SFFS743 November   2023 TPS3840

 

  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 TPS3840. The failure modes covered in this document include the typical pin-by-pin failure scenarios:

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 TPS3840 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the TPS3840 data sheet.

GUID-20231106-SS0I-9MXX-RF8L-5QBHRLQWZRQL-low.svgFigure 4-1 Pin Diagram

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

  • Vdd(min) < Vdd < Vdd (max) assumption
  • Reset is connected to VDD with 10.5-kΩ pull-up resistor
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
Pin Name Pin No. Description of Potential Failure Effects Failure Effect Class
RESET 1 Forces RESET to be held low. B
VDD 2 VDD short to GND Fault. The device is non-operational. B
GND 3 No damage to device. No impact to functionality. D
MR / NC 4 Normal operation. RESET will be asserted. B
CT 5 RESET is forced and held low when VDD goes below threshold. Device is non-operational. B
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin NamePin No.Description of Potential Failure EffectsFailure Effect Class
RESET1Unreliable reset output functionality.B
VDD2The device is unpowered and non-operational.B
GND3The RESET and VDD are both held low.B
MR / NC4Normal Operation. This pin can be left floating.D
CT5Normal Operation. This pin can be left floating.D
Table 4-4 Pin FMA for Device Pins Short-Circuited to Adjacent Pin
Pin NamePin No.Shorted toDescription of Potential Failure EffectsFailure Effect Class
RESET1VDDLarge current can flow into RESET when in error condition. This can cause permanent damage.A
VDD2GNDThe device is non-operational.B
GND3MR / NCNormal operation. RESET will be asserted.B
MR / NC4CTRESET is forced and held low when VDD goes below threshold. Device is non-operational.B
CT5RESETRESET is forced and held low when VDD goes below threshold. Device is non-operational.B
Table 4-5 Pin FMA for Device Pins Short-Circuited to supply
Pin NamePin No.Description of Potential Failure EffectsFailure Effect Class
RESET1Large current can flow into RESET when in error condition. This can cause permanent damage.A
VDD2Normal operation.D
GND3VDD short to GND fault. Device is non-operational.B
MR / NC4Normal operation.D
CT5Forces RESET to be held low. Device is non-operational.B