The TCAN1043A-Q1 has six
operating modes: normal, standby, silent, go-to-sleep, sleep, and off mode.
Operating mode selection is controlled using the nSTB pin and EN pin in conjunction
with supply conditions, temperature conditions, and wake events.
Figure 8-4 TCAN1043A-Q1 State
Machine
The enable pin can be in a
logical high or low state while in sleep mode but since it has an internal
pull-down, the lowest possible power consumption occurs when the pin is left
either floating or pulled low externally.
At power-up, the undervoltage
timers for VCC and VIO are disabled, allowing for longer
period for VCC and VIO supplies to power up (up to
tINACTIVE). VCC or VIO need to be above
UVCC(R) and UVIO(R) respectively to enable their
respective tUV timers. The VCC undervoltage timer starts
when VCC falls below UVCC(F), while VIO
undervoltage timer starts when VIO falls below UVIO(F).
When either of these timers exceed tUV, the device enters sleep mode.
The Sleep Wake Error (SWE) timer
starts as soon as the device enters Standby mode. The timer halts and resets as
soon as the device enters Normal mode. If the device enters Silent mode from
Standby mode, the SWE timer does not halt and the device needs to be
transitioned to Normal mode before the SWE timer expires. If the device enters
Silent mode from Normal mode, the SWE timer will not be active in Silent
mode.
When the Sleep mode is entered
from Go-To-Sleep Mode or from a UVCC or UVIO event, a
low-to-high transition on nSTB is required to move the device into Normal or
Silent mode. If EN is high during the rising edge on nSTB, the device moves to
Normal mode. If EN is low during the rising edge on nSTB, the device moves to
Silent mode. VIO must be above UVIO(R) in order to leave
Sleep mode using the EN and nSTB signals.
When Sleep mode is entered due to
an SWE timer timeout (>tINACTIVE), there is an extra requirement
to exit Sleep mode and transition into Normal or Silent mode directly using the
EN and nSTB signals. To move to Normal mode, the nSTB pin must be high and a
low-to-high transition must occur on EN. To move to Silent mode, the nSTB pin
must be high and a high-to-low transition must occur on EN. If the device
entered Sleep mode while the nSTB was already high, there must be a transition
on the EN pin while nSTB is low prior to the sequence described above. See Figure 8-5 for more
information. VIO must be above UVIO(R) to leave Sleep mode
by using the EN and nSTB signals.
nSTB must remain low for a
minimum of tMODE1 after the edge on EN. Once this
tMODE1 has elapsed, nSTB may be driven high. The following
edge on EN will cause the device to exit Sleep mode. The final edge on EN
does not have any minimum delay from the rising edge of nSTB. The enable pin
can be in a logical high or low state while in sleep mode, but since it has
an internal pull-down, the lowest possible power consumption occurs when the
pin is left either floating or pulled low externally.
Figure 8-5 TCAN1043A-Q1
Transitioning from Sleep Mode to Normal or Silent Mode if Sleep Mode is Entered
Due to SWE Timer Timeout