SFFS724 September 2023 TPSM365R1 , TPSM365R15
4 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.
| Class | Failure Effects |
|---|---|
| A | Potential device damage that affects functionality |
| B | No device damage, but loss of functionality |
| C | No device damage, but performance degradation |
| D | No 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.
| Pin Name | Pin 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 = 0 V, device is disabled. | B |
| VIN | 3 | VOUT = 0 V. | B |
| VOUT | 4 | Goes 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 |
| GND | 10 | Normal 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 |
| Pin Name | Pin 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 |
| VOUT | 4 | VOUT = 0 V. | B |
| SW | 5, 6 | Normal operation. | D |
| BOOT | 7 | Normal operation. | D |
| VCC | 8 | VCC output is unstable, can increase above 5.5 V | A |
| 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 |
| Pin Name | Pin No. | Shorted to | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|---|
| PGOOD | 1 | EN | If EN > 20 V, it damages devices connected to the PGOOD pin. | A |
| EN | 2 | VIN | VOUT normal (enable is on, all other blocks work). However, the device can no longer be disabled. | B |
| VIN | 3 | VOUT | If VIN >16 V, damage occurs. | A |
| VOUT | 4 | SW | Damage occurs. | A |
| SW | 6 | BOOT | VOUT = 0 V, HS does not turn on, no Cboot. | B |
| BOOT | 7 | VCC | Damage occurs to VCC LDO. The VCC LDO could no longer supply voltage to internal control circuits. | A |
| VCC | 8 | FB | Can be partially nonfunctional, no damage occurs. | B |
| FB | 9 | GND | VOUT = 0 V (for fixed option) switches at maximum duty cycle for ADJ option. | B |
| GND | 10 | 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 |
| Pin Name | Pin 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 |
| VOUT | 4 | Damage 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 |
| GND | 10 | VOUT = 0 V. | A |
RT | 11 | If Vin > 5.5 V, damage occurs. If Vin < 5.5 V, switching frequency is 1 MHz. | A |