SFFS245 February 2022 LM5143
This section provides a Failure Mode Analysis (FMA) for the pins of the LM5143. 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 LM5143 pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the LM5143 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, VOUT1 = 0 V, VOUT2 = 0 V. | B |
If FB = GND, VOUT1 = regulation, VOUT2 = 5 V. | B | ||
CS2 | 4 | VOUT1 = regulation, VOUT2 = oscillation | C |
VOUT2 | 5 | VOUT1 = regulation, VOUT2 = 0 V, excessive current from VIN, enters overcurrent protection | B |
VCCX | 6 | If VCCX = GND, VOUT1 = regulation and VOUT2 = regulation. | D |
If VCCX is connected to VOUT2, VOUT1 = regulation, VOUT2 = 0 V, and the internal VCC regulator is used. | B | ||
If VCCX is connected to an external supply, VOUT1 = regulation and VOUT2 = regulation. | B | ||
PG2 | 7 | VOUT1 = regulation, VOUT2 = regulation, PG2 forced low | B |
HOL2 | 8 | VOUT1 = 0 V, VOUT2 = 0 V, VCC is discharged through HB2. | B |
HO2 | 9 | VOUT1 = 0 V, VOUT2 = 0 V, VCC is discharged through HB2. | B |
SW2 | 10 | VOUT1 = regulation, VOUT2 = 0 V, excessive current from VIN | A |
HB2 | 11 | VOUT1 = 0 V, VOUT2 = 0 V, VCC regulator loaded to current limit | B |
LOL2 | 12 | VOUT1 = regulation, VOUT2 = regulation | D |
LO2 | 13 | VOUT1 = regulation, VOUT2 = regulation | C |
PGND2 | 14 | VOUT1 = regulation, VOUT2 = regulation | D |
VCC | 15 | VOUT1 = 0 V, VOUT2 = 0 V | B |
VCC | 16 | VOUT1 = 0 V, VOUT2 = 0 V | B |
PGND1 | 17 | VOUT1 = regulation, VOUT2 = regulation | D |
LO1 | 18 | VOUT1 = regulation, VOUT2 regulation | C |
LOL1 | 19 | VOUT1 = regulation, VOUT2 = regulation | C |
HB1 | 20 | VOUT1 = 0 V, VOUT2 = 0 V, VCC regulator load to current limit | B |
SW1 | 21 | VOUT1 = regulation, VOUT2 = 0 V, excessive current from VIN | B |
HO1 | 22 | VOUT1 = 0 V, VOUT2 = 0 V | B |
HOL1 | 23 | VOUT1 = 0 V, VOUT2 = 0 V | B |
PG1 | 24 | VOUT1 = regulation, VOUT2 = regulation, PG1 forced low | C |
VIN | 25 | VOUT1 = 0 V, VOUT2 = 0 V | A |
VOUT1 | 26 | VOUT1 = 0 V, VOUT2 = regulation, excessive current from VIN | B |
CS1 | 27 | VOUT1 = oscillation, VOUT2 = regulation | C |
FB1 | 28 | If FB1 = VDDA, VOUT1 = 0 V, VOUT2 = 0 V | B |
If FB1 = GND, VOUT1 = 5 V expected, 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 = regulation, VOUT2 = regulation, cannot exit hiccup mode | B |
DEMB | 33 | If DEMB = VDDA, VOUT1 = 0 V, VOUT2 = 0 V | B |
VOUT1 = regulation, VOUT2 = regulation | C | ||
MODE | 34 | If MODE = VDDA, VOUT1 = 0 V and VOUT2 = 0 V. | B |
If MODE = GND, VOUT1 = regulation and VOUT2 = regulation. | D | ||
AGND | 35 | VOUT1 = regulation, VOUT2 = regulation | D |
VDDA | 36 | VOUT1 = 0 V, VOUT2 = 0 V, no switching | B |
RT | 37 | VOUT1 = regulation, VOUT2 = regulation, operating at the maximum switching frequency | C |
DITH | 38 | VOUT1 = regulation, VOUT2 = regulation | C |
SYNCOUT | 39 | VOUT1 = regulation, 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 = regulation, VOUT2 = regulation | D |
