SFFS822 March 2024 SN74AXC8T245-Q1
4 Pin Failure Mode Analysis (Pin FMA)
This section provides a Failure Mode Analysis (FMA) for the pins of the SN74AXC8T245-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 SN74AXC8T245-Q1 pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the SN74AXC8T245-Q1 data sheet.
Figure 4-1 Pin DiagramTable 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 not device damage | B |
| DIR | 2 | Direction control will fix B --> A direction | B |
| A1 - A8 | 3 - 10 | If configured as an output then damage is possible. If configured as input, no damage, but output will not switch | A |
| GND | 11 - 13 | Normal Operation | D |
| B8 - B1 | 14 - 21 | If configured as an output then damage is possible. If configured as input, no damage, but output will not switch | A |
| OE (active low) | 22 | Outputs will remain enabled | B |
| VCCB | 23-24 | GND short to VCC, device will be bypassed - may cause system damage, but not device damage | 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 |
| DIR | 2 | Direction control will fix B --> A direction | B |
| A1 - A8 | 3 - 10 | If configured as output, normal operation. If configured as input, no damage, but output will not switch | B |
| GND | 11 - 13 | Device will not be powered | B |
| B8 - B1 | 14 - 21 | If configured as output, normal operation. If configured as input, no damage, but output will not switch | B |
| OE (active low) | 22 | Outputs will remain enabled | B |
| VCCB | 23-24 | 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 | DIR | Direction control will fix A --> B direction | B |
| DIR | 2 | A1 | If DIR is LOW, A1 will be an output and damage is possible. If DIR is HIGH, A1 will be an input and drive the output B1 low. | A |
| A(n) | 3 - 9 | A(n+1) | If A(n) and A(n+1) are configured as outputs then damage is possible. If configured as inputs, both bits will have the same value always | A |
| A8 | 10 | GND | If A8 is configured as an output then damage is possible. If configured as input, output B8 will be fixed low | A |
| GND | 11 - 12 | GND | Normal Operation | D |
| GND | 13 | B8 | If B8 is configured as an output then damage is possible. If configured as input, output A8 will be fixed low | A |
| B(n) | 14 - 20 | B(n-1) | If B(n) and B(n+1) are configured as outputs then damage is possible. If configured as inputs, both bits will have the same value always | A |
| B1 | 21 | VCCB | If B1 is configured as an output then damage is possible. If configured as input, no damage, but output A1 will remain high. | A |
| VCCB | 22-23 | VCCB | Normal Operation | D |
| VCCB | 24 | VCCA | VCCB short to VCCA, device will be bypassed - may cause system damage, but not device damage | 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 |
| DIR | 2 | Direction control will fix A --> B direction | B |
| A1 - A8 | 3 - 10 | If configured as an output then damage is possible. If configured as input, no damage, but output will not switch | A |
| GND | 11 - 13 | GND short to VCC, device will be bypassed - may cause system damage, but not device damage | B |
| B8 - B1 | 14 - 21 | If configured as an output then damage is possible. If configured as input, damage is possible if VIH/VIL not met | A |
| OE (active low) | 22 | Outputs will remain disabled | B |
| VCCB | 23-24 | VCCA short to VCCB, device will be bypassed - may cause system damage, but not device damage | 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 not device damage | B |
| DIR | 2 | If VCCA > VCCB, then the direction control will fix B-->A, If VCCA < VCCB, damage is possible if VIH/VIL not met | A |
| A1 - A8 | 3 - 10 | If A1 is configured as an output then damage is possible. If configured as input, damage is possible if VIH/VIL not met | A |
| GND | 11 - 13 | GND short to VCC, device will be bypassed - may cause system damage, but not device damage | B |
| B8 - B1 | 14 - 21 | If B2 is configured as an output then damage is possible. If configured as input, no damage, but output will not switch | A |
| OE (active low) | 22 | If VCCA > VCCB, then the outputs will remain disabled, If VCCA < VCCB, damage is possible if VIH/VIL not met | A |
| VCCB | 23-24 | Normal Operation | D |