SNVA995 October 2020 LM61440 , LM61460
This section provides a Failure Mode Analysis (FMA) for the pins of the LM61440 and LM61460. 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 LM61440 and LM61460 pin diagram. For a detailed description of the device pins please refer to the 'Pin Configuration and Functions' section in the LM61440 and LM61460 datasheet.
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 |
---|---|---|---|
BIAS | 1 | Normal Operation | D |
VCC | 2 | VOUT=0V | B |
AGND | 3 | Normal Operation | D |
FB | 4 | VOUT >> than programmed output voltage. | B |
PGOOD | 5 | PGOOD not valid signal. VOUT in regulation | D |
RT | 6 | VOUT=0V | B |
EN/SYNC | 7 | VOUT=0V | B |
VIN1 | 8 | VOUT=0V | B |
PGND1 | 9 | VOUT normal | D |
SW | 10 | Damage to HS FET | A |
PGND2 | 11 | VOUT normal | D |
VIN2 | 12 | VOUT=0V | B |
RBOOT | 13 | VOUT=0V | A |
CBOOT | 14 | VOUT=0V | B |
Pin Name | Pin No | Description of Potential Failure Effect(s) | Failure Effect Class |
---|---|---|---|
BIAS | 1 | Normal Operation | D |
VCC | 2 | VCC output will be unstable and can increase above 5.5V rating of VCC pin | A |
AGND | 3 | VOUT might be abnormal due to switching noise on analog circuits | B |
FB | 4 | VOUT >> than programmed output voltage. | B |
PGOOD | 5 | PGOOD not valid signal. VOUT in regulation | D |
RT | 6 | VOUT=0V | B |
EN/SYNC | 7 | Unpredictable operation | B |
VIN1 | 8 | VOUT normal. Current loop will be affected, potentially affecting noise/jitter/EMI/reliability. | C |
PGND1 | 9 | VOUT normal. Current loop will be affected, potentially affecting noise/jitter/EMI/reliability. | C |
SW | 10 | VOUT=0V | B |
PGND2 | 11 | VOUT normal. All current will be in this loop, potentially affecting noise/jitter/EMI/reliability. | C |
VIN2 | 12 | VOUT normal. All current will be in this loop, potentially affecting noise/jitter/EMI/reliability. | C |
RBOOT | 13 | VOUT normal | D |
CBOOT | 14 | VOUT=0V | B |
Pin Name | Pin No | Description of Potential Failure Effect(s) | Failure Effect Class |
---|---|---|---|
BIAS | 1 | VCC ESD clamp damaged if BIAS > 5V. | A |
VCC | 2 | VOUT=0V | B |
AGND | 3 | VOUT >> than programmed output voltage. | B |
FB | 4 | VOUT=0V, Damage if PGOOD>16V | A |
PGOOD | 5 | VOUT=0V | B |
RT | 6 | VOUT=0V, Damage if EN/SYNC>5.5V | A |
EN/SYNC | 7 | VOUT normal | D |
VIN1 | 8 | VOUT=0V | B |
PGND1 | 9 | VOUT=0V. Damage to low-side circuitry if PGND >> AGND | B |
SW | 10 | Damage to HS FET | A |
PGND2 | 11 | VOUT=0V. Damage to low-side circuitry if PGND >> AGND | B |
VIN2 | 12 | VOUT=0V | B |
RBOOT | 13 | VOUT normal | D |
CBOOT | 14 | VOUT=0V | B |
Pin Name | Pin No | Description of Potential Failure Effect(s) | Failure Effect Class |
---|---|---|---|
BIAS | 1 | If VIN exceeds 16V damage will occur. If below, normal operation | A |
VCC | 2 | If VIN exceeds 5.5V damage will occur. | A |
AGND | 3 | VOUT=0V. Damage to other pins referred to GND. | A |
FB | 4 | If VIN exceeds 16V damage will occur. VOUT=0V. | A |
PGOOD | 5 | VOUT=0V. PGOOD ESD clamp will run current to destruction | A |
RT | 6 | VOUT=0V | B |
EN/SYNC | 7 | VOUT normal | D |
VIN1 | 8 | Normal Operation | D |
PGND1 | 9 | VOUT=0V. Damage to low-side circuitry if PGND >> AGND | B |
SW | 10 | Damage to LS FET | A |
PGND2 | 11 | VOUT=0V. Damage to low-side circuitry if PGND >> AGND | B |
VIN2 | 12 | Normal Operation | D |
RBOOT | 13 | VOUT=0V. RBOOT ESD clamp will run current to destruction. | A |
CBOOT | 14 | VOUT=0V. CBOOT ESD clamp will run current to destruction. | A |