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This document contains information for TPS4H000-Q1 (HTSSOP package) to aid in a functional safety system design. Information provided are:
#GUID-E488EBD4-511E-41B0-B770-91A9719CA4DD shows the device functional block diagram for reference.
TPS4H000-Q1 was 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 TPS4H000-Q1 based on an industry-wide used reliability standard:
FIT IEC TR 62380 / ISO 26262 | FIT (Failures Per 109 Hours) |
---|---|
Total Component FIT Rate | 17 |
Die FIT Rate | 5 |
Package FIT Rate | 12 |
The failure rate and mission profile information in #GUID-3DB781EA-94EA-4B4F-9FE7-0FBF498806FA/GUID-D2F32BF7-F0F2-45BD-945E-5E9A117DF52F comes from the Reliability data handbook IEC TR 62380 / ISO 26262 part 11:
The failure mode distribution estimation for TPS4H000-Q1 in #GUID-E8925649-3681-40B6-ACC6-1D694E2B1883/GUID-2C783C7C-284A-48D4-BA1C-B05A1833C868 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 (%) |
---|---|
OUT1,2,3,4 open (HiZ) | 20% |
OUT1,2,3,4 stuck on (VS) | 10% |
OUT1,2,3,4 not in specification voltage or timing | 45% |
Diagnostics not in specification | 10% |
Protection functions fails to trip | 10% |
Pin to pin short any two pins | 5% |
This section provides a Failure Mode Analysis (FMA) for the pins of the TPS4H000-Q1. The failure modes covered in this document include the typical pin-by-pin failure scenarios:
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.
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 |
#GUID-59B67224-3CC4-4810-AE39-411866CAB6F7 shows the TPS4H000-Q1 pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the TPS4H000-Q1 data sheet.
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 Effects | Failure Effect Class |
---|---|---|---|
INx | 1, 2, 3, 4 | Shutdown of corresponding channel. | B |
STx | 5, 6, 7, 8 | Version A only. Status being reported erroneous. | B |
SEH | 5 | Version B only. If DIAG_EN is high then only channel 3 or 4's (depending on SEL) sense current output on SNS pin. | B |
SEL | 6 | Version B only. If DIAG_EN is high then only channel 1 or 2's (depending on SEH) sense current output on SNS pin. | B |
FAULT | 7 | Version B only. Status being reported erroneous. | B |
CS | 8 | Version B only. Sense current not valid from CS pin. | B |
CL | 9 | Device defaults to internal current limit. | C |
GND | 10 | Resistor/diode network bypassed if present. | B |
DIAG_EN | 11 | Diagnostics disabled. | B |
THER | 12 | Device defaults to "auto-retry" mode when encountering thermal fault. | B |
NC | 13, 14 | No effect. | D |
OUTx | 15, 16, 19, 20 | Current limit of device engages. | B |
VS | 17, 18 | Device has no input supply and therefore not function. | B |
Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
---|---|---|---|
INx | 1, 2, 3, 4 | Corresponding channel shutdown and INx pulled down internally. | B |
STx | 5, 6, 7, 8 | Version A only. STx pin cannot pull high and diagnostics cannot be reported. | B |
SEH | 5 | Version B only. Pulled low internally, however wrong SNS current potentially reported on CS if DIAG_EN is high. | B |
SEL | 6 | Version B only. If DIAG_EN is high then only channel 1 or 2's (depending on SEH) sense current output on SNS pin. | B |
FAULT | 7 | Version B only. Fault signal not reported. | B |
CS | 8 | Version B only. Correct sense current cannot be read. | B |
CL | 9 | Device defaults to internal current limit. | C |
GND | 10 | Loss of ground detection engages and device shuts off. | B |
DIAG_EN | 11 | Internally pulled down. Diagnostics disabled. | B |
