SLVAES3C May   2020  – October 2020 TPS61378-Q1

 

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

4 Pin Failure Mode Analysis (Pin FMA)

This section provides a Failure Mode Analysis (FMA) for the pins of the TPS61378-Q1, TPS613781-Q1, TPS613782-Q1, TPS613783-Q1, TPS613784-Q1, TPS613785-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
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 shows the TPS61378-Q1, TPS613781-Q1, TPS613782-Q1, TPS613783-Q1, TPS613784-Q1, TPS613785-Q1 pin diagram. For a detailed description of the device pins please refer to the 'Pin Configuration and Functions' section in the TPS61378-Q1 datasheet.

GUID-20200915-CA0I-S16K-P02V-T3L95RWN8CVZ-low.gif Figure 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 TPS61378-Q1 data sheet.
  • Configuration as shown in the 'Application and Implementation' found in the TPS61378-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 Device will not operate. Power supply is short. B
BST 2 Possibe device damage. A
SW 3 Potential damage to inductor and pin. A
SW 4 Potential damage to inductor and pin. A
MODE/SYNC 5 For TPS61378-Q1, TPS613781-Q1, TPS613782-Q1, device will remain in auto PFM mode. Loss of forced PWM mode, spread spectrum functionality and frequency synchronization functionality. C
For TPS613783-Q1, TPS613784-Q1, TPS613785-Q1, device will remain in auto PFM mode. Loss of forced PWM mode and frequency synchronization funtionality.
VCC 6 Output voltage out of regulation. B
GND 7 No effect. D
GND 8 No effect. D
VO 9 Device will reamin 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
ILIM 12 Correct output voltage. Peak switch current limit is maximum and can't be configured. C
FB 13 For TPS61378-Q1, TPS613783-Q1, Vout = 5 V. B
For TPS613781-Q1, TPS613784-Q1, Vout = 5.7 V.
For TPS613782-Q1, TPS613785-Q1, Vout = 9 V.
COMP 14 No output voltage. B
EN 15 Loss of ENABLE functionality. Device will remain in shut-down mode. B
FREQ 16 Switching frequency is 2MHz typically. C
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin Name Pin No. Description of Potential Failure Effects(s) Failure Effect Class
VIN 1 Device doesn’t work. Vout = 0 V. B
BST 2 Device damaged. A
SW 3 Possible device damage. A
SW 4 Possible device damage. A
MODE/SYNC 5 For TPS61378-Q1, TPS613781-Q1, TPS613782-Q1, device will remain in auto PFM mode. Loss of forced PWM mode, spread spectrum functionality and frequency synchronization functionality. C
For TPS613783-Q1, TPS613784-Q1, TPS613785-Q1, device will remain in auto PFM mode. Loss of forced PWM mode and frequency synchronization functionality.
VCC 6 High ripple on VCC pin. Effeiciency is lower. C
GND 7 Possible device damage. A
GND 8 Possible device damage. A
VO 9 No output voltage. B
OUT 10 Possible device damage. A
PG 11 Correct output voltage. Loss of PG functionality. C
ILIM 12 Output current capability decreases. B
FB 13 Output voltage is out of regulation. B
COMP 14 Output voltage is out of regulation. B
EN 15 Loss of ENABLE functionality. Device will remain in shut-down mode. B
FREQ 16 No output voltage. B
Table 4-4 Pin FMA for Device Pins Short-Circuited to Adjacent Pin
Pin Name Pin No. Shorted to Description of Potential Failure Effects(s) Failure Effect Class
VIN 1 BST Possible device damage. A
BST 2 SW Output voltage out of regulation. B
SW 3 SW No effect. D
SW 4 MODE/SYNC Possible device damage. A
MODE/SYNC 5 VCC Device will remain in forced PWM mode. Loss of auto PFM mode and frequency synchronization functionality. C
VCC 6 GND Device doesn't work. Vout = 0 V. B
GND 7 GND No effect. D
GND 8 VO Device will reamin in hiccup output short circuit protection mode. B
VO 9 OUT Loss of down mode functionality and hiccup output short circuit protection. B
OUT 10 PG Possible device damage. A
PG 11 ILIM Potential device damage if PG is pulled up to higher than 6 V. A
ILIM 12 FB OVP is triggered. B
FB 13 COMP No output voltage. B
COMP 14 EN OVP is triggered. B
EN 15 FREQ No output voltage. B
Table 4-5 Pin FMA for Device Pins Short-Circuited to supply
Pin Name Pin No. Description of Potential Failure Effects(s) Failure Effect Class
VIN 1 No effect. D
BST 2 Possible device damage. A
SW 3 Damage to internal power FETs. A
SW 4 Damage to internal power FETs. A
MODE/SYNC 5 MODE/SYNC pin damaged if supply voltage is higher than 6 V. A
VCC 6 VCC pin damaged if supply voltage is higher than 6 V. A
GND 7 Possible device damage due to large current. A
GND 8 Possible device damage due to large current. A
VO 9 Vo = Vin. B
OUT 10 Device ramain in hiccup mode. No output voltage. B
PG 11 Possible device damage. A
ILIM 12 ILIM pin damaged if supply voltage is higher than 6 V. A
FB 13 FB pin damaged if supply voltage is higher than 6 V. A
COMP 14 COMP pin damaged if supply voltage is higher than 6 V. A
EN 15 EN pin damaged if supply voltage is higher than 6 V. A
FREQ 16 FREQ pin damaged if supply voltage is higher than 6 V. A