SFFS257 August 2021 TPSM5601R5
4 Pin Failure Mode Analysis (Pin FMA)
This section provides a Failure Mode Analysis (FMA) for the pins of the TPSM5601R5 and TPSM5601R5S. 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 TPSM5601R5 and TPSM5601R5S pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the TPSM5601R5 and TPSM5601R5S data sheet.
Figure 4-1 Pin DiagramFollowing are the assumptions of use and the device configuration assumed for the pin FMA in this section:
- Application circuit, as per the TPSM5601R5 and TPSM5601R5S data sheet is used.
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 |
|---|---|---|---|
| VIN | 1, 14 | No output voltage will be generated. Possible damage to customer input supply, PCB can occur unless customer provides protection, or both. Reverse current from the SW pin to VIN pin, due to discharge of output capacitors, can damage regulator. | B |
| EN | 2 | This is a valid connection for the EN input. Enable functionality will be lost; the device will remain off with no output voltage generated. Damage to customer components connected to EN input can occur. | B |
| NC | 3, 6, 13 | Not connected to any circuitry within the module; no effect | D |
| SW | 4 | Shorting the SW pin to ground will result in large currents through the device and subsequent damage. No output voltage will be produced. | A |
| DNC | 5 | Driver supply to high side MOSFET will be lost. Output voltage will not be regulated. Possible damage to internal regulator and Cboot charging circuit | A |
| VOUT | 7, 8 | Loss of output voltage | B |
| FB | 9 | The regulator will operate at maximum duty cycle. Output voltage will rise to nearly the input voltage level. Possible damage to customer load, output stage components can occur, or both. | B |
| AGND | 10 | This is the ground pin, no effect | D |
| V5V | 11 | Internal circuits will be disabled. No output voltage will be generated. Possible increase in input current and possible damage to internal LDO | A |
| PGOOD | 12 | This is a valid connection for the PG output. PG functionality will be lost. Damage to customer components connected to PG input can occur. | D |
| PGND | 15 | This is the ground pin, no effect | D |
Table 4-3 Pin FMA for Device Pins Open-Circuited
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| VIN | 1, 14 | Loss of output voltage | B |
| EN | 2 | Loss of enable functionality. Erratic operation; probable loss of regulation | B |
| NC | 3, 6, 13 | Not connected to any circuitry within the module; no effect | D |
| SW | 4 | This is a valid connection for the SW node; no effect | D |
| DNC | 5 | This is a valid connection for DNC pin; no effect | D |
| VOUT | 7, 8 | Loss of output voltage | B |
| FB | 9 | Device will not regulate. Output voltage can rise or fall. Damage to customer load, output stage components is probable, or both. | B |
| AGND | 10 | Erratic operation; probable loss of regulation. Possible output voltage increase and damage to customer load | B |
| V5V | 11 | This is a valid connection for V5V pin; no effect | D |
| PGOOD | 12 | This is a valid connection for the PGOOD output. PGOOD functionality will be lost. | B |
| PGND | 15 | Erratic operation; probable loss of regulation. Possible output voltage increase and damage to customer load | 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 |
|---|---|---|---|---|
| VIN | 1 | EN | This is a valid connection for VIN. Enable functionality will be lost, the device will remain on. | D |
| EN | 2 | NC | Loss of enable functionality. Erratic operation; probable loss of regulation | B |
| NC | 3 | SW | NC pin not connected to any circuitry within the module; no effect | D |
| SW | 4 | DNC | Large currents will flow through internal circuits. Possible damage to internal regulator and CBOOT charging circuits. No output voltage will be produced. | A |
| DNC | 5 | NC | NC pin is not connected to any circuitry within the module; no effect | D |
| NC | 6 | VOUT | NC pin is not connected to any circuitry within the module; no effect | D |
| VOUT | 7 | PGND | Loss of output voltage | B |
| VOUT | 8 | FB | Erratic operation; loss of regulation. Possible damage to internal circuits will occur for VOUT > 5.5 V. | A |
| FB | 9 | AGND | The regulator will operate at maximum duty cycle. Output voltage will rise to nearly the input voltage level. Possible damage to customer load, output stage components can occur, or both. | B |
| AGND | 10 | V5V | Internal circuits will be disabled. No output voltage will be generated. Possible increase in input current and possible damage to internal LDO | A |
| V5V | 11 | PGOOD | Possible damage to internal circuitry | A |
| PGOOD | 12 | NC | No effect | D |
| NC | 13 | VIN | Normal operation; no effect | D |
| VIN | 14 | PGND | No output voltage will be generated. Possible damage to customer input supply, PCB can occur unless customer provides protection, or both. Reverse current from the SW pin to VIN pin, due to discharge of output capacitors, can damage the regulator. | B |
Table 4-5 Pin FMA for Device Pins Short-Circuited to
supply
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| VIN | 1, 14 | Normal operation | D |
| EN | 2 | Normal operation; enable functionality will be lost, the device will remain on. | D |
| NC | 3, 6, 13 | Normal operation | D |
| SW | 4 | Damage to the LS FET | A |
| DNC | 5 | VOUT = 0 V. CBOOT ESD clamp will run current to destruction. | A |
| VOUT | 7, 8 | Damage to LS FET. The output voltage will rise to nearly the level of VIN. Customer load will be damaged. Possible damage to device | A |
| FB | 9 | If VIN exceeds 5.5 V, damage will occur. VOUT = 0 V | A |
| AGND | 10 | VOUT = 0 V. Damage to other pins referred to GND | A |
| V5V | 11 | If VIN exceeds 5.5 V, damage will occur. | A |
| PGOOD | 12 | Damage to internal circuits | A |
| PGND | 15 | VOUT = 0 V. Damage to low-side circuitry if PGND >> AGND | A |