SFFS577 February 2024 LM74900-Q1 , LM74910-Q1
ADVANCE INFORMATION
4 Pin Failure Mode Analysis (Pin FMA)
This section provides a Failure Mode Analysis (FMA) for the pins of the LM74900-Q1, LM74910-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.
| 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 LM749x0-Q1 pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the LM749x0-Q1 data sheet.
Figure 4-1 Pin DiagramThe pin FMA is provided under the assumption that the device is operating under the specified ranges within the Recommended Operating Conditions section of the data sheet.
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
|
DGATE |
1 |
Device is damaged due to internal conduction. External DGATE FET can also damage due to maximum VGS rating violation. |
A |
|
A |
2 |
Input supply shorted to ground. Device not functional. |
B |
|
SW |
3 |
Device is damaged if enabled. |
A |
|
UVLO |
4 |
Device HGATE drive is off. |
B |
|
OV |
5 |
Overvoltage protection functionality is disabled. |
B |
|
EN |
6 |
Device is in shutdown mode. |
B |
|
SLEEP |
7 |
Device is in SLEEP mode. |
B |
|
N.C |
8, 17, 21 |
No effect on device operation. |
D |
|
TMR |
9 |
Timer functionality is not be available. |
B |
|
IMON |
10 |
Current monitoring output is not available. |
B |
|
ILIM |
11 |
Overcurrent protection with circuit breaker feature is not be available. |
B |
|
FLT |
12 |
Fault indication functionality is not be available. |
B |
|
GND |
13 |
No impact on the device functionality. |
D |
|
HGATE |
14 |
Device is damaged. |
A |
|
OUT |
15 |
External FET VGS(max) rating can exceed and damage external FET. Device can experience increase in quiescent current. |
D |
|
SLEEP_OV |
16 |
Overvoltage protection during SLEEP mode is not available. |
B |
|
ISCP |
18 |
Device damage is expected due to internal current flow. |
A |
|
CS- |
19 |
Device damage is expected due to internal current flow. |
A |
|
CS+ |
20 |
Device damage is expected due to internal current flow. |
A |
|
VS |
22 |
Device does not power up. |
B |
|
CAP |
23 |
Device is damaged due to internal conduction between VS and CAP. |
A |
|
C |
24 |
Linear regulation and reverse current blocking functionality is not available. Device quiescent current can increase. |
B |
|
RTN |
— |
Input reverse polarity protection feature is not available. |
B |
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| DGATE | 1 | Ideal diode FET can not be controlled. Reverse current blocking feature is not available. Load current flows through body diode of the FET. | B |
| A | 2 | Ideal diode FET is turned off due to linear regulation sink current. Load current flows through body diode of the FET. | B |
| SW | 3 | Battery voltage monitoring feature is not available. | B |
UVLO | 4 | Device HGATE drive is off due to internal pull down on UVLO pin. | B |
| OV | 5 | Overvoltage protection functionality is disabled as OV pin is internally pulled low. | B |
| EN | 6 | Device is in shutdown mode as EN pin is internally pulled low. | B |
SLEEP | 7 | SLEEP mode feature is not available. | B |
N.C | 8, 17, 21 | No effect on device operation. | D |
TMR | 9 | Device operation with default timer operation. Auto retry timer can not be set using external timer capacitor. | B |
IMON | 10 | Current monitoring output is not available. | B |
ILIM | 11 | ILIM pin is pulled high and device is in overcurrent protection mode. | B |
FLT | 12 | Fault indication functionality is not available. | B |
| GND | 13 | Device does not power up. | D |
| HGATE | 14 | HGATE control to turn on/off external FET is not available. | B |
| OUT | 15 | HGATE control to turn on/off external FET is not available. | D |
SLEEP_OV | 16 | Overvoltage protection during SLEEP mode is not available. | B |
ISCP | 18 | Short circuit protection feature is not available. | B |
