SFFS780 February 2024 TUSB4020BI-Q1
4 Pin Failure Mode Analysis (Pin FMA)
This section provides a failure mode analysis (FMA) for the pins of the TUSB4020BI-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 VDD (see Table 4-5)
- Pin short-circuited to VDD33 (see Table 4-6)
Table 4-2 through Table 4-6 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 TUSB4020BI-Q1 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the TUSB4020BI-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 configured for power managed downstream ports
- Device battery charging support is enabled
- All device downstream ports are connected to a USB receptacle.
- Device Upstream port is connected to a USB2 Host controller.
- 5V BUS is present on upstream port.
Table 4-2 Pin FMA for Device Pins
Short-Circuited to Ground
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| VDD | 1 | Device can get damaged | A |
| SCL/SMBCLK | 2 | Device not functional (I2C and SMBus not functional) | B |
| SDA/SMBDAT | 3 | Device not functional (I2C and SMBus not functional) | B |
| PWRCTL1/BATEN1 | 4 | USB2 downstream port 1 BC1.2 not functional. Also port power not functional | B |
| OVERCUR1Z | 5 | Device always communicates to system an overcurrent condition. Device never enables VBUS on the downstream port. | B |
| PWRCTL2/BATEN2 | 6 | USB2 downstream port 2 BC1.2 not functional. Also port power not functional | B |
| VDD33 | 7 | Device can get damaged | A |
| OVERCUR2Z | 8 | Device always communicates to system an overcurrent has occurred. Device never enables VBUS on downstream port 2. | B |
| USB_VBUS | 9 | VBUS on hub's upstream port is never detected. No communication with USB devices connected to Hub's downstream port 1 and 2 occurs. | B |
| TEST | 10 | No effect. Normal operation. | D |
| GRSTz | 11 | Device is held in reset and not functional | B |
| VDD | 12 | Device can get damaged | A |
| VDD33 | 13 | Device can get damaged | A |
| USB_DP_DN2 | 14 | Downstream port 2 not functional | B |
| USB_DM_DN2 | 15 | Downstream port 2 not functional | B |
| RSVD | 16 | No effect. Normal operation. | D |
| RSVD | 17 | No effect. Normal operation. | D |
| VDD | 18 | Device can get damaged | A |
| RSVD | 19 | No effect. Normal operation. | D |
| RSVD | 20 | No effect. Normal operation. | D |
| PWRCTL_POL | 21 | No impact to functionality if external VBUS power switch enable polarity is active high. If polarity is active low, then VBUS for hub's downstream ports 1 and 2 are not enabled. | B |
| SMBUSz | 22 | No effect if system intends to use hub in SMBus mode. If system intends to use hub in I2C mode, then I2C mode is not enabled. | B |
| VDD33 | 23 | Device can get damaged | A |
| USB_R1 | 24 | Device not functional | B |
| VDD33 | 25 | Device can get damaged | A |
| USB_DP_UP | 26 | Upstream port not functional | B |
| USB_DM_UP | 27 | Upstream port not functional | B |
| RSVD | 28 | No effect. Normal operation. | D |
| RSVD | 29 | No effect. Normal operation. | D |
| VDD | 30 | Device can get damaged | A |
| RSVD | 31 | No effect. Normal operation. | D |
| RSVD | 32 | No effect. Normal operation. | D |
| VDD33 | 33 | Device can get damaged | A |
| VDD | 34 | Device can get damaged | A |
| GANGED/SMBA2/HSUP | 35 | SMBus target address can be incorrect causing SMBus operation to fail. | B |
| FULLPWRMGMTz/SMBA1 | 36 | SMBus target address can be incorrect causing SMBus operation to fail. | B |
| VDD33 | 37 | Device can get damaged | A |
| XI | 38 | XI is input for oscillator. Without a clock, device is not functional. | B |
| XO | 39 | No impact to functionality if external clock is provided to XI. If external crystal is used, then device is not functional. | B |
| VDD33 | 40 | Device can get damaged | A |
| USB_DP_DN1 | 41 | Downstream port 1 not functional | B |
| USB_DM_DN1 | 42 | Downstream port 1 not functional | B |
| RSVD | 43 | No effect. Normal operation. | D |
| RSVD | 44 | No effect. Normal operation. | D |
| VDD | 45 | Device can get damaged | A |
| RSVD | 46 | No effect. Normal operation. | D |
| RSVD | 47 | No effect. Normal operation. | D |
