SFFS180 December   2021 SN65HVD1781A-Q1

 

  1.   Trademarks
  2. 1Overview
  3. 2Functional Safety Failure In Time (FIT) Rates
  4. 3Failure Mode Distribution (FMD)
  5. 4Pin Failure Mode Analysis (Pin FMA)

Pin Failure Mode Analysis (Pin FMA)

This section provides a Failure Mode Analysis (FMA) for the pins of the SN65HVD1781A-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 supply (see Table 4-5)

Table 4-2 through Table 4-5 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
ClassFailure Effects
APotential device damage that affects functionality
BNo device damage, but loss of functionality
CNo device damage, but performance degradation
DNo device damage, no impact to functionality or performance

Figure 4-1 shows the SN65HVD1781A-Q1 pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the SN65HVD1781A-Q1 datasheet.

Figure 4-1 Pin Diagram
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
Pin NamePin No.Description of Potential Failure Effect(s)Failure Effect Class
R1Host unable to receive data from bus via transceiver. Increased output current and ICC when the output state is high.B
RE2Receiver output always enabled.D
DE3Driver output always disabled.B
D4Host unable to transmit data to bus via transceiver. Output state is low when the driver is enabled.B
GND5Intended operation.D
A6Non-inverting signal stuck low; bus unable to reach differential high level. Communication errors likely.B
B7Inverting signal stuck low; bus unable to reach differential high level. Communication errors likely.B
VCC8Device unpowered; neither transmit nor receive functionality available. Large current load on the external VCC regulator.B
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
R 1 Host unable to receive data from the bus via transceiver B
RE 2 Receiver output always disabled. B
DE 3 Driver output always disabled. B
D 4 Host unable to transmit data to the bus via transceiver. Output state is indeterminate when the driver is enabled. B
GND 5 Device unpowered; neither transmit nor receive functionality available. B
A 6 Communication errors likely; may work with degraded margin if the bus termination is not implemented. B
B 7 Communication errors likely; may work with degraded margin if the bus termination is not implemented. B
VCC 8 Device unpowered; neither transmit nor receive functionality available. B
Table 4-4 Pin FMA for Device Pins Short-Circuited to Adjacent Pin
Pin NamePin No.Shorted toDescription of Potential Failure Effect(s)Failure Effect Class
R1REUndetermined state of shared net; receive functionality unlikely to work.B
RE2DEReceiver is enabled when driver is disabled, and the driver is enabled when the receiver is disabled. Transceiver state may not be well-defined when this short results in contention between two active control lines from the host.B
DE3DDriver output can only be output-high or disabled (high-Z). State may not be well-defined due to contention between host control lines.B
GND5ANon-inverting signal stuck low; bus unable to reach differential high level. Communication errors likely.B
A6BBus unable to reach differential-high or differential-low states; communication cannot occur on bus.B
B7VCCInverting signal stuck high; bus unable to reach differential high level. Communication errors likely.B
Table 4-5 Pin FMA for Device Pins Short-Circuited to supply
Pin NamePin No.Description of Potential Failure Effect(s)Failure Effect Class
R1Host unable to receive data from bus via transceiver. Increased input current when the output state is low.B
RE2Receiver output always disabled.B
DE3Driver output always enabled.D
D4Host unable to transmit data to bus via transceiver. Output state is high when driver is enabled.B
GND5Device unpowered; neither transmit nor receive functionality available. Large current load on the external VCC regulator.B
A6Non-inverting signal stuck high; bus unable to reach differential high level. Communication errors likely.B
B7Inverting signal stuck high; bus unable to reach differential high level. Communication errors likely.B
VCC8Intended operationD