SLVAEO9B February 2020 – January 2021 TPS62065-Q1 , TPS62067-Q1
This document contains information for TPS6206x-Q1 (WSON package) to aid in a functional safety system design. Information provided are:
Figure 1-1 shows the device functional block diagram for reference.
TPS6206x-Q1 was developed using a quality-managed development process, but was not developed in accordance with the IEC 61508 or ISO 26262 standards.
This section provides Functional Safety Failure In Time (FIT) rates for TPS6206x-Q1 based on an industry-wide used reliability standard:
FIT IEC TR 62380 / ISO 26262 | FIT (Failures Per 109 Hours) |
---|---|
Total Component FIT Rate | 5 |
Die FIT Rate | 3 |
Package FIT Rate | 2 |
The failure rate and mission profile information in Table 2-1 comes from the Reliability data handbook IEC TR 62380 / ISO 26262 part 11:
Table | Category | Reference FIT Rate | Reference Virtual TJ |
---|---|---|---|
5 | CMOS,
BICMOS Digital, analog / mixed |
25 FIT | 55°C |
The Reference FIT Rate and Reference Virtual TJ (junction temperature) in Table 2-2 come from the Siemens Norm SN 29500-2 tables 1 through 5. Failure rates under operating conditions are calculated from the reference failure rate and virtual junction temperature using conversion information in SN 29500-2 section 4.
The failure mode distribution estimation for TPS6206x-Q1 in Table 3-1 comes from the combination of common failure modes listed in standards such as IEC 61508 and ISO 26262, the ratio of sub-circuit function size and complexity and from best engineering judgment.
The failure modes listed in this section reflect random failure events and do not include failures due to misuse or overstress.
Die Failure Modes | Failure Mode Distribution (%) |
---|---|
SW no output | 35% |
SW output not in specification - voltage or timing | 45% |
SW power HS or LS FET stuck on | 15% |
Short circuit any two pins | 5% |
This section provides a Failure Mode Analysis (FMA) for the pins of the TPS6206x-Q1. 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.
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 TPS6206x-Q1 pin diagram. For a detailed description of the device pins please refer to the 'Pin Configuration and Functions' section in the TPS6206x-Q1 data sheet.
Following are the assumptions of use and the device configuration assumed for the pin FMA in this section:
Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
---|---|---|---|
PGND | 1 | Intended connection | D |
SW | 2 | Potential internal device damage | A |
AGND | 3 | Intended connection | D |
FB | 4 | Device not functional: Missing feedback path (Open Loop operation); output voltage out of spec; potential device damage | A |
EN | 5 | Intended connection: Device disabled | D |
MODE | 6 | TPS62065-Q1: Intended connection: Enabling power safe mode with automatic transition from PFM to fixed frequency PWM mode | D |
PG | 6 | TPS62067-Q1: Intended connection in case PG not used | D |
AVIN | 7 | Device not functional; supply short to ground | B |
PVIN | 8 | Device not functional; supply short to ground | B |
Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
---|---|---|---|
PGND | 1 | Internal ground shift; device not functional; potential internal damage | A |
SW | 2 | Device not function - open loop operation | B |
AGND | 3 | Internal ground shift; device not functional; potential internal damage | A |
FB | 4 | Device not functional - open loop operation | B |
EN | 5 | Undetermined state of pin EN; spec violation; potentially increased quiescent current | C |
MODE | 6 | TPS62065-Q1: Undetermined state of pin MODE/PG spec violation; potentially increased quiescent current | C |
PG | 6 | TPS62067-Q1: Intended connection in case PG not used | D |
AVIN | 7 | Missing power supply - device not functional | B |
PVIN | 8 | Missing power supply - device not functional | B |
Pin Name | Pin No. | Shorted to | Description of Potential Failure Effect(s) | Failure Effect Class |
---|---|---|---|---|
PGND | 1 | SW | Potential internal device damage | A |
SW | 2 | AGND | Potential internal device damage | A |
AGND | 3 | FB | Device not functional: Missing feedback path (Open Loop operation); output voltage out of spec; potential device damage | A |
EN | 5 | MODE | TPS62065-Q1: Intended connection: Device operation in fixed frequency PWM mode | D |
EN | 5 | PG | TPS62067-Q1: Potential internal damage | A |
MODE | 6 | AVIN | TPS62065-Q1: Intended connection: Device operation in fixed frequency PWM mode | D |
PG | 6 | AVIN | TPS62067-Q1: Potential internal damage | A |
AVIN | 7 | PVIN | Intended connection | D |
Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
---|---|---|---|
PGND | 1 | Device not functional; supply short to ground | B |
SW | 2 | Potential internal device damage | A |
AGND | 3 | Device not functional; supply short to ground | B |
FB | 4 | Device not functional: Missing feedback path (Open Loop operation); output voltage out of spec; potential device damage | A |
EN | 5 | Intended connection: Device enabled | D |
MODE | 6 | TPS62065-Q1: Intended connection: Device operation in fixed frequency PWM mode | D |
PG | 6 | TPS62067-Q1: Potential internal damage | A |
AVIN | 7 | Intended connection | D |
PVIN | 8 | Intended connection | D |