SFFS005A December   2020  – November 2021 ADS131B04-Q1

 

  1.   Trademarks
  2. 1Overview
  3. 2Functional Safety Failure In Time (FIT) Rates
  4. 3Failure Mode Distribution (FMD)
  5. 4Pin Failure Mode Analysis (Pin FMA)
  6. 5Revision History

4 Pin Failure Mode Analysis (Pin FMA)

This section provides a failure mode analysis (FMA) for the pins of the ADS131B04-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 ADS131B04-Q1 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the ADS131B04-Q1 data sheet.

Figure 4-1 Pin Diagram

Following are the assumptions of use and the device configuration assumed for the pin FMA in this section:

  • AVDD and DVDD use the same 3.3-V supply voltage.
  • Short circuit to supply means short to AVDD = DVDD.
  • Short circuit to ground means short to AGND = DGND.
  • Differential RC filters on every ADC channel.
    Series resistors are sized to limit the input currents into the analog inputs to <10 mA in all circumstances (for example, if the device is unpowered and input signal is applied).
  • External pulldown resistor (≥1 kΩ) on CLKIN to DGND if the device is configured for use with the internal oscillator.
  • Device is the only peripheral on the SPI bus.
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
AVDD 1 Device unpowered. Device not functional. Observe that the absolute maximum ratings for all pins of the device are met, otherwise device damage may be plausible. A
AGND 2 No effect. Normal operation. D
AIN0P 3 AIN0P stuck low. VIN0 = VAIN0P – VAIN0N = AGND – VAIN0N. Conversion results of ADC0 incorrect. B
AIN0N 4 AIN0N stuck low. VIN0 = VAIN0P – VAIN0N = VAIN0P – AGND. Conversion results of ADC0 incorrect. B
AIN1N 5 AIN1N stuck low. VIN1 = VAIN1P – VAIN1N = VAIN1P – AGND. Conversion results of ADC1 incorrect. B
AIN1P 6 AIN1P stuck low. VIN1 = VAIN1P – VAIN1N = AGND – VAIN1N. Conversion results of ADC1 incorrect. B
AIN2P 7 AIN2P stuck low. VIN2 = VAIN2P – VAIN2N = AGND – VAIN2N. Conversion results of ADC2 incorrect. B
AIN2N 8 AIN2N stuck low. VIN2 = VAIN2P – VAIN2N = VAIN2P – AGND. Conversion results of ADC2 incorrect. B
AIN3N 9 AIN3N stuck low. VIN3 = VAIN3P – VAIN3N = VAIN3P – AGND. Conversion results of ADC3 incorrect. B
AIN3P 10 AIN3P stuck low. VIN3 = VAIN3P – VAIN3N = AGND – VAIN3N. Conversion results of ADC3 incorrect. B
SYNC/RESET 11 SYNC/RESET stuck low. Device held in reset. B
CS 12 CS stuck low. Normal operation when trying to communicate with the ADS131B04-Q1. B
DRDY 13 DRDY stuck low. No data-ready indication through DRDY pin to host possible. Increase in supply current when DRDY tries to drive high if DRDY_HiZ bit = 0b. Device damage plausible if DRDY drives high for extended period of time. A
SCLK 14 SCLK stuck low. No SPI communication with device possible. B
DOUT 15 DOUT stuck low. No SPI communication back to host possible. Increase in supply current when DOUT tries to drive high. Device damage plausible if DOUT drives high for extended period of time. A
DIN 16 DIN stuck low. No SPI communication with device possible. B
CLKIN 17 Device configured for use with external clock: CLKIN stuck low. No clock provided to device. Device not functional, but SPI communication with device possible. B
Device configured for use with internal oscillator: CLKIN stuck low. No effect. Normal operation. D
CAP 18 Device unpowered. Device not functional. B
DGND 19 No effect. Normal operation. D
DVDD 20 Device unpowered. Device not functional. Observe that the absolute maximum ratings for all pins of the device are met, otherwise device damage may be plausible. A
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
AVDD 1 Device functionality undetermined. Device unpowered and not functional if all external analog pins are held low. Device may power up through internal ESD diodes to AVDD if voltages above the device power-on reset threshold are present on any of the analog pins. B
AGND 2 Device functionality undetermined. Device may be unpowered or connect to ground internally through alternate pin ESD diode and power up. B
AIN0P 3 State of AIN0P input undetermined. Conversion results of ADC0 undetermined. B
