SBOA465A november 2021 – june 2023 OPA2388-Q1
4 Pin Failure Mode Analysis (Pin FMA)
This section provides a Failure Mode Analysis (FMA) for the pins of the OPA2388-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 OPA2388-Q1 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the OPA2388-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:
- 'Short circuit to Power' means short to V+
- 'Short circuit to GND or Ground' means short to V‒
- V+ is equivalent to VCC and V‒ equivalent to VEE
Table 4-2 Pin FMA for Device Pins
Short-Circuited to Ground
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| OUT A | 1 | Depending on the circuit configuration, the device is likely to be forced into a short‒circuit condition with the OUT A voltage ultimately forced to the V‒ voltage. Prolonged exposure to short‒circuit conditions could result in long‒term reliability issues. | A |
| -IN A | 2 | The device does not receive negative feedback. Depending on the circuit configuration, the output most likely moves to the negative supply. | B |
| +IN A | 3 | Device common-mode is tied to the negative rail. Depending on the circuit configuration, the output likely does not respond because the device is in an invalid common‒mode condition. | C |
| +IN B | 5 | Device common-mode is tied to the negative rail. Depending on the circuit configuration, the output likely does not respond because the device is in an invalid common‒mode condition. | C |
| -IN B | 6 | The device does not receive negative feedback. Depending on the circuit configuration, the output most likely moves to the negative supply. | B |
| OUT B | 7 | Depending on the circuit configuration, the device is likely to be forced into a short‒circuit condition with the OUT B voltage ultimately forced to the V‒ voltage. Prolonged exposure to short‒circuit conditions could result in long‒term reliability issues. | A |
| V+ | 8 | Op-amp supplies are shorted together, leaving the V+ pin at some voltage between the V+ and V‒ sources (depending on the source impedance). | A |
Table 4-3 Pin FMA for Device Pins
Open-Circuited
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| OUT A | 1 | No negative feedback or ability for OUT A to drive the application. | B |
| -IN A | 2 | Inverting pin of the op amp is left floating. Negative feedback is not provided to the device, likely resulting in the device output moving between the positive and negative rails. The ‒IN A pin voltage likely ends up at the positive or negative rail because of leakage on the ESD diodes. | B |
| +IN A | 3 | Device common‒mode is disconnected. The op amp is not provided with common‒mode bias, and the device output likely ends up at the positive or negative rail. The +IN A pin voltage likely ends up at the positive or negative rail because of leakage on the ESD diodes. | B |
| V- | 4 | Negative supply is left floating. The op amp ceases to function because no current can source or sink to the device. | B |
| +IN B | 5 | Device common‒mode is disconnected. The op amp is not provided with common‒mode bias, and the device output likely ends up at the positive or negative rail. The +IN B pin voltage likely ends up at the positive or negative rail because of leakage on the ESD diodes. | B |
| -IN B | 6 | Inverting pin of the op amp is left floating. Negative feedback is not provided to the device, likely resulting in the device output moving between the positive and negative rails. The ‒IN B pin voltage likely ends up at the positive or negative rail because of leakage on the ESD diodes. | B |
| OUT B | 7 | No negative feedback or ability for OUT B to drive the application. | B |
| V+ | 8 | Positive supply is left floating. The op amp ceases to function because no current can source or sink to the device. | A |
Table 4-4 Pin FMA for Device Pins
Short-Circuited to Adjacent Pin
| Pin Name | Pin No. | Shorted to | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|---|
| OUT A | 1 | 2 | Depending on the circuit configuration, the circuit gain is reduced to unity gain, and the application might not function as intended. | B |
| -IN A | 2 | 3 | Both inputs are tied together. Depending on the offset of the device, the output voltage likely moves to near midsupply. | D |
| +IN A | 3 | 4 | Device common-mode is tied to the negative rail. Depending on the circuit configuration, the output likely does not respond because the device is in an invalid common‒mode condition. | C |
| V- | 4 | 5 | Device common-mode is tied to the negative rail. Depending on the circuit configuration, the output likely does not respond because the device is in an invalid common‒mode condition. | C |
| +IN B | 5 | 6 | Both inputs are tied together. Depending on the offset of the device, the output voltage likely moves to near midsupply. | D |
| -IN B | 6 | 7 | Depending on the circuit configuration, the circuit gain is reduced to unity gain, and the application might not function as intended. | B |
| OUT B | 7 | 8 | Depending on the circuit configuration, the device is likely to be forced into a short-circuit condition with the OUT B voltage ultimately forced to the V+ voltage. Prolonged exposure to short-circuit conditions could result in long-term reliability issues. | A |
| V+ | 8 | 1 | Depending on the circuit configuration, the device is likely to be forced into a short‒circuit condition with the V+ voltage ultimately forced to the OUT A voltage. Prolonged exposure to short‒circuit conditions could result in long‒term reliability issues. | A |
Table 4-5 Pin FMA for Device Pins
Short-Circuited to
supply
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| OUT A | 1 | Depending on the circuit configuration, the device is likely to be forced into a short‒circuit condition with the OUT A voltage ultimately forced to the V+ voltage. Prolonged exposure to short‒circuit conditions could result in long‒term reliability issues. | A |
| -IN A | 2 | The device does not receive negative feedback. Depending on the noninverting input voltage and circuit configuration, the output most likely moves to the negative supply. | B |
| +IN A | 3 | Depending on the circuit configuration, the application is likely not to function because device common‒mode voltage is connected to +IN A. | B |
| V- | 4 | Op-amp supplies are shorted together, leaving the V‒ pin at some voltage between the V‒ and V+ sources (depending on the source impedance). | A |
| +IN B | 5 | Depending on the circuit configuration, the application is likely not to function because device common‒mode voltage is connected to +IN B. | B |
| -IN B | 6 | The device does not receive negative feedback. Depending on the noninverting input voltage and circuit configuration, the output most likely moves to the negative supply. | B |
| OUT B | 7 | Depending on the circuit configuration, the device is likely to be forced into a short‒circuit condition with the OUT B voltage ultimately forced to the V+ voltage. Prolonged exposure to short‒circuit conditions could result in long‒term reliability issues. | A |