SFFS692 august   2023 TPS552872-Q1

 

  1.   1
  2.   Trademarks
  3. 1Overview
  4. 2Functional Safety Failure In Time (FIT) Rates
  5. 3Failure Mode Distribution (FMD)
  6. 4Pin Failure Mode Analysis (Pin FMA)

4 Pin Failure Mode Analysis (Pin FMA)

This section provides a Failure Mode Analysis (FMA) for the pins of the TPS552872-Q1. The failure modes covered in this document include the typical pin-by-pin failure scenarios:

  • Pin short-circuited to Ground (see Table 4-2)
  • Pin open-circuited (see Table 4-3)
  • Pin short-circuited to an adjacent pin (see Table 4-4)
  • Pin short-circuited to supply (see Table 4-5)

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 TPS552872-Q1 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the TPS552872-Q1 data sheet.

GUID-E0C89298-B0F7-4D01-BCDC-7E2E3A4A2FD3-low.svg Figure 4-1 TPS552872-Q1 Pin Diagram

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

  • The device is used within the Recommended Operating Conditions and the Absolute Maximum Ratings in the TPS552872-Q1 data sheet.
  • The configuration is as shown in the Application and Implementation section found in the TPS552872-Q1 data sheet.
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
EN/UVLO 1 Loss of ENABLE functionality. The device remains in shutdown mode. B
MODE 2 The device works in auto PFM mode, loss of forced PWM functionality. C
PG 3 Correct output voltage. Loss of power-good indication functionality. C
CC 4 Correct output voltage. Loss of constant current output indication functionality. C
DITH/SYNC 5 Correct output voltage. Loss of DITH/SYNC functionality. C
FSW 6 Possible device damage. A
VIN 7 The device does not operate. Power supply is short. B
SW1 8 Possible device damage. A
PGND 9 No effect. D
SW2 10 Possible device damage. A
VOUT 11 The device remains in hiccup output short circuit protection mode. B
ISP 12 The device remains in hiccup output short circuit protection mode. B
ISN 13 No output voltage. B
FB 14 Out rises to 23.5 V until output overvoltage protection is triggered. B
COMP 15 The output voltage is out of regulation. B
CDC 16 Loss of the cable voltage droop compensation functionality and the output voltage is overcompensated. B
AGND 17 The internal circuited can be disturbed. C
VCC 18 The device does not operate. VCC is short. B
BOOT2 19 No output voltage. B
BOOT1 20 No output voltage. B
EXTVCC 21 The device selects the external power supply to supply the device through the VCC pin. If there is no external 5-V rail supplying VCC, the device does not operate and output is 0 V. If there is external 5-V rail supplying VCC, no effect on device operating. B
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
EN/UVLO 1 No output voltage. Loss of ENABLE functionality. B
MODE 2 Correct output voltage. But working mode is not fixed. C
PG 3 Correct output voltage. Loss of power-good indication functionality. C
CC 4 Correct output voltage. Loss of constant current output indication functionality. C
DITH/SYNC 5 Correct output voltage. Loss of DITH/SYNC functionality. C
FSW 6 No output voltage. B
VIN 7 The device does not work and there is no output voltage. B
SW1 8 Possible device damage. A
PGND 9 Possible device damage. A
SW2 10 Possible device damage. A
VOUT 11 Possible device damage. A
ISP 12 No output voltage. B
ISN 13 The output voltage is out of regulation. B
FB 14 OVP is triggered. B
COMP 15 Output voltage is out of regulation. B
CDC 16 Loss of CDC functionality and no cable voltage drop compensation. C
AGND 17 Possible device damage. A
VCC 18 Possible device damage. A
BOOT2 19 Efficiency is lower. B
BOOT1 20 Possible device damage. A
EXTVCC 21 The device always selects internal LDO as VCC source. Loss of external VCC supply functionality. C
Table 4-4 Pin FMA for Device Pins Short-Circuited to Adjacent Pin
Pin Name Pin No. Shorted to Description of Potential Failure Effect(s) Failure Effect Class
EN/UVLO 1 MODE The MODE pin is damaged if EN/UVLO pin is higher than 6 V. A
MODE 2 PG Correct output voltage. Loss of MODE and PG functionality. B
PG 3 CC Correct output voltage. Loss of PG and CC functionality. C
CC 4 DITH/SYNC Correct output voltage. Loss of CC and DITH/SYNC functionality. C
DITH/SYNC 5 FSW Possible device damage. A
FSW 6 VIN The FSW pin is damaged if VIN pin is higher than 6 V. A
VIN 7 SW1 Possible device damage. A
SW1 8 PGND Possible device damage. A
PGND 9 SW2 Possible device damage. A
SW2 10 VOUT Possible device damage. A
VOUT 11 ISP Output current limit accuracy is affected. C
ISP 12 ISN Correct output voltage. Loss of output current limit functionality. C
ISN 13 FB Output voltage equals 1.2 V. B
FB 14 COMP Output voltage is out of regulation. B
COMP 15 CDC Output voltage is out of regulation. B
CDC 16 AGND Loss of the cable voltage droop compensation functionality and the output voltage is overcompensated. B
AGND 17 VCC The device does not operate. VCC is short. B
VCC 18 BOOT2 The VCC pin is damaged if BOOT2 is higher than 6 V. A
BOOT2 19 VOUT Possible device damage. A
BOOT1 20 VIN Possible device damage. A
BOOT1 20 EXTVCC Possible device damage. A
EXTVCC 21 EN/UVLO EXTVCC pin is damaged if EN/UVLO pin is higher than 6 V. A
Table 4-5 Pin FMA for Device Pins Short-Circuited to Supply
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
EN/UVLO 1 The EN/UVLO pin is damaged if supply voltage is higher than 20 V. A
MODE 2 The MODE pin is damaged if supply voltage is higher than 6 V. A
PG 3 The PG pin is damaged if supply voltage is higher than 6 V. A
CC 4 The CC pin is damaged if supply voltage is higher than 6 V. A
DITH/SYNC 5 The DITH/SYNC pin is damaged if supply voltage is higher than 6 V. A
FSW 6 The FSW pin is damaged if supply voltage is higher than 6 V. A
VIN 7 No effect. D
SW1 8 Possible device damage. A
PGND 9 The device does not operate. Power supply is short. B
SW2 10 The device is damaged if supply voltage is higher than 25 V. A
VOUT 11 The VOUT pin is damaged if supply voltage is higher than 25 V. The output voltage is equal to the supply voltage. A
ISP 12 The ISP pin is damaged if supply voltage is higher than 25 V. The output voltage is equal to the supply voltage. A
ISN 13 The ISN pin damaged if supply voltage is higher than 25 V. The output voltage is equal to the supply voltage. A
FB 14 The FB pin is damaged if supply voltage is higher than 6 V. A
COMP 15 The COMP pin is damaged if supply voltage is higher than 6 V. A
CDC 16 The CDC pin is damaged if supply voltage is higher than 6 V. A
AGND 17 The device does not operate. Power supply is short. B
VCC 18 The VCC pin is damaged if supply voltage is higher than 6 V. A
BOOT2 19 The BOOT2 pin is damaged if supply voltage is higher than 31 V. A
BOOT1 20 Possible device damage. A
EXTVCC 21 The EXTVCC pin is damaged if supply voltage is higher than 6 V. A