SFFS724 September   2023 TPSM365R1 , TPSM365R15

 

  1.   1
  2.   Trademarks
  3. 1Overview
  4. 2Functional Safety Failure In Time (FIT) Rates
    1. 2.1 TPSM365R15
    2. 2.2 TPSM365R1
  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 TPSM365R1x. 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 TPSM365R1x pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the TPSM365R1x data sheet.

GUID-9027FDAD-9668-4455-93A4-5A69EF0A33DA-low.svg
1. See the data sheet for more details. Pin 1 trimmed and factory-set for externally adjustable switching frequency RT variants only.
2. Pin 11 factory-set for fixed switching frequency MODE/SYNC variants only.
3. Pin 9 trimmed and factory-set for fixed output voltage VOUT/BIAS variants only.
4. Pin 9 factory-set for adjustable output voltage FB variants only.
Figure 4-1 Pin Diagram
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
Pin NamePin No.Description of Potential Failure Effect(s)Failure Effect Class
PGOOD1When not in use, this pin can be left open or grounded. However, PGOOD is no longer reliably relays Power-Good information to devices connected to this pin.

B

EN2VOUT = 0 V, device is disabled.

B

VIN3VOUT = 0 V.B
VOUT4Goes into hiccup, short-circuit operation.B
SW

5, 6

Damage occurs.A
BOOT

7

VOUT = 0 V, HS FET does not turn on.B
VCC

8

VOUT = 0 V.B
VOUT/BIAS or FB

9

VOUT = 0 V.B
GND10Normal operation.D
RT or MODE

11

For RT, the switching frequency is set to 2.2 MHz. For MODE/SYNC the device goes into PFM mode.B
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin NamePin No.Description of Potential Failure Effect(s)Failure Effect Class
PGOOD

1

When not in use, this pin can be left open or grounded. However, PGOOD is no longer reliably relays Power-Good information to devices connected to this pin.

B
EN

2

VOUT behavior is not defined. VOUT may be 0V, but it also may be up. Do not float this pin. Device can no longer reliably be enabled or disabled by other devices connected to this pin.

B
VIN

3

VOUT = 0 V.B
VOUT4VOUT = 0 V.B
SW5, 6Normal operation.

D

BOOT

7

Normal operation.

D

VCC

8

VCC output is unstable, can increase above 5.5 VA
FB

9

VOUT = 0 V. Do not float this pin.

B

GND

10

VOUT can be abnormal, as reference voltage is not fixed.

B

RT or MODE

11

If it is RT device, then frequency is not defined. If it is a MODE/SYNC device, then the device can go back and forth between FPWM and PFM. VOUT is up, but only partially functional.

C
Table 4-4 Pin FMA for Device Pins Short-Circuited to Adjacent Pin
Pin NamePin No.

Shorted to

Description of Potential Failure Effect(s)Failure Effect Class
PGOOD1

EN

If EN > 20 V, it damages devices connected to the PGOOD pin. A
EN2

VIN

VOUT normal (enable is on, all other blocks work). However, the device can no longer be disabled.

B
VIN3VOUTIf VIN >16 V, damage occurs.A
VOUT

4

SWDamage occurs.A
SW6

BOOT

VOUT = 0 V, HS does not turn on, no Cboot.B
BOOT7

VCC

Damage occurs to VCC LDO. The VCC LDO could no longer supply voltage to internal control circuits.A
VCC8

FB

Can be partially nonfunctional, no damage occurs.B
FB9

GND

VOUT = 0 V (for fixed option) switches at maximum duty cycle for ADJ option.B
GND10

RT or MODE

For RT, Switching Frequency is set to 2.2 MHz. For MODE/SYNC the device goes into PFM mode.

B

RT or MODE

11

PGOOD

If PGOOD is high and < 5.5 V, then Fsw = 1 MHz for RT, and is in FPWM mode for MODE/SYNC; If PGOOD is low, then Fsw = 2.2 MHz for RT, and PFM mode for RT. PGOOD absmax being 20 V, RT ESD damages if PG goes to 20 V.

A

Table 4-5 Pin FMA for Device Pins Short-Circuited to supply
Pin NamePin No.Description of Potential Failure Effect(s)Failure Effect Class
PGOOD

1

If VIN > 20 V, it damages PGOOD. PGOOD is no longer reliably relays Power-Good information to devices connected to this pin.A
EN

2

VOUT normal (enable is on, all other blocks work). However, the device can no longer be disabled.B
VIN

3

Normal operation.

D
VOUT4Damage occurs, if VIN > 16 V.A
SW

5, 6

Damage occurs.

A
BOOT

7

Damage occurs, the BOOT ESD clamp is damaged.A
VCC

8

If Vin > 5.5 V, damage occurs.A
FB

9

If VIN > 20 V, damage occurs.A
GND10VOUT = 0 V.

A

RT

11

If Vin > 5.5 V, damage occurs. If Vin < 5.5 V, switching frequency is 1 MHz.

A