COMP2 | 2 | VOUT1 = regulation, VOUT2 = oscillation and will not regulate | C |
FB2 | 3 | VOUT2 = regulation, VOUT2 = will not regulate, and the controller will be configured for adjustable output. | B |
CS2 | 4 | VOUT1 = regulation, VOUT2 oscillation, no overcurrent detection | A |
VOUT2 | 5 | VOUT1 = regulation, VOUT2 = oscillation, will not regulate | A |
VCCX | 6 | VOUT1 = regulation, VOUT2 = regulation | D |
PG2 | 7 | VOUT1 = regulation, VOUT2 = regulation, no PG2 information | C |
HOL2 | 8 | VOUT1 = regulation, VOUT2 = VIN, will not regulate, excessive current from VIN | D |
HO2 | 9 | VOUT1 = regulation, VOUT2 = 0 V, will not regulate | B |
SW2 | 10 | VOUT1 = regulation, VOUT2 = VIN, high-side FET control floating | A |
HB2 | 11 | VOUT1 = regulation, VOUT2 = 0 V, 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 = regulation, VOUT2 = regulation, lower efficiency | C |
PGND2 | 14 | VOUT1 = 0 V, VOUT2 = 0 V, uncontrolled behavior because of the floating ground | B |
VCC | 15 | VOUT1 = 0 V, VOUT2 = 0 V | B |
VCC | 16 | VOUT1 = 0 V, VOUT2 = 0 V | B |
PGND1 | 17 | VOUT1 = 0 V, VOUT2 = 0 V, uncontrolled behavior because of the floating ground | B |
LO1 | 18 | VOUT1 = regulation, lower efficiency VOUT2 = regulation | C |
LOL1 | 19 | VOUT1 = 0 V, no discharge path for low-side MOSFET, VOUT2 = regulation | B |
HB1 | 20 | VOUT1 = regulation, VOUT2 = 0 V, high-side gate drive floating | B |
SW1 | 21 | VOUT1 = no regulation, high-side FET control floating, VOUT2 = regulation | A |
HO1 | 22 | VOUT1 = will not regulate, VOUT2 = regulation | B |
HOL1 | 23 | VOUT1 = VIN, will not regulate, excessive current from VIN, VOUT2 = regulation | C |
PG1 | 24 | VOUT1 = regulation, VOUT2 = regulation, no PG1 information | C |
VIN | 25 | VOUT1 = 0 V, VOUT2 = 0 V | B |
VOUT1 | 26 | VOUT1 = oscillation, will not regulate, VOUT2 = regulation | A |
CS1 | 27 | VOUT1 = oscillation, no over current detection, VOUT2 = regulation | A |
FB1 | 28 | VOUT2 = will not regulate, the controller will be configured for adjustable output, VOUT2 = regulation | B |
COMP1 | 29 | VOUT1 = oscillation and will not regulate, VOUT2 = regulation | B |
SS1 | 30 | VOUT1 = regulation, VOUT2 = regulation | D |
EN1 | 31 | VOUT1 = 0 V, VOUT2 = 0 V | B |
RES | 32 | VOUT1 = regulation, VOUT2 = regulation, exit hiccup mode current limit quickly | C |
DEMB | 33 | VOUT1 = regulation, VOUT2 = regulation, erratic switching | C |
MODE | 34 | VOUT1 = regulation, VOUT2 = 0 V, error amplifier CH2 is set to zero | B |
AGND | 35 | VOUT1 = 0 V, VOUT2 = 0 V | B |
VDDA | 36 | VOUT1 = 0 V, VOUT2 = 0 V, noisy bias rail | B |
RT | 37 | VOUT1 = 0 V, VOUT2 = 0 V | B |
DITH | 38 | VOUT1 = regulation, VOUT2 = regulation, no spread spectrum | C |
SYNCOUT | 39 | VOUT1 = 0 V, VOUT2 = 0 V, cannot be synchronized to another part | C |
EN2 | 40 | VOUT1 = 0 V, 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, VOUT2 = VIN | A |
If FB2 = GND, VOUT1 regulation, VOUT2 = 0 V | B | |||
