SFFS087 April   2021 DRV8705-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)

Pin Failure Mode Analysis (Pin FMA)

This section provides a Failure Mode Analysis (FMA) for the pins of the DRV8705-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 for SPI variant, see Table 4-3 for HW variant)
  • Pin open-circuited (see Table 4-4 for SPI variant, see Table 4-5 for HW variant)
  • Pin short-circuited to an adjacent pin (see Table 4-6 for SPI variant, see Table 4-7 for HW variant)
  • Pin short-circuited to supply (PVDD) (see Table 4-8 for SPI variant, see Table 4-9 for HW variant)

Table 4-2 through Table 4-9 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
ClassFailure Effects
APotential device damage that affects functionality
BNo device damage, but loss of functionality
CNo device damage, but performance degradation
DNo device damage, no impact to functionality or performance

Figure 4-1 and Figure 4-2 show the DRV8705-Q1 pin diagrams. The DRV8705-Q1 has two pin diagram variants, an SPI variant (DRV8705S-Q1) and a HW variant (DRV8705H-Q1). For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the DRV8705-Q1 data sheet.

GUID-1760ED63-05C0-461E-9D9D-01E9424F755D-low.gifFigure 4-1 DRV8705S-Q1 Pin Diagram
GUID-CE9176F9-4419-4EA1-9B77-FABCDE9B103B-low.gifFigure 4-2 DRV8705H-Q1 Pin Diagram

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

  • The device is used with external components consistent with the values described in the external component table and primary application section of the datasheet.
Table 4-2 DRV8705S-Q1 (SPI Variant) Pin FMA for Device Pins Short-Circuited to Ground
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
GND 1 No impact. Intended operation. D
DVDD 2 Device external digital power supply stuck low. Device non-operational. B
nSCS 3 SPI communication compromised. B
SCLK 4 SPI communication compromised. B
SDI 5 SPI communication compromised. B
SDO 6 SPI communication compromised. B
IN1/EN 7 Gate driver control input stuck low. Driver output may not match input. B
nHIZ1 8 Gate driver control input stuck low. Driver output disabled. B
IN2/PH 9 Gate driver control input stuck low. Driver output may not match input. B
nHIZ2 10 Gate driver control input stuck low. Driver output disabled. B
nSLEEP 11 Device stuck in sleep state. Outputs non-operational. B
DRVOFF 12 Driver disable input stuck low. Gate driver disable function non-operational. B
nFAULT 13 Device fault output indicator always active. B
SO 14 Device current sense feedback invalid. B
RSVD 15 No impact. Intended operation. D
AREF 16 Device external analog power supply stuck low. Current sense invalid. B
AGND 17 No impact. Intended operation. D
SP 18 Device current sense feedback invalid. B
SN 19 Device current sense feedback invalid. B
GH1 20 HS1 external MOSFET off, energy limited by TDRIVE. Device VGS fault. B
SH1 21 HS1 external MOSFET non-operational. Device VDS fault. B
GL1 22 LS1 external MOSFET off, energy limited by TDRIVE. Device VGS fault. B
SL1 23 No impact. Intended operation. D
SL2 24 No impact. Intended operation. D
GL2 25 LS2 external MOSFET off, energy limited by TDRIVE. Device VGS fault. B
SH2 26 HS2 external MOSFET non-operational. Device VDS fault. B
GH2 27 HS2 external MOSFET off, energy limited by TDRIVE. Device VGS fault. B
DRAIN 28 Device overcurrent monitors and open load diagnostic non-operational. B
PVDD 29 Device external power supply stuck low. Device gate drivers and shunt amplifier non-operational. B
VCP 30 Device charge pump non-operational. Device CPUV fault. A
CPH 31 Device charge pump non-operational. Device CPUV fault. A
CPL 32 Device charge pump non-operational. Device CPUV fault. A
Table 4-3 DRV8705H-Q1 (HW Variant) Pin FMA for Device Pins Short-Circuited to Ground
