SFFS023 May 2022 TPS62871-Q1

4 Pin Failure Mode Analysis (Pin FMA)

This section provides a Failure Mode Analysis (FMA) for the pins of the TPS62871-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 VIN (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 TPS62871-Q1 pin diagram. For a detailed description of the device pins, please refer to the Pin Configuration and Functions section in the TPS62871-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:

The device is running in the typical application. Please refer to the 'Simplified Schematics' on the first page in the TPS6287x-Q 12.7-V to 6-V Input, 6-A/9-A/12-A/15-A, Automotive, Stackable,Synchronous Step-Down Converters with Fast Transient Response data sheet.

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
COMP	1	The device does not power up and there is no output voltage.	B
GOSNS	2	Normal operation, but output voltage accuracy gets worse	C
VOSNS	3	Maximum duty cycle operation and no regulated output voltage. Output voltage follows the input voltage.	B
EN	4	The device is disabled. Normal operation	C
VIN	5	The device does not power up and there is no output voltage.	B
GND	6	Normal operation	D
SW	7	Potential device damage	A
GND	8	Normal operation	D
VIN	9	The device does not power up and there is no output voltage.	B
PG	10	Normal operation and loss of PG indication	B
MODE/SYNC	11	Normal operation. Power save mode is enabled.	C
SDA	12	Normal operation and no I²C communication	B
SCL	13	Normal operation and no I²C communication	B
SYNC_OUT	14	Potential device damage	A
VSEL	15	Normal operation. Defines start-up voltage	C
FSEL	16	Normal operation. Defines switching frequency	C

Table 4-3 Pin FMA for Device Pins Open-Circuited

Pin Name	Pin No.	Description of Potential Failure Effect(s)	Failure Effect Class
COMP	1	No loop compensation and can cause the output voltage to oscillate. Oscillation frequency cannot be predicted.	B
GOSNS	2	No output voltage regulation and can cause the output voltage to oscillate. Oscillation frequency cannot be predicted.	B
VOSNS	3	No output voltage regulation and can cause the output voltage to oscillate. Oscillation frequency cannot be predicted.	B
EN	4	Undetermined device operation. The device can power up and operate normal. Stays turned off	B
VIN	5	Normal operation. Pin 9 is still connected.	C
GND	6	Normal operation. Pin 8 and the exposed thermal pad are still connected.	C
SW	7	No output voltage	B
GND	8	Normal operation. Pin 6 and the exposed thermal pad are still connected.	C
VIN	9	Normal operation. Pin 5 is still connected.	C
PG	10	Normal operation and loss of PG indication	B
MODE/SYNC	11	Normal operation. Operation mode is undefined.	B
SDA	12	Normal operation and no I²C communication	B
SCL	13	Normal operation and no I²C communication	B
SYNC_OUT	14	Normal operation	D
VSEL	15	Normal operation. Start-up voltage is undefined.	B
FSEL	16	Normal operation. Switching frequency is undefined.	B

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
COMP	1	2	The device does not power up and there is no output voltage.	B
GOSNS	2	3	Maximum duty cycle operation and no regulated output voltage. Output voltage follows the input voltage.	B
VOSNS	3	4	The device does not power up or there is potential device damage.	A
EN	4	5	Potential device damage	A
VIN	5	6	The device does not power up and there is no output voltage.	B
GND	6	7	Potential device damage	A
SW	7	8	Potential device damage	A
GND	8	9	The device does not power up and there is no output voltage.	B
VIN	9	10	Potential device damage	A
PG	10	11	Potential device damage if MODE/SYNC is tied high. Loss of PG indication	A
MODE/SYNC	11	12	Potential device damage if MODE/SYNC is tied high. No I²C communication	A
SDA	12	13	Normal operation and no I²C communication	B
SCL	13	14	Potential device damage	A
SYNC_OUT	14	15	Potential device damage if VSEL is tied high or low	A
VSEL	15	16	Normal operation. Defines start-up voltage and switching frequency	B
FSEL	16	1	No output voltage regulation and can cause the output voltage to oscillate. Oscillation frequency cannot be predicted.	B

Table 4-5 Pin FMA for Device Pins Short-Circuited to VIN

Pin Name	Pin No.	Description of Potential Failure Effect(s)	Failure Effect Class
COMP	1	Potential device damage	A
GOSNS	2	Potential device damage	A
VOSNS	3	The device will not start up. Output voltage stays low or there is potential device damage.	A
EN	4	Potential device damage	A
VIN	5	Normal operation	D
GND	6	The device does not power up and there is no output voltage.	B
SW	7	Potential device damage	A
GND	8	The device does not power up and there is no output voltage.	B
VIN	9	Normal operation	D
PG	10	Potential device damage	A
MODE/SYNC	11	Normal operation and forced PWM operation	C
SDA	12	Potential device damage	A
SCL	13	Potential device damage	A
SYNC_OUT	14	Potential device damage	A
VSEL	15	Normal operation. Defines start-up voltage	C
FSEL	16	Normal operation. Defines switching frequency	C