FB2 | 3 | CS2 | If FB2 = VDDA, then VOUT1 = regulation, VOUT2 = 3.3 V | B |
If FB2 = GND, VOUT1 = regulation, VOUT = 0 V | B | |||
CS2 | 4 | VOUT2 | VOUT1 = regulation, VOUT2 = oscillation | B |
VOUT2 | 5 | VCCX | If VOUT2 < 6.5 V, VOUT1 = regulation, VOUT2 = regulation | B |
If VOUT2 > 6.5V, the device damage exceeds the absolute maximum raring. | A | |||
VCCX | 6 | PG2 | VOUT1 = regulation, VOUT2 = regulation, PG2 corrupted | B |
PG2 | 7 | HOL2 | VOUT2 = regulation, VOLUT2 = regulation, PG2 corrupted | B |
If HOL2 > 6.5 V, exceeds the maximum rating PG2 is damaged | A | |||
HOL2 | 8 | HO2 | VOUT1 = regulation, 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 = 0 V, VOUT2 = 0 V | B |
LOL2 | 12 | LO2 | VOUT1 = regulation, VOUT2 = regulation | B |
LO2 | 13 | PGND2 | VOUT1 = regulation, VOUT2 - regulation | B |
PGND2 | 14 | VCC | VOUT1 = 0 V, VOUT2 = 0 V | A |
VCC | 15 | VCC | VOUT1 = regulation, VOUT2 = regulation | D |
VCC | 16 | PGND1 | VOUT1 = 0 V, VOUT2 = 0 V | A |
PGND1 | 17 | LO1 | VOUT1 = regulation, VOUT2 = regulation | C |
LO1 | 18 | LOL1 | VOUT1 = regulation, 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 = regulation, VOUT2 = regulation | D |
HOL1 | 23 | PG1 | VOUT1 = regulation, VOUT2 = regulation, PG1 corrupted | D |
If HOL1 > 6.5 V, exceeds the maximum ratings PG1 can be damaged. | A | |||
PG1 | 24 | VIN | If VIN < 6.5 V, VOUT1 = regulation, and VOUT2 = regulation. If VIN > 6.5 V, exceeds the maximum rating of PG1 and the device is damaged. | A |
If VIN > 6.5 V, exceeds the maximum rating of PG1 and 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, 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, VOUT1 = regulation 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, VOUT1 = regulation 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 = regulation, VOUT2 = regulation | B |
DEMB | 33 | MODE | If DEMB = MODE = GND, then the device is configured as an independent dual-output, VOUT1 = regulation, and VOUT2 = regulation. | B |
If DEMB = MODE = VDDA, then the device is configured as a single-output interleaved VOUT1 = 0 V, and VOUT2 = 0 V. | B | |||
MODE | 34 | AGND | If MODE = GND, VOUT1 = regulation, VOUT2 = regulation and is always in independent dual-output operation. | D |
AGND | 35 | VDDA | VOUT1 = 0 V, VOUT2 = 0 V | B |
VDDA | 36 | RT | VOUT1 = 0 V, VOUT2 = 0 V, no switching | B |
RT | 37 | DITH | VOUT1 = VOUT2 = oscillation | B |
DITH | 38 | SYNCOUT | VOUT1 = regulation, VOUT2 = regulation, no spread spectrum | C |
SYNCOUT | 39 | EN2 | VOUT1 = regulation, VOUT2 = 0 V | B |
EN2 | 40 | SS2 | If EN < 6.5 V, VOUT1 = regulation, 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, VOUT1 = regulation and VOUT2 = regulation. | D |
If VIN > 6.5 V, exceeds the SS1 maximum rating and there is SS1 pin damage. | A | ||
COMP2 | 2 | If VIN > 5 V and < 6.5 V, VOUT1 = 0 V and VOUT2 = 0 V. | B |