AIN0N 4 State of AIN0N input undetermined. Conversion results of ADC0 undetermined. B
AIN1N 5 State of AIN1N input undetermined. Conversion results of ADC1 undetermined. B
AIN1P 6 State of AIN1P input undetermined. Conversion results of ADC1 undetermined. B
AIN2P 7 State of AIN2P input undetermined. Conversion results of ADC2 undetermined. B
AIN2N 8 State of AIN2N input undetermined. Conversion results of ADC2 undetermined. B
AIN3N 9 State of AIN3N input undetermined. Conversion results of ADC3 undetermined. B
AIN3P 10 State of AIN3P input undetermined. Conversion results of ADC3 undetermined. B
SYNC/RESET 11 State of SYNC/RESET input undetermined. Device functionality undetermined. Device may operate normally or be held in reset. B
CS 12 State of CS input undetermined. SPI communication corrupted. B
DRDY 13 State of DRDY output undetermined. No data-ready indication through DRDY pin to host possible. B
SCLK 14 State of SCLK input undetermined. No SPI communication with device possible. B
DOUT 15 State of DOUT output undetermined. No SPI communication back to host possible. B
DIN 16 State of DIN input undetermined. No SPI communication with device possible. B
CLKIN 17 Device configured for use with external clock: state of CLKIN input undetermined. No clock provided to device. Device not functional, but SPI communication with device possible. B
Device configured for use with internal oscillator: state of CLKIN input undetermined. No effect. Normal operation. D
CAP 18 Internal digital LDO unstable. Device functionality undetermined. B
DGND 19 Device functionality undetermined. Device may be unpowered or connect to ground internally through alternate pin ESD diode and power up. B
DVDD 20 Device functionality undetermined. Device unpowered and not functional if all external digital pins are held low. Device may power up through internal ESD diodes to DVDD if voltages above the device power-on reset threshold are present on any of the digital pins. B
Table 4-4 Pin FMA for Device Pins Short-Circuited to Adjacent Pin
Pin Name Pin No. Shorted to Description of Potential Failure Effect(s) Failure Effect Class
AVDD 1 AGND Device unpowered. Device not functional. Observe that the absolute maximum ratings for all pins of the device are met, otherwise device damage may be plausible. A
AGND 2 AIN0P AIN0P stuck low. VIN0 = VAIN0P – VAIN0N = AGND – VAIN0N. Conversion results of ADC0 incorrect. B
AIN0P 3 AIN0N VIN0 = VAIN0P – VAIN0N = 0 V. Conversion result of ADC0 close to 0 V. B
AIN0N 4 AIN1N Conversion results of ADC0 and ADC1 undetermined. B
AIN1N 5 AIN1P VIN1 = VAIN1P – VAIN1N = 0 V. Conversion result of ADC1 close to 0 V. B
AIN1P 6 AIN2P Conversion results of ADC1 and ADC2 undetermined. B
AIN2P 7 AIN2N VIN2 = VAIN2P – VAIN2N = 0 V. Conversion result of ADC2 close to 0 V. B
AIN2N 8 AIN3N Conversion results of ADC2 and ADC3 undetermined. B
AIN3N 9 AIN3P VIN3 = VAIN3P – VAIN3N = 0 V. Conversion result of ADC3 close to 0 V. B
AIN3P 10 SYNC/RESET Not considered. Corner pin. D
SYNC/RESET 11 CS Device behavior dependent on drive strength of control signals driving CS and SYNC/RESET pins. If SYNC/RESET control signal can overdrive CS control signal: CS stuck high or SPI communication corrupted. No SPI communication with device possible. If CS control signal can overdrive SYNC/RESET control signal: device synchronizes conversions every time CS transitions high. Conversion results are valid but data ready is indicated outside the expected time window. If the SYNC/RESET pin is held low for longer than the reset time period, then device reset occurs. B
CS 12 DRDY SPI communication corrupted. No SPI communication with device possible. Increase in supply current possible when DRDY tries to drive low while CS is driven high and vice versa. Device damage plausible if this condition exists for extended period of time. A
DRDY 13 SCLK SPI communication corrupted. No SPI communication with device possible. Increase in supply current possible when DRDY tries to drive low while SCLK is driven high and vice versa. Device damage plausible if this condition exists for extended period of time. A
