SFFS842A March 2024 – May 2025 TMCS1123-Q1 , TMCS1126-Q1 , TMCS1127-Q1 , TMCS1133-Q1
4.4 TMCS1133-Q1 Pin FMA
This section provides a failure mode analysis (FMA) for the pins of the TMCS1133-Q1. The failure modes covered in this document include the typical pin-by-pin failure scenarios:
- Pin short-circuited to ground (see Table 4-14)
- Pin open-circuited (see Table 4-15)
- Pin short-circuited to an adjacent pin (see Table 4-16)
- Pin short-circuited to supply (see Table 4-17)
Table 4-14 through Table 4-17 also indicate how these pin conditions can affect the device as per the failure effects classification in Table 4-1.
Figure 4-3shows the TMCS1133-Q1 pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the TMCS1133-Q1 data sheet.
Figure 4-4 TMCS1133-Q1 Pin DiagramFollowing are the assumptions of use and the device configuration assumed for the pin FMA in this section:
- TA = -40°C to +125°C
- VS = 3V to 5.5V
- VCM = -1.3kV to 1.3kV
Table 4-14 Pin FMA for Device Pins
Short-Circuited to Ground
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| IN+ | 1 | For forward current, hall-sensor bypassed, providing no signal to be sensed and amplified. If the IN+ pin is at a large potential above GND, this state results in a large amount of current being sunk. Depending upon layout and configuration, this result can damage the input current system supply, the load device, or the actual device. | A |
| IN- | 2 | For reverse current, hall-sensor bypassed, providing no signal to be sensed and amplified. If the IN- pin is at a large potential above GND, this state result in a large amount of current being sunk. Depending upon layout and configuration, this result can damage the input current system supply, the load device, or the actual device. | A |
| GND | 3 | Normal operation. | D |
| ALERT | 4 | Alert is not able to trigger since ALERT is shorted to GND. | B |
| NC | 5 | Normal operation. | D |
| VOUT | 6 | Output is pulled to GND and the output current is short circuit limited. When left in this configuration, while VS is connected to a high-load-capable supply and for certain high-load conditions through the IN+ and IN- pins, the die temperature can approach or exceed 150°C. | A |
| OC | 7 | Alert is not able to trigger since OC is shorted to GND. | B |
| VOC | 8 | The threshold at GND means that all voltages trip the alert. As a result, the alert is stuck in active mode. | B |
| VS | 9 | Power supply is shorted to ground. | B |
| VS | 10 | Power supply is shorted to ground. | B |
Table 4-15 Pin FMA for Device Pins
Open-Circuited
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| IN+ | 1 | No current running through inputs. | B |
| IN- | 2 | No current running through inputs. | B |
| GND | 3 | GND is floating. The output is incorrect as the output is no longer referenced to GND. | B |
| ALERT | 4 | Alert open; cannot read alert. | B |
| NC | 5 | Normal operation. | D |
| VOUT | 6 | Output is present at the pin, having no loading does not affect the output. However, the user sees unpredictable results further down on the signal chain. | B |
| OC | 7 | Alert open, cannot read alert. | B |
| VOC | 8 | No alert threshold set. Alert output is unpredictable. | B |
| VS | 9 | No power to the device if both VS pins are open. | B if both VS pins open |
| D otherwise |
|||
| VS | 10 | No power to the device if both VS pins are open. | B if both VS pins open |
| D otherwise |
Table 4-16 Pin FMA for Device Pins
Short-Circuited to Adjacent Pin
| Pin Name | Pin No. | Shorted to | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|---|
| IN+ | 1 | IN- | IN+ shorted to IN-. This creates a current divider which increases sensitivity error inversely proportional to the resistance of the short. | C |
| IN- | 2 | GND | For reverse current, hall-sensor bypassed, providing no signal to be sensed and amplified. If the IN- pin is at a large potential above GND, this state result in a large amount of current being sunk. Depending upon layout and configuration, this result can damage the input current system supply, the load device, or the actual device. | A |
| GND | 3 | ALERT | Alert is not able to trigger since ALERT is shorted to GND. | B |
| ALERT | 4 | NC | Normal operation. | D |
| NC | 5 | VOUT | Normal operation. | D |
| VOUT | 6 | OC | OC and output are incorrect. | A |
| OC | 7 | VOC | OC is unpredictable. | B |
| VOC | 8 | VS | VOC is shorted to VS, overcurrent threshold is at the wrong threshold. | B |
| VS | 9 | VS | Normal operation. | D |
| VS | 10 | IN+ | If IN+ > 6V, the device can be damaged. If IN+ < Vs and IN+ is at a large potential above ground, large current can be flowing between VS and the input current system supply. | A if IN+ > 6V |
| B otherwise |
Table 4-17 Pin FMA for Device Pins
Short-Circuited to
supply
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| IN+ | 1 | If IN+ > 6V, the device is damaged. If IN+ < Vs, a large amount of current can be pulled from VS. | A |
| IN- | 2 | If IN- > 6V, the device is damaged. If IN- < Vs, a large amount of current can be pulled from VS. | A |
| GND | 3 | VS is shorted to GND. | B |
| ALERT | 4 | The ALERT pin is stuck high and potentially has too high of a current draw when triggered. | B |
| NC | 5 | Normal operation. | D |
| VOUT | 6 | Output is pulled to VS and the output current is short circuit limited. When left in this configuration, while VS is connected to a high-load-capable VS and for certain high-load conditions through the IN+ and IN- pins, the die temperature can approach or exceed 150°C. | A |
| OC | 7 | The OC pin is stuck high and potentially has too high of a current draw when triggered. | B |
| VOC | 8 | The overcurrent threshold is at the wrong threshold. | B |
| VS | 9 | Normal operation. | D |
| VS | 10 | Normal operation. | D |