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This document contains information for TIOS102(x) family of devices (TIOS102, TIOS1023 and TIOS1025) to aid in a functional safety system design. Infomation provided are:
Figure 1-1 and Figure 1-2 show the device functional block diagrams for reference.
The devices were developed using a quality-managed development process, but was not developed in accordance with the IEC 61508 or ISO 26262 standards.
This section provides Functional Safety Failure In Time (FIT) rates for TIOS102(x) based on two different industry-wide used reliability standards:
FIT IEC TR 62380 / ISO 26262 | FIT (Failures Per 109 Hours) DRC-10 (VSON Package) |
---|---|
Total Component FIT Rate | 9 |
Die FIT Rate | 5 |
Package FIT Rate | 4 |
The failure rate and mission profile information in Table 2-1 comes from the Reliability data handbook IEC TR 62380 / ISO 26262 part 11:
FIT IEC TR 62380 / ISO 26262 | FIT (Failures Per 109 Hours) DRC-10 (VSON Package) |
---|---|
Total Component FIT Rate | 7 |
Die FIT Rate | 3 |
Package FIT Rate | 4 |
The failure rate and mission profile information in Table 2-2 comes from the Reliability data handbook IEC TR 62380 / ISO 26262 part 11:
Table | Category | Reference FIT Rate | Reference Virtual TJ |
---|---|---|---|
5 | BICMOS, ASIC, Analog & Mixed ≤ 50 V Supply | 25 FIT | 55°C |
The Reference FIT Rate and Reference Virtual TJ (junction temperature) in Table 2-3 come from the Siemens Norm SN 29500-2 tables 1 through 5. Failure rates under operating conditions are calculated from the reference failure rate and virtual junction temperature using conversion information in SN 29500-2 section 4.
The failure mode distribution estimation for TIOS102, TIOS1023 and TIOS1025 in Table 3-1 comes from the combination of common failure modes listed in standards such as IEC 61508 and ISO 26262, the ratio of sub-circuit function size and complexity and from best engineering judgment.
The failure modes listed in this section reflect random failure events and do not include failures due to misuse or overstress.
Die Failure Modes | Failure Mode Distribution (%) (TIOS1023, TIOS125) | Failure Mode Distribution (%) (TIOS102) |
---|---|---|
Transmitter failure | 75% | 75% |
VCC_OUT LDO failure | 6% | Not applicable |
VCC_IN internal logic failure | Not applicable | 6% |
NFAULT logic failure | 13% | 13% |
Control logic failure | 6% | 6% |
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 |
DATE | REVISION | NOTES |
---|---|---|
November 2022 | * | Initial Release |