Properties

JITX allows us to associate arbitrary properties with pins, components, and modules. These properties are used throughout OCDB for design calculations and design review checks. Everyone is free to define and use their own parameters, but when we collaborate on a shared set it is easier to write better automation. What follows is documentation of the properties defined in OCDB.

Component properties

These are properties associated with components, including passive components like resistors, capacitors, and inductors.

Generic properties

These properties apply to all components.

Name	Type	Values	Unit	Description
`temperature`	`Double`		degC	Bulk temperature of the component
`rated-temperature`	`Toleranced False`	e.g. `min-max()` or `false`	degC	Rated operating temperature of component. Use `false` if property does not apply.
`trust`	`String`	“low”		The data for this component came from a distributor/other
		“datasheet”, "medium"		The data from this component came from the datasheet
		“built”, "high"		This component was used on a board without issue
		“characterized”		The this model data was characterized in the lab
`dimensions`	`[Double, Double, Double]`	[Length, Width, Height]	[mm, mm, mm]	Length, width and height (x,y,z) of the bounding box of the component
`mounting`	`String`	“smd” “through-hole”		How is this component mounted to the board
`case`	`String`	“0402”, "0805"		Common name of the component package

Resistor properties

These are properties associated with resistors, as used by gen-res-cmp in ocdb/utils/generic-components.

Name	Type	Values	Unit	Description
`resistor`	`True\|False`	true		Identifies resistor component
`type`	`String`	“thick-film”, “metal-film”, ...		Type of resistor
`resistance`	`Double`		Ohm	Nominal resistance
`tolerance`	`Double`		Ohms/Ohm	Guaranteed tolerance from manufacturer
`rated-voltage`	`Double`		Volts	Maximum voltage rating from manufacturer
`rated-power`	`Double\|PWL[temp]`	`Watts\|[degC, Watts]`		Power dissipation limit as rated by manufacturer. One value, or set of points for PWL function.
`derating`	`PWL[temp]`	`[degC, derate factor]`		Temperature-based derating of resistance
`TCR`	`Double`	Ohms/Ohm*degC		Temperature coefficient of resistance

Capacitor properties

These are properties associated with capacitors, as used by gen-cap-cmp in ocdb/utils/generic-components.

Name	Type	Values	Unit	Description
`capacitor`	`True\|False`	true		Identifies capacitor component
`type`	`String`	“ceramic”, “film”, “electrolytic"		Type of capacitor
`anode`	`String`	“aluminum”, “tantalum”, “niobium-oxide”		Anode material of electrolytic capacitor
`electrolyte`	`String`	“polymer”, “manganese-dioxide”, “hybrid”, “non-solid”		Electrolyte material of electrolytic capacitor
`temperature-coefficient`	`String`	“X7R”,"X5R", "NP0", "C0G",...		Temperature coefficient of capacitance
`capacitance`	`Double`	Farad		Nominal capacitance
`tolerance`	`Double`	Farad/Farad		Guaranteed tolerance from manufacturer
`rated-voltage`	`Double`		Volts	Maximum voltage rating from manufacturer
`rated-current-pk`	`Double`		Amperes	Maximum peak current rating from manufacturer
`rated-current-rms`	`Double\|PWL[temp]`		Amperes	Maximum rms current rating from manufacturer

Inductor properties

These are properties associated with inductors, as used by gen-ind-cmp in ocdb/utils/generic-components.

Name	Type	Values	Unit	Description
`inductor`	`True\|False`	true		Identifies component as inductor
`type`	`String`	“wirewound”, “Thick Film”, ...		Type of inductor
`material-core`	`String`	“ceramic”, “ferrite”, ...		Composition of inductor
`inductance`	`Double`		Henry	Nominal inductance
`tolerance`	`Double`		henry/henry	Guaranteed tolerance from manufacturer
`current-rating`	`Double`		Amperes	Maximum steady-state current rating from manufacturer
`saturation-current`	`Double`		Amperes	Percentage inductance drop (typ 20-30%) at peak currents
`shielding`	`String`	“semi-shielded”, “shielded”, “unshielded”		Magnetic field status
`dc-resistance`	`Double`		ohm	Nominal resistance
`quality-factor`	`Double`		ratio@freq	Loss factor inverse - ratio between inductors resistance and inductance
`self-resonant-frequency`	`Double`		Hertz	Frequency at which inductor impedance becomes very high / open circuit

Crystal properties

These are properties associated with crystals, as used by gen-xtal-cmp in ocdb/utils/generic-components.

