SFFS926 June   2024 PGA308

 

  1.   1
  2.   Trademarks
  3. 1Overview
  4. 2Functional Safety Failure In Time (FIT) Rates
    1. 2.1 VSSOP (DGS) Package
    2. 2.2 VSON (DRK) Package
  5. 3Failure Mode Distribution (FMD)
  6. 4Pin Failure Mode Analysis (Pin FMA)
    1. 4.1 VSSOP (DGS) Package
    2. 4.2 VSON (DRK) Package

4.1 VSSOP (DGS) Package

Figure 4-1 shows the PGA308 pin diagram. For a detailed description of the device pins, see the Pin Configuration and Functions section in the PGA308 data sheet.

PGA308 Pin DiagramFigure 4-1 Pin Diagram
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
Pin NamePin No.Description of Potential Failure EffectsFailure Effect Class
DOUT/VCLAMP1

If configured as DOUT, approaches absolute maximum rating for PIN 1 voltage, potentially degrading performance long-term.

If configured as VCLAMP, sets clamping voltage to VEE resulting in a loss of output signal.

B
1W2Loss of communication with device, PIN 1 remains in previous configuration.D
VS4Op-amp supplies are shorted together, leaving the VS pin at some voltage between the VS and GND sources (depending on the source impedance).A
VIN15VIN1 pin is shorted to ground, leaving the device outside the linear range resulting in unpredictable device output voltage.B
VIN26VIN2 pin is shorted to ground, leaving the device outside the linear range resulting in unpredictable device output voltage.B
VSJ7There is potential for device damage depending on circuit configuration.A
VFB8Loss of device functionality, damage to the device is not likely.B
VOUT9Depending on the circuit configuration, the device can be forced into a short-circuit condition with the VOUT voltage ultimately forced to the GND voltage. Prolonged exposure to short-circuit conditions can result in long-term reliability issues.A
VREF10Loss of device functionality, damage to the device is not likely.B
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin NamePin No.Description of Potential Failure EffectsFailure Effect Class
DOUT/VCLAMP1

If configured as DOUT, digital communication is lost with external sensors resulting in a loss of device functionality.

If configured as VCLAMP, clamping voltage, at some voltage between VEE and VCC, potentially result in the device output not functioning as intended.

B
1W2Loss of communication with device, PIN 1 remains in previous configuration.D
GND3Negative supply is left floating. The op amp ceases to function because no current can source or sink to the device.B
VS4Positive supply is left floating. The op amp ceases to function because no current can source or sink to the device.B
VIN15Signal input voltage 1 is left floating. VIN1 voltage can end up at the positive or negative rail because of leakage on the ESD diodes, possibly resulting in a device output voltage between the negative and positive rails.B
VIN26Signal input voltage 2 is left floating. VIN2 voltage can end up at the positive or negative rail because of leakage on the ESD diodes, possibly resulting in a device output voltage between the negative and positive rails.B
VSJ7Loss of external compensation, device can continue to function.D
VFB8Depending on circuit configuration, VOUT can be forced to either VCC or VEE.B
VOUT9No negative feedback or ability for VOUT to drive the application.B
VREF10Loss of functionality for course offset DAC, fine offset DAC, underscale DAC, overscale DAC, and fault monitor.D
Table 4-4 Pin FMA for Device Pins Short-Circuited to Adjacent Pin
Pin Name Pin No. Shorted to Description of Potential Failure Effects Failure Effect Class
DOUT / VCLAMP12If configured as DOUT, results in a loss of device functionality.

If configured as VCLAMP, clamping voltage is set to 1W voltage, potentially resulting in device output not functioning as intended.

B
1W23Loss of communication with device, PIN 1 remains in previous configuration.D
GND34Op-amp supplies are shorted together, leaving the GND pin at some voltage between the GND and VS sources (depending on the source impedance).A
VS45VIN1 pin is shorted to supply, leaving the device outside the linear range resulting in unpredictable device output voltage.B
VIN156Both inputs are tied together. Output voltage is set to some value-based device gain configuration and the course offset value is set by VREF voltage.B
VIN267Oscillation is possible due to additional capacitance on the VSJ pin resulting in erratic behavior on the output.B
VSJ78Depending on circuit configuration, erroneous gain can result in a loss of intended functionality. Potential stability issues can arise by shorting the isolation resistor, typically found between VSJ and VFB.B
VFB89No loss of functionality and no potential damage to the device. If an external filter is used, the filter is bypassed.D
VOUT910Device output behaves unpredictably, resulting in a loss of functionality. No potential damage to the device.B
VREF101If PIN 1 is configured as DOUT, the output voltage is unpredictable, resulting in a loss of functionality.

If PIN 1 is configured as VCLAMP, clamping voltage is set to VREF voltage, potentially resulting in an erroneous output voltage, if the VREF voltage is less than the intended output.

B
Table 4-5 Pin FMA for Device Pins Short-Circuited to supply
Pin NamePin No.Description of Potential Failure EffectsFailure Class
DOUT1If configured as DOUT, approaches the absolute maximum rating for PIN 1 voltage, potentially degrading performance long term.

If configured as VCLAMP, sets clamping voltage to VCC, allowing the full output range.

C
1W2Loss of communication with device, PIN 1 remains in previous configuration.D
GND3Op-amp supplies are shorted together, leaving the GND pin at some voltage between the GND and VS sources (depending on the source impedance).A
VIN15VIN1 pin is shorted to supply, leaving the device outside the linear range, resulting in an unpredictable device output voltage.B
VIN26VIN2 pin is shorted to supply, leaving the device outside the linear range, resulting in an unpredictable device output voltage.B
VSJ

7

Device damage is possible depending on circuit configuration.A
VFB8Loss of device functionality, damage to the device is not likely.B
VOUT

9

Depending on the circuit configuration, the device can be forced into a short-circuit condition with the VOUT voltage ultimately forced to the VS voltage. Prolonged exposure to short-circuit conditions can result in long-term reliability issues.A
VREF10Loss of device functionality, damage to the device is not likely.B