SFFS380 February 2022 TIOL112 , TIOL1123 , TIOL1125
This section provides a Failure Mode Analysis (FMA) for the pins of the TIOL112, TIOL1123, and TIOL1125. The failure modes covered in this document include the typical pin-by-pin failure scenarios:
Pin short-circuited to VCC_OUT (for TIOL1123, TIOL1125, see Table 4-6)
Pin short-circuited to VCC_IN (for TIOL112, see Table 4-7)
| 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 4-2show the pin diagram for TIOL112(x) family. For a detailed description of the device pins please refer to the 'Pin Configuration and Functions ' section in the TIOL112(x) datasheet.
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| VCC_OUT (TIOL1123, TIOL1125) | 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 (TIOL112) | 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 |
| RX | 3 | Receiver output stuck at low fault. | B |
| TX | 4 | CQ output 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 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 |
L- | 7 | None | D |
| CQ | 8 | CQ output stuck at low and no commnunication is possible. When EN=H and TX=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 |
| L+ | 9 | Device is unpowered and not functional. | B |
| WAKE | 10 | IO-link wake-up functionality will not work as intended. Microprocessor may recognize the short event as a wake-up event and turn-off the driver. | B |
Thermal Pad | - | None | D |
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| VCC_OUT (TIOL1123, TIOL1125) | 1 | Sensor/Microcontroller will not be functional if VCC_OUT is powering the sensor/microcontroller. | B |
VCC_IN (TIOL112) | 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 |
| RX | 3 | Data will not be received by the microcontroller | B |
| TX | 4 | No data can be transmitted from the Sensor FE/Micro to the output | B |
| EN | 5 | Device is always tri-stated. 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 |
| L- | 7 | Device is unpowered | B |
| CQ | 8 | No communication over the bus. | B |
| L+ | 9 | Device is unpowered | B |
| WAKE | 10 | Wake signal will not be indicated to the microcontroller | B |
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 (TIOL1123, TIOL1125) | 1 | NFAULT | High ICC current during internal NFAULT active conditions. No external NFAULT active indication | B |
VCC_IN (TIOL112) | High ICC_IN current during internal NFAULT active conditions. No external NFAULT active indication | B | ||
| NFAULT | 2 | RX | Contention between driver output at the RX pin and the MCU output driving the TX input. Device functionality is lost. | B |
| RX | 3 | TX | Contention between driver output at RX pin and driver output at the NFAULT pin. Receiver & fault detection functionality is lost. | B |
| TX | 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 | L- | Device operates at the maximum current limit. Overcurrent fault will not be indicated and the driver will not be disabled due to overcurrent fault. | B |
| L- | 7 | CQ | CQ output stuck at low and no commnunication is possible. When EN=H and TX=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 |
| CQ | 8 | L+ | No communication over the bus. Internal reverse polarity protection helps protect the device as long as absolute maximum operating conditions are not exceeded. | B |
| L+ | 9 | WAKE | Absolute maximum operating condition exceeded for the WAKE pin | A |
| WAKE | 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/VCC_IN pin. Sensor FE/MCU damaged by VCC_OUT/VCC_IN over-voltage. | A |
| NFAULT | 2 | Absolute maximum operating condition exceeded | A |
| RX | 3 | Absolute maximum operating condition exceeded | A |
| TX | 4 | Absolute maximum operating condition exceeded | A |
| EN | 5 | Absolute maximum operating condition exceeded | A |
| ILIM_ADJ | 6 | Absolute maximum operating condition exceeded | A |
| L- | 7 | Device not functional. Ensure that the absolute maximum ratings are not exceeded otherwise device damage may be plausible. | B |
| CQ | 8 | Device not functional. Ensure that the absolute maximum ratings are not exceeded otherwise device damage may be plausible. | B |
| L+ | 9 | NA | D |
| WAKE | 10 | Absolute maximum operating condition exceeded | A |
| 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 |
| RX | 3 | Receiver output will be in stuck at high fault. | B |
| TX | 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 TX pin | B |
| ILIM_ADJ | 6 | May cause degradation in the current limiting functionality. | C |
| L- | 7 | Device I/O logic blocks unpowered . Thermal shutdown may be activated due to excessive current draw from the internal LDO. | B |
| CQ | 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 |
| L+ | 9 | Absolute maximum operating condition exceeded on VCC_OUT pin | A |
| WAKE | 10 | IO-link wake-up functionality is lost | B |
| 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 |
| RX | 3 | Receiver output will be in stuck at high fault. If the receiver output is internally pulled low, there could be high current draw from VCC_IN. | B |
| TX | 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 TX pin | B |
| ILIM_ADJ | 6 | May cause degradation in the current limiting functionality. | C |
| L- | 7 | Device I/O logic blocks unpowered. High current draw from the external LDO supplying VCC_IN. | B |
| CQ | 8 | Communication is not possible over the bus. | B |
| L+ | 9 | Absolute maximum operating condition exceeded on VCC_IN pin | A |
| WAKE | 10 | IO-link wake-up functionality is lost | B |