SFFSB11 December 2025 TCAN843-Q1
4 Pin Failure Mode Analysis (Pin FMA)
This section provides a failure mode analysis (FMA) for the pins of the TCAN843-Q1. The failure modes covered in this document include the typical pin-by-pin failure scenarios:
- Pin short-circuited to ground (see Table 4-2)
- Pin open-circuited (see Table 4-3)
- Pin short-circuited to an adjacent pin (see Table 4-4)
- Pin short-circuited to VCC (see Table 4-5)
- Pin short-circuited to VSUP (see Table 4-6)
- Pin short-circuited to VIO (Table 4-7)
Table 4-2 through Table 4-7 also indicate how these pin conditions can affect the device as per the failure effects classification in Table 4-1.
Table 4-1 TI Classification of Failure Effects
| Class | Failure Effects |
|---|---|
| A | Potential device damage that affects functionality. |
| B | No device damage, but loss of functionality. |
| C | No device damage, but performance degradation. |
| D | No device damage, no impact to functionality or performance. |
Figure 4-1 shows the D (SOIC, 14) pin diagram. Figure 4-2 shows the DMT (VSON, 14) pin diagram. Figure 4-3 shows the DYY (SOT, 14) pin diagram.
For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the TCAN843-Q1 datasheet.
Figure 4-1 D (SOIC, 14) Pin Diagram
Figure 4-2 DMT (VSON,
14) Pin DiagramFigure 4-3 DYY (SOT, 14) Pin DiagramFollowing are the assumptions of use and the device configuration assumed for the pin FMA in this section:
- VCC = 4.5V to 5.5V
- VSUP = 4.5V to 28V
- VIO = 2.9V to 5.5V
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| TXD | 1 | The TXD pin becomes biased dominant indefinitely. The device enters dominant time-out mode and is unable to transmit data. | B |
| GND | 2 | None. | D |
| VCC | 3 | The CAN transmitter is not powered and the device enters sleep mode. There is a high current draw from the external regulator supplying to the VCC pin. | B |
| RXD | 4 | The RXD output is biased recessive indefinitely. The host is unable to receive data from the bus. | B |
| VIO | 5 | The device enters sleep mode. The transceiver is passive on the bus. There is a high current draw from the external regulator that supplies to VIO. | B |
| EN | 6 | The EN pin becomes biased low. The device is not able to enter normal mode and is unable to communicate. | B |
| INH | 7 | High ISUP current can occur. The INH pin can be damaged and indication from sleep mode transition is not available. | A |
| nFAULT | 8 | The nFAULT pin is biased low indefinitely, which indicates a fault indefinitely to the MCU. | B |
| WAKE | 9 | The WAKE pin is biased low indefinitely, and the device is not able to utilize the local wake-up function. | B |
| VSUP | 10 | The device becomes unpowered. There is high current flowing from the source supplying to the VSUP pin (battery) to ground. | B |
| NC | 11 | None. | D |
| CANL | 12 | The VO(REC) specification is violated, and EMC performance potentially degrades. | C |
| CANH | 13 | The device cannot drive the dominant bit to the bus, so communication is not possible. | B |
| nSTB | 14 | The nSTB pin becomes biased low indefinitely. The transceiver is unable to enter normal mode and is unable to communicate. | B |
| Thermal Pad | - | None. | D |
Note: The VSON package includes a thermal pad.
Table 4-3 Pin FMA for Device Pins Open-Circuited
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| TXD | 1 | The TXD pin defaults to a recessive bias. The driver is always recessive and the system is unable to transmit data. | B |
| GND | 2 | The device becomes unpowered. | B |
| VCC | 3 | The CAN transmitter is not powered and the device enters sleep mode. There is a high current draw from the external regulator supplying to the VCC pin. | B |
| RXD | 4 | The MCU is unable to receive data from the transceiver. | B |
| VIO | 5 | The device enters protected mode. | B |
| EN | 6 | The EN pin defaults to a logic-low bias. The device is not able to enter normal mode and is unable to communicate. | B |
| INH | 7 | The system power control is potentially affected. | C |
| nFAULT | 8 | The MCU becomes unable to monitor faults in the system. | B |
| WAKE | 9 | The local wake-up function is not able to be used. | B |
| VSUP | 10 | The device becomes unpowered. | B |
| NC | 11 | None. | D |
| CANL | 12 | The device cannot drive dominant on the bus and is unable to communicate. | B |
| CANH | 13 | The device cannot drive dominant on the bus and is unable to communicate. | B |
| nSTB | 14 | The nSTB defaults to a logic-low bias. The device is not able to enter normal mode and is unable to communicate. | B |
| Thermal Pad | - | None. | D |
Note: The VSON package includes a thermal pad.
Table 4-4 Pin FMA for Device Pins Short-Circuited to Adjacent Pin
| Pin Name | Pin No. | Shorted to | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|---|
| TXD | 1 | GND | The TXD pin is biased dominant indefinitely. The device enters dominant time-out mode and is unable to transmit data. | B |
| GND | 2 | VCC | The CAN transmitter is not powered and the device enters sleep mode. There is a high current draw from the external regulator supplying to the VCC pin. | B |
| VCC | 3 | RXD | The RXD output becomes biased recessive indefinitely. The controller is unable to receive data from CAN bus. | B |
| RXD | 4 | VIO | The RXD output becomes biased recessive indefinitely. The controller is unable to receive data from CAN bus. | B |
| VIO | 5 | EN | The EN pin becomes biased high indefinitely. The device is unable to enter standby and silent mode. | B |
| EN | 6 | INH | There is an absolute maximum violation on the EN pin, except in sleep mode. The transceiver can be damaged. | A |
| nFAULT | 8 | WAKE | There is a potential absolute maximum violation on the nFAULT pin if WAKE is biased high. The transceiver can be damaged. | A |
| WAKE | 9 | VSUP | The WAKE pin becomes biased high indefinitely. The local wake-up function is not able to be used. | B |
| VSUP | 10 | NC | None. | D |
| NC | 11 | CANL | None. | D |
| CANL | 12 | CANH | The CAN bus becomes stuck recessive. Communication is not possible. IOS current can be reached on the CANH or CANL pins. | B |
| CANH | 13 | nSTB | The driver and receiver turn off when the CAN bus is recessive. The device potentially does not enter normal mode. | B |
Note: The VSON package
includes a thermal pad. All device pins are adjacent to the thermal pad. The behavior of the
device, when pins are shorted to the thermal pad, depends on the net that is connected to
the thermal pad.
