SFFSAU6 September 2025 TPS482H85-Q1
4 Pin Failure Mode Analysis (Pin FMA)
This section provides a failure mode analysis (FMA) for the pins of the TPS482H85-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 TPS482H85-Q1 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the TPS482H85-Q1 data sheet.
Figure 4-1 Pin DiagramFollowing are the assumptions of use and the device configuration assumed for the pin FMA in this section:
- The device pins are connected per the recommendation in the data sheet, including pullup and pulldown resistors, as needed.
- The data sheet recommendations for operating conditions, external component selection, and PCB layout are followed.
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| VOUT1 | 1 | The current limit of the output channel engages, and thermal protection turns off the FET. | B |
| VOUT2 | 2 | The current limit of the output channel engages, and thermal protection turns off the FET. | B |
| VBB | 3 | The output stages are not powered, and the FET does not turn ON. | B |
| LATCH / FLT | 4 | For the A and C variants, fault recovery is set at auto-retry mode. For the B variant, the reported fault status is potentially erroneous. | B |
| VDD | 5 | The internal regulator is enabled; the device consumes higher quiescent current through the VBB pin. | C |
| SEL | 6 | When the DIAG_EN pin is high, the SNS output shows the signal corresponding to channel 1. | B |
| EN2 | 7 | The main FET for channel 2 is turned off. | B |
| DIAG_EN | 8 | Diagnostics features do not function, including current sense and fault reporting. | B |
| EN1 | 9 | The main FET for channel 1 is turned off. | B |
| SNS | 10 | The reported SNS current or fault status on the SNS pin is erroneous. | B |
| GND | 11 | Any GND network, connected for protection, is bypassed. | B |
| ILIM | 12 | The current limit is set at 9A. | C |
Table 4-3 Pin FMA for Device Pins Open-Circuited
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| VOUT1 | 1 | During the OFF state of the device, if the DIAG_EN pin is high, an open-load fault reports. | B |
| VOUT2 | 2 | During the OFF state of the device, if the DIAG_EN pin is high, an open-load fault reports. | B |
| VBB | 3 | The device is not powered, and the switch is kept OFF. | B |
| LATCH / FLT | 4 | For the A and C variants, fault recovery is set at auto-retry mode. For the B variant, the fault condition is not reported. | B |
| VDD | 5 | The internal regulator is enabled, the device consumes higher quiescent current through the VBB pin. | C |
| SEL | 6 | When the DIAG_EN pin is high, the SNS output shows the signal corresponding to channel 1. | B |
| EN2 | 7 | The main FET for channel 2 is turned off. | B |
| DIAG_EN | 8 | Diagnostics features do not function; including current sense and fault reporting. | B |
| EN1 | 9 | The main FET for channel 1 is turned off. | B |
| SNS | 10 | The current sense voltage of the pin is clamped internally and no current sense information is available. | B |
| GND | 11 | The loss of ground detection engages, and the device turns OFF. | B |
| ILIM | 12 | The current limit is set at 10A. | 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 |
|---|---|---|---|---|
| VOUT1 | 1 | VOUT2 | If the outputs are shorted together during power-up, a thermal shutdown potentially occurs. If the outputs are shorted after power-up, a thermal shutdown does not occur, but a parametric shifts potentially occurs. | B |
| VOUT2 | 2 | VBB | The output for channel 2 is pulled to the supply voltage. A short-to-battery detection triggers during the OFF state if the DIAG_EN pin is high. | B |
| VBB | 3 | LATCH / FLT | No effect, the pin is rated for VBB. | D |
| LATCH / FLT | 4 | VDD | For the A and C variants, fault recovery can be permanently set to latch mode. For the B variant, the fault condition potentially does not report. The internal regulator can also be enabled, and the device can consume higher quiescent current through the VBB pin. | B |
| VDD | 5 | SEL | The SNS output shows the signal corresponding to channel 2 only, or the internal regulator is enabled, and the device consumes higher quiescent current through the VBB pin. | B |
| SEL | 6 | EN2 | The SNS output potentially does not show the signal corresponding to the selected channel, or the main FET for channel 2 is potentially turned off. | B |
| EN2 | 7 | DIAG_EN | The diagnostic features potentially do not function. The main FET for channel 2 can also turn off. | B |
| DIAG_EN | 8 | EN1 | The diagnostic features potentially do not function. The main FET for channel 1 can also turn off. | B |
| EN1 | 9 | SNS | The current sense information is potentially erroneous, assuming the EN1 voltage does not exceed the ADC pin voltage rating. The main FET for channel 1 can also turn off. | B |
| SNS | 10 | GND | The reported SNS current or fault status on the SNS pin is erroneous. | B |
| GND | 11 | ILIM | The current limit is set at 9A. | C |
| ILIM | 12 | VBB | No effect, the pin is rated for VBB. | D |
| VBB | 3 | VOUT1 | The output for channel 1 is pulled to the supply voltage. A short-to-battery detection triggers during the OFF state if the DIAG_EN pin is high. | B |
Table 4-5 Pin FMA for Device Pins Short-Circuited to Supply
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| VOUT1 | 1 | The output is pulled to the supply voltage. A short-to-battery detection triggers during the OFF state if the DIAG_EN pin is high. | B |
| VOUT2 | 2 | The output is pulled to the supply voltage. A short-to-battery detection triggers during the OFF state if the DIAG_EN pin is high. | B |
| VBB | 3 | No effect. | D |
| LATCH / FLT | 4 | No effect. | D |
| VDD | 5 | There is a potential violation of the absolute maximum rating for the pin and a possible breakdown of the ESD cell. | A |
| SEL | 6 | There is a potential violation of the absolute maximum rating for the pin and a possible breakdown of the ESD cell. | A |
| EN2 | 7 | There is a potential violation of the absolute maximum rating for the pin and a possible breakdown of the ESD cell. | A |
| DIAG_EN | 8 | There is a potential violation of the absolute maximum rating for the pin and a possible breakdown of the ESD cell. | A |
| EN1 | 9 | There is a potential violation of the absolute maximum rating for the pin and a possible breakdown of the ESD cell. | A |
| SNS | 10 | There is a potential violation of the absolute maximum rating for the pin and a possible breakdown of the ESD cell. | A |
| GND | 11 | The supply power is bypassed, and the device stays OFF. | B |
| ILIM | 12 | No effect. | D |