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
GND 1 No impact. Intended operation. D
DVDD 2 Device external digital power supply stuck low. Device non-operational. B
GAIN 3 Device GAIN setting potentially incorrect. B
VDS 4 Device VDS setting potentially incorrect. B
IDRIVE 5 Device IDRIVE setting potentially incorrect. B
MODE 6 Device MODE setting potentially incorrect. B
IN1/EN 7 Gate driver control input stuck low. Driver output may not match input. B
nHIZ1 8 Gate driver control input stuck low. Driver output disabled. B
IN2/PH 9 Gate driver control input stuck low. Driver output may not match input. B
nHIZ2 10 Gate driver control input stuck low. Driver output disabled. B
nSLEEP 11 Device stuck in sleep state. Outputs non-operational. B
DRVOFF 12 Driver disable input stuck low. Gate driver disable function non-operational. B
nFAULT 13 Device fault output indicator always active. B
SO 14 Device current sense feedback invalid. B
RSVD 15 No impact. Intended operation. D
AREF 16 Device external analog power supply stuck low. Current sense invalid. B
AGND 17 No impact. Intended operation. D
SP 18 Device current sense feedback invalid. B
SN 19 Device current sense feedback invalid. B
GH1 20 HS1 external MOSFET off, energy limited by TDRIVE. Device VGS fault. B
SH1 21 HS1 external MOSFET non-operational. Device VDS fault. B
GL1 22 LS1 external MOSFET off, energy limited by TDRIVE. Device VGS fault. B
SL1 23 No impact. Intended operation. D
SL2 24 No impact. Intended operation. D
GL2 25 LS2 external MOSFET off, energy limited by TDRIVE. Device VGS fault. B
SH2 26 HS2 external MOSFET non-operational. Device VDS fault. B
GH2 27 HS2 external MOSFET off, energy limited by TDRIVE. Device VGS fault. B
DRAIN 28 Device overcurrent monitors and open load diagnostic non-operational. B
PVDD 29 Device external power supply stuck low. Device gate drivers and shunt amplifier non-operational. B
VCP 30 Device charge pump non-operational. Device CPUV fault. A
CPH 31 Device charge pump non-operational. Device CPUV fault. A
CPL 32 Device charge pump non-operational. Device CPUV fault. A
Table 4-4 DRV8705S-Q1 (SPI Variant) Pin FMA for Device Pins Open-Circuited
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
GND 1 Device behavior undefined, may retain operation due to alternative AGND pin path. C
DVDD 2 Device external digital power supply missing. Device non-operational. B
nSCS 3 SPI communication compromised. B
SCLK 4 SPI communication compromised. B
SDI 5 SPI communication compromised. B
SDO 6 SPI communication compromised. B
IN1/EN 7 Gate driver control input pulled low. Driver output may not match input. B
nHIZ1 8 Gate driver control input pulled low. Driver output disabled. B
IN2/PH 9 Gate driver control input pulled low. Driver output may not match input. B
nHIZ2 10 Gate driver control input pulled low. Driver output disabled. B
nSLEEP 11 Device stuck in sleep state. Outputs non-operational. B
DRVOFF 12 Driver disable input pulled low. Gate driver disable function non-operational. B
nFAULT 13 Device fault output indicator invalid. B
SO 14 Device current sense feedback invalid. B
RSVD 15 No impact. Intended operation. D
AREF 16 Device external analog power supply missing. Current sense invalid. B
AGND 17 Device behavior undefined, may retain operation due to alternative GND pin path. C
SP 18 Device current sense feedback invalid. B
SN 19 Device current sense feedback invalid. B
GH1 20 HS1 external MOSFET non-operational. B
SH1 21 HS1 external MOSFET non-operational. Device VDS fault. B
GL1 22 LS1 external MOSFET non-operational. B
SL1 23 LS1 VDS monitor non-operational. B
SL2 24 LS2 VDS monitor non-operational. B
GL2 25 LS2 external MOSFET non-operational. B
