mode
Overtemp mode is provided to prevent the UJA1161 being damaged by excessive
temperatures. The UJA1161 switches immediately to Overtemp mode from Normal or
Standby mode when the global chip temperature rises above the overtemperature
protection activation threshold, T
th(act)otp
.
In Overtemp mode, the CAN transmitter and receiver are disabled and the CAN pins are
in a high-ohmic state. No wake-up event will be detected, but a pending wake-up will still
be signalled by a LOW level on pin RXD, which will persist after the overtemperature
event has been cleared. V
BUF
is off in Overtemp mode.
The UJA1161 exits Overtemp mode:
• and switches to Standby mode if the chip temperature falls below the overtemperature
protection release threshold, T
th(rel)otp
• if the device is forced to switch to Off mode (V
BAT
< V
th(det)poff
)
6.1.1.5 Hardware characterization for the UJA1161 operating modes
Table 3. Hardware characterization by functional block
Block Operating mode
Off Standby Normal Overtemp
V
BUF
off on/off
[1]
on off
CAN off Offline Active off
RXD V
IO
level V
IO
level/LOW if wake-up
detected
CAN bit stream V
IO
level/LOW if wake-up
detected
