SFFS340 February   2022 LM5164

 

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

4 Pin Failure Mode Analysis (Pin FMA)

This section provides a Failure Mode Analysis (FMA) for the pins of the LM5164. 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
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 LM5164 pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the LM5164 data sheet.

GUID-20210106-CA0I-CLWV-VL0D-BKRMR1DWRBMG-low.pngFigure 4-1 Pin Diagram

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

  • Application circuit, as per the LM5163, LM5163-Q1, LM5164, and LM5164-Q1 data sheets, is used
    • PGOOD is pulled up to VOUT
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
GND 1 D
VIN 2 VOUT = 0 V B
EN/UVLO 3 VOUT = 0 V B
RON 4 VOUT unregulated; 0 ≤ VOUT < set voltage B
FB 5 VOUT >> set voltage. PGOOD can become damaged if VIN > 14 V. A
PGOOD 6 PGOOD is invalid flag. B
BST 7 VOUT = 0 V B
SW 8 Power FET damage A
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin Name Pin No Description of Potential Failure Effect(s) Failure Effect Class
GND 1 VOUT = 0 V B
VIN 2 VOUT = 0 V B
EN/UVLO 3 VOUT = 0 V B
RON 4 VOUT > set voltage B
FB 5 VOUT >> set voltage. PGOOD can become damaged if VIN > 14 V. A
PGOOD 6 PGOOD flag invalid B
BST 7 VOUT = 0 V B
SW 8 VOUT = 0 V B
Table 4-4 Pin FMA for Device Pins Short-Circuited to Adjacent Pin
Pin Name Pin No Description of Potential Failure Effect(s) Failure Effect Class
GND 1 VOUT = 0 V B
VIN 2 D
EN/UVLO 3 VIN > 5.5 V can lead to device damage. A
RON 4 VOUT < set voltage B
FB 5 PGOOD flag invalid. VOUT can be unregulated. A
PGOOD 6 VOUT = 0 V B
BST 7 VOUT = 0 V B
SW 8 VOUT = 0 V B
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
GND 1 VOUT = 0 V B
VIN 2 D
EN/UVLO 3 D
RON 4 VIN > 5.5 V can lead to device damage. A
FB 5 VIN > 5.5 V can lead to device damage. A
PGOOD 6 VIN > 14 V can lead to device damage. A
BST 7 VOUT = 0 V B
SW 8 VOUT = VIN. PGOOD can be damaged if VIN > 14 V. A