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

5.1.5 VCC1

The VCC1 output pin has both an UV monitor and a UV pre-warning that is used to watch the voltage on the output of VCC1. There are four different choices of UV thresholds for both devices where VCC1 = 3.3V and VCC1 = 5V; however, there only exists one pre-warning threshold within the device.

Since VCC1 is used for many internal functions of the SBC as well as the fact that most VCC1 outputs are used to power up the companion controller to SBC, UV events on the VCC1 rail have a much more complex reaction to UV events. The device first detects the VCC1 voltage dropping below the prewarning threshold and if this condition is held until for a long enough period to be detected by the UV filter timer this can set the prewarning interrupt and if UV event is gone this can remain in the same state. If the voltage continues to drop to where a UVCC1 event is triggered the device can then transition to Restart Mode with the SBC indicating the mode by pulling nRST low and the restart counter, if enabled can be incremented. If the restart counter hasn’t been exceeded the device can start the restart timer and if the UVCC1 condition clears, VCC1 > UVCC1R for tRSTN_act, before the end of the restart timer the device can transition back into standby mode. If the restart timer times out before the UVCC1 condition clears the device can enter fail-safe mode, if enabled, or sleep otherwise. As previously mentioned, the UVCC1 threshold has four configurable options for each device in the TCAN28XX family of devices.

UVCC1 State Diagram Figure 5-3 UVCC1 State Diagram