SFFS661 November   2023 LMR38015-Q1 , LMR38025-Q1

 

  1.   1
  2.   Trademarks
  3. 1Overview
  4. 2Functional Safety Failure In Time (FIT) Rates
  5. 3Failure Mode Distribution (FMD)
  6. 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 LMR38015-Q1, LMR38025-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
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 LMR38015-Q1, LMR38025-Q1 pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the LMR38015-Q1, LMR38025-Q1 data sheet.

GUID-20230118-SS0I-N9TS-GVV5-C9MSXLKHHW6F-low.svg Figure 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 LMR38015-Q1, LMR38025-Q1 datasheet
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 1/2 Normal operation D
EN 3 VOUT = 0 V B
VIN 5/6 VOUT = 0 V B
RT/SYNC 7 Switching Frequency >> 3 MHz C
FB 8 VOUT >> than programmed output voltage B
PG 9 No power good function B
BOOT 10 VOUT = 0 V B
SW 11/12 Damage to HS FET A
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin Name Pin No Description of Potential Failure Effect(s) Failure Effect Class
GND1/2VOUT might be abnormal due to switching noise on analog circuitsB
EN3Device can shut offB
VIN5/6Device can shut offB
RT/SYNC7No Switching frequency B
FB8VOUT >> than programmed output voltageB
PG9No power good functionB
BST10VOUT = 0 VB
SW11/12VOUT = 0 VB
Table 4-4 Pin FMA for Device Pins Short-Circuited to Adjacent Pin
Pin Name 1 Pin Name 2Description of Potential Failure Effect(s)Failure Effect Class
GNDENVOUT = 0 VB
ENVINNormal Vout operationB
FBPGVOUT less than programmed output voltageB
PGBOOTPGOOD Pin ESD damage if BOOT pin voltage >20 VA
BOOTSWVOUT = 0 VB
Table 4-5 Pin FMA for Device Pins Short-Circuited to Supply
Pin NamePin NoDescription of Potential Failure Effect(s)Failure Effect Class
GND1/2VOUT = 0 V. Damage to other pins referred to GND.A
EN3Device enabledD
VIN5/6Normal modeD
RT/SYNC7RT/SYNC Pin ESD damage if VIN > 5.5 VA
FB8If VIN exceeds 5.5 V damage will occur. VOUT = 0 VA
PG9PGOOD Pin ESD damage if VIN >20VB
BOOT10VOUT = 0 V. CBOOT ESD clamp will run current to destructionA
SW11/12Damage to LS FETA