SFFS766 November 2023 OPA2377-Q1

4 Pin Failure Mode Analysis (Pin FMA)

This section provides a failure mode analysis (FMA) for the pins of the OPA2377-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 OPA2377-Q1 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the OPA2377-Q1 data sheet.

Figure 4-1 Pin Diagram

Following are the assumptions of use and the device configuration assumed for the pin FMA in this section:

'Short circuit to Power' means to V+ supply.
'Short circuit to GND or Ground' means to V‒ supply.

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 circuit configuration, device will likely be forced into short circuit condition with OUT A voltage ultimately forced to V‒ voltage. Prolonged exposure to short circuit conditions could result in long term reliability issues.	A
‒IN A	2	Negative feedback not present to device. Depending on circuit configuration, output will most likely move to negative supply.	B
+IN A	3	Device common‒mode tied to negative rail. Depending on circuit configuration, output will likely not respond due to the device being put in an invalid common‒mode condition.	C
+IN B	5	Device common‒mode tied to negative rail. Depending on circuit configuration, output will likely not respond due to the device being put in an invalid common‒mode condition.	C
‒IN B	6	Negative feedback not present to device. Depending on circuit configuration, output will most likely move to negative supply.	B
OUT B	7	Depending on circuit configuration, device will likely be forced into short circuit condition with OUT B voltage ultimately forced to V‒ voltage. Prolonged exposure to short circuit conditions could result in long term reliability issues.	A
V+	8	Op‒Amp supplies will be shorted together leaving V+ pin at some voltage between V+ and V‒ sources (depending on 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 application.	B
‒IN A	2	Inverting pin of Op‒Amp left floating. Negative feedback will not be provided to device, likely resulting in device output moving between positive and negative rail. ‒IN A pin voltage will likely end up at positive or negative rail due to leakage on ESD diodes.	B
+IN A	3	Input common‒mode left floating. Op‒Amp will not be provided with common‒mode bias, device output will likely end up at positive or negative rail. +IN A pin voltage will likely end up at positive or negative rail due to leakage on ESD diodes.	B
V‒	4	Negative supply left floating. Op‒Amp will cease to function as no current can source/sink to the device.	A
+IN B	5	Input common‒mode left floating. Op‒Amp will not be provided with common‒mode bias, device output will likely end up at positive or negative rail. +IN B pin voltage will likely end up at positive or negative rail due to leakage on ESD diodes.	B
‒IN B	6	Inverting pin of Op‒Amp left floating. Negative feedback will not be provided to device, likely resulting in device output moving between positive and negative rail. ‒IN B pin voltage will likely end up at positive or negative rail due to leakage on ESD diodes.	B
OUT B	7	No negative feedback or ability for OUT B to drive application.	B
+V	8	Positive supply left floating. Op‒Amp will cease to function as no current can source/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	‒IN A	Depending on circuit configuration, gain of circuit will be reduced to unity gain and application may not function as intended	B
‒IN A	2	+IN A	Both inputs will be tied together. Depending on the offset of the device, this will likely move the output voltage near mid supply.	D
+IN A	3	V‒	Device common‒mode tied to negative rail. Depending on circuit configuration, output will likely not respond due to the device being put in an invalid common‒mode condition.	C
V‒	4	+IN B	Device common‒mode tied to negative rail. Depending on circuit configuration, output will likely not respond due to the device being put in an invalid common‒mode condition.	C
+IN B	5	‒IN B	Both inputs will be tied together. Depending on the offset of the device, this will likely move the output voltage near mid supply.	D
‒IN B	6	OUT B	Depending on circuit configuration, gain of circuit will be reduced to unity gain and application may not function as intended	B
OUT B	7	V+	Depending on circuit configuration, device will likely be forced into short circuit condition with OUT B voltage ultimately forced to V+ voltage. Prolonged exposure to short circuit conditions could result in long term reliability issues.	A
V+	8	OUT A	Depending on circuit configuration, device will likely be forced into short circuit condition with V+ voltage ultimately forced to 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 circuit configuration, device will likely be forced into short circuit condition with OUT A voltage ultimately forced to V+ voltage. Prolonged exposure to short circuit conditions could result in long term reliability issues.	AB
‒IN A	2	Negative feedback not present to device. Depending on non‒inverting input voltage and circuit configuration, output will most likely move to negative supply.	B
+IN A	3	Depending on circuit configuration, application will likely not function due to the device common‒mode being connected to +IN A.	B
V‒	4	Op‒Amp supplies will be shorted together leaving V‒ pin at some voltage between V‒ and V+ sources (depending on source impedance).	A
+IN B	5	Depending on circuit configuration, application will likely not function due to the device common‒mode being connected to +IN B.	B
‒IN	6	Negative feedback not present to device. Depending on non‒inverting input voltage and circuit configuration, output will most likely move to negative supply.	B
OUT B	7	Depending on circuit configuration, device will likely be forced into short circuit condition with OUT B voltage ultimately forced to V+ voltage. Prolonged exposure to short circuit conditions could result in long term reliability issues.	A