SNOAA48A December 2019 – November 2024 LM4040-N-Q1
4 Pin Failure Mode Analysis (Pin FMA)
This section provides a failure mode analysis (FMA) for the pins of the LM4040-N-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 LM4040-N-Q1 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the LM4040-N-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:
- Vdd (min) < Vdd < Vdd max
- Cathode is connected to supply with a 100Ω resistor to keep the current in the operating range.
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| Cathode | 1 | The output does not regulate and the cathode pin is held low. | B |
| Anode | 2 | No effect to functionality; the device is operating as intended. | D |
| * | 3 | No effect to device functionality. Pin 3 must be left floating or connected to pin 2. | D |
Table 4-3 Pin FMA for Device Pins Open-Circuited
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| Cathode | 1 | The device is not powered. | B |
| Anode | 2 | The output does not regulate and follows the supply voltage. | B |
| * | 3 | No effect to device functionality. Pin 3 must be left floating or connected to pin 2. | 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 |
|---|---|---|---|---|
| Cathode | 1 | Anode | The output does not regulate and the cathode pin is held low. | B |
| Anode | 2 | * | No effect to device functionality. Pin 3 must be left floating or connected to pin 2. | D |
| * | 3 | Cathode | Not a recommended connection; Iq can increase. | C |
Table 4-5 Pin FMA for Device Pins Short-Circuited to supply
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| Cathode | 1 | No effect to device functionality; the device is operating as intended. | D |
| Anode | 2 | The output does not regulate. The cathode pin is held low. | B |
| * | 3 | Not a recommended connection; Iq can increase | C |