SFFSB09 December 2025 TPSI2240-Q1
4 Pin Failure Mode Analysis (Pin FMA)
This section provides a failure mode analysis (FMA) for the pins of the TPSI2240-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 short-circuited to VDD (See Table 4-3)
- Pin open-circuited (see Table 4-4)
- Pin short-circuited to adjacent pin (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.
Note: When the pin short to ground case is discussed, only
primary-side ground shorts are considered.
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 TPSI2240-Q1 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the TPSI2240-Q1 datasheet.
Figure 4-1 TPSI2240-Q1 Pin Diagram Table 4-2 Pin FMA for Device Pins
Short-Circuited to Ground
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| VDD | 1 | The device is in the OFF state (UVLO). The secondary-side switch is in the OFF state. | B |
| GND | 2 | There is no effect on the device. | D |
| EN | 3 | The device is in the OFF state. The secondary-side switch is in the OFF state. | B |
| NC/GND | 4 | There is no effect on the device. | D |
| NC/GND | 5 | There is no effect on the device. | D |
| NC/GND | 6 | There is no effect on the device. | D |
| NC/GND | 7 | There is no effect on the device. | D |
| GND | 8 | There is no effect on the device. | D |
| S2 | 9 | N/A | N/A |
| NC | 10 | N/A | N/A |
| S1 | 11 | N/A | N/A |
Table 4-3 Pin FMA for Device Pins Short-Circuited to VDD
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| VDD | 1 | There is no effect on the device. | D |
| GND | 2 | The device is in the OFF state (UVLO), the secondary-side switch is in the OFF state. | B |
| EN | 3 | The device is in the ON state. The secondary side switch is in the ON state. | B |
| NC/GND | 4 | If pin 3 is high, there is no effect on the device. | D |
| If pin 3 is low, the standoff voltage of the secondary side switch is halved. | C | ||
| NC/GND | 5 | If pin 3 is high, there is no effect on the device. | D |
| If pin 3 is low, the standoff voltage of the secondary side switch is halved. | C | ||
| NC/GND | 6 | There is no effect on the device. | D |
| NC/GND | 7 | There is no effect on the device. | D |
| GND | 8 | The device is in the OFF state (UVLO), the secondary-side switch is in the OFF state. | B |
| S2 | 9 | N/A | N/A |
| NC | 10 | N/A | N/A |
| S1 | 11 | N/A | N/A |
Table 4-4 Pin FMA for Device Pins
Open-Circuited
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| VDD | 1 | The device is in the OFF state (UVLO). The secondary-side switch is in the OFF state. | B |
| GND | 2 | If pin 8 is not connected, the device is in the OFF state (UVLO), the secondary-side switch is in the OFF state. | B |
| EN | 3 | The device is in the OFF state. The secondary-side switch is in the OFF state. | B |
| NC/GND | 4 | There is no effect on the device. | D |
| NC/GND | 5 | There is no effect on the device. | D |
| NC/GND | 6 | There is no effect on the device. | D |
| NC/GND | 7 | There is no effect on the device. | D |
| GND | 8 | If pin 2 is not connected, the device is in the OFF state (UVLO), the secondary-side switch is in the OFF state. | B |
| S2 | 9 | There is no effect on the device. | D |
| NC | 10 | There is no effect on the device. | D |
| S1 | 11 | There is no effect on the device. | D |
Table 4-5 Pin FMA for Device Pins
Short-Circuited to Adjacent Pin
| Pin Name | Pin No. | Shorted to Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|---|
| VDD | 1 | 2 | The device is in the OFF state (UVLO). The secondary-side switch is in the OFF state. | B |
| GND | 2 | 3 | The device is in the OFF state. The secondary-side switch is in the OFF state. | B |
| EN | 3 | 4 | No effect if pin 4 is NC, if pin 4 is GND, the device is in the OFF state, and the secondary-side switch is in the OFF state. | D |
| B | ||||
| NC/GND | 4 | 5 | There is no effect on the device. | D |
| NC/GND | 5 | 6 | There is no effect on the device. | D |
| NC/GND | 6 | 7 | There is no effect on the device. | D |
| NC/GND | 7 | 8 | There is no effect on the device. | D |
| GND | 8 | 9 | N/A | N/A |
| S2 | 9 | 10 | There is no effect on the device. | D |
| NC | 10 | 11 | There is no effect on the device. | D |
| S1 | 11 | 1 | N/A | N/A |