SFFS775 February 2025 LM74912-Q1
4 Pin Failure Mode Analysis (Pin FMA)
This section provides a failure mode analysis (FMA) for the pins of the LM74912-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.
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 LM74912-Q1 pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the LM74912-Q1 data sheet.
Figure 4-1 Pin DiagramFollowing are the assumptions of use and the device configuration assumed for the pin FMA in this section:
- The device is operating under the specified ranges within the Recommended Operating Conditions section of the data sheet.
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
| Pin Name | Pin No. | Description of Potential Failure Effects | 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 is shorted to ground. Device is 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 |
| NC | 8, 9, 10, 11, 17, 21 | No effect on device operation. | D |
| FLT | 12 | Fault indication functionality is not available. | B |
| GND | 13 | No impact on device functionality. | D |
| HGATE | 14 | Device is damaged. | A |
| OUT | 15 | External FET VGS(max) rating can be exceeded and damage the external FET. The device can experience an 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 functionality and reverse current blocking functionality are not available. Device quiescent current can increase. | B |
| RTN | — | The input reverse polarity protection feature is not available. | B |
Table 4-3 Pin FMA for Device Pins Open Circuited
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| DGATE | 1 | The appropriate diode FET cannot be controlled. The reverse current blocking feature is not available. Load current flows through the body diode of the FET. | B |
| A | 2 | The appropriate diode FET is turned off due to linear regulation sink current. Load current flows through the body diode of the FET. | B |
| SW | 3 | The battery voltage monitoring feature is not available. | B |
| UVLO | 4 | Device HGATE drive is off due to internal pulldown on the UVLO pin. | B |
| OV | 5 | Overvoltage protection functionality is disabled as the OV pin is internally pulled low. | B |
| EN | 6 | Device is in shutdown mode as the EN pin is internally pulled low. | B |
| SLEEP | 7 | The SLEEP mode feature is not available. | B |
| NC | 8, 9, 10, 11, 17, 21 | No effect on device operation. | D |
| FLT | 12 | Fault indication functionality is not available. | B |
| GND | 13 | Device does not power up. | D |
| HGATE | 14 | HGATE control to turn on or turn off the external FET is not available. | B |
| OUT | 15 | HGATE control to turn on or turn off the external FET is not available. | D |
| SLEEP_OV | 16 | Overvoltage protection during SLEEP mode is not available. | B |
| ISCP | 18 | The short circuit protection feature is not available. | B |
| CS- | 19 | Device is in overcurrent protection mode and the 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 |
Table 4-4 Pin FMA for Device Pins Short Circuited to Adjacent Pin
| Pin Name | Pin No. | Shorted to | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|---|
| DGATE | 1 | A | The appropriate diode FET is off. Load current flows through the body diode of the FET. | B |
| A | 2 | SW | No effect on device operation. | D |
| SW | 3 | UVLO | UVLO feature is not available. | B |
| UVLO | 4 | OV | Either OV or UVLO comparator trigger and HGATE is off. | B |
| OV | 5 | EN | HGATE drive is off in case device is enabled (EN = High). | B |
| SLEEP | 7 | NC | No effect on device operation. | D |
| FLT | 12 | NC | No effect on device operation. | D |
| GND | 13 | HGATE | GND shorted to HGATE can cause device damage. | A |
| HGATE | 14 | OUT | HGATE FET is off as HGATE is shorted to OUT causing VGS short condition. | B |
| OUT | 15 | SLEEP_OV | No effect on device operation. Device supports only overvoltage clamp operation during SLEEP mode. | B |
| SLEEP_OV | 16 | NC | No effect on device operation. | B |
| ISCP | 18 | NC | No effect on device operation. | D |
| CS- | 19 | CS+ | Short circuit and overcurrent protection is not available. | B |
| CS+ | 20 | NC | Overcurrent limit and current monitoring output parameters are out of specification. | B |
| VS | 22 | CAP | Device charge pump does not come up. DGATE and HGATE drive are off. | B |
| CAP | 23 | C | Device charge pump does not come up. DGATE and HGATE drive are off. | B |
Table 4-5 Pin FMA for Device Pins Short Circuited to Supply
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| DGATE | 1 | DGATE is shorted to supply. The appropriate 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 |
| NC | 8, 9, 10, 11, 17, 21 | No effect on device operation. | D |
| 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 or turn off the external FET is not available. Device quiescent current can increase. | B |
| OUT | 15 | Supply is shorted to output. The appropriate diode (DGATE) and load disconnect (HGATE) features are not functional as supply is shorted to output. | B |
| SLEEP_OV | 16 | Device provides overvoltage cut-off functionality only during SLEEP mode. | B |
| ISCP | 18 | Device has a 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 | The appropriate diode functionality is not available (reverse current blocking). | B |
| RTN | — | No effect on device operation. | D |