SH2 26 HS2 external MOSFET non-operational. Device VDS fault. B
GH2 27 HS2 external MOSFET non-operational. B
DRAIN 28 HS1 and HS2 VDS monitors and open load diagnostics non-operational. B
PVDD 29 Device external power supply missing. Device gate drivers and shunt amplifier non-operational. B
VCP 30 Device charge pump non-operational. Device CPUV fault. B
CPH 31 Device charge pump non-operational. Device CPUV fault. B
CPL 32 Device charge pump non-operational. Device CPUV fault. B
Table 4-5 DRV8705H-Q1 (HW Variant) Pin FMA for Device Pins Open-Circuited
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
GND 1 Device behavior undefined, may retain operation due to alternative AGND pin path. C
DVDD 2 Device external digital power supply missing. Device non-operational. B
GAIN 3 Device GAIN setting fixed to level 3. B
VDS 4 Device VDS setting fixed to level 4. B
IDRIVE 5 Device IDRIVE setting fixed to level 4. B
MODE 6 Device MODE setting fixed to level 3. B
IN1/EN 7 Gate driver control input pulled low. Driver output may not match input. B
nHIZ1 8 Gate driver control input pulled low. Driver output disabled. B
IN2/PH 9 Gate driver control input pulled low. Driver output may not match input. B
nHIZ2 10 Gate driver control input pulled low. Driver output disabled. B
nSLEEP 11 Device stuck in sleep state. Outputs non-operational. B
DRVOFF 12 Driver disable input pulled low. Gate driver disable function non-operational. B
nFAULT 13 Device fault output indicator invalid. B
SO 14 Device current sense feedback invalid. B
RSVD 15 No impact. Intended operation. D
AREF 16 Device external analog power supply missing. Current sense invalid. B
AGND 17 Device behavior undefined, may retain operation due to alternative GND pin path. C
SP 18 Device current sense feedback invalid. B
SN 19 Device current sense feedback invalid. B
GH1 20 HS1 external MOSFET non-operational. B
SH1 21 HS1 external MOSFET non-operational. Device VDS fault. B
GL1 22 LS1 external MOSFET non-operational. B
SL1 23 LS1 VDS monitor non-operational. B
SL2 24 LS2 VDS monitor non-operational. B
GL2 25 LS2 external MOSFET non-operational. B
SH2 26 HS2 external MOSFET non-operational. Device VDS fault. B
GH2 27 HS2 external MOSFET non-operational. B
DRAIN 28 HS1 and HS2 VDS monitors and open load diagnostics non-operational. B
PVDD 29 Device external power supply missing. Device gate drivers and shunt amplifier non-operational. B
VCP 30 Device charge pump non-operational. Device CPUV fault. B
CPH 31 Device charge pump non-operational. Device CPUV fault. B
CPL 32 Device charge pump non-operational. Device CPUV fault. B
Table 4-6 DRV8705S-Q1 (SPI Variant) Pin FMA for Device Pins Short-Circuited to Adjacent Pin
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
GND 1 Device external digital power supply stuck low. Device non-operational. B
DVDD 2 SPI communication compromised. B
nSCS 3 SPI communication compromised. B
SCLK 4 SPI communication compromised. B
SDI 5 SPI communication compromised. B
SDO 6 SPI communication compromised. Gate driver control input mismatch. B
IN1/EN 7 Gate driver control input mismatch. B
nHIZ1 8 Gate driver control input mismatch. B
IN2/PH 9 Gate driver control input mismatch. B
nHIZ2 10 Gate driver control input mismatch. Device may enter sleep state. B
nSLEEP 11 Device may enter sleep state or disable gate drivers. B
DRVOFF 12 Device may disable gate driver or fault output indicator invalid. B
nFAULT 13 Device fault indicator or current sense invalid. B
SO 14 No impact. Intended operation. D
RSVD 15 No impact. Intended operation. D
AREF 16 Device external analog power supply stuck low. Current sense invalid. B
AGND 17 Current sense invalid. B
SP 18 Current sense invalid. B
