SFFS928 July 2024 TPS55287-Q1
4 Pin Failure Mode Analysis (Pin FMA)
This section provides a failure mode analysis (FMA) for the pins of the TPS55287-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
| 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 TPS55287-Q1 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the TPS55287-Q1 data sheet.
Figure 4-1 TPS55287-Q1 Pin DiagramFollowing are the assumptions of use and the device configuration assumed for the pin FMA in this section:
- The device is used within the Recommended Operating Conditions and the Absolute Maximum Ratings in the TPS55287-Q1 data sheet.
- The configuration is as shown in the Application and Implementation section found in the TPS55287-Q1 data sheet.
Table 4-2 Pin FMA for Device Pins
Short-Circuited to Ground
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| EN/UVLO | 1 | Loss of ENABLE functionality. The device remains in shutdown mode. | B |
| MODE | 2 | The device I2C address is fixed at 75H. Loss of I2C configuration when application target address is 74H. | B |
| SCL | 3 | There is no output voltage. | B |
| SDA | 4 | There is no output voltage. | B |
| DITH/SYNC | 5 | Correct output voltage. Loss of DITH/SYNC functionality. | C |
| FSW | 6 | Device damage is possible. | A |
| VIN | 7 | The device does not operate. Power supply is short. | B |
| SW1 | 8 | Device damage is possible. | A |
| PGND | 9 | No effect. | D |
| SW2 | 10 | Device damage is possible. | A |
| VOUT | 11 | The device remains in hiccup output short circuit protection mode. | B |
| ISP | 12 | The device remains in hiccup output short circuit protection mode. | B |
| ISN | 13 | No output voltage. | B |
| FB/INT | 14 | When internal feedback is used, this pin always indicates low even in the normal condition. When external feedback is used, OVP is triggered. | B |
| COMP | 15 | The output voltage is out of regulation. | B |
| CDC | 16 | Loss of the cable voltage droop compensation functionality and the output voltage is overcompensated. | B |
| AGND | 17 | The internal circuited can be disturbed. | C |
| VCC | 18 | The device does not operate. VCC is short. | B |
| BOOT2 | 19 | No output voltage. | B |
| BOOT1 | 20 | No output voltage. | B |
| EXTVCC | 21 | The device selects the external power supply to supply the device through the VCC pin. If there is no external 5V rail supplying VCC, the device does not operate and output is 0V. If there is an external 5V rail supplying VCC, there is no effect on device operation. | B |
Table 4-3 Pin FMA for Device Pins
Open-Circuited
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| EN/UVLO | 1 | No output voltage. Loss of ENABLE functionality. | B |
| MODE | 2 | The I2C target address is not fixed. | B |
| SCL | 3 | There is no output voltage. | B |
| SDA | 4 | There is no output voltage. | B |
| DITH/SYNC | 5 | Correct output voltage. Loss of DITH/SYNC functionality. | C |
| FSW | 6 | No output voltage. | B |
| VIN | 7 | The device does not work and there is no output voltage. | B |
| SW1 | 8 | Device damage is possible. | A |
| PGND | 9 | Device damage is possible. | A |
| SW2 | 10 | Device damage is possible. | A |
| VOUT | 11 | Device damage is possible. | A |
| ISP | 12 | No output voltage. | B |
| ISN | 13 | The output voltage is out of regulation. | B |
| FB/INT | 14 | There is a loss of the FAULT indicator function when internal feedback is used. OVP is triggered when external feedback is used. | B |
| COMP | 15 | Output voltage is out of regulation. | B |
| CDC | 16 | Loss of CDC functionality and no cable voltage drop compensation. | C |
| AGND | 17 | Device damage is possible. | A |