Name	Type	Values	Unit	Description
`crystal-resonator`	`CrystalResonator()`	see below		Collection of properties for a resonator

public pcb-struct ocdb/utils/property-structs/CrystalResonator :
  load-capacitance:Double     ; Load capacitance in Farads                
  shunt-capacitance:Double    ; Shunt capacitance in Farads                
  motional-capacitance:Double ; Motional capacitance in Farads                    
  ESR:Double                  ; Series resistance of crystal in Ohms  
  frequency:Double            ; Fundamental frequency in Hz        
  frequency-tolerance:Double  ; Frequency tolerance in Hz                
  max-drive-level:Double      ; Max drive level in W      

; Example call
  property(self.crystal-resonator) = ocdb/utils/property-structs/CrystalResonator(cl, cs, cm, esr, f, df * f, dl)

Pin properties

These properties are associated with component pins like power, reset, and logic pins.

Power pins

Name	Type	Values	Unit	Description
`power-pin`	`PowerPin(Toleranced)`	e.g. `min-max()` or `min-typ-max()`	Volts	Power pin definition using the structure `PowerPin()` taking a `Toleranced` argument for the allowable voltage range
`supply-pin`	`PowerSupplyPin(Toleranced, Double)`		Volts\|[Volts,Amps]	Nominal voltage and optional current capacity of the power pin
`gnd-ref`	`pin or net object`	JITXObject		Identifier for a pin or net that is the 0v reference for this pin
`power-request`	`[Double,Double,Double]`	[Voltage, Current, Noise]	[Volts, Amperes, Volts]	Defines a load by nominal voltage, current, and allowable noise to be satisfied by the power solver.

Logic pins

Digital pins

These are properties to check the generic rated voltage and ESD protection of pins, used by the checks in ocdb/utils/checks. | Name | Type | Values | Unit | Description | |:-----|:-----|:-------|:-----|:------------| | generic-pin | GenericPin() | see below | | Properties for rated voltage and ESD protection. |

; Library property name: generic-pin
public pcb-struct ocdb/utils/property-structs/GenericPin :
  max-voltage:Toleranced|RelativeVoltage    ; Maximum voltage that can be applied to pin (V)
  rated-esd:Double                          ; Rated ESD voltage (V)

; Example call
property(self.SDA.generic-pin) = GenericPin(min-max(-0.3, 3.6), 1500.0)

Name	Type	Values	Unit	Description
`digital-input`	`DigitalInput()`	see below		Properties to check digital inputs

; Library property name: digital-input
public pcb-struct ocdb/utils/property-structs/DigitalInput :
  vil:Toleranced|RelativeVoltage    ; Range of voltages that will read as logic low (V)
  vih:Toleranced|RelativeVoltage    ; Range of voltages that will read as logic high (V)
  vdd-pin:JITXObject                ; Pin that powers the high reference 
  gnd-pin:JITXObject                ; Pin that powers the low reference
  leakage-current:Double            ; Leakage current in Amps

; Example call
property(UART-RX.digital-input) = DigitalInput(0.4, 0.7 * vcc, VCCIO, GND, 1.0e-6)

Name	Type	Values	Unit	Description
`digital-output`	`DigitalOutput()`	see below		Properties to check digital inputs

; Library property name: digital-output
public pcb-struct ocdb/utils/property-structs/DigitalOutput :
  driver:LogicFamily          ; Driver model of the output
  tristateable:True|False     ; Can this pin be put in a high-impedance mode?
  vdd-pin:JITXObject          ; Pin that powers the high reference 
  gnd-pin:JITXObject          ; Pin that powers the low reference

; Example Call
property(UART-TX.digital-output) = DigitalOutput(CMOSOutput(min-max(0.3, 0.5), min-max(2.6, 3.3)), false, VCCIO, GND)

Name	Type	Values	Unit	Description
`digital-io`	`DigitalIO()`	see below		Properties to check digital io pins

; Library property name: digital-io
public pcb-struct ocdb/utils/property-structs/DigitalIO :
  driver:LogicFamily                ; Driver model of the output
  vil:Toleranced|RelativeVoltage    ; Range of voltages that will read as logic low (V)
  vih:Toleranced|RelativeVoltage    ; Range of voltages that will read as logic high (V)  gnd-pin:JITXObject          ; Pin that powers the driver low reference
  vdd-pin:JITXObject                ; Pin that powers the high reference 
  gnd-pin:JITXObject                ; Pin that powers the low reference
  leakage-current:Double            ; Leakage current in Amps

; Example call
property(PA[3].digital-io) = DigitalIO(CMOSOutput(min-max(0.0, 0.4), min-max(3.3 - 0.4, 3.3)), typ(0.3 * 3.3), typ(0.7 * 3.3), self.VDD, self.VSS, 50.0e-9)

JITX Documentation