SFFS247 February   2022 LM25143

 

  1.   Trademarks
  2. 1Overview
  3. 2Functional Safety Failure In Time (FIT) Rates
  4. 3Failure Mode Distribution (FMD)
  5. 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 LM25143. 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
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 LM25143 pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the LM25143 data sheet.

GUID-14A4491E-C7C7-44B3-8355-F9280B66B781-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:

  • Application Circuit as per LM25143 data sheet is used
  • PG1 and PG2 are pulled-up to VOUT1 and VOUT2
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
SS2 1 VOUT1 = regulation, VOUT2 = 0 V B
COMP2 2 VOUT1 = regulation, VOUT2 = 0 V B
FB2 3 If FB = VDDA, then VOUT1 and VOUT2 = 0 V. B
If FB = GND, then VOUT1 = regulation and VOUT2 = 5 V. B
CS2 4 VOUT1 = regulation, VOUT2 = oscillation C
VOUT2 5 VOUT1 = regulation, VOUT2 = 0 V, excessive current from VIN, and enters overcurrent protection B
VCCX 6 If VCCX = GND, then VOUT1 and VOUT2 = regulation. D
If VCCX is connected to VOUT2, then VOUT1 = regulation, VOUT2 = 0 V, and the internal VCC regulator is used. B
If VCCX is connected to an external supply, then VOUT1 and VOUT2 = regulation. B
PG2 7 VOUT1 and VOUT2 = regulation, and PG2 is forced low. B
HOL2 8 VOUT1 and VOUT2 = 0 V. VCC will be discharged through HB2. B
HO2 9 VOUT1 and VOUT2 = 0 V. VCC will be discharged through HB2. B
SW2 10 VOUT1 = regulation, VOUT2 = 0 V, and excessive current from VIN A
HB2 11 VOUT1 and VOUT2 = 0 V. VCC regulator is loaded to current limit. B
LOL2 12 VOUT1 and VOUT2 = regulation D
LO2 13 VOUT1 and VOUT2 = regulation C
PGND2 14 VOUT1 and VOUT2 = regulation D
VCC 15 VOUT1 and VOUT2 = 0 V B
VCC 16 VOUT1 and VOUT2 = 0 V B
PGND1 17 VOUT1 and VOUT2 = regulation D
LO1 18 VOUT1 and VOUT2 = regulation C
LOL1 19 VOUT1 and VOUT2 = regulation C
HB1 20 VOUT1 and VOUT2 = 0 V. VCC regulator is loaded to current limit. B
SW1 21 VOUT1 = regulation, VOUT2 = 0 V, and excessive current from VIN B
HO1 22 VOUT1 and VOUT2 = 0 V B
HOL1 23 VOUT1 and VOUT2 = 0 V B
PG1 24 VOUT1 and VOUT2 = regulation, and PG1 is forced low. C
VIN 25 VOUT1 and VOUT2 = 0 V A
VOUT1 26 VOUT1 = 0 V, VOUT2 = regulation, and excessive current from VIN B
CS1 27 VOUT1 = oscillation, VOUT2 = regulation C
FB1 28 If FB1 = VDDA, then VOUT1 and VOUT2 = 0 V. B
If FB1 = GND, then VOUT1 = 5 V expected and VOUT2 = regulation. B
COMP1 29 VOUT1 = 0 V, VOUT2 = regulation B
SS1 30 VOUT1 = 0 V, VOUT2 = regulation B
EN1 31 VOUT1 = 0 V, VOUT2 = regulation B
RES 32 VOUT1 and VOUT2 = regulation, cannot exit hiccup mode B
DEMB 33 If DEMB = VDDA, then VOUT1 and VOUT2 = 0 V. B
VOUT1 and VOUT2 = regulation C
MODE 34 If MODE = VDDA, then VOUT1 and VOUT2 = 0 V. B
If MODE = GND, then VOUT1 and VOUT2 = regulation. D
AGND 35 VOUT1 and VOUT2 = regulation D
VDDA 36 VOUT1 and VOUT2 = 0 V, no switching B
RT 37 VOUT1 and VOUT2 = regulation, operating at the maximum switching frequency C
DITH 38 VOUT1 and VOUT2 = regulation C
