SFFS271 January 2022 TPS61088-Q1

4 Pin Failure Mode Analysis (Pin FMA)

This section provides a failure mode analysis (FMA) for the pins of the TPS61088-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 TPS61088-Q1 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the TPS61088-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:

Device used within the 'Recommended Operating Conditions' and the 'Absolute Maximum Ratings' found in the TPS61088-Q1 data sheet.
Configuration as shown in the 'Application and Implementation' found in the TPS61088-Q1 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
VCC	1	Output voltage out of regulation	B
EN	2	Loss of ENABLE functionality. The device remains in shutdown mode.	B
FSW	3	The device does not operate.	B
SW	4	Potential damage to inductor and pin	A
SW	5	Potential damage to inductor and pin	A
SW	6	Potential damage to inductor and pin	A
SW	7	Potential damage to inductor and pin	A
BOOT	8	Potential damage to device	A
VIN	9	The device does not operate. The power supply is short.	B
SS	10	The device does not operate.	B
NC	11	No effect	D
NC	12	No effect	D
MODE	13	The device remains in PWM, PFM is lost.	C
VOUT	14	Potential damage to device	A
VOUT	15	Potential damage to device	A
VOUT	16	Potential damage to device	A
FB	17	OVP is triggered and output voltage is out of regulation.	B
COMP	18	No output voltage	B
ILIM	19	Correct output voltage. No current limit	C
AGND	20	No effect	D
PGND	21	No effect	D

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

Pin Name	Pin No.	Description of Potential Failure Effect(s)	Failure Effect Class
VCC	1	High ripple on the VCC pin. Efficiency is lower.	C
EN	2	Loss of ENABLE functionality. Device remains in shutdown mode.	B
FSW	3	The device does not operate.	B
SW	4	Potential damage to inductor and pin	A
SW	5	Potential damage to inductor and pin.	A
SW	6	Potential damage to inductor and pin.	A
SW	7	Potential damage to inductor and pin.	A
BOOT	8	Possible device damage	A
VIN	9	The device does not work. V_OUT = 0 V	B
SS	10	Loss of soft start functionality	C
NC	11	Worse thermal dissipation	C
NC	12	Worse thermal dissipation	C
MODE	13	The device remains in PFM, PWM is lost.	C
VOUT	14	Potential damage to inductor and pin	A
VOUT	15	Potential damage to inductor and pin	A
VOUT	16	Potential damage to inductor and pin	A
FB	17	Output voltage is out of regulation	B
COMP	18	Output voltage is out of regulation	B
ILIM	19	Triggers minimum on time. The output voltage cannot be set.	B
AGND	20	Possible device damage	A
PGND	21	Possible device damage	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
VCC	1	EN	Loss of ENABLE functionality. The device remains in operating mode.	C
EN	2	FSW	Unstable working frequency	C
FSW	3	SW	Maximum working frequency	C
SW	4	SW	No effect	D
SW	5	SW	No effect	D
SW	6	SW	No effect	D
SW	7	BOOT	Bad thermal performance	C
BOOT	8	IN	Possible device damage	A
VIN	9	SS	The SS pin is damaged if supply voltage is higher than 7 V.	A
SS	10	NC	The device does not operate if NC is grounded.	B
NC	11	NC	No effect	D
NC	12	MODE	The device remains in PWM. PFM is lost if NC is grounded.	C
MODE	13	VOUT	The MODE pin damaged if output voltage is higher than 7 V.	A
VOUT	14	VOUT	No effect	D
VOUT	15	VOUT	No effect	D
VOUT	16	FB	The FB pin damaged if VOUT voltage is higher than 3.6 V.	A
FB	17	COMP	Triggers minimum on time. The output voltage is out of regulation.	B
COMP	18	ILIM	Triggers minimum on time. The output voltage is out of regulation.	B
ILIM	19	AGND	Correct output voltage. No current limit	C
AGND	20	PGND	No effect	D

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
VCC	1	The VCC pin damaged if supply voltage is higher than 7 V.	A
EN	2	The EN pin damaged if supply voltage is higher than 7 V.	A
FSW	3	Maximum working frequency	C
SW	4	Damage to internal power FETs	A
SW	5	Damage to internal power FETs	A
SW	6	Damage to internal power FETs	A
SW	7	Damage to internal power FETs	A
BOOT	8	Possible device damage	A
VIN	9	No effect	D
SS	10	The SS pin is damaged if supply voltage is higher than 7 V.	A
NC	11	Possible device damage due to large current when NC is grounded	A
NC	12	Possible device damage due to large current when NC is grounded	A
MODE	13	The MODE pin damaged if supply voltage is higher than 7 V.	A
VOUT	14	V_O = V_IN	B
VOUT	15	V_O = V_IN	B
VOUT	16	V_O = V_IN	B
FB	17	The FB pin is damaged if supply voltage is higher than 3.6 V.	A
COMP	18	The COMP pin is damaged if supply voltage is higher than 7 V.	A
ILIM	19	The ILIM pin is damaged if supply voltage is higher than 3.6 V.	A
AGND	20	Possible device damage due to large current	A
PGND	21	Possible device damage due to large current	A