SFFSA20 November 2024 LM25190 , LM5190

4 Pin Failure Mode Analysis (Pin FMA)

This section provides a failure mode analysis (FMA) for the pins of the LM5190 and LM25190. 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 LM5190 and LM25190 pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the LM5190 and LM25190 data sheets.

Figure 4-1 Pin Diagram

Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground

Pin Name	Pin No.	Description of Potential Failure Effects	Failure Effect Class
ISET	1	VOUT = 0V. ISET is not functional.	B
RT	2	VOUT attempts to regulate at maximum fsw, causing maximum power dissipation.	C
COMP	3	VOUT = 0V.	B
FB	4	VOUT target set to 5V.	B
AGND	5	AGND is GND. VOUT = expected VOUT.	D
IMON/ILIM	6	VOUT = expected VOUT. Current monitor and CC limit are not functional.	B
VCC	7	VOUT = 0V, no switching, loaded VCC output.	B
PGND	8	PGND is GND. VOUT = expected VOUT.	D
LO	9	VOUT = 0V, the VCC regulator is loaded to current limit.	B
VIN	10	VOUT = 0V.	B
HO	11	VOUT = 0V, the VCC regulator is loaded to current limit.	B
SW	12	VOUT = 0V. High-side FET is shorted from VIN to GND.	A
CBOOT	13	VOUT = 0V. High-side FET is shorted from VIN to GND.	B
BIAS	14	VOUT = expected VOUT. Internal VCC regulator provides bias voltage.	C
PGOOD	15	VOUT = expected VOUT. PGOOD is not functional.	C
FPWM/SYNC	16	VOUT = expected VOUT. No synchronization is available and always in PFM mode.	C
EN	17	VOUT = 0V. Always in shutdown.	B
ISNS+	18	VOUT = 0V.	A
VOUT	19	VOUT = 0V.	B

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

Pin Name	Pin No.	Description of Potential Failure Effects	Failure Effect Class
ISET	1	VOUT = expected VOUT. ISET is not functional.	C
RT	2	RT regulates to 1V, but the internal oscillator does not function.	B
COMP	3	VOUT oscillates.	A
FB	4	VOUT = VIN.	A
AGND	5	VOUT is indeterminate.	B
IMON/ILIM	6	VOUT = 0V. Current monitor and CC limit are not functional.	B
VCC	7	VOUT = 0V.	B
PGND	8	VOUT = 0V.	B
LO	9	VOUT = expected VOUT with reduced efficiency.	C
VIN	10	VOUT = 0V.	B
HO	11	If HO is opened while HO to SW has voltage, the high-side FET never turns off. VOUT = VIN.	A
SW	12	VOUT is indeterminate. The CBOOT floating rail has no reference to the actual SW node. VOUT = VIN.	A
CBOOT	13	VOUT = 0V.	B
BIAS	14	VOUT = expected VOUT. Internal VCC regulator provides bias voltage.	C
PGOOD	15	VOUT = expected VOUT. PGOOD is not functional.	C
FPWM/SYNC	16	VOUT = expected VOUT. No synchronization is available and always in FPWM mode.	C
EN	17	VOUT = 0V.	B
ISNS+	18	The open ISNS+ pin blocks current limit and causes VOUT oscillations.	A
VOUT	19	VOUT = 0V, if the internal feedback is used.	B

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
ISET	1	RT	If RT resistor is tied to VCC, ISET pin can be damaged. If RT resistor is tied to AGND, VOUT = expected VOUT. The switching frequency is lower. CC operation is affected.	A
RT	2	COMP	If RT resistor is tied to VCC, COMP pin can be damaged. If RT resistor is tied to AGND, VOUT = 0V.	A
COMP	3	FB	External FB mode: COMP regulates to 0.8V and output is unregulated. VOUT = indeterminate.	B
			Internal FB mode FB = VCC, device is damaged.	A
			Internal FB mode FB = GND, VOUT = 0V.	B
FB	4	AGND	VOUT target set to 5V.	B
AGND	5	IMON/ILIM	VOUT = expected VOUT. Current monitor and CC limit are not functional.	C
IMON/ILIM	6	VCC	Device damage.	A
VCC	7	PGND	VCC is grounded. VOUT = 0V.	B
PGND	8	LO	VOUT = 0V. VCC is loaded by the LO driver.	B
LO	9	VIN	VOUT = 0V. The driver is damaged if VIN > 8V.	A
VIN	10	HO	For VIN > 8V, exceeds the maximum ratings and the HO pin is damaged. For VIN < 8V, VOUT = dropout lower than VIN, no switching, and excess current from VIN.	A
HO	11	SW	VOUT = 0V.	B
SW	12	CBOOT	VOUT = 0V.	B
CBOOT	13	BIAS	Device damage if CBOOT > 30V.	A
BIAS	14	PGOOD	PG pulldown can damage. VOUT = expected VOUT.	A
PGOOD	15	FPWM/SYNC	VOUT = expected VOUT. If FPWM is tied to VCC, PG pulldown can be damaged.	A
FPWM/SYNC	16	EN	VOUT = expected VOUT.	A
EN	17	ISNS+	EN is high-voltage rated. VOUT = expected VOUT if VOUT > 1V. If VOUT < 1V, the device is disabled.	B
ISNS+	18	VOUT	Current limit is disabled since the current limit resistor is shorted. VOUT cannot regulate since current-mode feedback is shorted.	A
VOUT	19	ISET	VOUT = 0V. If prebias VOUT > 5.5V, ISET pin is damaged.	A

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

Pin Name	Pin No.	Description of Potential Failure Effects	Failure Effect Class
ISET	1	Device damage if VIN > 5.5V.	A
RT	2	Device damage if VIN > 8V.	A
COMP	3	Device damage if VIN > 5.5V If VIN < 5.5V, VOUT out of regulation.	A
FB	4	Device damage if VIN > 8V. If VIN < 8V, VOUT = VIN.	A
AGND	5	VOUT = 0V.	B
IMON/ILIM	6	Device damage if VIN > 5.5V.	A
VCC	7	Device damage if VIN > 8V. If VIN < 8V, VOUT = expected VOUT.	A
PGND	8	VOUT = 0V.	B
LO	9	VOUT = 0V. The driver is damaged if VIN > 8V.	A
VIN	10	N/A	D
HO	11	For VIN > 8V, exceeds maximum ratings and the HO pin is damaged For VIN < 8V, VOUT = dropout lower than VIN, no switching, and excess current from VIN	A
SW	12	VOUT = VIN, excess current from VIN. LO turns on and shorts against VIN.	B
CBOOT	13	Device damage if VIN > 8V. If VIN < 8V, VOUT < expected VOUT.	A
BIAS	14	Device damage if VIN > 30V.	A
PGOOD	15	Device damage.	A
FPWM/SYNC	16	Device damage if VIN > 8V. If VIN < 8V, VOUT = expected VOUT but always FPWM mode.	A
EN	17	Always on. VOUT = expected VOUT.	C
ISNS+	18	Device damage.	A
VOUT	19	VOUT = VIN.	B