THER | 12 | Internally pulled down. Device defaults to "auto-retry" mode when encountering thermal fault. | B |
NC | 13, 14 | No effect. | D |
OUTx | 15, 16, 19, 20 | No effect. If configured, open load detection triggers. | B |
VS | 17, 18 | Device has no input supply and therefore not function. | B |
Pin Name | Pin No. | Shorted to | Description of Potential Failure Effects | Failure Effect Class |
---|---|---|---|---|
IN1 | 1 | IN2 | IN1 signal affects IN2 signal and vice versa. | B |
IN2 | 2 | IN3 | IN2 signal affects IN3 signal and vice versa. | B |
IN3 | 3 | IN4 | IN3 signal affects IN4 signal and vice versa. | B |
IN4 | 4 | ST1 | Version A only. If ST1 is high then channel 4 is on. | B |
IN4 | 4 | SEH | Version B only. IN4 signal affects SEH and vice versa. | B |
ST1 | 5 | ST2 | Version A only. Fault reporting of channel 1 and channel 2 erroneous. | B |
SEH | 5 | SEL | Version B only. SEH signal affects SEL and vice versa. If DIAG_EN is high only channel 1 or 4 can be read at SNS. | B |
ST2 | 6 | ST3 | Version A only. Fault reporting of channel 2 and channel 3 erroneous. | B |
SEL | 6 | FAULT | Version B only. If FAULT high and DIAG_EN high, only channel 2 or channel 4 can be read at SNS. | B |
ST3 | 7 | ST4 | Version A only. Fault reporting of channel 3 and channel 4 erroneous. | B |
FAULT | 7 | CS | Version B only. Fault reporting and current sense reporting erroneous. | B |
ST4 | 8 | CL | Version A only. ST4 voltage can cause erroneous current limit to be set on device. | B |
CS | 8 | CL | Version B only. Voltage level on CS can cause erroneous current limit to be set on device. | B |
CL | 9 | GND | Device defaults to internal current limit. | C |
DIAG_EN | 11 | THER | DIAG_EN signal affects THER signal and vice versa. | B |
THER | 12 | NC | No effect | D |
NC | 14 | OUT4 | No effect. | D |
OUT4 | 15 | OUT3 | Output of channel 4 tied to output of channel 3. | B |
OUT3 | 16 | VS | Channel 3 cannot be turned off. Short-to-battery detection triggered if configured. | B |
VS | 17 | VS | No effect. | D |
VS | 18 | OUT2 | Channel 2 cannot be turned off. Short-to-battery detection triggered if configured. | B |
OUT2 | 19 | OUT1 | Output of channel 2 tied to output of channel 1. | B |
Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
---|---|---|---|
INx | 1, 2, 3, 4 | Potential violation of absolute maximum rating of pin and possible breakdown of ESD cell. | A |
STx | 5, 6, 7, 8 | Version A only. Potential violation of absolute maximum rating of pin and possible breakdown of ESD cell. | A |
SEH | 5 | Version B only. Potential violation of absolute maximum rating of pin and possible breakdown of ESD cell | A |
SEL | 6 | Version B only. Potential violation of absolute maximum rating of pin and possible breakdown of ESD cell. | A |
FAULT | 7 | Version B only. Potential violation of absolute maximum rating of pin and possible breakdown of ESD cell. | A |
CS | 8 | Version B only. Potential violation of absolute maximum rating of pin and possible breakdown of ESD cell. | A |
CL | 9 | Potential violation of absolute maximum rating of pin and possible breakdown of ESD cell. | A |
GND | 10 | Supply power bypassed and device does not turn on. | B |
DIAG_EN | 11 | Potential violation of absolute maximum rating of pin and possible breakdown of ESD cell. | A |
THER | 12 | Potential violation of absolute maximum rating of pin and possible breakdown of ESD cell. | A |
NC | 13, 14 | No effect. | D |
OUTx | 15, 16, 19, 20 | Output pulled to supply voltage. Short-to-battery detection triggered if configured. | B |
VS | 17, 18 | No effect. | A |
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