SLVAEL2A december 2019 – april 2023 TPS7B4250-Q1
4 Pin Failure Mode Analysis (Pin FMA)
This section provides a failure mode analysis (FMA) for the pins of the TPS7B4250-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 VIN (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
| 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 TPS7B4250-Q1 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the TPS7B4250-Q1 data sheet.
Figure 4-1 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 |
|---|---|---|---|
| ADJ/EN | 1 | The device is disabled, resulting in no output voltage. | B |
| GND | 2 | No effect. Normal operation. | D |
| VIN | 3 | Power is not supplied to the device. System performance depends on upstream current limiting. | B |
| VOUT | 4 | Regulation is not possible, the device operates at current limit. The device can cycle in and out of thermal shutdown. | B |
| GND | 5 | No effect. Normal operation. | D |
Table 4-3 Pin FMA for Device Pins
Open-Circuited
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| ADJ/EN | 1 | VADJ/EN is undetermined; therefore, regulation is not possible. | B |
| GND | 2 | The device is still functional with degraded transient performance. | C |
| VIN | 3 | Power is not supplied to the device, resulting in no output voltage. | B |
| VOUT | 4 | The device output is disconnected from the load. | B |
| GND | 5 | The device is still functional with degraded transient performance. | C |
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 |
|---|---|---|---|---|
| ADJ/EN | 1 | GND (pin 2) | The device is forced off. | B |
| GND | 2 | VIN (pin 3) | Power is not supplied to the device. System performance depends on upstream current limiting. | B |
| VIN | 3 | VOUT (pin 4) | The device has protection for out to in short circuit. Potential damage when VINexceeds 22 V because this value violates the VOUT absolute maximum. | B/A |
| VOUT | 4 | GND (pin 5) | Regulation is not possible, the device operates at current limit. The device can cycle in and out of thermal shutdown. | B |
Table 4-5 Pin FMA for Device Pins
Short-Circuited to VIN
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| ADJ/EN | 1 | Potential damage when VIN is greater than 22 V because this value violates the absolute maximum for VADJ/EN . | B/A |
| GND | 2 | Power is not supplied to the device. System performance depends on upstream current limiting. | D |
| VIN | 3 | No effect. Normal operation. | B |
| VOUT | 4 | The device has protection for out to in short circuit. Potential damage when VINis greater than 22 V because this value violates the absolute maximum for VOUT. | B/A |
| GND | 5 | Power is not supplied to the device. System performance depends on upstream current limiting. | B |