SFFS091 March   2021 TMCS1100-Q1

 

  1. 1Overview
  2. 2Functional Safety Failure In Time (FIT) Rates
  3. 3Failure Mode Distribution (FMD)
  4. 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 TMCS1100-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 TMCS1100-Q1 pin diagram. For a detailed description of the device pins please refer to the Pin Configuration and Functions section in the TMCS1100-Q1 data sheet.

GUID-21D9CA32-0B34-4691-8A3B-79606BC37F2D-low.gif Figure 4-1 TMCS1100-Q1 Pin Diagram

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

  • TA=-40°C to 125°C
  • VS=3V to 5.5V
  • VCM=-600V to 600V
  • VREF=0V to VS
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
IN+ 1 For forward current, hall-sensor bypassed, providing no signal to be sensed and amplified. If IN+ is at a large potential above GND, this will result in a lot of current being sunk. Depending upon layout and configuration, this could damage the input current system supply, the load device, or the TMCS1100. A
IN+ 2 For forward current, hall-sensor bypassed, providing no signal to be sensed and amplified. If IN+ is at a large potential above GND, this will result in a lot of current being sunk. Depending upon layout and configuration, this could damage the input current system supply, the load device, or the TMCS1100. A
IN- 3 For reverse current, hall-sensor bypassed, providing no signal to be sensed and amplified. If IN- is at a large potential above GND, this will result in a lot of current being sunk. Depending upon layout and configuration, this could damage the input current system supply, the load device, or the TMCS1100. A
IN- 4 For reverse current, hall-sensor bypassed, providing no signal to be sensed and amplified. If IN- is at a large potential above GND, this will result in a lot of current being sunk. Depending upon layout and configuration, this could damage the input current system supply, the load device, or the TMCS1100. A
GND 5 Normal Operation D
VREF 6 If intended connection is anything other than GND, functionality will be affected. D if VREF=GND; C otherwise
VOUT 7 'Output will be pulled to GND and output current will be short circuit limited. When left in this configuration while VS connected to a high load capable supply and for certain high load conditions through the IN+ and IN- pins, die temperature could approach or exceed 150°C. B
VS 8 Power supply shorted to ground B
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin Name Pin No. Description of Potential Failure Effect(s) Failure Effect Class
IN+ 1 If left open and pin 2 is connected, pin 2 could suffer thermal stress for currents approaching SOA boundary ratings. For normal operating conditions, sensitivity error may increase. A
IN+ 2 If left open and pin 1 is connected, pin 1 could suffer thermal stress for currents approaching SOA boundary ratings. For normal operating conditions, sensitivity error may increase. A
IN- 3 If left open and pin 4 is connected, pin 4 could suffer thermal stress for currents approaching SOA boundary ratings. For normal operating conditions, sensitivity error may increase. A
IN- 4 If left open and pin 3 is connected, pin 3 could suffer thermal stress for currents approaching SOA boundary ratings. For normal operating conditions, sensitivity error may increase. A
GND 5 GND is floating. Output will be incorrect as it is no longer referenced to GND. B
VREF 6 REF will float to an unknown value. REF is incorrect and output is incorrect. C
VOUT 7 Output will be present at the pin; having no loading will not affect the output. However, the user will see unpredictable results further down on the signal chain. B
VS 8 No power to device. VOUT will stay at GND. 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
IN+ 1 2 - IN+ Normal Operation. D
IN+ 2 3 - IN- IN+ shorted to IN-. This creates a current divider which increase sensitivity error inversely proportional to the resistance of the short. C
IN- 3 4 - IN- Normal Operation. D
IN- 4 5 - GND For reverse current, hall-sensor bypassed, providing no signal to be sensed and amplified. If IN- is at a large potential above GND, this will result in a lot of current being sunk. Depending upon layout and configuration, this could damage the input current system supply, the load device, or the TMCS1100. A
GND 5 6 - VREF If VREF intended connection is anything other than GND, functionality will be affected. D if VREF=GND; C otherwise
VREF 6 7 - VOUT Output will be pulled to VREF and output current will be short circuit limited. When left in this configuration while VREF connected to a high load capable supply and for certain high load conditions through the IN+ and IN- pins, die temperature could approach or exceed 150°C. B
VOUT 7 8 - VS Output will be pulled to VS and output current will be short circuit limited. When left in this configuration while VS connected to a high load capable supply and for certain high load conditions through the IN+ and IN- pins, die temperature could approach or exceed 150°C. B
VS 8 1 - IN+ If 6V>IN+ > 5.5V, device will be operating in non-linear range. If IN+>6V, the device will be damaged. If IN+ < Vs, a lot of current may be pulled from the stage supplying the TMCS1100 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
IN+ 1 If 6V>IN+ > 5.5V, device will be operating in non-linear range. If IN+>6V, the device will be damaged. If IN+ < Vs, a lot of current may be pulled from the stage supplying the TMCS1100. A
IN+ 2 If 6V>IN+ > 5.5V, device will be operating in non-linear range. If IN+>6V, the device will be damaged. If IN+ < Vs, a lot of current may be pulled from the stage supplying the TMCS1100. A
IN- 3 If 6V>IN- > 5.5V, device will be operating in non-linear range. If IN->6V, the device will be damaged. If IN- < Vs, a lot of current may be pulled from the stage supplying the TMCS1100. A
IN- 4 If 6V>IN- > 5.5V, device will be operating in non-linear range. If IN->6V, the device will be damaged. If IN- < Vs, a lot of current may be pulled from the stage supplying the TMCS1100. A
GND 5 Output shorts to supply. Stage supplying the TMCS1100 will pull a lot of current B
VREF 6 Output will rail to supply and only reverse current will be measurable D if REF=VS by design; C otherwise
VOUT 7 Output will be pulled to VS and output current will be short circuit limited. When left in this configuration while VS connected to a high load capable supply and for certain high load conditions through the IN+ and IN- pins, die temperature could approach or exceed 150°C. B
VS 8 Normal operation D