If VIN > 6.5 V, exceeds the COMP2 maximum rating and there is COMP2 pin damage. | 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 = 0 V, VOUT2 = 0 V, and excessive current from VIN | B | ||
If VIN > 6.5 V, exceeds the maximum ratings of the FB2 pin voltage and FB2 pin damage. | A | ||
CS2 | 4 | If VIN < 60 V, VOUT1 = regulation and VOUT2 = VIN. | B |
If VIN > 60 V, exceeds the maximum ratings of the CS2 pin and there is CS2 pin damage. | A | ||
VOUT2 | 5 | If VIN < 60 V, VOUT1 = regulation and VOUT2 = VIN. | B |
If VIN > 60 V, exceeds the maximum ratings of the VOUT2 pin and there is VOUT2 pin damage. | A | ||
VCCX | 6 | If VIN < 6.5 V, if VCCX = VOUT2, VOUT1 = regulation and VOUT2 = VIN. | B |
If VIN > 6.5 V, exceeds the maximum ratings of the VCCX pin and the VCCX pin is damaged. | A | ||
PG2 | 7 | If VIN < 6.5 V, VOUT1 = regulation, VOUT2 = regulation and PG2 forced high. | D |
If VIN > 6.5 V, exceeds the maximum ratings of the PG2 pin and the PG2 is pin damaged. | A | ||
HOL2 | 8 | If VIN < 6.5 V, VOUT1 = regulation, VOUT2 = VIN – dropout, and there is no switching. | B |
If VIN > 6.5 V, exceeds the maximum ratings of the HOL2 pin and the LOL2 pin is damaged. | A | ||
HO2 | 9 | If VIN < 6.5 V, VOUT1 = regulation, VOUT2 = VIN – dropout, and there is no switching. | B |
If VIN > 6.5 V, exceeds the maximum ratings of the HO2 pin and 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, VOUT1 = regulation, VOUT2 = regulation, and there is erratic switching on CH2. | B |
If VIN > 6.5 V, exceeds the maximum ratings of the HB2 pin and the HB2 pin is damaged. | A | ||
LOL2 | 12 | If VIN < 6.5 V, VOUT1 = 0 V, VOUT2 = 0 V, and there is excessive current from VIN. | B |
If VIN > 6.5 V, exceeds the maximum ratings of the LOL2 pin and the LOL2 pin is damaged. | A | ||
LO2 | 13 | If VIN < 6.5 V, VOUT1 = 0 V, VOUT2 = 0 V and there is excessive current from VIN. | B |
If VIN > 6.5 V, exceeds the maximum ratings of the LO2 pin and the LO2 pin is damaged. | A | ||
PGND2 | 14 | VOUT = 0 V, VOUT2 = 0 V, and excessive current from VIN | B |
VCC | 15 | If VIN < 6.5 V, VOUT1 = regulation and VOUT2 = regulation. | D |
If VIN > 6.5 V, exceeds the maximum ratings of the VCC pin and the VCC pin is damaged. | A | ||
VCC | 16 | If VIN < 6.5 V, VOUT1 = regulation and VOUT2 = regulation. | D |
If VIN > 6.5 V, exceeds the maximum ratings of the VCC pin and the VCC pin is damaged. | A | ||
PGND1 | 17 | VOUT1 = 0 V, VOUT2 = 0 V, and excessive current from VIN | B |
LO1 | 18 | If VIN < 6.5 V, VOUT1 = 0 V, VOUT2 = 0 V, and there is excessive current from VIN. | B |
If VIN > 6.5 V, exceeds the maximum ratings of the LO1 pin and the LO1 pin is damaged. | A | ||
LOL1 | 19 | If VIN < 6.5 V, VOUT1 = 0 V, VOUT2 = 0 V, and there is excessive current from VIN. | B |
If VIN > 6.5 V, exceeds the maximum ratings of the LOL1 pin and the LOL1 pin is damaged. | A | ||
HB1 | 20 | If VIN < 6.5 V, VOUT1 = regulation and VOUT2 = regulation. | C |
