SFFS342 September   2022 LM5021

 

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

4.1 VSSOP Package

Figure 4-1 shows the LM5021 pin diagram for the VSSOP package. For a detailed description of the device pins, see the Pin Configuration and Functions section in the LM5021 data sheet.

GUID-2FB91246-84C1-4B12-99FF-F8F510CE7BB1-low.gif Figure 4-1 Pin Diagram (VSSOP) Package
Table 4-2 Pin FMA for Device Pins Short-Circuited to Ground
Pin NamePin No.Description of Potential Failure Effect(s)Failure Effect Class
COMP1OUT remains low. Converter has no output.B
VIN2IC is not biased. OUT remains low. Converter has no output.B
VCC3IC is not biased. OUT remains low. Converter has no output.B
OUT4OUT remains low. Converter has no output. IC might get damaged.A
GND5No effect.D
CS6OUT operates with maximum duty cycle. Power stage might get damaged. Once power stage is damaged, the IC might get damaged.A
RT7OUT operates with maximum frequency. Converter might have no output. Over load protection might be triggered. OUT remains low after protection is triggered. OUT keeps retrying.B
SS8OUT remains low. Converter has no output.B
Table 4-3 Pin FMA for Device Pins Open-Circuited
Pin NamePin No.Description of Potential Failure Effect(s)Failure Effect Class
COMP1Over load protection is triggered. OUT remains low. OUT keeps retrying. Converter has no output.B
VIN2IC is not biased. OUT remains low. Converter has no output.B
VCC3VCC linear regulator might become unstable. UVLO will be triggered and converter has no output.B
OUT4Converter has no gate driver voltage. Converter has no output.B
GND5IC behavior is unpredictable. IC damage is possible.A
CS6OUT operates with minimum on time. Converter has no power handling capability. Over load protection might be triggered. OUT remains low after protection is triggered. OUT keeps retrying.B
RT7Converter operates with minimum switching frequency. Converter has no output. Over load protection might be triggered. OUT remains low after protection is triggered. OUT keeps retrying.B
SS8Lost soft start function.C
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
COMP1VINCOMP pin stays high, OUT duty cycle is maximum. Converter output loses regulation. Over load protection might be triggered. OUT remains low after protection is triggered. OUT keeps retrying. IC might get damaged.A
VIN2VCCVCC loses linear regulation function. IC damage is possible.A
VCC3OUTOUT remains high. Power stage will be damaged. IC damage is possible.A
OUT4N/A
GND5CSOUT operates with maximum duty cycle. Power stage damage is possible. Once power stage is damaged, IC damage is possible.A
CS6RTOUT operates with maximum frequency. Converter might have no output. Over load protection might be triggered. OUT remains low after protection is triggered. OUT keeps retrying.B
RT7SSOUT operates with maximum frequency. Converter might have no output. Over load protection might be triggered. OUT remains low after protection is triggered. OUT keeps retrying.B
SS8N/A
Table 4-5 Pin FMA for Device Pins Short-Circuited to supply
Pin NamePin No.Description of Potential Failure Effect(s)Failure Effect Class
COMP1COMP pin stays high, OUT duty cycle is maximum. Converter output loses regulation. IC might get damaged. Over load protection might be triggered. OUT remains low after protection is triggered. OUT keeps retrying.A
VIN2No effect.D
VCC3VCC loses linear regulation function. IC damage is possible.A
OUT4OUT remains high. Power stage will be damaged. IC damage is possible.A
GND5IC is not biased. OUT remains low. Converter has no output.B
CS6OUT has minimum on time. IC damage is possible.A
RT7OUT remains low. IC damage is possible.A
SS8Soft start function is lost. IC damage is possible.A