**************************************************************************** **************************************************************************** BUFFER ISSUE RESOLUTION DOCUMENT (BIRD) BIRD ID#: 87 ISSUE TITLE: Series Pin Mapping Clarifications REQUESTOR: Arpad Muranyi, Intel Corporation DATE SUBMITTED: January 19, 2004 DATE REVISED: DATE ACCEPTED BY IBIS OPEN FORUM: February 20, 2004 **************************************************************************** **************************************************************************** STATEMENT OF THE ISSUE: The usage rules of the [Series Pin Mapping] keyword in the IBIS 4.0/4.1 specification fails to mention that the third column (model_name) may also reference a [Model Selector] name, not just [Model] name. Also, the usage rules section does not mention whether using the same pin name in multiple associations with models or model selectors is prohibited or not. Strictly speaking, the absent prohibition implies that it is allowed, but spelling out this rule could eliminate questions and confusion. **************************************************************************** STATEMENT OF THE RESOLVED SPECIFICATIONS: Add a few more words to the usage rules as shown below to clarify the issues mentioned above. Changes are marked with the * characters at the beginning of each line. |=========================================================================== | Keyword: [Series Pin Mapping] | Required: No | Description: Used to associate two pins joined by a series model. | Sub-Params: pin_2, model_name, function_table_group | Usage Rules: Enter only series pin pairs. The first column, [Series Pin | Mapping], contains the series pin for which input impedances | are measured. The second column, pin_2, contains the other | connection of the series model. Each pin must match the pin | names declared previously in the [Pin] section of the IBIS |* file. The third column, model_name, associates models of |* type Series or Series_switch, or model selectors containing |* references to models of type Series or Series_switch for |* the pair of pins in the first two columns. Each model_name |* must have a corresponding model or model selector name |* listed in a [Model] or [Model Selector] keyword below. The |* usage of reserved model names (POWER, GND, or NC) within the |* [Series Pin Mapping] keyword is not allowed. The fourth | column, function_table_group, contains an alphanumeric | designator string to associate those sets of Series_switch | pins that are switched together. | | Each line must contain either three or four columns. When | using four columns, the header function_table_group must be | listed. | | One possible application is to model crossbar switches where | the straight through On paths are indicated by one | designator and the cross over On paths are indicated by | another designator. If the model referenced is a Series | model, then the function_table_group entry is omitted. | | The column length limits are: | [Series Pin Mapping] 5 characters max | pin_2 5 characters max | model_name 20 characters max | function_table_group 20 characters max | | Other Notes: If the model_name is for a non-symmetrical series model, | then the order of the pins is important. The [Series Pin | Mapping] and pin_2 entries must be in the columns that | correspond with Pin 1 and Pin 2 of the referenced model. | | This mapping covers only the series paths between pins. The | package parasitics and any other elements such as additional | capacitance or clamping circuitry are defined by the | model_name that is referenced in the [Pin] keyword. The | model_names under the [Pin] keyword that are also referenced | by the [Series Pin Mapping] keyword may include any legal | model or reserved model except for Series and Series_switch | models. Normally the pins will reference a [Model] whose | Model_type is 'Terminator'. For example, a Series_switch | model may contain Terminator models on EACH of the pins to | describe both the capacitance on each pin and some clamping | circuitry that may exist on each pin. In a similar manner, | Input, I/O or Output models may exist on each pin of a | Series model that is serving as a differential termination. | |* Also, a pin name may appear on more than one entry under the |* [Series Pin Mapping] keyword. This allows for multiple and |* perhaps different models or model selectors to be placed |* between the same, or any arbitrary pin pair combinations. |--------------------------------------------------------------------------- **************************************************************************** ANALYSIS PATH/DATA THAT LED TO SPECIFICATION: Since the usage rules of the [Pin] keyword includes this statement: | ... The | third column, model_name, maps a pin to a specific I/O | buffer model or model selector name. Each model_name must | have a corresponding model or model selector name listed | in a [Model] or [Model Selector] keyword below, unless it is | a reserved model name (POWER, GND, or NC). and the usage rules of the [Model Selector] keyword includes this statement: | ... The name of the | [Model Selector] keyword must match the corresponding model | name listed under the [Pin] or [Series Pin Mapping] keyword | and must not contain more than 20 characters. the intent was obviously to allow the [Series Pin Mapping] keyword to reference [Model Selectors]. The missing statement under the [Series Pin Mapping] keyword seems to have been just and editorial oversight. **************************************************************************** **************************************************************************** ANY OTHER BACKGROUND INFORMATION: ****************************************************************************