SN 19 Current sense invalid and HS1 external MOSFET off, energy limited by TDRIVE. Device VGS fault B
GH1 20 HS1 external MOSFET off, energy limited by TDRIVE. Device VGS fault B
SH1 21 GL1 output invalid, may violate GL1 voltage rating. A
GL1 22 LS1 external MOSFET off, energy limited by TDRIVE. Device VGS fault. B
SL1 23 Low-side VDS monitor sense accuracy impacted. C
SL2 24 LS2 external MOSFET off, energy limited by TDRIVE. Device VGS fault. B
GL2 25 GL2 output invalid, may violate GL1 voltage rating. A
SH2 26 HS2 external MOSFET off, energy limited by TDRIVE. Device VGS fault. B
GH2 27 HS2 external MOSFET off, energy limited by TDRIVE. Device VGS fault. B
DRAIN 28 High-side VDS monitor sense accuracy impact. C
PVDD 29 Device charge pump non-operational. Device CPUV fault. B
VCP 30 Device charge pump non-operational. Device CPUV fault. B
CPH 31 Device charge pump non-operational. Device CPUV fault. A
CPL 32 Device charge pump non-operational. Device CPUV fault. A
Table 4-7 DRV8705H-Q1 (HW Variant) Pin FMA for Device Pins Short-Circuited to Adjacent Pin
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
GND 1 Device external digital power supply stuck low. Device non-operational. B
DVDD 2 Device GAIN setting potentially incorrect. B
GAIN 3 Device GAIN and VDS setting potentially incorrect. B
VDS 4 Device VDS and IDRIVE setting potentially incorrect. B
IDRIVE 5 Device IDRIVE and MODE setting potentially incorrect. B
MODE 6 Device MODE setting potentially incorrect and gate driver control input mismatch. B
IN1/EN 7 Gate driver control input mismatch. B
nHIZ1 8 Gate driver control input mismatch. B
IN2/PH 9 Gate driver control input mismatch. B
nHIZ2 10 Gate driver control input mismatch. Device may enter sleep state. B
nSLEEP 11 Device may enter sleep state or disable gate drivers. B
DRVOFF 12 Device may disable gate driver or fault output indicator invalid. B
nFAULT 13 Device fault indicator or current sense invalid. B
SO 14 No impact. Intended operation. D
RSVD 15 No impact. Intended operation. D
AREF 16 Device external analog power supply stuck low. Current sense invalid. B
AGND 17 Current sense invalid. B
SP 18 Current sense invalid. B
SN 19 Current sense invalid and HS1 external MOSFET off, energy limited by TDRIVE. Device VGS fault B
GH1 20 HS1 external MOSFET off, energy limited by TDRIVE. Device VGS fault B
SH1 21 GL1 output invalid, may violate GL1 voltage rating. A
GL1 22 LS1 external MOSFET off, energy limited by TDRIVE. Device VGS fault. B
SL1 23 Low-side VDS monitor sense accuracy impacted. C
SL2 24 LS2 external MOSFET off, energy limited by TDRIVE. Device VGS fault. B
GL2 25 GL2 output invalid, may violate GL1 voltage rating. A
SH2 26 HS2 external MOSFET off, energy limited by TDRIVE. Device VGS fault. B
GH2 27 HS2 external MOSFET off, energy limited by TDRIVE. Device VGS fault. B
DRAIN 28 High-side VDS monitor sense accuracy impact. C
PVDD 29 Device charge pump non-operational. Device CPUV fault. B
VCP 30 Device charge pump non-operational. Device CPUV fault. B
CPH 31 Device charge pump non-operational. Device CPUV fault. A
CPL 32 Device charge pump non-operational. Device CPUV fault. A
Table 4-8 DRV8705S-Q1 (SPI Variant) Pin FMA for Device Pins Short-Circuited to Supply (PVDD)
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
GND 1 Device external power supply stuck low. Device gate drivers and shunt amplifier non-operational. B
DVDD 2 Low voltage pin max voltage violated. A
nSCS 3 Low voltage pin max voltage violated. A
SCLK 4 Low voltage pin max voltage violated. A
SDI 5 Low voltage pin max voltage violated. A
SDO 6 Low voltage pin max voltage violated. A
IN1/EN 7 Low voltage pin max voltage violated. A
nHIZ1 8 Low voltage pin max voltage violated. A
IN2/PH 9 Low voltage pin max voltage violated. A