| VCC | 18 | Device damage is possible. | A |
| BOOT2 | 19 | Device damage is possible. | A |
| BOOT1 | 20 | Device damage is possible. | A |
| EXTVCC | 21 | The device always selects internal LDO as VCC source. Loss of external VCC supply functionality. | 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 |
|---|---|---|---|---|
| EN/UVLO | 1 | MODE | The MODE pin is damaged if EN/UVLO pin is higher than 6V. | A |
| MODE | 2 | SCL | There is no output voltage. | B |
| SCL | 3 | SDA | There is no output voltage. | B |
| SDA | 4 | DITH/SYNC | There is no output voltage. | B |
| DITH/SYNC | 5 | FSW | Device damage is possible. | A |
| FSW | 6 | VIN | The FSW pin is damaged if VIN pin is higher than 6V. | A |
| VIN | 7 | SW1 | Device damage is possible. | A |
| SW1 | 8 | PGND | Device damage is possible. | A |
| PGND | 9 | SW2 | Device damage is possible. | A |
| SW2 | 10 | VOUT | Device damage is possible. | A |
| VOUT | 11 | ISP | Output current limit accuracy is affected. | C |
| ISP | 12 | ISN | Correct output voltage. Loss of output current limit functionality. | C |
| ISN | 13 | FB/INT | The FB/INT pin is damaged if ISN is higher than 6V. | A |
| FB/INT | 14 | COMP | Output voltage is out of regulation. | B |
| COMP | 15 | CDC | Output voltage is out of regulation. | B |
| CDC | 16 | AGND | Loss of the cable voltage droop compensation functionality and the output voltage is overcompensated. | B |
| AGND | 17 | VCC | The device does not operate. VCC is short. | B |
| VCC | 18 | BOOT2 | The VCC pin is damaged if BOOT2 is higher than 6V. | A |
| BOOT2 | 19 | VOUT | Device damage is possible. | A |
| BOOT1 | 20 | VIN | Device damage is possible. | A |
| BOOT1 | 20 | EXTVCC | Device damage is possible. | A |
| EXTVCC | 21 | EN/UVLO | EXTVCC pin is damaged if EN/UVLO pin is higher than 6V. | A |
Table 4-5 Pin FMA for Device Pins
Short-Circuited to
Supply
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| EN/UVLO | 1 | The EN/UVLO pin is damaged if supply voltage is higher than 20V. | A |
| MODE | 2 | The MODE pin is damaged if supply voltage is higher than 6V. | A |
| SCL | 3 | The SCL pin is damaged if supply voltage is higher than 6V. | A |
| SDA | 4 | The SDA pin is damaged if supply voltage is higher than 6V. | A |
| DITH/SYNC | 5 | The DITH/SYNC pin is damaged if supply voltage is higher than 6V. | A |
| FSW | 6 | The FSW pin is damaged if supply voltage is higher than 6V. | A |
| VIN | 7 | No effect. | D |
| SW1 | 8 | Device damage is possible. | A |
| PGND | 9 | The device does not operate. Power supply is short. | B |
| SW2 | 10 | The device is damaged if supply voltage is higher than 25V. | A |
| VOUT | 11 | The VOUT pin is damaged if supply voltage is higher than 25V. The output voltage is equal to the supply voltage. | A |
| ISP | 12 | The ISP pin is damaged if supply voltage is higher than 25V. The output voltage is equal to the supply voltage. | A |
| ISN | 13 | The ISN pin damaged if supply voltage is higher than 25V. The output voltage is equal to the supply voltage. | A |
| FB/INT | 14 | The FB/INT pin is damaged if supply voltage is higher than 6V. | A |
| COMP | 15 | The COMP pin is damaged if supply voltage is higher than 6V. | A |
| CDC | 16 | The CDC pin is damaged if supply voltage is higher than 6V. | A |
| AGND | 17 | The device does not operate. Power supply is short. | B |
| VCC | 18 | The VCC pin is damaged if supply voltage is higher than 6V. | A |
| BOOT2 | 19 | The BOOT2 pin is damaged if supply voltage is higher than 31V. | A |
| BOOT1 | 20 | Device damage is possible. | A |
| EXTVCC | 21 | The EXTVCC pin is damaged if supply voltage is higher than 6V. | A |