SLUAA92 November 2020 UCC28700-Q1

4 Pin Failure Mode Analysis (Pin FMA)

This section provides a Failure Mode Analysis (FMA) for the pins of the UCC28700-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 UCC28700-Q1 pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the UCC28700-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 UCC28700-Q1 is connected according to the UCC28700-Q1 datasheet Figure 17, typical application circuit

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
CBC	1	Cable compensation will be set at its highest value.	C
VDD	2	No positive supply applied to device. Device is non-functional.	B
DRV	3	DRV remains low. The output of the flyback converter remains at zero.	B
CS	4	When CS pin is shorted to ground before IC operation, CS pin short protection. The output of the flyback converter remains at zero.	B
CS	4	When CS pin is shorted to ground after IC operation, DRV pin remains high. Potential power stage damage and it might cause IC damange.	A
GND	5	No effect	D
VS	6	IC reamins in input under voltage protection mode. The output of the flyback converter remains at zero.	B

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

Pin Name	Pin No.	Description of Potential Failure Effect(s)	Failure Effect Class
CBC	1	Cable Compensation is Reduce to It's Minimal Value.	C
VDD	2	No positive supply applied to device. Device is non-functional.	B
DRV	3	The output of the Flyback converter remains at zero.	B
CS	4	CS pin open protection. The output of the Flyback converter remains at zero.	B
GND	5	Device damage	A
VS	6	IC reamins in input under voltage protection mode. The output of the Flyback converter remains at zero.	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
CBC	1	VDD	DRV remains low. Possible IC damage.	A
VDD	2	DRV	DRV remians high. Possible IC damange and Flyback siwtch damage.	A
DRV	3	N/A
CS	4	GND	When CS pin is shorted to ground before IC operation, CS pin short protection. The output of the flyback converter remains at zero.	B
CS	4	GND	When CS pin is shorted to ground after IC operation, DRV pin remains high. Potential power stage damage and it might cause IC damange.	A
GND	5	VS	IC reamins in input under voltage protection mode. The output of the flyback converter remains at zero.	B
VS	6	N/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
CBC	1	DRV remains low. Possible IC damage.	A
VDD	2	No effect	D
DRV	3	DRV remians high. Possible IC damange and Flyback siwtch damage.	A
CS	4	DRV remains low. Possible IC damage.	A
GND	5	No positive supply applied to device. Device is non-functional.	B
VS	6	IC damage. DRV remains low.	A