SYNCOUT 39 VOUT1 and VOUT2 = regulation D
EN2 40 VOUT1 = 0 V, VOUT2 = regulation B
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
SS2 1 VOUT1 and VOUT2 = regulation D
COMP2 2 VOUT1 = regulation, VOUT2 = oscillation, and will not regulate C
FB2 3 VOUT2 = regulation, VOUT2 = will not regulate. The controller will be configured for adjustable output. B
CS2 4 VOUT1 = regulation, VOUT2 oscillation, and no overcurrent detection A
VOUT2 5 VOUT1 = regulation, VOUT2 = oscillation, and will not regulate A
VCCX 6 VOUT1 and VOUT2 = regulation D
PG2 7 VOUT1 and VOUT2 = regulation, no PG2 information C
HOL2 8 VOUT1 = regulation, VOUT2 = VIN, will not regulate, and excessive current from VIN D
HO2 9 VOUT1 = regulation, VOUT2 = 0 V, and will not regulate B
SW2 10 VOUT1 = regulation, VOUT2 = VIN, and high-side FET control floating A
HB2 11 VOUT1 = regulation, VOUT2 = 0 V, and high-side gate drive floating B
LOL2 12 VOUT1 = regulation, VOUT2 = 0 V, no gate discharge path for low-side MOSFET B
LO2 13 VOUT1 and VOUT2 = regulation, lower efficiency C
PGND2 14 VOUT1 and VOUT2 = 0 V, uncontrolled behavior because of the floating ground B
VCC 15 VOUT1 and VOUT2 = 0 V B
VCC 16 VOUT1 and VOUT2 = 0 V B
PGND1 17 VOUT1 and VOUT2 = 0 V, uncontrolled behavior because of the floating ground B
LO1 18 VOUT1 = regulation, lower efficiency, and VOUT2 = regulation C
LOL1 19 VOUT1 = 0 V, no discharge path for low-side MOSFET, and VOUT2 = regulation B
HB1 20 VOUT1 = regulation, VOUT2 = 0 V, and high-side gate drive floating B
SW1 21 VOUT1 = no regulation, high-side FET control floating, and VOUT2 = regulation A
HO1 22 VOUT1 = will not regulate, VOUT2 = regulation B
HOL1 23 VOUT1 = VIN, will not regulate, excessive current from VIN, and VOUT2 = regulation C
PG1 24 VOUT1 = regulation, VOUT2 = regulation, and no PG1 information C
VIN 25 VOUT1 and VOUT2 = 0 V B
VOUT1 26 VOUT1 = oscillation, will not regulate, and VOUT2 = regulation A
CS1 27 VOUT1 = oscillation, no overcurrent detection, and VOUT2 = regulation A
FB1 28 VOUT2 = will not regulate, the controller will be configured for adjustable output, and VOUT2 = regulation. B
COMP1 29 VOUT1 = oscillation and will not regulate, VOUT2 = regulation B
SS1 30 VOUT1 and VOUT2 = regulation D
EN1 31 VOUT1 and VOUT2 = 0 V B
RES 32 VOUT1 and VOUT2 = regulation, exit hiccup mode current limit quickly C
DEMB 33 VOUT1 and VOUT2 = regulation, erratic switching C
MODE 34 VOUT1 = regulation, VOUT2 = 0 V, and error amplifier CH2 is set to zero. B
AGND 35 VOUT1 and VOUT2 = 0 V B
VDDA 36 VOUT1 and VOUT2 = 0 V, noisy bias rail B
RT 37 VOUT1 and VOUT2 = 0 V B
DITH 38 VOUT1 and VOUT2 = regulation, no spread spectrum C
SYNCOUT 39 VOUT1 and VOUT2 = 0 V, cannot be synchronized to another part C
EN2 40 VOUT1 and VOUT2 = 0 V B
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
SS1 1 COMP2 VOUT1 = regulation, VOUT2 = VIN B
COMP2 2 FB2 If FB2 = VDDA, then VOUT1 = regulation and VOUT2 = VIN. A
If FB2 = GND, then VOUT1 regulation and VOUT2 = 0 V. B