Table 4-5 Pin FMA for Device Pins Short-Circuited to VCC
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| TXD | 1 | The TXD pin becomes biased recessive indefinitely. The device is unable to transmit data. | B |
| GND | 2 | The CAN transmitter is not powered and the device enters sleep mode. There is a high current draw from the external regulator supplying to the VCC pin. | B |
| VCC | 3 | None. | D |
| RXD | 4 | The RXD output becomes biased recessive indefinitely. The controller is unable to receive data from CAN bus. | B |
| VIO | 5 | The I/O pins operate as 5V inputs and outputs. The microcontroller can be damaged if VCC > VIO. | C |
| EN | 6 | The EN pin becomes biased high indefinitely. The device is unable to enter standby and silent mode. | B |
| INH | 7 | The INH pin is biased at VCC voltage. The system potentially does not wake up. High current draw from the INH pin is possible. | B |
| nFAULT | 8 | The nFAULT pin becomes biased high indefinitely. The transceiver is unable to report faults. | B |
| WAKE | 9 | The local wake-up function is not able to be used. | B |
| VSUP | 10 | The power rails of the system are short-circuited. Damage to the transceiver potentially occurs depending on the stronger power source if the absolute maximum rating of VCC is exceeded. | A |
| NC | 11 | None. | D |
| CANL | 12 | IOS current can be reached. The CAN bus can potentially become stuck recessive, and the device is unable to drive a dominant signal onto the bus. | B |
| CANH | 13 | The VO(REC) specification is violated, and EMC performance potentially degrades. | C |
| nSTB | 14 | The nSTB pin becomes biased high indefinitely. The transceiver is unable to enter standby and sleep mode. | B |
Table 4-6 Pin FMA for Device Pins Short-Circuited to VSUP
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| TXD | 1 | An absolute maximum violation occurs and the transceiver can be damaged. | A |
| GND | 2 | The device becomes unpowered, and high ISUP current potentially occurs. | B |
| VCC | 3 | An absolute maximum violation occurs and the transceiver can be damaged. | A |
| RXD | 4 | An absolute maximum violation occurs and the transceiver can be damaged. | A |
| VIO | 5 | An absolute maximum violation occurs and the transceiver can be damaged. | A |
| EN | 6 | An absolute maximum violation occurs and the transceiver can be damaged. | A |
| INH | 7 | The INH pin becomes stuck at the VSUP level. The external regulator potentially does not enter low-power mode once the transceiver transitions to sleep mode. | D |
| nFAULT | 8 | An absolute maximum violation occurs and the transceiver can be damaged. | A |
| WAKE | 9 | The WAKE pin becomes biased high. The local wake-up function is not able to be used. | B |
| VSUP | 10 | None. | D |
| NC | 11 | None. | D |
| CANL | 12 | IOS current can be reached. The bus becomes stuck recessive, and communication is not possible. | B |
| CANH | 13 | The VO(REC) specification is violated, and EMC performance potentially degrades. There is an increased likelihood of communication errors on the CAN bus. | C |
| nSTB | 14 | An absolute maximum violation occurs and the transceiver can be damaged. | A |
Table 4-7 Pin FMA for Device Pins Short-Circuited to VIO
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| TXD | 1 | The TXD pin becomes biased recessive indefinitely. The device is unable to transmit data. | B |
| GND | 2 | The device enters low-power mode. There is a high current draw from the external regulator supplying to the VIO pin. | B |
| VCC | 3 | If VIO < UVCC, an undervoltage condition potentially occurs on VCC. | C |
| RXD | 4 | The RXD output becomes biased recessive indefinitely. The controller is unable to receive data from CAN bus. | B |
| VIO | 5 | None. | D |
| EN | 6 | The EN pin becomes biased high indefinitely. The device is unable to enter standby and silent mode. | B |
| INH | 7 | The INH pin is biased at VIO voltage. The system potentially does not wake up. High current draw from the INH pin is possible. | A |
| nFAULT | 8 | The nFAULT pin becomes biased high indefinitely. The transceiver is unable to report faults. | B |
| WAKE | 9 | The local wake-up function is not able to be used. | B |
| VSUP | 10 | The power rails of the system are short-circuited. Damage to the transceiver potentially occurs, depending on the stronger power source, if the absolute maximum rating of VIO is exceeded. | A |
| NC | 11 | None. | D |
| CANL | 12 | IOS current can be reached. The CAN bus potentially becomes stuck recessive, and the device is unable to drive a dominant signal onto the bus. | B |
| CANH | 13 | The VO(REC) specification is violated, and EMC performance potentially degrades. | C |
| nSTB | 14 | The nSTB pin becomes biased high indefinitely. The transceiver is unable to enter standby and sleep mode. | B |