Product data

UJA1167 All information provided in this document is subject to legal disclaimers. © NXP Semiconductors N.V. 2014. All rights reserved.
Product data sheet Rev. 2 — 18 April 2014 6 of 60
NXP Semiconductors
UJA1167
Mini high-speed CAN system basis chip with Standby/Sleep modes &
watchdog
6. Functional description
6.1 System controller
The system controller manages register configuration and controls the internal functions
of the UJA1167. Detailed device status information is collected and made available to the
microcontroller.
6.1.1 Operating modes
The system controller contains a state machine that supports seven operating modes:
Normal, Standby, Sleep, Reset, Forced Normal, Overtemp and Off. The state transitions
are illustrated in Figure 3
.
6.1.1.1 Normal mode
Normal mode is the active operating mode. In this mode, all the hardware on the device is
available and can be activated (see Table 3
). Voltage regulator V1 is enabled to supply the
microcontroller.
The CAN interface can be configured to be active and thus to support normal CAN
communication. Depending on the SPI register settings, the watchdog may be running in
Window or Timeout mode and the INH/VEXT output may be active.
Normal mode can be selected from Standby mode via an SPI command (MC = 111).
6.1.1.2 Standby mode
Standby mode is the first-level power-saving mode of the UJA1167, offering reduced
current consumption. The transceiver is unable to transmit or receive data in Standby
mode. The SPI remains enabled and V1 is still active; the watchdog is active (in Timeout
mode) if enabled. The behavior of INH/VEXT is determined by the SPI setting.
If remote CAN wake-up is enabled (CWE = 1; see Table 26
), the receiver monitors bus
activity for a wake-up request. The bus pins are biased to GND (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).
Pin RXD is forced LOW when any enabled wake-up event is detected. This can be either
a regular wake-up (via the CAN bus or pin WAKE) or a diagnostic wake-up such as an
overtemperature event (see Section 6.10
).
The UJA1167 switches to Standby mode via Reset mode:
• from Off mode if the battery voltage rises above the power-on detection threshold
(V
th(det)pon
)
• from Overtemp mode if the chip temperature falls below the overtemperature
protection release threshold, T
th(rel)otp
• from Sleep mode on the occurrence of a regular or diagnostic wake-up event
Standby mode can also be selected from Normal mode via an SPI command (MC = 100).