SFFS535B September   2022  – September 2025 TPSM33615 , TPSM33625

 

  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)
  7. 5Revision History

4 Pin Failure Mode Analysis (Pin FMA)

This section provides a failure mode analysis (FMA) for the pins of the TPSM33625 and TPSM33615. 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 TPSM33625 and TPSM33615 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the TPSM33625 and TPSM33615 data sheets.

TPSM33625 TPSM33615 Pin Diagram Figure 4-1 Pin Diagram

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

  • The product data sheet application circuit is followed.
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
Pin Name Pin No. Description of Potential Failure Effects Failure Effect Class
PGOOD 1 When not in use, this pin can be left grounded (PGOOD is not a valid signal and VOUT is normal). D
EN/UVLO 2 VOUT = 0V; part is disabled. B
VIN 3 VOUT = 0V. B
VOUT 4 Goes into hiccup; short-circuit operation. B
SW 5 Device damage. A
6
BOOT 7 VOUT = 0V, the high-side FET does not turn on. B
VCC 8 Internal circuits are disabled. No output voltage is generated. B
FB 9 Switches at maximum duty cycle and VOUT approaches VIN. B
GND 10 VOUT normal. D
RT 11 Switching frequency is 2.2MHz. D
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin Name Pin No. Description of Potential Failure Effects Failure Effect Class
PGOOD 1 When not in use, this pin can be left open (PGOOD is not a valid signal and VOUT is normal). D
EN/UVLO 2 Pin cannot be left floating. B
VIN 3 VOUT = 0V. B
VOUT 4 Loss of output voltage. B
SW 5 Normal operation. D
6
BOOT 7 Normal operation. D
VCC 8 VCC output is unstable, can increase above 5.5V. A
FB 9 Switches at maximum duty cycle and VOUT approaches VIN. Damage to customer load and output stage components are possible. No effect on device. B
GND 10 VOUT can be abnormal, as reference voltage is not fixed. B
RT 11 If part is RT, frequency is not defined. If part is MODE/SYNC, then part can go back and forth between FPWM and PFM. The part is up and functional. C
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
RT 11 PGOOD If PGOOD is high and < 5.5V, Fsw = 1MHz; if PGOOD is low, Fsw = 2.2MHz. RT or MODE/SYNC absolute maximum is 5.5V. A
PGOOD 1 EN/UVLO If EN > 20V, devices connected to the PGOOD pin are damaged. A
EN/UVLO 2 VIN VOUT normal. D
VIN 3 SW Damage to the low-side FET. A
SW 5 BOOT VOUT = 0V, the high-side does not turn on, no CBOOT. B
6
BOOT 7 VCC Damage occurs, breaks the VCC pin. A
VCC 8 FB Can be nonfunctional, no damage occurs. B
FB 9 GND Switches at maximum duty cycle and VOUT approaches VIN. B
GND 10 RT VOUT is normal if RT/MODE/SYNC pin is low, otherwise not functional. D
VOUT 4 SW Damage occurs. A
Table 4-5 Pin FMA for Device Pins Short-Circuited to Supply
Pin Name Pin No. Description of Potential Failure Effects Failure Effect Class
PGOOD 1 If VIN > 20V, damage to PGOOD occurs. A
EN/UVLO 2 VOUT normal. D
VIN 3 VOUT normal. D
VOUT 4 Damage occurs if VIN > 16V. Customer load is damaged. A
SW 5 Damage to the low-side FET. A
6
BOOT 7 Damage occurs and BOOT ESD clamp is damaged. A
VCC 8 If VIN > 5.5V, damage occurs. A
FB 9 Damage occurs if VIN > 16V. A
GND 10 VOUT = 0V. B
RT 11 If VIN > 5.5V, damage occurs. If VIN < 5.5V, switching frequency is 1MHz. A