SFFS286 September 2021 TLVH431B-Q1

4 Pin Failure Mode Analysis (Pin FMA)

This section provides a failure mode analysis (FMA) for the pins of the TLVH431B-Q1 (DBV and DBZ package). The failure modes covered in this document include the typical pin-by-pin failure scenarios:

Pin short-circuited to ground (see Table 4-2 (DBV) and Table 4-3 (DBZ))
Pin open-circuited (see Table 4-4 (DBV) and Table 4-5 (DBZ))
Pin short-circuited to an adjacent pin (see Table 4-6 (DBV) and Table 4-7 (DBZ))
Pin short-circuited to Cathode pin (see Table 4-8 (DBV) and Table 4-9 (DBZ))

Table 4-2 through Table 4-9 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 TLVH431B-Q1 pin diagram for the DBV package. For a description of the device pins, see the TLVH431B-Q1 datasheet.

Figure 4-1 Pin Diagram (DBV) Package

CATHODE is connected to VDD through a series resistor
ANODE is connected to the ground
REF is connected to ground and cathode via resistors as shown in the Figure 4-2
NC and * pin is left floating

Figure 4-2 Test Circuit for V_KA > V_REF

Figure 4-3 shows the TLVH431B-Q1 pin diagram for the DBZ package. For a description of the device pins, see the the TLVH431B-Q1 datasheet.

Figure 4-3 Pin Diagram (DBZ) Package

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

CATHODE is connected to VDD through a series resistor
ANODE is connected to the ground
REF is connected to ground and cathode via resistors as shown in the Figure 4-4

Figure 4-4 Test Circuit for V_KA > V_REF

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

PIN NAME	PIN NUM.	DESCRIPTION OF POTENTIAL FAILURE EFFECT(S)	FAILURE EFFECT CLASS
NC	1	Normal Operation	D
*	2	Works fine when anode is connected to Ground but can affect application functionality otherwise	C
CATHODE	3	Potential damage to the device depending on the location of the short. Shorts output voltage to ground, increases system current	A
REF	4	Turns off the regulator. No damage to device but can affect application functionality	B
ANODE	5	Works fine when anode is connected to Ground but can affect application functionality otherwise	C

Table 4-3 Pin FMA for Device Pins Short-Circuited to Ground on DBZ Package

PIN NAME	PIN NUM.	DESCRIPTION OF POTENTIAL FAILURE EFFECT(S)	FAILURE EFFECT CLASS
REF	1	Turns off the regulator. No damage to device but can affect application functionality	B
CATHODE	2	Potential damage to the device depending on the location of the short. Shorts output voltage to ground, increases system current	A
ANODE	3	Works fine when anode is connected to Ground but can affect application functionality otherwise	C

Table 4-4 Pin FMA for Device Pins Open-Circuited on DBV Package

PIN NAME	PIN NUM.	DESCRIPTION OF POTENTIAL FAILURE EFFECT(S)	FAILURE EFFECT CLASS
NC	1	Normal Operation	D
*	2	Normal Operation	D
CATHODE	3	No damage to device but can affect application functionality	C
REF	4	No damage to device but can affect application functionality	C
ANODE	5	No damage to device but can affect application functionality	C

Table 4-5 Pin FMA for Device Pins Open-Circuited on DBZ Package

PIN NAME	PIN NUM.	DESCRIPTION OF POTENTIAL FAILURE EFFECT(S)	FAILURE EFFECT CLASS
REF	1	No damage to device but can affect application functionality	C
CATHODE	2	No damage to device but can affect application functionality	C
ANODE	3	No damage to device but can affect application functionality	C

Table 4-6 Pin FMA for Device Pins Short-Circuited to Adjacent Pin on DBV Package

PIN NAME	PIN NUM.	SHORTED TO	DESCRIPTION OF POTENTIAL FAILURE EFFECT(S)	FAILURE EFFECT CLASS
NC	1	*	Normal Operation	D
*	2	CATHODE	Potential damage to the device depending on the location of the short. Shorts output voltage to ground, increases system current	A
CATHODE	3	REF	Works fine when used in REF to CATHODE direct feedback but can affect application functionality otherwise	C
REF	4	ANODE	Turns off the regulator. No damage to device but can affect application functionality	B
ANODE	5	NC	Normal Operation	D

Table 4-7 Pin FMA for Device Pins Short-Circuited to Adjacent Pin on DBZ Package

PIN NAME	PIN NUM.	SHORTED TO	DESCRIPTION OF POTENTIAL FAILURE EFFECT(S)	FAILURE EFFECT CLASS
REF	1	CATHODE	Works fine when used in REF to CATHODE direct feedback but can affect application functionality otherwise	C
CATHODE	2	ANODE	Potential damage to the device depending on the location of the short. Shorts output voltage to ground, increases system current	B
ANODE	3	REF	Turns off the regulator. No damage to device but can affect application functionality	B

Table 4-8 Pin FMA for Device Pins Short-Circuited to Cathode on DBV Package

PIN NAME	PIN NUM.	DESCRIPTION OF POTENTIAL FAILURE EFFECT(S)	FAILURE EFFECT CLASS
NC	1	Normal Operation	D
*	2	Potential damage to the device depending on the location of the short. Shorts output voltage to ground, increases system current	A
CATHODE	3	Normal Operation	D
REF	4	Works fine when used in REF to CATHODE direct feedback but can affect application functionality otherwise	C
ANODE	5	Potential damage to the device depending on the location of the short. Shorts output voltage to ground, increases system current	A

Table 4-9 Pin FMA for Device Pins Short-Circuited to Cathode on DBZ Package

PIN NAME	PIN NUM.	DESCRIPTION OF POTENTIAL FAILURE EFFECT(S)	FAILURE EFFECT CLASS
REF	1	Works fine when used in REF to CATHODE direct feedback but can affect application functionality otherwise	C
CATHODE	2	Normal Operation	D
ANODE	3	Potential damage to the device depending on the location of the short. Shorts output voltage to ground, increases system current	A