SFFS492 august   2023 AMC3336-Q1

 

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

4 Pin Failure Mode Analysis (Pin FMA)

This section provides a failure mode analysis (FMA) for the pins of the AMC3336-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
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 shows the AMC3336-Q1 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the AMC3336-Q1 data sheet.

GUID-D341995A-2DAF-43B2-A219-B98CBA049B8F-low.gif Figure 4-1 Pin Diagram

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

  • INN is connected to HGND.
  • INP is connected to a resistive divider and the resitors are sized to limit the input current into INP to <10 mA under all circumstances (for example, if the device is powered off and the input signal is applied).
  • For pins on input side (hot side):
    Short-circuited to ground means short to HGND.
    As the input side is powered internally from the output side (cold side), Short-circuited to supply does not apply.
  • For pins on output side (cold side):
    Short-circuited to ground means short to GND.
    Short-circuited to supply means short to VDD.
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
Pin NamePin No.Description of Potential Failure Effect(s)Failure Effect Class
DCDC_OUT1Signal chain on input side powered off. Device outputs fail-safe state (see data sheet for details). Observe that the absolute maximum ratings for INP and INN of the device are met, otherwise device damage plausible.A
DCDC_HGND2No effect. Normal operation.D
HLDO_IN3Signal chain on input side powered off. Increased power consumption. Device outputs fail-safe state (see data sheet for details). Long-term damage plausible.A
NC4No effect. Pin has no internal connection.D
HLDO_OUT5Signal chain on input side powered off. Increased power consumption. Device outputs fail-safe state (see data sheet for details). Long-term damage plausible.A
INP6INP stuck low (GND1) resulting in zero differential input voltage. DOUT output bitstream is mid-scale (50% zeros, 50% ones).C
INN7INN stuck low (HGND). Value of DOUT output bitstream proportional to voltage difference (VINP – VHGND). Normal operation for the assumed use case.D
HGND8No effect. Normal operation.D
GND 9 No effect. Normal operation. D
DOUT 10 DOUT stuck low (GND). No valid DOUT output bitstream. DOUT output bitstream looks like fail-safe output response (see data sheet for details). Excess current consumption from VDD source when DOUT tries to drive high. Long-term damage plausible. A
CLKIN 11 CLKIN stuck low (GND). Device not functional due to missing clock input. DOUT stuck in same state (high or low) as when CLKIN stopped. No valid DOUT output bitstream. A
VDD 12 Device is powered off. DOUT is driven to GND. B
LDO_OUT 13 DC/DC converter is powered off. Device outputs fail-safe state (see data sheet for details). Long-term damage plausible. A
DIAG 14 DIAG stuck low (GND). Device operates normally but falsely indicates that high-side in non-operational (see data sheet for details). B
DCDC_GND 15 No effect. Normal operation. D
DCDC_IN 16 DC/DC converter converter is powered off. Device outputs fail-safe state (see data sheet for details). Long-term damage 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
DCDC_OUT 1 Signal chain on input side powered off. Device outputs fail-safe state (see data sheet for details). B
DCDC_HGND 2 DCDC_HGND internally connected to HGND through diode. Device outputs fail-safe state (see data sheet for details). B
HLDO_IN 3 Signal chain on input side powered off. Device outputs fail-safe state (see data sheet for details). Long-term damage plausible. A
NC 4 No effect. Pin has no internal connection. D
HLDO_OUT 5 No decoupling capacitor connected to the output of the high-side LDO. Device remains functional, parametric degradation plausible. C
INP 6 Differential input (VINP – VINN) undetermined. DOUT output bitstream is undetermined. B
INN 7 Differential input (VINP – VINN) undetermined. DOUT output bitstream is undetermined. B
HGND 8 HGND internally connected to DCDC_HGND through diode. Device outputs fail-safe state (see data sheet for details). B
GND 9 GND internally connected to DCDC_GND through diode. Device remains functional but common-mode output voltage shifts up (out of specification). C
DOUT 10 DOUT undetermined. No valid DOUT output bitstream. B
CLKIN 11 CLKIN floating. Device not functional due to missing clock input. DOUT stuck in same state (high or low) as when CLKIN stopped. No valid DOUT output bitstream. B
VDD 12 Device is periodically powered through ESD diode of the CLKIN pin when CLKIN is driven high. DOUT output bitstream is undetermined. B
LDO_OUT 13 DC/DC converter is powered off. Device outputs fail-safe state (see data sheet for details). B
