SFFS134 November 2022 TIOS1023 , TIOS1025
This section provides a Failure Mode Analysis (FMA) for the pins of the TIOS102(x) device family. The failure modes covered in this document include the typical pin-by-pin failure scenarios:
Pin short-circuited to VCC_IN (for TIOS102, see Table 4-7)
Table 4-2 through Table 4-7 also indicate how these pin conditions can affect the device as per the failure effects classification in Table 4-1.
| 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 and Figure 4-2 show the pin diagrams for TIOS102(x) family. For a detailed description of the device pins please refer to the 'Pin Configuration and Functions' section in the TIOS102(x) datasheet.
Following are the assumptions of use and the device configuration assumed for the pin FMA in this section:
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| VCC_OUT (TIOS1023, TIOS1025) | 1 | Device I/O logic blocks unpowered. Although LDO current is internally limited to 35 mA ±20%, thermal shutdown may be activated depending upon ambient temperature and the power dissipation in the LDO. | B |
VCC_IN (TIOS102) | Device not functional. Logic I/O blocks powered by VCC_IN will be unpowered. No communication with MCU. | B | |
| NFAULT | 2 | Incorrect fault indicator output. Microcontroller will assume device is in the fault state for the duration of the short event. | B |
| NC | 3 | None | D |
| IN | 4 | OUT pin will be stuck at high (high-side switch ON) for the duration of the short event if EN is high. Device transmitter is not functional. | B |
| EN | 5 | Device Driver is always tri-stated. Device transmitter is not functional. | B |
| ILIM_ADJ | 6 | Device operates with the highest current limit setting. Overcurrent fault will not be indicated and the driver will not be disabled due to overcurrent fault. Thermal shutdown may be triggered. | B |
| GND | 7 | None | D |
| OUT | 8 | Output stuck at low and no commnunication is possible. When EN=H and IN=LOW, device will go into current fault due to overcurrent condition cycling into driver turn-off and auto-recovery cycles. Thermal shutdown may be triggered. | B |
| VCC | 9 | Device is unpowered and not functional. | B |
| NC | 10 | None | D |
Thermal Pad | - | None | D |
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| VCC_OUT (TIOS1023, TIOS1025) | 1 | Sensor/Microcontroller will not be functional if VCC_OUT is powering the sensor/microcontroller. No communication with MCU. | B |
VCC_IN (TIOS102) | 1 | Device will not be functional. Logic I/O blocks powered by VCC_IN will be unpowered. No communication with MCU. | B |
| NFAULT | 2 | No NFAULT information provided to the microcontroller. | B |
| NC | 3 | None | D |
| IN | 4 | No data can be transmitted from the Sensor/Microcontroller to the output | B |
| EN | 5 | Device driver is always tri-stated due to internal pull-down. Device can only receive data | B |
| ILIM_ADJ | 6 | Device operates with a different current limit setting than intended. Overcurrent fault will be indicated without blanking time and the driver will not be disabled due to overcurrent fault. | B |
| GND | 7 | Device is unpowered. | B |
| OUT | 8 | No communication with other devices over the bus. | B |
| VCC | 9 | Device is unpowered. | B |
| NC | 10 | None | D |
Thermal Pad | - | If thermal pad is not connected to GND planes in the PCB, thermal performance will not be optimal | C |
| Pin Name | Pin No. | Shorted to | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|---|
| VCC_OUT (TIOS1023, TIOS1025) | 1 | NFAULT | High ICC current during internal NFAULT active conditions. No external NFAULT active indication | B |
VCC_IN (TIOS102) | High ICC_IN current during internal NFAULT active conditions. No external NFAULT active indication | B | ||
| NFAULT | 2 | NC | None as long as NC is not connected to anything external to the device | D |
| NC | 3 | IN | None as long as NC is not connected to anything external to the device | D |
| IN | 4 | EN | If IN and EN are driven to different states communication and device state can be compromised | B |
| EN | 5 | NA | None | D |
| ILIM_ADJ | 6 | GND | Device operates at the maximum current limit. Overcurrent fault will not be indicated and the driver will not be disabled due to overcurrent fault. Thermal shutdown may be triggered. | B |
| GND | 7 | OUT | Output stuck at low and no commnunication is possible. When EN=H and IN=LOW, device will go into current fault due to overcurrent condition cycling into driver turn-off and auto-recovery cycles. Thermal shutdown may be triggered. | B |
| OUT | 8 | VCC | No communication over the bus. Internal reverse polarity protection helps protect the device as long as absolute maximum operating conditions are not exceeded. | B |
| VCC | 9 | NC | None as long as NC is not connected to anything external to the device | D |
| NC | 10 | NA | None | D |
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| VCC_OUT/ VCC_IN | 1 | ABS Max violation on VCC_OUT pin. Sensor /Microcontroller damaged by VCC_IN/VCC_OUT over-voltage. | A |
| NFAULT | 2 | Absolute maximum operating condition exceeded | A |
| NC | 3 | None as long as NC is not connected to anything external to the device | D |
| IN | 4 | Absolute maximum operating condition exceeded | A |
| EN | 5 | Absolute maximum operating condition exceeded | A |
| ILIM_ADJ | 6 | Absolute maximum operating condition exceeded | A |
| GND | 7 | Device not functional. Ensure that the absolute maximum ratings are not exceeded otherwise device damage may be plausible | B |
| OUT | 8 | Device not functional. Ensure that the absolute maximum ratings are not exceeded otherwise device damage may be plausible. | B |
| VCC | 9 | NA | D |
| NC | 10 | None as long as NC is not connected to anything external to the device | D |
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| VCC_OUT | 1 | NA | D |
| NFAULT | 2 | High current draw from the internal LDO current when the NFAULT is pulled low internal to the device. No fault indication to the microcontroller. | B |
|
NC |
3 |
None |
D |
|
IN |
4 | Device transmitter will always output low on the bus. Device transmitter functionality is lost. | B |
| EN | 5 | Transmitter is always enabled. Receiver will loop back the data on the IN pin | B |
| ILIM_ADJ | 6 | May cause degradation in the current limiting functionality. | C |
|
GND |
7 | Device I/O logic blocks unpowered . Thermal shutdown may be activated due to excessive current draw from the internal LDO. | B |
|
OUT |
8 | Device not functional. Ensure that the absolute maximum ratings are not exceeded otherwise device damage may be plausible on the VCC_OUT pin | B |
|
VCC |
9 | Absolute maximum operating condition exceeded on VCC_OUT pin | A |
| NC | 10 |
None |
D |
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| VCC_IN | 1 | NA | D |
| NFAULT | 2 | High current draw from the external LDO that's supplying VCC_IN when the NFAULT is pulled low internal to the device. No fault indication to the microcontroller. | B |
NC | 3 | None. | D |
IN | 4 | Device transmitter will always output low on the bus. Device transmitter functionality is lost. | B |
| EN | 5 | Transmitter is always enabled. Receiver will loop back the data on the IN pin | B |
| ILIM_ADJ | 6 | May cause degradation in the current limiting functionality. | C |
GND | 7 | Device I/O logic blocks unpowered. High current draw from the external LDO supplying VCC_IN. | B |
OUT | 8 | Communication is not possible over the bus. | B |
VCC | 9 | Absolute maximum operating condition exceeded on VCC_IN pin | A |
| NC | 10 | None | D |