PCA82C252和TJA1053容错CAN收发器的计算实例

1. Comparison PCA82C252 / TJA1053 / TJA1054..........................................................................3
1.1. System parameters ..................................................................................................................3
1.2. Device parameters ...................................................................................................................3
2. Series Resistor at Pin BAT of the TJA1053 / TJA1054..............................................................4
3. Vcc Supply and Recommended Bypass Capacitance ..............................................................5
3.1. List of used Abbreviations.........................................................................................................5
3.2. Summary.................................................................................................................................6
3.3. Average Supply Current at Absence of Bus Short-Circuit Conditions.........................................7
3.3.1. Maximum dominant supply current (without bus wiring faults) .............................................7
3.3.2. Example calculation ...........................................................................................................7
3.3.3. Thermal considerations (without bus wiring faults) ..............................................................7
3.3.4. Example calculation ...........................................................................................................7
3.4. Average Supply Current at Presence of a Short-Circuit of one Bus Wire ..................................8
3.4.1. Maximum dominant supply current (with CANH shorted to GND)........................................8
3.4.2. Example calculation ...........................................................................................................8
3.4.3. Thermal considerations (with CANH shorted to GND).........................................................8
3.4.4. Example calculation ...........................................................................................................8
3.4.5. Vcc extra supply current in single fault condition.................................................................9
3.4.6. Example calculation ...........................................................................................................9
3.5. Worst Case Max Vcc Supply at Presence of a Dual Short Circuit ............................................10
3.5.1. Max Vcc supply current in worst case dual fault condition.................................................10
3.5.2. Example calculation .........................................................................................................10
3.5.3. Vcc extra supply current in dual fault condition .................................................................11
3.5.4. Example calculation .........................................................................................................11
3.6. Calculation of worst-case bypass capacitor.............................................................................11
3.6.1. Example calculation, separate supplied transceiver @ 83,33kBit/s ...................................12
3.6.2. Example calculation, shared supply..................................................................................12
4. Calculation of Bus Termination Resistors and EMC issues...................................................13
4.1. How to dimension the Bus Termination Resistor values, some basic rules ..............................13
4.1.1. Variable System Size, Optional Nodes .............................................................................13
4.1.2. Example calculation, Variable System Size ......................................................................14
4.2. Tolerances of Bus Termination Resistors, EMC Considerations..............................................14
4.3. Output Current and Power Dissipation of Bus Termination Resistors RT..................................15
4.3.1. Summary .........................................................................................................................15
4.3.2. Average power dissipation, no bus failures.......................................................................15
4.3.3. Example calculation, average power dissipation...............................................................15
4.3.4. Maximum continuous power dissipation............................................................................15
4.3.5. Example calculation, maximum continuous power dissipation...........................................15
4.3.6. Maximum peak power dissipation.....................................................................................16
4.3.7. Example calculation, maximum peak power dissipation....................................................16
5. ESD Protection Circuit Concept ..............................................................................................16