DIAG 14 Pull-up resistor disconnected. No effect on primary function of the device. Diagnostic output not observable (see data sheet for details). B
DCDC_GND 15 DCDC_GND internally connected to GND through diode. Device outputs fail-safe state (see data sheet for details) with increased power consumption from VDD source. Long-term damage plausible. A
DCDC_IN 16 DC/DC converter is powered off. Device outputs fail-safe state (see data sheet for details). B
Table 4-4 Pin FMA for Device Pins Short-Circuited to Adjacent Pin
Pin NamePin No.Shorted toDescription of Potential Failure Effect(s)Failure Effect Class
DCDC_OUT1DCDC_HGNDSignal chain on input side powered off. Device outputs fail-safe state (see data sheet for details). Long-term damage plausible.A
DCDC_HGND2HLDO_INSignal chain on input side powered off. Device outputs fail-safe state (see data sheet for details). Long-term damage plausible.A
HLDO_IN3NCNo effect. Pin 4 has no internal connection.D
NC4HLDO_OUTNo effect. Pin has no internal connection. D
HLDO_OUT5INPINP stuck high (HLDO_OUT). DOUT bitstream proportional to voltage difference (VHLDO_OUT – VINN). Overrange detection is likely to trigger (see data sheet for more details).B
INP6INNINP shorted to INN resulting in zero differential input voltage. DOUT output bitstream is mid-scale (50% zeros, 50% ones).B
INN7HGNDINN stuck low (HGND). Value of DOUT output bitstream proportional to voltage difference (VINP – VHGND). Normal operation for the assumed use case.D
HGND8GNDNot considered. Corner pin.N/A
GND 9 DOUT DOUT stuck low (GND). No valid DOUT output bitstream. DOUT output bitstream looks like fail-safe output response (see data sheet for details). Excess current consumption from VDD source when DOUT tries to drive high. Long-term damage plausible. A
DOUT 10 CLKIN DOUT output bit stream corrupted. Excess current consumption from DVDD source when DOUT tries to drive high, while CLKIN drives low and vice versa. Long-term damage plausible. A
CLKIN 11 VDD CLKIN stuck high (VDD). Device not functional because of missing clock input. DOUT stuck in same state (high or low) as when CLKIN stopped. No valid DOUT output bitstream. A
VDD 12 LDO_OUT DC/DC converter is supplied from VDD. Device functions normally with increased power consumption from VDD source. Long-term damage plausible. A
LDO_OUT 13 DIAG DIAG stuck high (LDO_OUT). Device operates normally with excessive power dissipation if DIAG is driven low (e.g. during startup). Long-term damage plausible. A
DIAG 14 DCDC_GND DIAG stuck low (GND). Device operates normally but falsely indicates that high-side in non-operational (see data sheet for details). B
DCDC_GND 15 DCDC_IN DC/DC converter powered off. Device outputs fail-safe state (see data sheet for details). B
DCDC_IN 16 DCDC_OUT Not considered. Corner pin. N/A
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
DCDC_OUT 1 Not considered. Input side (hot side) is not connected to external supply. N/A
DCDC_HGND 2 Not considered. Input side (hot side) is not connected to external supply. N/A
HLDO_IN 3 Not considered. Input side (hot side) is not connected to external supply. N/A
NC 4 Not considered. Input side (hot side) is not connected to external supply. N/A
HLDO_OUT 5 Not considered. Input side (hot side) is not connected to external supply. N/A
INP 6 Not considered. Input side (hot side) is not connected to external supply. N/A
INN 7 Not considered. Input side (hot side) is not connected to external supply. N/A
HGND 8 Not considered. Input side (hot side) is not connected to external supply. N/A
GND 9 Device is powered off. DOUT is driven to GND.
Observe that GND and DCDC_GND are diode connected and ESD protection on CLKIN can forward bias. Device damage plausible.		 A
DOUT 10 DOUT stuck high (VDD). No valid DOUT output bitstream. Excess current consumption from VDD source when DOUT tries to drive low. Long-term damage plausible. A
CLKIN 11 CLKIN stuck high (VDD). Device not functional because of missing clock input. DOUT stuck in same state (high or low) as when CLKIN stopped. No valid DOUT output bitstream. B
VDD 12 No effect. Normal operation. D
LDO_OUT 13 DC/DC converter is supplied from VDD. Device functions normally with increased power consumption from VDD source. Long-term damage plausible. A
DIAG 14 DIAG stuck high (VDD). Device operates normally with excessive power dissipation if DIAG is driven low (e.g. during startup). Long-term damage plausible. A
DCDC_GND 15 DC/DC converter is powered off. Observe that GND and DCDC_GND are diode connected. Device damage plausible. A
DCDC_IN 16 DC/DC converter is supplied from VDD. Device functions normally with increased power consumption from VDD source. Long-term damage plausible. A