SFFS049 March   2021 TPS61379-Q1

 

  1. 1Overview
  2. 2Functional Safety Failure In Time (FIT) Rates
  3. 3Failure Mode Distribution (FMD)
  4. 4Pin Failure Mode Analysis (Pin FMA)

Pin Failure Mode Analysis (Pin FMA)

This section provides a Failure Mode Analysis (FMA) for the pins of the TPS61379-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.

Table 4-1 TI Classification of Failure Effects
ClassFailure Effects
APotential device damage that affects functionality
BNo device damage, but loss of functionality
CNo device damage, but performance degradation
DNo device damage, no impact to functionality or performance

Figure 4-1 shows the TPS61379-Q1 pin diagram. For a detailed description of the device pins please refer to the 'Pin Configuration and Functions' section in the TPS61379-Q1 data sheet.

GUID-20210107-CA0I-Z3F0-CNKZ-S5RLZ0KD9974-low.gifFigure 4-1 Pin Diagram

Following are the assumptions of use and the device configuration assumed for the pin FMA in this section:

  • Device used within the Recommended Operating Conditions and the Absolute Maximum Ratings found in the TPS61379-Q1 data sheet.
  • Configuration as shown in the Application and Implementation section found in the TPS61379-Q1 data sheet.

Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
Pin Name Pin No. Description of Potential Failure Effects(s) Failure Effect Class
VIN 1 The device does not operate. Power supply is short. B
BST 2 Possible device damage A
SW 3 Potential damage to inductor and pin A
SW 4 Potential damage to inductor and pin A
MODE/SYNC 5 The device remains in Auto PFM mode. Loss of forced PWM mode, spread spectrum functionality, and frequency synchronization functionality C
VCC 6 Output voltage out of regulation B
GND 7 No effect D
GND 8 No effect D
VO 9 The device remains in hiccup output short circuit protection mode. B
OUT 10 Potential damage to device A
PG 11 Correct output voltage. Loss of PG functionality C
NC 12 No effect D
FB 13 Output voltage is regulated to 5 V. B
COMP 14 No output voltage B
EN 15 Loss of ENABLE functionality. The device remains in Shut Down mode. B
FREQ 16 Switching frequency is 2 MHz typically. C
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin NamePin No.Description of Potential Failure Effects(s)Failure Effect Class
VIN1The device does not work. Output voltage is 0 V.B
BST2The device is damaged.A
SW3Possible device damageA
SW4Possible device damageA
MODE/SYNC5Device remains in auto PFM mode. Loss of Forced PWM mode, spread spectrum functionality, and frequency synchronization functionalityC
VCC6High ripple on VCC pin. Efficiency is lower.C
GND7Possible device damageA
GND8Possible device damageA
VO9No output voltageB
OUT10Possible device damageA
PG11Correct output voltage. Loss of PG functionalityC
NC12No effectD
FB13Output voltage is out of regulation.B
COMP14Output voltage is out of regulation.B
EN15Loss of ENABLE functionality. The device remains in Shut Down mode.B
FREQ16No output voltageB
Table 4-4 Pin FMA for Device Pins Short-Circuited to Adjacent Pin
Pin NamePin No.Shorted toDescription of Potential Failure Effects(s)Failure Effect Class
VIN1BSTPossible device damageA
BST2SWOutput voltage out of regulationB
SW3SWNo effectD
SW4MODE/SYNCPossible device damageA
MODE/SYNC5VCCThe device remains in forced PWM mode. Loss of Auto PFM mode and frequency synchronization functionalityC
VCC6GNDThe device does not work. VOUT = 0 VB
GND7GNDNo effectD
GND8VOThe device remains in hiccup output short circuit protection mode.B
VO9OUTLoss of Down mode functionality and hiccup output short circuit protectionB
OUT10PGPossible device damageA
PG11NCPotential device damage if PG is pulled up to higher than 6 V.A
NC12FBNo effect

D

FB13COMPNo output voltageB
COMP14ENOVP is triggeredB
EN15FREQNo output voltageB
FREQ16VINThe FREQ pin is damaged if supply voltage is higher than 6 V.A
Table 4-5 Pin FMA for Device Pins Short-Circuited to VIN
Pin NamePin No.Description of Potential Failure Effects(s)Failure Effect Class
VIN1No effectD
BST2Possible device damageA
SW3Damage to internal power FETsA
SW4Damage to internal power FETsA
MODE/SYNC5The MODE/SYNC pin damaged if supply voltage is higher than 6 V.A
VCC6VCC pin is damaged if supply voltage is higher than 6 V.A
GND7Possible device damage due to large currentA
GND8Possible device damage due to large currentA
VO9VO = VINB
OUT10The device remains in Hiccup mode. No output voltageB
PG11Possible device damageA
NC12The NC pin is damaged if supply voltage is higher than 6 V.A
FB13The FB pin is damaged if supply voltage is higher than 6 V.A
COMP14The COMP pin is damaged if supply voltage is higher than 6 V.A
EN15The EN pin is damaged if supply voltage is higher than 6 V.A
FREQ16The FREQ pin is damaged if supply voltage is higher than 6 V.A