FB2 3 CS2 If FB2 = VDDA, then VOUT1 = regulation and VOUT2 = 3.3 V. B
If FB2 = GND, then VOUT1 = regulation and VOUT = 0 V. B
CS2 4 VOUT2 VOUT1 = regulation, VOUT2 = oscillation B
VOUT2 5 VCCX If VOUT2 < 6.5 V, then VOUT1 and VOUT2 = regulation, B
If VOUT2 > 6.5 V, then the device damage exceeds the absolute maximum raring. A
VCCX 6 PG2 VOUT1 and VOUT2 = regulation, PG2 corrupted B
PG2 7 HOL2 VOUT1 and VOUT2 = regulation, PG2 corrupted B
If HOL2 > 6.5 V and exceeds the maximum rating, PG2 is damaged A
HOL2 8 HO2 VOUT1 and VOUT2 = regulation D
HO2 9 SW2 VOUT1 = regulation, VOUT2 < 3 V B
SW2 10 HB2 VOUT1 = regulation, VOUT2 = 0 V B
HB2 11 LOL2 VOUT1 and VOUT2 = 0 V B
LOL2 12 LO2 VOUT1 and VOUT2 = regulation B
LO2 13 PGND2 VOUT1 and VOUT2 = regulation B
PGND2 14 VCC VOUT1 and VOUT2 = 0 V A
VCC 15 VCC VOUT1 and VOUT2 = regulation D
VCC 16 PGND1 VOUT1 and VOUT2 = 0 V A
PGND1 17 LO1 VOUT1 and VOUT2 = regulation C
LO1 18 LOL1 VOUT1 and VOUT2 = regulation D
LOL1 19 HB1 VOUT1 = 0 V, VOUT2 = regulation B
HB1 20 SW1 VOUT1 = 0 V, VOUT2 = regulation B
SW1 21 HO1 VOUT1 = 0 V, VOUT2 = regulation B
HO1 22 HOL1 VOUT1 and VOUT2 = regulation D
HOL1 23 PG1 VOUT1 and VOUT2 = regulation, PG1 corrupted D
If HOL1 > 6.5 V and exceeds the maximum ratings, PG1 can be damaged. A
PG1 24 VIN If VIN < 6.5 V, then VOUT1 and VOUT2 = regulation. If VIN > 6.5 V and exceeds the maximum rating of PG1, the device is damaged. A
If VIN > 6.5 V and exceeds the maximum rating of PG1, the device is damaged. A
VIN 25 VOUT1 VOUT1 = VIN no switching, VOUT2 = regulation B
VOUT1 26 CS1 VOUT1 = oscillation, VOUT2 = regulation B
CS1 27 FB1 If FB1 = VDDA, then VOUT1 = 3.3 V and VOUT2 = regulation. B
If FB1 = GND, then VOUT1 = 0 V and VOUT2 = regulation. B
FB1 28 COMP1 If FB1 = VDDA, then VOUT1 = VIN, excessive current from VIN, and VOUT2 = regulation. A
If FB1 = GND, then VOUT1 = 0 V and VOUT2 = regulation. B
COMP1 29 SS1 VOUT1 = VIN, VOUT2 = regulation B
SS1 30 EN1 If EN < 6.5 V, then VOUT1 and VOUT2 = regulation. D
If EN1 > 6.5 V, this exceeds the maximum ratings of SS1 pin and the device will be damaged. A
EN1 31 RES If EN < 6.5 V, then VOUT1 and VOUT2 = regulation. D
If EN1 > 6.5 V, this exceeds the maximum ratings of RES pin and the device will be damaged. A
RES 32 DEMB VOUT1 and VOUT2 = regulation B
DEMB 33 MODE If DEMB = MODE = GND, then configured as independent dual-output, VOUT1 and VOUT2 = regulation. B
If DEMB = MODE = VDDA, then configured as single-output interleaved VOUT1 and VOUT2 = 0 V. B
MODE 34 AGND If MODE = GND, then VOUT1 and VOUT2 = regulation and is always in independent dual-output operation. D
AGND 35 VDDA VOUT1 and VOUT2 = 0 V B
VDDA 36 RT VOUT1 and VOUT2 = 0 V, no switching B
RT 37 DITH VOUT1 = VOUT2 = oscillation B
DITH 38 SYNCOUT VOUT1 and VOUT2 = regulation, no spread spectrum C
SYNCOUT 39 EN2 VOUT1 = regulation, VOUT2 = 0 V B
EN2 40 SS2 If EN < 6.5 V, then VOUT1 and VOUT2 = regulation. D
If EN1 > 6.5 V, this exceeds the maximum ratings of SS1 pin and the device will be damaged. A
Table 4-5 Pin FMA for Device Pins Short-Circuited to VIN
