SFFS468 august   2023 AMC3330-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 AMC3330-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 AMC3330-Q1 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the AMC3330-Q1 data sheet.

GUID-20230719-SS0I-6XXN-LGSB-HXW4CFDTTXBH-low.svg 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 unpowered 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 unpowered. 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 is plausible.A
DCDC_HGND2No effect. Normal operation.D
HLDO_IN3Signal chain on input side unpowered. 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 unpowered. Increased power consumption. Device outputs fail-safe state (see data sheet for details). Long-term damage plausible.A
INP6INP stuck low (GND1). Differential output (VOUTP – VOUTN) = 0 V with common-mode voltage approximately 1.44 V (for the assumed use case).C
INN7INN stuck low (HGND). Differential output (VOUTP – VOUTN) = VINP × 0.4 with common-mode voltage approximately 1.44 V. Normal operation for the assumed use case.D
HGND8No effect. Normal operation.D
GND 9 No effect. Normal operation. D
OUTN 10 OUTN stuck low (GND). Excess current consumption from VDD source because of short-circuit condition. Long-term damage plausible. A
OUTP 11 OUTP stuck low (GND). Excess current consumption from VDD source because of short-circuit condition. Long-term damage plausible. A
VDD 12 Device is unpowered. OUTP and OUTN pins are driven to GND. B
LDO_OUT 13 DC/DC converter is unpowered. 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 unpowered. 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 unpowered. 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 unpowered. 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 cpacitor connected to the output of the high-side LDO. Device remains functional, parametric degradation is plausible. C
INP 6 Differential output (VOUTP – VOUTN) undetermined. B
INN 7 Differential output (VOUTP – VOUTN) 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 ouput voltage shifts up (out of specification). C
OUTN 10 Differential output (VOUTP – VOUTN) undetermined. B
OUTP 11 Differential output (VOUTP – VOUTN) undetermined. B
VDD 12 Device is unpowered. OUTP and OUTN pins are driven to GND. B
LDO_OUT 13 DC/DC converter is unpowered. 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 unpowered. 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 unpowered. Device outputs fail-safe state (see data sheet for details). Long-term damage plausible.A
DCDC_HGND2HLDO_INSignal chain on input side unpowered. 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 (VHLDO_OUT). Differential output (VOUTP – VOUTN) = VCLIPout. See data sheet for details.B
INP6INNDifferential input shorted. Differential output (VOUTP – VOUTN) = 0 V.B
INN7HGNDINN stuck low (HGND). Differential output (VOUTP – VOUTN) = VINP × 0.4 with common-mode voltage approximately 1.44 V. Normal operation for the assumed use case.D
HGND8GNDNot considered. Corner pin.N/A
GND 9 OUTN OUTN stuck low (GND2). Excess current consumption from VDD2 source because of short-circuit condition. Long-term damage plausible. A
OUTN 10 OUTP Differential output (VOUTP – VOUTN) = 0 V with common-mode voltage of approximately 1.44 V. Excess current consumption from VDD source. Long-term damage plausible. A
OUTP 11 VDD VOUTP stuck high (VDD). Excess current consumption from VDD source. Long-term damage plausible. 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 statup). 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 unpowered. 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 unpowered. OUTP and OUTN pins are driven to GND.
Observe that GND and DCDC_GND are diode connected. Device damage plausible.		 A
OUTN 10 OUTN stuck high (VDD2). Excess current consumption from VDD source. Long-term damage plausible. A
OUTP 11 OUTP stuck high (VDD). Excess current consumption from VDD source. Long-term damage plausible. A
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 statup). Long-term damage plausible. A
DCDC_GND 15 Device is unpowered. OUTP and OUTN pins are driven to GND. 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