SFFS747 January   2024 TPS61299-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)

4 Pin Failure Mode Analysis (Pin FMA)

This section provides a failure mode analysis (FMA) for the pins of the TPS61299-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 to 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 TPS61299-Q1 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the TPS61299-Q1 data sheet.

Figure 4-1 Pin Diagram (SOT563 Package)
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
Pin Name Pin No. Description of Potential Failure Effects Failure Effect Class
VIN 1 The device does not operate. Power supply is short. B
SW 2 Possible damage to inductor and device. A
EN 3 Loss of ENABLE functionality. The device remains in shutdown mode. B
VSEL 4 If short before start-up, target output voltage is 3.3V. D
If short after start-up and load current is low, no change to the device, output voltage remains the same. D
VOUT 5 Device is in short-to-ground protection mode, device working at the boundary of DCM and CCM. B
GND 6 No effect. D
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin Name Pin No. Description of Potential Failure Effects Failure Effect Class
VIN 1 State of SCLK input undetermined. No SPI communication with device possible. B
SW 2 No output voltage. B
EN 3 The device does not work and there is no output voltage. B
VSEL 4 Select 5V fast transient mode operation. C
VOUT 5 Possible damage to device. A
GND 6 Possible damage to device. A
Table 4-4 Pin FMA for Device Pins Short-Circuited to Adjacent Pin
Pin Name Pin No. Shorted to Description of Potential Failure Effects Failure Effect Class
VIN 1 SW Possible damage to the device and no output. A
SW 2 VIN Possible damage to the device and no output. A
EN Shutdown the device . Possibly can cause damage to the device and no output. A
EN 3 SW Shutdown the device. Possibly can cause damage to the device and no output. A
VSEL 4 VOUT If the short happens before EN start process, the converter will be regulated to 5V fast mode. D
If the short happens after EN start process, the converter will keep regulating to target voltage as normal. D
VOUT 5 GND Device goes into short protection mode. B
VSEL If the short happens before EN start process, the converter will be regulated to 5V fast mode. C
If the short happens after EN start process, the converter will keep regulating to target voltage as normal. D
GND 6 VOUT Device goes into short protection mode. B
Table 4-5 Pin FMA for Device Pins Short-Circuited to supply
Pin Name Pin No. Description of Potential Failure Effects Failure Effect Class
VIN 1 No effect. D
SW 2 Damage to device. A
EN 3 Loss of disable functionality. B
VSEL 4 Depends on the input voltage value to select different Vout targets. B
VOUT 5 The output voltage is equal to the supply voltage. B
GND 6 No output voltage; power supply is shorted. B