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
SS1 1 If VIN < 6.5 V, then VOUT1 and VOUT2 = regulation. D
If VIN > 6.5 V, then exceeds the SS1 maximum rating and the SS1 pin is damaged. A
COMP2 2 If VIN > 5 V and < 6.5 V, then VOUT1 and VOUT2 = 0 V. B
If VIN > 6.5 V, then exceeds the COMP2 maximum rating and the COMP2 pin is damaged. A
FB2 3 If VIN < 6.5 V and FB2 = VDDA, then VOUT1 = regulation and VOUT2 = 3.3 V. B
If VIN < 6.5 V and FB2 = GND, then VOUT1 and VOUT2 = 0 V and there is excessive current from VIN. B
If VIN > 6.5 V and exceeds the maximum ratings of the FB2 pin voltage, then the FB2 pin is damaged. A
CS2 4 If VIN < 60 V, then VOUT1 = regulation and VOUT2 = VIN. B
If VIN > 60 V and exceeds the maximum ratings of the CS2 pin, then the CS2 pin is damaged. A
VOUT2 5 If VIN < 60 V, then VOUT1 = regulation and VOUT2 = VIN. B
If VIN > 60 V and exceeds the maximum ratings of the VOUT2 pin, then the VOUT2 pin is damaged. A
VCCX 6 If VIN < 6.5 V, if VCCX = VOUT2, then VOUT1 = regulation and VOUT2 = VIN. B
If VIN > 6.5 V and exceeds the maximum ratings of the VCCX pin, then the VCCX pin is damaged. A
PG2 7 If VIN < 6.5 V, then VOUT1 and VOUT2 = regulation and PG2 forced is high. D
If VIN > 6.5 V and exceeds the maximum ratings of the PG2 pin, the PG2 pin is damaged. A
HOL2 8 If VIN < 6.5 V, then VOUT1 = regulation, VOUT2 = VIN – dropout, and there is no switching. B
If VIN > 6.5 V and exceeds the maximum ratings of the HOL2 pin, then the HOL2 pin is damaged. A
HO2 9 If VIN < 6.5 V, then VOUT1 = regulation, VOUT2 = VIN – dropout, and there is no switching. B
If VIN > 6.5 V and exceeds the maximum ratings of the HO2 pin, then the HO2 pin is damaged. A
SW2 10 VOUT1 = regulation, VOUT2 = VIN, and excessive current from VIN B
HB2 11 If VIN < 6.5 V, then VOUT1 and VOUT2 = regulation and erratic switching on CH2. B
If VIN > 6.5 V and exceeds the maximum ratings of the HB2 pin, then the HB2 pin is damaged. A
LOL2 12 If VIN < 6.5 V, then VOUT1 and VOUT2 = 0 V and excessive current from VIN. B
If VIN > 6.5 V and exceeds the maximum ratings of the LOL2 pin, then the LOL2 pin is damaged. A
LO2 13 If VIN < 6.5 V, then VOUT1 and VOUT2 = 0 V and excessive current from VIN. B
If VIN > 6.5 V and exceeds the maximum ratings of the LO2 pin, then the LO2 pin is damaged. A
PGND2 14 VOUT and VOUT2 = 0 V, excessive current from VIN B
VCC 15 If VIN < 6.5 V, then VOUT1 and VOUT2 = regulation. D
If VIN > 6.5 V and exceeds the maximum ratings of the VCC pin, then the VCC pin is damaged. A
VCC 16 If VIN < 6.5 V, then VOUT1 and VOUT2 = regulation. D
If VIN > 6.5 V and exceeds the maximum ratings of the VCC pin, then the VCC pin is damaged. A
PGND1 17 VOUT1 and VOUT2 = 0 V, excessive current from VIN B
LO1 18 If VIN < 6.5 V, then VOUT1 and VOUT2 = 0 V, and excessive current from VIN. B
If VIN > 6.5 V and exceeds the maximum ratings of the LO1 pin, then the LO1 pin is damaged. A
LOL1 19 If VIN < 6.5 V, then VOUT1 and VOUT2 = 0 V and excessive current from VIN. B
