SFFS342 September 2022 LM5021
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.
Figure 4-1 Pin Diagram (VSSOP) PackageTable 4-2 Pin FMA for Device Pins
Short-Circuited to Ground
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| COMP | 1 | OUT remains low. Converter has no output. | B |
| VIN | 2 | IC is not biased. OUT remains low. Converter has no output. | B |
| VCC | 3 | IC is not biased. OUT remains low. Converter has no output. | B |
| OUT | 4 | OUT remains low. Converter has no output. IC might get damaged. | A |
| GND | 5 | No effect. | D |
| CS | 6 | OUT operates with maximum duty cycle. Power stage might get damaged. Once power stage is damaged, the IC might get damaged. | A |
| RT | 7 | OUT 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 |
| SS | 8 | OUT remains low. Converter has no output. | B |
Table 4-3 Pin FMA for Device Pins
Open-Circuited
| Pin Name | Pin No. | Description of Potential Failure Effect(s) | Failure Effect Class |
|---|---|---|---|
| COMP | 1 | Over load protection is triggered. OUT remains low. OUT keeps retrying. Converter has no output. | B |
| VIN | 2 | IC is not biased. OUT remains low. Converter has no output. | B |
| VCC | 3 | VCC linear regulator might become unstable. UVLO will be triggered and converter has no output. | B |
| OUT | 4 | Converter has no gate driver voltage. Converter has no output. | B |
| GND | 5 | IC behavior is unpredictable. IC damage is possible. | A |
| CS | 6 | OUT 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 |
| RT | 7 | Converter 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 |
| SS | 8 | Lost soft start function. | C |
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 |
|---|---|---|---|---|
| COMP | 1 | VIN | COMP 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 |
| VIN | 2 | VCC | VCC loses linear regulation function. IC damage is possible. | A |
| VCC | 3 | OUT | OUT remains high. Power stage will be damaged. IC damage is possible. | A |
| OUT | 4 | N/A | ||
| GND | 5 | CS | OUT operates with maximum duty cycle. Power stage damage is possible. Once power stage is damaged, IC damage is possible. | A |
| CS | 6 | RT | OUT 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 |
| RT | 7 | SS | OUT 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 |
| SS | 8 | N/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 |
|---|---|---|---|
| COMP | 1 | COMP 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 |
| VIN | 2 | No effect. | D |
| VCC | 3 | VCC loses linear regulation function. IC damage is possible. | A |
| OUT | 4 | OUT remains high. Power stage will be damaged. IC damage is possible. | A |
| GND | 5 | IC is not biased. OUT remains low. Converter has no output. | B |
| CS | 6 | OUT has minimum on time. IC damage is possible. | A |
| RT | 7 | OUT remains low. IC damage is possible. | A |
| SS | 8 | Soft start function is lost. IC damage is possible. | A |