nHIZ2 10 Low voltage pin max voltage violated. A
nSLEEP 11 Low voltage pin max voltage violated. A
DRVOFF 12 Low voltage pin max voltage violated. A
nFAULT 13 Low voltage pin max voltage violated. A
SO 14 Low voltage pin max voltage violated. A
RSVD 15 No impact. Intended operation. D
AREF 16 Low voltage pin max voltage violated. A
AGND 17 Device external power supply stuck low. Device gate drivers and shunt amplifier non-operational. B
SP 18 Current sense invalid. B
SN 19 Current sense invalid. B
GH1 20 HS1 external MOSFET gate stuck high, energy limited by TDRIVE. Device VGS fault. B
SH1 21 LS1 external MOSFET non-operational. Device VDS fault. B
GL1 22 LS1 external MOSFET gate stuck high, energy limited by TDRIVE. Device VGS fault. May violate GL1 voltage rating. A
SL1 23 Device external power supply stuck low. Device gate drivers and shunt amplifier non-operational. B
SL2 24 Device external power supply stuck low. Device gate drivers and shunt amplifier non-operational. B
GL2 25 LS1 external MOSFET gate stuck high, energy limited by TDRIVE. Device VGS fault. May violate GL1 voltage rating. A
SH2 26 LS2 external MOSFET non-operational. Device VDS fault. B
GH2 27 HS2 external MOSFET gate stuck high, energy limited by TDRIVE. Device VGS fault. B
DRAIN 28 High-side VDS monitor sense accuracy impact. B
PVDD 29 No impact. Intended operation. D
VCP 30 Device charge pump non-operational. Device CPUV fault. B
CPH 31 Device charge pump non-operational. Device CPUV fault. B
CPL 32 Device charge pump non-operational. Device CPUV fault. A
Table 4-9 DRV8705H-Q1 (HW Variant) Pin FMA for Device Pins Short-Circuited to Supply (PVDD)
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
GND 1 Device external power supply stuck low. Device gate drivers and shunt amplifier non-operational. B
DVDD 2 Low voltage pin max voltage violated. A
GAIN 3 Low voltage pin max voltage violated. A
VDS 4 Low voltage pin max voltage violated. A
IDRIVE 5 Low voltage pin max voltage violated. A
MODE 6 Low voltage pin max voltage violated. A
IN1/EN 7 Low voltage pin max voltage violated. A
nHIZ1 8 Low voltage pin max voltage violated. A
IN2/PH 9 Low voltage pin max voltage violated. A
nHIZ2 10 Low voltage pin max voltage violated. A
nSLEEP 11 Low voltage pin max voltage violated. A
DRVOFF 12 Low voltage pin max voltage violated. A
nFAULT 13 Low voltage pin max voltage violated. A
SO 14 Low voltage pin max voltage violated. A
RSVD 15 No impact. Intended operation. D
AREF 16 Low voltage pin max voltage violated. A
AGND 17 Device external power supply stuck low. Device gate drivers and shunt amplifier non-operational. B
SP 18 Current sense invalid. B
SN 19 Current sense invalid. B
GH1 20 HS1 external MOSFET gate stuck high, energy limited by TDRIVE. Device VGS fault. B
SH1 21 LS1 external MOSFET non-operational. Device VDS fault. B
GL1 22 LS1 external MOSFET gate stuck high, energy limited by TDRIVE. Device VGS fault. May violate GL1 voltage rating. A
SL1 23 Device external power supply stuck low. Device gate drivers and shunt amplifier non-operational. B
SL2 24 Device external power supply stuck low. Device gate drivers and shunt amplifier non-operational. B
GL2 25 LS1 external MOSFET gate stuck high, energy limited by TDRIVE. Device VGS fault. May violate GL1 voltage rating. A
SH2 26 LS2 external MOSFET non-operational. Device VDS fault. B
GH2 27 HS2 external MOSFET gate stuck high, energy limited by TDRIVE. Device VGS fault. B
DRAIN 28 High-side VDS monitor sense accuracy impact. B
PVDD 29 No impact. Intended operation. D
VCP 30 Device charge pump non-operational. Device CPUV fault. B
CPH 31 Device charge pump non-operational. Device CPUV fault. B
CPL 32 Device charge pump non-operational. Device CPUV fault. A