SFFS767 March 2024 TPS3808E

4 Pin Failure Mode Analysis (Pin FMA)

This section provides a Failure Mode Analysis (FMA) for the pins of the TPS3808E. 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

Table 4-1 shows the TPS3808E pin diagram. For a detailed description of the device pins please refer to TPS3760-Q1 in the Pin Configuration and Functions section of the data sheet.

Figure 4-1 Pin Diagram DYY Package14-Pin SOT-23

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

At V_{DD (MIN)} ≤ VDD ≤ V_{DD (MAX)}
MR = Open, C_T = Open,
Output reset Pullup Resistor (R_PULLUP) = 10kΩ, Output reset pullup voltage (V_PULLUP = 3.5V
Sense is monitoring VDD
Typical values are at T_A = 25°C, V_DD = 3.5V, C_VDD=0.1µF, and V_IT = 3.3V unless stated otherwise.

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
RESET	1	Forces RESET to be held low.	B
GND	2	No damage to device. No impact to functionality.	D
MR	3	RESET will be asserted.	B
CT	4	RESET is latched low if an undervoltage condition occurs.	B
SENSE	5	RESET will be asserted.	B
VDD	6	VDD short to GND, Device has no power for normal operation	B

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

PIN NAME	PIN NO.	DESCRIPTION OF POTENTIAL FAILURE EFFECT(S)	FAILURE EFFECT CLASS
RESET	1	Reset functionality will be lost since it's not being pulled up to VDD.	B
GND	2	Device is unpowered.	B
MR	3	Normal operation.	D
CT	4	Normal operation.	D
SENSE	5	No damage to the device. Reset is asserted.	B
VDD	6	Device is unpowered.	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
RESET	1	GND	Forces RESET to be held low.	B
GND	2	/MR	RESET will be asserted.	B
MR	3	CT	RESET is latched low if an undervoltage condition occurs.	B
CT	4	SENSE	RESET is latched low if an undervoltage condition occurs.	B
SENSE	5	VDD	Normal operation.	D
VDD	6	/RESET	Large current can flow into RESET when in error condition. This can cause permanent damage.	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
RESET	1	Large current can flow into RESET when in error condition. This can cause permanent damage.	A
GND	2	Device has no power for normal operation	B
MR	3	Normal operation.	D
CT	4	RESET is latched low if an undervoltage condition occurs.	B
SENSE	5	Normal operation.	D
VDD	6	Normal operation.	D