The TCAN1473A-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.
- 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) 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 7-5 for more information. VIO must be above UVIO(R) to leave Sleep mode by using the EN and nSTB signals.
Table 7-4 TCAN1473A-Q1 Mode OverviewMODE | VCC and VIO | VSUP | EN | nSTB | WAKERQ FLAG | DRIVER | RECEIVER | RXD | INH |
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Normal | > UVCC and > UVIO | > UVSUP | High | High | X | Enabled | Enabled | Mirrors bus state | On |
Silent | > UVCC and > UVIO | > UVSUP | Low | High | X | Disabled | Enabled | Mirrors bus state | On |
Standby | > UVCC and > UVIO | > UVSUP | High | Low | Set | Disabled | Low power bus monitor enabled | Low signals wake-up | On |
> UVCC and > UVIO | > UVSUP | Low | Low | X | Disabled | Low power bus monitor enabled | Low signals wake-up | On |
> UVCC and < UVIO | > UVSUP | Low | Low | X | Disabled | Low power bus monitor enabled | High impedance | On |
Go-to-sleep(1) | > UVCC and > UVIO | > UVSUP | High | Low | Cleared | Disabled | Low power bus monitor enabled | High or high impedance (no VIO) | On(2) |
Sleep(3) | > UVCC and > UVIO | > UVSUP | High | Low | Cleared | Disabled | Low power bus monitor enabled | High or high impedance (no VIO) | High Impedance |
< UVCC or <UVIO | > UVSUP | X | X | X | Disabled | Low power bus monitor enabled | High or high impedance (no VIO) | High impedance |
Protected | X | < UVSUP | X | X | X | Disabled | Disabled | High impedance | High impedance |
(1) Go-to-sleep: Transitional mode for EN = H, nSTB = L until tGOTOSLEEP timer has expired.
(2) The INH pin transitions to high impedance after the tGOTOSLEEP timer has expired.
(3) Mode change from go-to-sleep mode to sleep mode once tGOTOSLEEP timer has expired.