SLLA651 April   2025 TCAN2845-Q1 , TCAN2847-Q1 , TCAN2855-Q1 , TCAN2857-Q1

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1Introduction
  5. 2Device States
    1. 2.1 Init Mode
    2. 2.2 Restart Mode
    3. 2.3 Standby Mode
    4. 2.4 Normal Mode
    5. 2.5 Sleep Mode
    6. 2.6 Fail-Safe Mode
  6. 3Power Electronics
    1. 3.1 VSUP
    2. 3.2 VHSS
    3. 3.3 VCAN
    4. 3.4 VCC1
    5. 3.5 VCC2
    6. 3.6 VEXMON, VEXCTRL, and VEXCC
    7. 3.7 HSSx
  7. 4Communication Capabilities
    1. 4.1 CAN-FD and Classical CAN
    2. 4.2 CAN-SIC
    3. 4.3 LIN
  8. 5Protection Features
    1. 5.1 Undervoltage (UV) Monitors
      1. 5.1.1 VSUP
      2. 5.1.2 VHSS
      3. 5.1.3 VCAN
      4. 5.1.4 VEXCC
      5. 5.1.5 VCC1
      6. 5.1.6 VCC2
    2. 5.2 Overvoltage (OV) Monitors
      1. 5.2.1 HSSx
      2. 5.2.2 VCC1
      3. 5.2.3 VCC2
      4. 5.2.4 VEXCC
    3. 5.3 Short Circuit (SC) Monitors
      1. 5.3.1 VCC1
      2. 5.3.2 VCC2
      3. 5.3.3 VEXCC
    4. 5.4 Electrical Faults and Impact on SBC Mode
    5. 5.5 Temperature Sensors
    6. 5.6 Watchdog
      1. 5.6.1 Watchdog Error Counter
      2. 5.6.2 Timeout
      3. 5.6.3 Window
      4. 5.6.4 Initial Long Window
      5. 5.6.5 Q&A
    7. 5.7 Communication Fault Monitoring
      1. 5.7.1 CAN
      2. 5.7.2 LIN
    8. 5.8 LIMP
  9. 6Programming, Memory, and Control
    1. 6.1 SPI
    2. 6.2 EEPROM
    3. 6.3 Interrupts
    4. 6.4 Control
  10. 7Miscellaneous Features
    1. 7.1 Local Wake Ups
    2. 7.2 CAN Bus Wake Up (BWRR)
    3. 7.3 Partial Networking
    4. 7.4 GFO, nRST, and SW
  11. 8Summary
  12. 9References

2.5 Sleep Mode

Sleep mode is another common operational mode and is the power saving mode of the device. In sleep mode the transceivers can be set to wake-capable, watch dog timer can be set to timeout (default state is off), power regulation is off but can be set to be on, SPI is off unless VCC1 is set to on, and the HSS act as programmed. Before the device enters sleep, mode there must be one method of wake-up available or else the device does not transition to sleep mode and an interrupt can be set.

There are seven different ways to enter sleep mode across two general categories: SPI command and fault condition. The only standard, without fault, way to enter sleep mode is through a SPI command that can transition device from standby, normal, or fail-safe mode (if enabled). The other six ways to enter sleep mode are various fault conditions. If VCC1 is off during sleep mode (default) a SWE timer timeout can transition to the device to sleep mode. Another way for the device to enter sleep is if the restart timer timeouts during restart mode which can cause the SBC to enter sleep mode. The other four entrances can only happen if fail-safe mode is disabled – these are thermal shutdown on VCC1, overvoltage on VCC1 (OVCC1), short circuit on VCC1 (VCC1_SC), or a restart counter overflow – if fail-safe mode is enabled these faults can cause a transition to fail-safe instead.

There are four generalized ways to exit sleep mode depending on device configuration. The only universal way to exit sleep mode regardless of configuration is a device wake event which can cause the device to transition to restart mode. If VCC1 is on during sleep mode there are 3 other exits possible. The first of these is a SPI command to transition the device out of sleep mode to either standby or normal mode. A UVCC1 can cause the device to transition to restart mode. If watchdog is enabled during sleep mode a watchdog error counter overflow can cause a device transition to restart mode.

Sleep Mode Figure 2-6 Sleep Mode