SFFSAD0 April 2025 HDC3120-Q1
4 Pin Failure Mode Analysis (Pin FMA)
This section provides a failure mode analysis (FMA) for the pins of the HDC3120-Q1. 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
| 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 HDC3120-Q1 pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the HDC3120-Q1 data sheet.
Figure 4-1 Pin DiagramFollowing are the assumptions of use and the device configuration assumed for the pin FMA in this section:
- Device is the only target on the I2C bus
- External pull-up resistor on SCL and SDA pins
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| RH | 1 | RH stuck low, not functional, not possible to read the RH voltage output. | B |
| GND | 2 | No effect. Normal operation. | D |
| GND | 3 | No effect. Normal operation. | D |
| TEMP | 4 | TEMP stuck low, not functional, not possible to read the TEMP voltage output. | B |
| VDD | 5 | Device not powered. Device not functional. Observe that the absolute maximum ratings for all pins of the device are met, otherwise device damage is plausible. | A |
| RESET_EN | 6 | RESET_EN stuck low, RESET_EN is permanently enabled, device non-functional until reset is cleared. | B |
| HEAT_EN | 7 | HEAT_EN stuck low, the heater is not able to be turned on, the heater is the only function lost. | B |
| GND | 8 | No effect. Normal operation. | D |
Table 4-3 Pin FMA for Device Pins Open-Circuited
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| RH | 1 | Reading the RH output is impossible. | B |
| GND | 2 | Device functionality is undetermined. Device potentially does not power or connect to ground internally through the alternate pin ESD diode and power up. | B |
| GND | 3 | Device functionality is undetermined. Device potentially does not power or connect to ground internally through alternate pin ESD diode and power up. | B |
| TEMP | 4 | Reading the TEMP output is impossible. | B |
| VDD | 5 | Device functionality is undetermined. Device not powered if all external analog and digital pins are held low. Device can power up through the internal ESD diodes to VDD, if voltages above the power-on reset threshold for the device are present on any of the analog or digital pins. | B |
| RESET_EN | 6 | RESET_EN can inadvertently trigger if the floating input voltage clears the VIH threshold, resetting the device. | B |
| HEAT_EN | 7 | HEAT_EN can trigger the heater to inadvertently turn on if the floating input voltage clears the VIH threshold. | B |
| GND | 8 | Device functionality is undetermined. Device potentially does not power or connect to ground internally through alternate pin ESD diode and power up. | B |
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 |
|---|---|---|---|---|
| RH | 1 | GND | RH stuck low, not functional, not possible to read the RH voltage output. | B |
| GND | 2 | GND | No effect. Normal operation. | D |
| GND | 3 | TEMP | TEMP stuck low, not functional, not possible to read the TEMP voltage output. | B |
| VDD | 5 | RESET_EN | RESET_EN stuck high, cannot issue resets with nRESET pin. | B |
| RESET_EN | 6 | HEAT_EN | Heater enables when reset is not triggered and reset triggers when the heater is disabled. Leads to inadvertent heater activation and reset events, loss of functionality. | B |
| HEAT_EN | 7 | GND | HEAT_EN stuck low, the heater is not able to be turned on, the heater is the only function lost. | B |
Table 4-5 Pin FMA for Device Pins Short-Circuited to Supply
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| RH | 1 | RH stuck high, not functional, not possible to read the RH voltage output. | B |
| GND | 2 | Device functionality is undetermined. Observe that the absolute maximum ratings for all pins of the device are met, otherwise device damage is plausible. | A |
| GND | 3 | Device functionality is undetermined. Observe that the absolute maximum ratings for all pins of the device are met, otherwise device damage is plausible. | A |
| TEMP | 4 | TEMP stuck high, not functional, not possible to read the TEMP voltage output. | B |
| VDD | 5 | No effect. Normal operation. | D |
| RESET_EN | 6 | RESET_EN stuck high, cannot issue resets with the RESET_EN pin. | B |
| HEAT_EN | 7 | HEAT_EN stuck high, the heater is permanently enabled, degrades performance and accuracy of the RH and TEMP outputs. | B |
| VDD | 8 | Device functionality is undetermined. Observe that the absolute maximum ratings for all pins of the device are met, otherwise device damage is plausible. | A |