CS- | 19 | Device is in overcurrent protection mode and HGATE drive is turned off. | B |
CS+ | 20 | Overcurrent protection and current monitoring output is not available. | B |
| VS | 22 | Device does not power up. | B |
| CAP | 23 | Charge pump does not build up and gate drives DGATE and HGATE are disabled. | B |
| C | 24 | DGATE drive remains off. | B |
RTN | — | No effect on device operation. | D |
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| DGATE | 1 | Ideal diode FET is off. Load current flows through body diode of the FET. | B |
| A | 2 | No effect on device operation. | D |
| SW | 3 | UVLO feature is not available. | B |
UVLO | 4 | Either OV or UVLO comparator trigger and HGATE is off. | B |
| OV | 5 | HGATE drive is off in case device is enabled (EN=High). | B |
| EN | 6 | No effect on device operation. | D |
SLEEP | 7 | No effect on device operation. | D |
N.C | 8, 17, 21 | No effect on device operation. | D |
TMR | 9 | Timer (TMR) and current monitoring (IMON) functionality are out of data sheet specification. | B |
IMON | 10 | Current monitoring output is out of data sheet specification. | B |
ILIM | 11 | Device is in overcurrent protection mode based on FLT voltage level. | B |
FLT | 12 | No effect on device operation. | D |
| GND | 13 | GND shorted to HGATE can cause device damage. | A |
| HGATE | 14 | HGATE FET is off as HGATE is shorted to OUT causing VGS short condition. | B |
| OUT | 15 | No effect on device operation. Device supports only overvoltage clamp operation during SLEEP mode. | B |
SLEEP_OV | 16 | No effect on device operation. | B |
ISCP | 18 | No effect on device operation. | D |
CS- | 19 | Short circuit and overcurrent protection is not available. | B |
CS+ | 20 | Overcurrent limit, current monitoring output parameters are out of specification. | B |
| VS | 22 | Device charge pump does not come up. DGATE and HGATE drive are off. | B |
| CAP | 23 | Device charge pump does not come up. DGATE and HGATE drive are off. | B |
| C | 24 | No effect on device operation. | B |
RTN | — | No effect on device operation. | D |
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| DGATE | 1 | DGATE is shorted to supply. Ideal diode FET remains off. | B |
| A | 2 | No effect on device operation. | D |
| SW | 3 | Battery voltage monitoring feature is available irrespective of EN pin status. | B |
UVLO | 4 | UVLO functionality is not available. | B |
| OV | 5 | HGATE is turned off due to OV comparator input going high. | B |
| EN | 6 | Device is always on as EN is pulled to supply. | B |
SLEEP | 7 | SLEEP mode feature is not available. | B |
N.C | 8, 17, 21 | No effect on device operation. | D |
TMR | 9 | Device is damaged if supply voltage level >5.5V. | A |
IMON | 10 | Device is damaged if supply voltage level >5.5V. | A |
ILIM | 11 | Device is damaged if supply voltage level >5.5V. | A |
FLT | 12 | Fault indication functionality is not available. | B |
| GND | 13 | Device does not power up due to supply shorted to GND. | D |
| HGATE | 14 | HGATE control to turn on/off external FET is not available. Device quiescent current can increase. | B |
| OUT | 15 | Supply is shorted to output. Ideal diode (DGATE), load disconnect (HGATE) features will not be functional as supply is shorted to output. | B |
SLEEP_OV | 16 | Device is able to provide overvoltage cut-off functionality only during SLEEP mode. | B |
ISCP | 18 | Device has default short circuit protection threshold of 20mV. | B |
CS- | 19 | Overcurrent protection functionality is not available. | B |
CS+ | 20 | Device is in overcurrent protection mode. | B |
| VS | 22 | No effect on device operation. | B |
| CAP | 23 | Charge pump does not build up and gate drives DGATE and HGATE are disabled. | B |
| C | 24 | Ideal diode functionality is not available (reverse current blocking). | B |
RTN | — | No effect on device operation. | D |