SFFS296 October   2021 AMC1411-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 AMC1411-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 AMC1411-Q1 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the AMC1411-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:

  • The SHTDN pin is permanently tied to GND1 through a 10-kΩ pulldown resistor.
  • RC filter on IN.
    The series resistor is sized to limit the input currents into IN to <10 mA in all circumstances (for example, if the device is unpowered and the input signal is applied).
  • For pins on primary side:
    Short-circuited to ground means short to GND1.
    Short-circuited to supply means short to VDD1.
  • For pins on secondary 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 primary side unpowered. Fail-safe output (see data sheet for more details). Observe that the absolute maximum ratings for the IN of the device are met, otherwise device damage may be plausible. A
IN 2 IN stuck low (GND1). Differential output (VOUTP – VOUTN) = 0 V with common-mode voltage approximately 1.44 V. B
SHTDN 3 No effect. Normal operation. 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 because of short-circuit condition. Device damage plausible if condition is present for extended period of time. A
OUTP 7 OUTP stuck low (GND2). Excess current consumption from VDD2 source because of short-circuit condition. Device damage plausible if condition is present for extended period of time. A
VDD2 8 Device secondary side unpowered. OUTP and OUTN pins are driven to GND2. B
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin NamePin No.Description of Potential Failure Effect(s)Failure Effect Class
VDD11Device primary side unpowered. Fail-safe output (see data sheet for more details).B
IN2Differential output (VOUTP – VOUTN) undetermined.B
SHTDN3Internal 100-kΩ pullup resistor drives SHTDN pin to VDD1. Device is in shutdown. Fail-safe output (see data sheet for more details).B
GND14Primary side is powered through ESD diode on SHTDN pin to GND1. Internal GND1 node of device is lifted by one diode drop compared to external GND1 potential. Differential output (VOUTP – VOUTN) = (VIN – approximately 300 mV). For VIN close to 0 V the differential output is negative.B
GND25Device behavior undetermined. VOUTN and VOUTP undetermined.B
OUTN6Differential output (VOUTP – VOUTN) undetermined.B
OUTP7Differential output (VOUTP – VOUTN) undetermined.B
VDD28Device secondary side unpowered. OUTP and OUTN pins are driven to GND2.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 IN IN stuck high (VDD1). OUTP and OUTN pins clipped at differential approximately 2.516 V. B
IN 2 SHTDN Voltage on IN smaller than expected because of resistor divider formed by series resistor on IN and pulldown resistor on SHTDN pin. Result is increased gain error on differential output. IN drives the SHTDN pin. Device in shutdown if SHTDN is driven above logic high level. In that case fail-safe output (see data sheet for more details). B
SHTDN 3 GND1 No effect. Normal operation. D
GND1 4 GND2 Not considered. Corner pin. D
GND2 5 OUTN OUTN stuck low (GND2). Excess current consumption from VDD2 source because of short-circuit condition. 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 NamePin No.Description of Potential Failure Effect(s)Failure Effect Class
VDD11No effect. Normal operation.D
IN2IN stuck high (VDD1). OUTP and OUTN pins clipped at differential approximately 2.516 V.B
SHTDN3SHTDN stuck high (VDD1). Device is in shutdown. Fail-safe output (see data sheet for more details).B
GND14Device primary side unpowered. Fail-safe output (see data sheet for more details). Observe that the absolute maximum ratings for IN of the device are met, otherwise device damage may be plausible.A
GND25Device secondary side unpowered. OUTP and OUTN pins are driven to GND2.B
OUTN6OUTN stuck high (VDD2). Excess current consumption from VDD2 source. Device damage plausible if condition is present for extended period of time.A
OUTP7OUTP stuck high (VDD2). Excess current consumption from VDD2 source. Device damage plausible if condition is present for extended period of time.A
VDD28No effect. Normal operation.D