SCLK 14 DOUT SPI communication corrupted. No SPI communication with device possible. Increase in supply current possible when DOUT tries to drive low while SCLK is driven high and vice versa. Device damage plausible if this condition exists for extended period of time. A
DOUT 15 DIN SPI communication corrupted. No SPI communication with device possible. Increase in supply current possible when DOUT tries to drive low while DIN is driven high and vice versa. Device damage plausible if this condition exists for extended period of time. A
DIN 16 CLKIN Device configured for use with external clock: SPI communication corrupted. No SPI communication with device possible. CLKIN signal corrupted. Device behavior undetermined. B
Device configured for use with internal oscillator: No effect. Normal operation as long as DIN can drive the pulldown resistor between CLKIN and DGND. D
CLKIN 17 CAP Device configured for use with external clock: device behavior undetermined. Device damage plausible when CLKIN pin drives digital core LDO output on CAP pin to >1.8 V. A
Device configured for use with internal oscillator: digital core LDO output drives external pulldown resistor on CLKIN pin to 1.8 V. Increase in digital supply current. Otherwise normal operation. D
CAP 18 DGND Device unpowered. Device not functional. B
DGND 19 DVDD Device unpowered. Device not functional. Observe that the absolute maximum ratings for all pins of the device are met, otherwise device damage may be plausible. A
DVDD 20 AVDD Not considered. Corner pin. D
Table 4-5 Pin FMA for Device Pins Short-Circuited to Supply
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
AVDD 1 No effect. Normal operation. D
AGND 2 Device unpowered. Device not functional. Observe that the absolute maximum ratings for all pins of the device are met, otherwise device damage may be plausible. A
AIN0P 3 AIN0P stuck high. VIN0 = VAIN0P – VAIN0N = AVDD – VAIN0N. Conversion results of ADC0 incorrect. B
AIN0N 4 AIN0N stuck high. VIN0 = VAIN0P – VAIN0N = VAIN0P – AVDD. Conversion results of ADC0 incorrect. B
AIN1N 5 AIN1N stuck high. VIN1 = VAIN1P – VAIN1N = VAIN1P – AVDD. Conversion results of ADC1 incorrect. B
AIN1P 6 AIN1P stuck high. VIN1 = VAIN1P – VAIN1N = AVDD – VAIN1N. Conversion results of ADC1 incorrect. B
AIN2P 7 AIN2P stuck high. VIN2 = VAIN2P – VAIN2N = AVDD – VAIN2N. Conversion results of ADC2 incorrect. B
AIN2N 8 AIN2N stuck high. VIN2 = VAIN2P – VAIN2N = VAIN2P – AVDD. Conversion results of ADC2 incorrect. B
AIN3N 9 AIN3N stuck high. VIN3 = VAIN3P – VAIN3N = VAIN3P – AVDD. Conversion results of ADC3 incorrect. B
AIN3P 10 AIN3P stuck high. VIN3 = VAIN3P – VAIN3N = AVDD – VAIN3N. Conversion results of ADC3 incorrect. B
SYNC/RESET 11 No effect. Normal operation. Device cannot be reset or synchronized using the SYNC/RESET pin anymore. B
CS 12 CS stuck high. No SPI communication with device possible. B
DRDY 13 DRDY stuck high. No data-ready indication through DRDY pin to host possible. Increase in supply current when DRDY tries to drive low. Device damage plausible if DRDY drives low for extended period of time. A
SCLK 14 SCLK stuck high. No SPI communication with device possible. B
DOUT 15 DOUT stuck high. No SPI communication back to host possible. Increase in supply current when DOUT tries to drive low. Device damage plausible if DOUT drives low for extended period of time. A
DIN 16 DIN stuck high. No SPI communication with device possible. B
CLKIN 17 Device configured for use with external clock: CLKIN stuck high. No clock provided to device. Device not functional, but SPI communication with device possible. B
Device configured for use with internal oscillator: CLKIN stuck high. No effect. Normal operation. D
CAP 18 Device may operate normally, but permanent device damage within short period of time is very plausible. Device not functional anymore in case of damage. A
DGND 19 Device unpowered. Device not functional. Observe that the absolute maximum ratings for all pins of the device are met, otherwise device damage may be plausible. A
DVDD 20 No effect. Normal operation. D