SFFS247 February 2022 LM25143
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.
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.
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 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 |
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 |
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 |
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 |