| VDD33 | 48 | Device can get damaged | A |
| Thermal pad | 49 | 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 |
|---|---|---|---|
| VDD | 1 | Device unpowered. Device not functional. | B |
| SCL/SMBCLK | 2 | SMBus and load from an external I2C EEPROM not functional. | B |
| SDA/SMBDAT | 3 | SMBus and load from an external I2C EEPROM not functional. | B |
| PWRCTL1/BATEN1 | 4 | Battery charge support for downstream port 1 is disabled. There is no VBUS control. | B |
| OVERCUR1Z | 5 | Device has internal pull-up resistor. Overcurrent detection not functional. | B |
| PWRCTL2/BATEN2 | 6 | Battery charge support for downstream port 2 is disabled. There is no VBUS control. | B |
| VDD33 | 7 | Device unpowered. Device not functional. | B |
| OVERCUR2Z | 8 | Device has internal pull-up resistor. Overcurrent detection not functional. | B |
| USB_VBUS | 9 | VBUS on hub's upstream port never detected. No communication with USB devices connected to Hub's DFP can occur. | B |
| TEST | 10 | No effect. Normal operation. Device has a internal pull-down. | D |
| GRSTz | 11 | Device has internal pull-up resistor. No effect. Normal operation. | D |
| VDD | 12 | Device unpowered. Device not functional. | B |
| VDD33 | 13 | Device unpowered. Device not functional. | B |
| USB_DP_DN2 | 14 | Downstream port 2 not functional. | B |
| USB_DM_DN2 | 15 | Downstream port 2 not functional. | B |
| RSVD | 16 | No effect. Normal operation. | D |
| RSVD | 17 | No effect. Normal operation. | D |
| VDD | 18 | Device unpowered. Device not functional. | B |
| RSVD | 19 | No effect. Normal operation. | D |
| RSVD | 20 | No effect. Normal operation. | D |
| PWRCTL_POL | 21 | Device has internal pull-down. No effect if system requires VBUS power switch enable polarity to be active high. | B |
| SMBUSz | 22 | No effect if system intends to use hub in I2C mode. If system intends to use hub in SMBus mode, then SMBus not functional. | B |
| VDD33 | 23 | Device unpowered. Device not functional. | B |
| USB_R1 | 24 | Device not functional. | B |
| VDD33 | 25 | Device unpowered. Device not functional. | B |
| USB_DP_UP | 26 | Hub upstream communication not functional. All USB2 downstream ports of hub also not functional. | B |
| USB_DM_UP | 27 | Hub upstream communication not functional. All USB2 downstream ports of hub also not functional. | B |
| RSVD | 28 | No effect. Normal operation. | D |
| RSVD | 29 | No effect. Normal operation. | D |
| VDD | 30 | Device unpowered. Device not functional. | B |
| RSVD | 31 | No effect. Normal operation. | D |
| RSVD | 32 | No effect. Normal operation. | D |
| VDD33 | 33 | Device unpowered. Device not functional. | B |
| VDD | 34 | Device unpowered. Device not functional. | B |
| GANGED/SMBA2/HSUP | 35 | Pin has an internal pull-up resistor. Floating pin causes device to operate in Ganged power switch mode instead of per port power switch. | B |
| FULLPWRMGMTz/SMBA1 | 36 | Pin has an internal pull-up resistor. Floating pin causes device to operation without downstream port power management. | B |
| VDD33 | 37 | Device unpowered. Device not functional. | B |
| XI | 38 | XI is input for oscillator. Without a clock, device is not functional. | B |
| XO | 39 | Device functional if clock provided to XI pin. If external crystal is used, then device is not functional | B |
| VDD33 | 40 | Device unpowered. Device not functional. | B |
| USB_DP_DN1 | 41 | USB2 downstream port 1 not functional. | B |
| USB_DM_DN1 | 42 | USB2 downstream port 1 not functional. | B |
| RSVD | 43 | No effect. Normal operation. | D |
| RSVD | 44 | No effect. Normal operation. | D |
| VDD | 45 | Device unpowered. Device not functional. | B |
| RSVD | 46 | No effect. Normal operation. | D |
| RSVD | 47 | No effect. Normal operation. | D |
| VDD33 | 48 | Device unpowered. Device not functional. | B |
| Thermal pad | 49 | Thermal performance degraded. Thermal pad is also used for device ground and leave floating can cause device to not function. | B |
Table 4-4 Pin FMA for Device Pins
Short-Circuited to Adjacent Pin
