SBAA447 September   2021 AMC1302-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)

4 Pin Failure Mode Analysis (Pin FMA)

This section provides a failure mode analysis (FMA) for the pins of the AMC1302-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 AMC1302-Q1 pin diagram. For a detailed description of the device pins see the Pin Configuration and Functions section in the AMC1302-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:

  • Differential RC filter between INP and INN.
    The series resistors are sized to limit the input currents into INP and INN to <10 mA in all circumstances (for example, if the device is unpowered and the input signal is applied).
  • INN is connected to GND1 through the filter resistor.
  • For pins on high side:
    Short-circuited to ground means short to GND1.
    Short-circuited to supply means short to VDD1.
  • For pins on low side:
    Short-circuited to ground means short to GND2.
    Short-circuited to supply means short to VDD2.

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
VDD1 1 Device high side unpowered. Fail-safe output (see data sheet for more details). B
INP 2 INP stuck low (GND1). Differential output (VOUTP – VOUTN) = –VINN x 41 with common-mode voltage approximately 1.44 V. B
INN 3 INN stuck low (GND1). Differential output (VOUTP – VOUTN) = VINP x 41 with common-mode voltage approximately 1.44 V. D
GND1 4 No effect. Normal operation. D
GND2 5 No effect. Normal operation. D
OUTN 6 OUTN stuck low (GND2). Excess current consumption from VDD2 source. Device damage plausible if condition is present for extended period of time. A
OUTP 7 OUTP stuck low (GND2). Excess current consumption from VDD2. Device damage plausible if condition is present for extended period of time. A
VDD2 8 Device low side unpowered. OUTP and OUTN pins are driven to GND2. B
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
VDD1 1 Device high side unpowered. Fail-safe output (see data sheet for more details). B
INP 2 Differential output (VOUTP – VOUTN) undetermined, but with tendency to output +FS. B
INN 3 Differential output (VOUTP – VOUTN) undetermined. B
GND1 4 Device high side unpowered. Fail-safe output (see data sheet for more details). B
GND2 5 Device behavior undetermined. VOUTN and VOUTP undetermined. B
OUTN 6 Differential output (VOUTP – VOUTN) undetermined. B
OUTP 7 Differential output (VOUTP – VOUTN) undetermined. B
VDD2 8 Device low side unpowered. VOUTN and VOUTP undetermined. 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
VDD1 1 INP INP stuck high (VDD1). In case VCM < VCMov, differential output (VOUTP – VOUTN) = +FS. In case VCM ≥ VCMov, fail-safe output (see data sheet for more details). B
INP 2 INN Differential input shorted. Differential output (VOUTP – VOUTN) = 0 V B
INN 3 GND1 INN stuck low (GND1). Differential output (VOUTP – VOUTN) = VINP x 41 with common-mode voltage approximately 1.44 V. D
GND1 4 GND2 Not considered. Corner pin. D
GND2 5 OUTN OUTN stuck low (GND2). Excess current consumption from VDD2 source. Device damage plausible if condition is present for extended period of time. A
OUTN 6 OUTP Differential output (VOUTP – VOUTN) = 0 V with common-mode voltage approximately 1.44 V. Excess current consumption from VDD2 source. Device damage plausible if condition is present for extended period of time. A
OUTP 7 VDD2 OUTP stuck high (VDD2). Excess current consumption from VDD2 source. Device damage plausible if condition is present for extended period of time. A
VDD2 8 VDD1 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
VDD1 1 No effect. Normal operation. D
INP 2 INP stuck high (VDD1). In case VCM < VCMov, differential output (VOUTP – VOUTN) = +FS. In case VCM ≥ VCMov, fail-safe output (see data sheet for more details). B
INN 3 INN stuck high (VDD1). In case VCM < VCMov, differential output (VOUTP – VOUTN) incorrect. In case VCM ≥ VCMov, fail-safe output (see data sheet for more details). B
GND1 4 Device high side unpowered. Fail-safe output (see data sheet for more details). B
GND2 5 Device low side unpowered. OUTP and OUTN pins are driven to GND2. B
OUTN 6 OUTN stuck high (VDD2). Excess current consumption from VDD2 source. Device damage plausible if condition is present for extended period of time. A
OUTP 7 OUTP stuck high (VDD2). Excess current consumption from VDD2 source. Device damage plausible if condition is present for extended period of time. A
VDD2 8 No effect. Normal operation. D