If VIN > 6.5 V, exceeds the maximum ratings of the HB1 pin and 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, VOUT1 = VIN – dropout, VOUT2 = regulation, and there is no switching. | B |
If VIN > 6.5 V, exceeds the maximum ratings of the HB1 pin and the HO1 pin is damaged. | A | ||
HOL1 | 23 | If VIN < 6.5 V, VOUT1 = VIN – dropout, VOUT2 = regulation, there is no switching. | B |
If VIN > 6.5 V, exceeds the maximum ratings of the HB1 pin and the HOL1 pin is damaged. | A | ||
PG1 | 24 | If VIN < 6.5 V, VOUT1 = regulation, VOUT2 = regulation, and PG1 is forced high. | D |
If VIN > 6.5 V, exceeds the maximum ratings of the PG1 pin and the PG1 pin is damaged. | A | ||
VIN | 25 | VOUT1 = regulation, VOUT2 = regulation | D |
VOUT1 | 26 | If VIN < 60 V, VOUT1 = VIN and VOUT2 = regulation. | B |
If VIN > 60 V, exceeds the maximum ratings of the VOUT1 pin and the VOUT1 pin is damaged. | A | ||
CS1 | 27 | If VIN < 60 V, VOUT1 = VIN and VOUT2 = regulation. | B |
If VIN > 60 V, exceeds the maximum ratings of the CS1 pin and 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 = 0 V, VOUT2 = 0 V, and there is excessive current from VIN. | B | ||
If VIN > 6.5 V, exceeds the maximum ratings of the FB1 pin voltage and there is FB1 pin damage. | A | ||
COMP1 | 29 | If VIN > 5 V and < 6.5 V, VOUT1 = 0 V and VOUT2 = 0 V. | B |
If VIN > 6.5 V, exceeds the COMP1 maximum rating and there is COMP1 pin damage. | A | ||
SS1 | 30 | If VIN < 6.5 V, VOUT1 = regulation and VOUT2 = regulation. | D |
If VIN > 6.5 V, exceeds the SS1 maximum rating and there is SS1 pin damage. | A | ||
EN1 | 31 | VOUT1 = regulation, VOUT2 regulation | D |
RES | 32 | If VIN < 6.5 V, VOUT1 = regulation, VOUT2 = regulation, and no hiccup mode. | C |
If VIN > 6.5 V, exceeds the RES maximum rating and there is RES pin damage. | A | ||
DEMB | 33 | If VIN < 6.5 V, VOUT1 = regulation and VOUT2 = regulation. | B |
If VIN > 6.5 V, exceeds the DEMB maximum rating and there is DEMB pin damage. | A | ||
MODE | 34 | If MODE = GND, VOUT1 = 0 V and VOUT2 = 0 V. | B |
If MODE = VDDA = and VIN < 6.5 V, then VOUT1 = regulation and VOUT2 = regulation. | B | ||
If VIN > 6.5 V, exceeds the MODE pin maximum rating and the MODE pin is damaged. | A | ||
AGND | 35 | VOUT1 = 0 V, VOUT2 = 0 V, and there is excessive current from VIN. | B |
VDDA | 36 | If VIN < 6.5 V, VOUT1 = regulation, and VOUT2 = regulation. | D |
If VIN > 6.5 V, exceeds the VDDA pin maximum rating and the VDDA pin is damaged. | A | ||
RT | 37 | If VIN < 6.5 V, VOUT1 = 0 V and VOUT2 = 0 V. | B |
If VIN > 6.5 V, exceeds the RT pin maximum rating and the RT pin is damaged. | A | ||
DITH | 38 | If VIN < 6.5 V, VOUT1 = regulation and VOUT2 = regulation. | B |
If VIN > 6.5 V, exceeds the DITH pin maximum rating and the DITH pin is damaged. | A | ||
SYNCOUT | 39 | If VIN < 6.5 V, VOUT1 = regulation and VOUT2 = regulation. | B |
If VIN > 6.5 V, exceeds the SYNCOUT pin maximum rating and the SYNCOUT pin is damaged. | A | ||
EN2 | 40 | VOUT1 = regulation and VOUT2 = regulation | D |