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| VDD | 1 | I2C and SMBus not functional. | B |
| SCL/SMBCLK | 2 | I2C and SMBus not functional. | B |
| SDA/SMBDAT | 3 | I2C and SMBus not functional. | B |
| PWRCTL1/BATEN1 | 4 | I2C and SMBus not functional. Downstream port 1 VBUS control not functional. | B |
| OVERCUR1Z | 5 | Overcurrent for downstream port 1 not functional. | B |
| PWRCTL2/BATEN2 | 6 | Downstream port 2 VBUS control not functional. | B |
| VDD33 | 7 | Device not functional. | B |
| OVERCUR2Z | 8 | Overcurrent for downstream port 2 not functional | B |
| USB_VBUS | 9 | Device not functional. | B |
| TEST | 10 | Device not functional. | B |
| GRSTz | 11 | Device not functional. | B |
| VDD | 12 | Device can get damaged. | A |
| VDD33 | 13 | Device can get damaged. | A |
| USB_DP_DN2 | 14 | Downstream port 2 not functional. | B |
| USB_DM_DN2 | 15 | Downstream port 2 not functional. | B |
| RSVD | 16 | Downstream piort 2 not functional. | B |
| RSVD | 17 | No effect. Normal operation. | D |
| VDD | 18 | No effect. Normal operation. | D |
| RSVD | 19 | No effect. Normal operation. | D |
| RSVD | 20 | Device not functional. | B |
| PWRCTL_POL | 21 | Device not functional. | B |
| SMBUSz | 22 | Device not functional. | B |
| VDD33 | 23 | Device can get damaged. | A |
| USB_R1 | 24 | Device can get damaged. | A |
| VDD33 | 25 | Device can get damaged. | A |
| USB_DP_UP | 26 | Device can get damaged. | A |
| USB_DM_UP | 27 | Upstream port not functional. | B |
| RSVD | 28 | Upstream port not functional. | B |
| RSVD | 29 | Device can get damaged. | A |
| VDD | 30 | Device can get damaged. | A |
| RSVD | 31 | Device can get damaged. | A |
| RSVD | 32 | Device can get damaged. | A |
| VDD33 | 33 | Device can get damaged. | A |
| VDD | 34 | Device can get damaged. | A |
| GANGED/SMBA2/HSUP | 35 | Device not functional. | B |
| FULLPWRMGMTz/SMBA1 | 36 | Device not functional. | B |
| VDD33 | 37 | Device can get damaged. | A |
| XI | 38 | Device can get damaged. | A |
| XO | 39 | Device can get damaged. | A |
| VDD33 | 40 | Device can get damaged. | A |
| USB_DP_DN1 | 41 | Downstream port 1 not functional. | B |
| USB_DM_DN1 | 42 | Downstream port 1 not functional. | A |
| RSVD | 43 | Downstream port 1 not functional. | A |
| RSVD | 44 | No effect. Normal operation. | D |
| VDD | 45 | No effect. Normal operation. | D |
| RSVD | 46 | No effect. Normal operation. | D |
| RSVD | 47 | Device can get damaged. | A |
| VDD33 | 48 | Device can get damaged. | A |
| Thermal pad | 49 | Device can get damaged. | A |
Table 4-5 Pin FMA for Device Pins
Short-Circuited to
VDD
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| VDD | 1 | No effect. Normal operation. | D |
| SCL/SMBCLK | 2 | Device not functional. | B |
| SDA/SMBDAT | 3 | Device not functional. | B |
| PWRCTL1/BATEN1 | 4 | Downstream port 1 power control not functional. | B |
| OVERCUR1Z | 5 | Device overcurrent detection behavior can be indeterminate since VDD is between VIL and VIH. | B |
| PWRCTL2/BATEN2 | 6 | Downstream port 2 power control not functional. | B |
| VDD33 | 7 | Device can get damaged. | A |
| OVERCUR2Z | 8 | Device overcurrent detection behavior can be indeterminate since VDD is between VIL and VIH. | B |
| USB_VBUS | 9 | Device can get damaged. | A |
| TEST | 10 | Device behavior can be indeterminate since device can enter an internal test mode. | B |
| GRSTz | 11 | Device can be in an indeterminate state because device was not reset properly. | B |
| VDD | 12 | No effect. Normal operation. | D |
| VDD33 | 13 | Device can get damaged. | A |
| USB_DP_DN2 | 14 | Downstream port 2 not functional. | B |
| USB_DM_DN2 | 15 | Downstream port 2 not functional. | B |
| RSVD | 16 | No effect. Normal operation. | D |
| RSVD | 17 | No effect. Normal operation. | D |
| VDD | 18 | No effect. Normal operation. | D |
| RSVD | 19 | No effect. Normal operation. | D |
| RSVD | 20 | No effect. Normal operation. | D |
| PWRCTL_POL | 21 | Device not functional. | B |
| SMBUSz | 22 | Device not functional. | B |
| VDD33 | 23 | Device can get damaged. | A |
| USB_R1 | 24 | Device not functional. | B |
