SFFS818 March 2024 SN74AXC2T45-Q1
4 Pin Failure Mode Analysis (Pin FMA)
This section provides a Failure Mode Analysis (FMA) for the pins of the SN74AXC2T45-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 VCCA (see Table 4-5)
- Pin short-circuited to VCCB (see Table 4-6)
Table 4-2 through Table 4-6 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 SN74AXC2T45-Q1 pin diagram. For a detailed description of the device pins please refer to the 'Pin Configuration and Functions' section in the SN74AXC2T45-Q1 data sheet.
Figure 4-1 Pin DiagramFollowing are the assumptions of use and the device configuration assumed for the pin FMA in this section:
- 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 VCCA (see Table 4-5)
- Pin short-circuited to VCCB (see Table 4-6)
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| VCCA | 1 | GND short to VCC, device will be bypassed; may cause system damage, but damage to the device does not occur | B |
| A1 | 2 | If configured as an output then damage is possible. If configured as input, no damage, but output will not switch | A |
| A2 | 3 | If configured as an output then damage is possible. If configured as input, no damage, but output will not switch | A |
| GND | 4 | Normal Operation | D |
| DIR | 5 | Direction control will fix B --> A direction | B |
| B2 | 6 | If configured as an output then damage is possible. If configured as input, no damage, but output will not switch | A |
| B1 | 7 | If configured as an output then damage is possible. If configured as input, no damage occurs, but output will not switch | A |
| VCCB | 8 | GND short to VCC, device will be bypassed; may cause system damage, but damage to the device does not occur | B |
Table 4-3 Pin FMA for Device Pins Open-Circuited
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| VCCA | 1 | Device will not be powered | B |
| A1 | 2 | If configured as output, normal operation. If configured as input, no damage, but output will not switch | B |
| A2 | 3 | If configured as output, normal operation. If configured as input, no damage, but output will not switch | B |
| GND | 4 | Device will not be powered | B |
| DIR | 5 | Direction control will fix B --> A direction | B |
| B2 | 6 | If configured as output, normal operation. If configured as input, no damage, but output will not switch | B |
| B1 | 7 | If configured as output, normal operation. If configured as input, no damage, but output will not switch | B |
| VCCB | 8 | Device will not be powered | B |
Table 4-4 Pin FMA for Device Pins
Short-Circuited to Adjacent Pin
| Pin Name | Pin No. | Shorted to | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|---|
| VCCA | 1 | A1 | If configured as an output then damage is possible. If configured as input, no damage occurs, but output will not switch | A |
| A1 | 2 | A2 | Two inputs shorted together will not cause damage unless there is external bus contention that drives the input such that VIL < Input Voltage < VIH in which case excessive supply current to GND may cause damage. Two outputs shorted together may cause damage if there is external bus contention that drives one output LOW while driving the other output HIGH. If both outputs are HIGH or both outputs are LOW, then nothing will occur; no damage. | A |
| A2 | 3 | GND | If configured as an output then damage is possible. If configured as input, no damage, but output will not switch | A |
| GND | 4 | DIR | Direction control will fix B --> A direction | B |
| DIR | 5 | B2 | If DIR is LOW, B will be an input and drive the output low. If DIR is HIGH, B will be an output and damage is possible based on state of A | A |
| B2 | 6 | B1 | Two inputs shorted together will not cause damage unless there is external bus contention that drives the input such that VIL is less than Input Voltage is less than VIH in which case excessive supply current to GND may cause damage. Two outputs shorted together may cause damage if there is external bus contention that drives one output LOW while driving the other output HIGH. If both outputs are HIGH or both outputs are LOW, then nothing will occur, no damage occurs. | A |
| B1 | 7 | VCCB | If configured as an output then damage is possible. If configured as input, no damage occurs, but output will not switch | A |
| VCCB | 8 | VCCA | VCCB short to VCCA, device will be bypassed; may cause system damage, but no damage to the device occurs | B |
Table 4-5 Pin FMA for Device Pins
Short-Circuited to VCCA
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| VCCA | 1 | Normal Operation | D |
| A1 | 2 | If configured as an output then damage is possible. If configured as input, no damage occurs, but output will not switch | A |
| A2 | 3 | If configured as an output then damage is possible. If configured as input, no damage occurs, but output will not switch | A |
| GND | 4 | GND short to VCC, device will be bypassed; may cause system damage, but no damage to the device occurs | B |
| DIR | 5 | Direction control will fix A --> B direction | B |
| B2 | 6 | If configured as an output then damage is possible. If configured as input, damage is possible if VIH/VIL is not met | A |
| B1 | 7 | If configured as an output then damage is possible. If configured as input, damage is possible if VIH/VIL is not met | A |
| VCCB | 8 | VCCA short to VCCB, device will be bypassed; may cause system damage, but no damage to the device occurs | B |
Table 4-6 Pin FMA for Device Pins
Short-Circuited to VCCB
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| VCCA | 1 | VCCB short to VCCA, device will be bypassed - may cause system damage, but damage to the device does not occur | B |
| A1 | 2 | If configured as an output then damage is possible. If configured as input, damage is possible if VIH/VIL is not met | A |
| A2 | 3 | If configured as an output then damage is possible. If configured as input, damage is possible if VIH/VIL is not met | A |
| GND | 4 | GND short to VCC, device will be bypassed; may cause system damage, but damage to the device does not occur | B |
| DIR | 5 | If VCCB>VCCA, DIR will fix B --> A direction OR if VCCB<VCCA, input could be inappropriate logic level potentially causing damage | A |
| B2 | 6 | If configured as an output then damage is possible. If configured as input, damage does not occur, but output will not switch | A |
| B1 | 7 | If configured as an output then damage is possible. If configured as input, damage does not occur, but output will not switch | A |
| VCCB | 8 | Normal Operation | D |