SFFS181 June   2021 LM5145-Q1

 

  1.   Trademarks
  2. 1Overview
  3. 2Failure Mode Distribution (FMD)
  4. 3Functional Safety Failure In Time (FIT) Rates
  5. 4Pin Failure Mode Analysis (Pin FMA)

Pin Failure Mode Analysis (Pin FMA)

This section provides a Failure Mode Analysis (FMA) for the pins of the LM5145-Q1. The failure modes covered in this document include the typical pin-by-pin failure scenarios:

Table 4-2 through Table 4-6 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
ClassFailure Effects
APotential device damage that affects functionality
BNo device damage, but loss of functionality
CNo device damage, but performance degradation
DNo device damage, no impact to functionality or performance

Figure 4-1 shows the LM5145-Q1 pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the LM5145-Q1 data sheet.

GUID-20200624-SS0I-ZQXV-2GL0-ZBCGXQJ17BTT-low.gif Figure 4-1 Pin Diagram
Table 4-2 Pin FMA for Short to GND
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
EN/UVLO 1 VOUT = 0 V B
RT 2 VOUT = 0 V B
SS/TRK 3 VOUT = 0 V B
COMP 4 VOUT = 0 V B
FB 5 VOUT is limited by when the part enters into hiccup mode B
AGND 6 Normal operation D
SYNCOUT 7 VOUT = 0 V B
SYNCIN 8 Normal operation with DCM at light loads B
NC9 9 Normal operation D
PGOOD 10 Normal operation C
ILIM 11 Normal operation B
PGND 12 Normal operation D
LO 13 VOUT = 0 V B
VCC 14 VOUT = 0 V B
EP 15 Normal operation D
NC16 16 Normal operation D
BST 17 VOUT = 0 V B
HO 18 VOUT = 0 V B
SW 19 VOUT = 0 V A
VIN 20 VOUT = 0 V B
Table 4-3 Pin FMA for Short to VIN ≥ 12 V
Pin NamePin No.Description of Potential Failure Effect(s)Failure Effect Class
EN/UVLO1ESD protection runs full current and RT pin destroyed (VOUT = 0 V)C
RT2ESD protection runs full current and SS pin destroyed (VOUT = 0 V)A
SS/TRK3ESD protection runs full current and COMP destroyed (VOUT = 0 V)A
COMP 4 ESD protection runs full current and COMP pin destroyed (VOUT = 0 V) A
FB 5 ESD protection runs full current and FB pin destroyed (VOUT = 0 V) A
AGND 6 VOUT = 0 V D
SYNCOUT 7 ESD protection runs full current and SYNCOUT pin destroyed (VOUT = 0 V) A
SYNCIN 8 ESD protection runs full current and SYNCIN pin destroyed, but the part continues to work normally A
NC9 9 Normal operation D
PGOOD 10 ESD protection runs full current and PGOOD pin destroyed, but VOUT might not be affected A
ILIM 11 Buck operation is not affected C
PGND 12 VOUT = 0 V B
LO 13 VOUT = 0 V B
VCC 14 ESD protection runs full current and VCC pin destroyed (VOUT = 0 V) A
EP 15 Normal operation D
NC16 16 Normal operation D
BST 17 ESD protection runs full current and BST pin destroyed (VOUT = 0 V) A
HO 18 VOUT = VIN A
SW 19 VOUT = VIN B
VIN 20 Normal operation D
Table 4-4 Pin FMA for Short to VOUT
Pin Name Pin Number Description of Potential Failure Effect(s) Failure Class
EN/UVLO 1 VOUT = 0 V B
RT 2 VOUT = 0 V A
SS/TRK 3 VOUT = 0 V A
COMP 4 VOUT = 0 V A
FB 5 VOUT = VREF A
AGND 6 VOUT = 0 V B
SYNCOUT 7 Normal operation A
SYNCIN 8 Normal operation. FPWM enabled A
NC9 9 Normal operation D
PGOOD 10 Normal operation A
ILIM 11 Normal operation C
PGND 12 VOUT = 0 V B
LO 13 VOUT = 0 V B
VCC 14 VOUT = 0 V A
EP 15 Normal operation D
NC16 16 Normal operation D
BST 17 VOUT = 0 V B
HO 18 VOUT = 0 V B
SW 19 VOUT = 0 V B
VIN 20 VOUT = VIN B
Table 4-5 Pin FMA Open-Circuited
Pin Name Pin Number Description of Potential Failure Effect(s) Failure Class
EN/UVLO 1 VOUT = 0 V B
RT 2 VOUT = 0 V B
SS/TRK 3 Normal operation C
COMP 4 Regulated to required voltage. SW freq is all over the place B
FB 5 VOUT = 0 V B
AGND 6 VOUT = 0 V B
SYNCOUT 7 Normal operation C
SYNCIN 8 Normal operation. DCM mode C
NC9 9 Normal operation D
PGOOD 10 Normal operation C
ILIM 11 Normal operation C
PGND 12 VOUT = 0 V B
LO 13 Normal operation. DCM mode enabled at light loads B
VCC 14 VOUT = 0 V B
EP 15 Normal operation D
NC16 16 Normal operation D
BST 17 VOUT = 0 V B
HO 18 VOUT = 0 V B
SW 19 VOUT = 0 V B
VIN 20 VOUT = 0 V B
Table 4-6 Pin FMA for Short-Circuited to Adjacent Pin
Pin Name Pin Number Description of Potential Failure Effect(s) Failure Class Neighbor
EN/UVLO 1 Normal operation C VIN
RT 2 VOUT = 0 V B SS/TRK
SS/TRK 3 VOUT = 0 V B COMP
COMP 4 VOUT is not regulated to required voltage and is controlled by the ON time it makes when COMP is 0.8 V and the switching frequency set by RT pin B FB
FB 5 VOUT is limited by when the part enters into hiccup mode B AGND
AGND 6 VOUT = 0 V B SYNCOUT
SYNCOUT 7 Normal operation C SYNCIN
SYNCIN 8 Normal operation D NC9
NC9 9 Normal operation D
PGOOD 10 Normal operation A ILIM
ILIM 11 Normal operation D
PGND 12 VOUT = 0 V A LO
LO 13 VOUT = 0 V B VCC
VCC 14 Normal operation D EP
EP 15 Normal operation D NC16
NC16 16 Normal operation D BST
BST 17 VOUT = 0 V B HO
HO 18 VOUT = 0 V B SW
SW 19 Normal operation D
VIN 20 Normal operation D