| VDD33 | 25 | Device can get damaged. | A |
| USB_DP_UP | 26 | Upstream port not functional. | B |
| USB_DM_UP | 27 | Upstream port not functional. | B |
| RSVD | 28 | Device can get damaged. | A |
| RSVD | 29 | Device can get damaged. | A |
| VDD | 30 | No effect. Normal operation. | D |
| RSVD | 31 | Device can get damaged. | A |
| RSVD | 32 | Device can get damaged. | A |
| VDD33 | 33 | Device can get damaged. | A |
| VDD | 34 | No effect. Normal operation. | D |
| GANGED/SMBA2/HSUP | 35 | Device not functional. | B |
| FULLPWRMGMTz/SMBA1 | 36 | Device not functional. | B |
| VDD33 | 37 | Device can get damaged. | A |
| XI | 38 | Device not functional. | B |
| XO | 39 | Device not functional. | B |
| VDD33 | 40 | Device can get damaged. | A |
| USB_DP_DN1 | 41 | Downstream port 1 not functional. | B |
| USB_DM_DN1 | 42 | Downstream port 1 not functional. | B |
| RSVD | 43 | No effect. Normal operation. | D |
| RSVD | 44 | No effect. Normal operation. | D |
| VDD | 45 | No effect. Normal operation. | D |
| RSVD | 46 | No effect. Normal operation. | D |
| RSVD | 47 | No effect. Normal operation. | D |
| VDD33 | 48 | Device can get damaged. | A |
| Thermal pad | 49 | Device can get damaged. | A |
Table 4-6 Pin FMA for Device Pins
Short-Circuited to
VDD33
| Pin Name | Pin No. | Description of Potential Failure Effects | Failure Effect Class |
|---|---|---|---|
| VDD | 1 | Device can get damaged. | A |
| SCL/SMBCLK | 2 | Device not functional. | B |
| SDA/SMBDAT | 3 | Device not functional. | B |
| PWRCTL1/BATEN1 | 4 | Downstream port 1 power control not functional. | B |
| OVERCUR1Z | 5 | Overcurrent detection for downstream port 1 not functional | B |
| PWRCTL2/BATEN2 | 6 | Downstream port 2 power control not functional. | B |
| VDD33 | 7 | No effect. Normal operation. | D |
| OVERCUR2Z | 8 | Overcurrent detection for downstream port 1 not functional | B |
| USB_VBUS | 9 | Device can get damaged. | A |
| TEST | 10 | Device not functional. | B |
| GRSTz | 11 | Device not functional. | B |
| VDD | 12 | Device can get damaged. | A |
| VDD33 | 13 | No effect. Normal operation. | D |
| USB_DP_DN2 | 14 | Downstream port 2 not functional. | B |
| USB_DM_DN2 | 15 | Downstream port 2 not functional. | B |
| RSVD | 16 | Device can get damaged. | A |
| RSVD | 17 | Device can get damaged. | A |
| VDD | 18 | Device can get damaged. | A |
| RSVD | 19 | Device can get damaged. | A |
| RSVD | 20 | Device can get damaged. | A |
| PWRCTL_POL | 21 | No effect if system requires VBUS power switch enable polarity to be active low. For active high polarity, VBUS power control not functional. | B |
| SMBUSz | 22 | No effect if system intends to use hub in I2C mode. If system intends to use hub in SMBus mode, then SMBus not functional. | B |
| VDD33 | 23 | No effect. Normal operation. | D |
| USB_R1 | 24 | Device can get damaged. | A |
| VDD33 | 25 | No effect. Normal operation. | D |
| USB_DP_UP | 26 | Upstream port not functional. | B |
| USB_DM_UP | 27 | Upstream port not functional. | B |
| RSVD | 28 | Device can get damaged. | A |
| RSVD | 29 | Device can get damaged. | A |
| VDD | 30 | Device can get damaged. | A |
| RSVD | 31 | Device can get damaged. | A |
| RSVD | 32 | Device can get damaged. | A |
| VDD33 | 33 | No effect. Normal operation. | D |
| VDD | 34 | Device can get damaged. | A |
| GANGED/SMBA2/HSUP | 35 | Device not functional | B |
| FULLPWRMGMTz/SMBA1 | 36 | Device not functional | B |
| VDD33 | 37 | No effect. Normal operation. | D |
| XI | 38 | Device can get damaged. | A |
| XO | 39 | Device can get damaged. | A |
| VDD33 | 40 | No effect. Normal operation. | D |
| USB_DP_DN1 | 41 | Downstream port 1 not functional. | B |
| USB_DM_DN1 | 42 | Downstream port 1 not functional. | B |
| RSVD | 43 | Device can get damaged. | A |
| RSVD | 44 | Device can get damaged. | A |
| VDD | 45 | Device can get damaged. | A |
| RSVD | 46 | Device can get damaged. | A |
| RSVD | 47 | Device can get damaged. | A |
| VDD33 | 48 | No effect. Normal operation. | D |
| Thermal pad | 49 | Device can get damaged. | A |