If VIN > 6.5 V and exceeds the maximum ratings of the LOL1 pin, then the LOL1 pin is damaged. A
HB1 20 If VIN < 6.5 V, then VOUT1 and VOUT2 = regulation. C
If VIN > 6.5 V and exceeds the maximum ratings of the HB1 pin, then the HB1 pin is damaged. A
SW1 21 VOUT1 = VIN, VOUT2 = regulation, and excessive current from VIN B
HO1 22 If VIN < 6.5 V, then VOUT1 = VIN – dropout, VOUT2 = regulation, and no switching. B
If VIN > 6.5 V and exceeds the maximum ratings of the HB1 pin, then the HO1 pin is damaged. A
HOL1 23 If VIN < 6.5 V, then VOUT1 = VIN – dropout, VOUT2 = regulation, and no switching. B
If VIN > 6.5 V and exceeds the maximum ratings of the HB1 pin, then the HOL1 pin is damaged. A
PG1 24 If VIN < 6.5 V, VOUT1 and VOUT2 = regulation and PG1 is forced high. D
If VIN > 6.5 V and exceeds the maximum ratings of the PG1 pin, then PG1 pin is damaged. A
VIN 25 VOUT1 and VOUT2 = regulation D
VOUT1 26 If VIN < 60 V, then VOUT1 = VIN and VOUT2 = regulation. B
If VIN > 60 V and exceeds the maximum ratings of the VOUT1 pin, then the VOUT1 pin is damaged. A
CS1 27 If VIN < 60 V, then VOUT1 = VIN and VOUT2 = regulation. B
If VIN > 60 V and exceeds the maximum ratings of the CS1 pin, then the CS1 pin is damaged. A
FB1 28 If VIN < 6.5 V and FB1= VDDA, then VOUT1 = 3.3 V and VOUT2 = regulation. B
If VIN < 6.5 V and FB1 = GND, then VOUT1 and VOUT2 = 0 V and excessive current from VIN. B
If VIN > 6.5 V and exceeds the maximum ratings of the FB1 pin voltage, the FB1 pin is damaged. A
COMP1 29 If VIN > 5 V and < 6.5 V, then VOUT1 and VOUT2 = 0 V. B
If VIN > 6.5 V and exceeds the COMP1 maximum rating, then COMP1 pin is damaged. A
SS1 30 If VIN < 6.5 V, then VOUT1 and VOUT2 = regulation. D
If VIN > 6.5 V and exceeds the SS1 maximum rating, then SS1 pin is damaged. A
EN1 31 VOUT1 and VOUT2 regulation D
RES 32 If VIN < 6.5 V, then VOUT1 = regulation, VOUT2 = regulation, and no hiccup mode. C
If VIN > 6.5 V and exceeds the RES maximum rating, then the RES pin is damaged. A
DEMB 33 If VIN < 6.5 V, then VOUT1 and VOUT2 = regulation. B
If VIN > 6.5 V and exceeds the DEMB maximum rating, then the DEMB pin is damaged. A
MODE 34 If MODE = GND, then VOUT1 and VOUT2 = 0 V. B
If MODE = VDDA = and VIN < 6.5 V, then VOUT1 and VOUT2 = regulation. B
If VIN > 6.5 V and exceeds the MODE pin maximum rating, then the MODE pin is damaged. A
AGND 35 VOUT1 and VOUT2 = 0 V, excessive current from VIN B
VDDA 36 If VIN < 6.5 V, then VOUT1 and VOUT2 = regulation. D
If VIN > 6.5 V and exceeds the VDDA pin maximum rating, then the VDDA pin is damaged. A
RT 37 If VIN < 6.5 V, then VOUT1 and VOUT2 = 0 V. B
If VIN > 6.5 V and exceeds the RT pin maximum rating, then the RT pin is damaged. A
DITH 38 If VIN < 6.5 V, then VOUT1 and VOUT2 = regulation. B
If VIN > 6.5 V and exceeds the DITH pin maximum rating, then the DITH pin is damaged. A
SYNCOUT 39 If VIN < 6.5 V, then VOUT1 and VOUT2 = regulation. B
If VIN > 6.5 V and exceeds the SYNCOUT pin maximum rating, then the SYNCOUT pin is damaged. A
EN2 40 VOUT1 and VOUT2 = regulation D