AMIS-4168X Datasheet, PDF (8/20 Pages) AMI SEMICONDUCTOR – Fault Tolerant CAN Transceiver

AMIS-4168x
7.3 Low Power Modes
The transceiver provides three low power modes, which can be entered and exited via pins STBB and EN (see Figure 6: Low Power
Modes). (Go-to-sleep mode is only a transition mode.)
The sleep mode is the mode with the lowest power consumption. Pin INH is switched to high-impedance for deactivation of the external
voltage regulator. Pin CANL is biased to the battery voltage via Pin RTL. If the supply voltage is provided, Pins RXD and ERRB will
signal the wake-up interrupt signal.
The standby mode will react the same as the sleep mode but with a high-level on pin INH.
The power-on standby mode is the same as the standby mode with the battery power-on flag instead of the wake-up interrupt signal on
Pin ERRB. The output on Pin RXD will show the wake-up interrupt. This mode is only for reading out the power-on flag.
Wake-up request is detected by the following events:
• Local wake-up: Rising or falling edge on input WAKEB (levels maintained for a certain period).
• Remote wake-up from CAN bus: A message with five consecutive dominant bits.
On a wake-up request the transceiver will set the output on Pin INH high which can be used to activate the external supply voltage
regulator. Note: Pin INH is also set similarly as an after wake up event by V_BAT voltage being below the battery power on flag level.
(See FLAG_V_BAT in Figure 6: Low Power Modes)
If VCC is provided, the wake-up request can be read on the ERR-B or RXD outputs so the external microcontroller can wake-up the
transceiver (switch to normal operating mode) via Pins STB-B and EN.
In the low power modes the failure detection circuit remains partly active to prevent increased power consumption in the event of
failures 3, 3a, 4, and 7.
The go-to-sleep-mode is only a transition mode. The Pin INH stays active for a limited time. During this time the circuit can still go to
another low-power mode. After this time the circuit goes to the sleep-mode. In case of a wake up request (from BUS or WAKEB pin)
during this transition time, the wake up request ha higher priority than go-to-sleep and INH will not be deactivated.
Once VCC is below the threshold level of LAG_Vcc , the signals on Pins STB-B and EN will internally be set to low-level to provide fail
safe functionality.
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