****************************************************************************** ****************************************************************************** BIRD ID#: 109.1 ISSUE TITLE: S_overshoot_high/S_overshoot_low Clarification REQUESTER: Anders Ekholm, Ericsson DATE SUBMITTED: May 14, 2008 DATE REVISED: June 6, 2008 DATE ACCEPTED BY IBIS OPEN FORUM: June 6, 2008 ****************************************************************************** ****************************************************************************** STATEMENT OF THE ISSUE: The parameters S_overshoot_high and S_overshoot_low is stated as the DC voltage values for which the model is no longer guaranteed to function correctly. Then the specification states, "Typically these are voltages that would cause the physical component to be destroyed". In some cases the overshoot parameter will use different values to guarantee function and to keep the component from being destroyed. The wording in the specification is not clear on what values are expected for the overshoot parameters in cases that two different values exists for function and destruction. Since the specification threats the two different overshoot limits as the same we can not be sure what values a model creator will put in the model, it might be limits for function or for destruction. Analysing a design would normally require problems to be found based on the function limit values. To make sure those are the values that will be put in a model an update to the specification is required. ****************************************************************************** STATEMENT OF THE RESOLVED SPECIFICATIONS: Changes are noted in the relevant sections below by |* lines. Replace the following text, of the [Model Spec] keyword in section 6: (from the 4.2 spec) | | S_overshoot_high, S_overshoot_low rules: | | The static overshoot subparameters provide the DC voltage | values for which the model is no longer guaranteed to function | correctly. Typically these are voltages that would cause the | physical component to be destroyed. | | D_overshoot_high, D_overshoot_low, D_overshoot_time rules: | | The dynamic overshoot values provide a time window during | which the overshoot may exceed the static overshoot limits | but be below the dynamic overshoot limits. D_overshoot_time | is required for dynamic overshoot testing. In addition, if | D_overshoot_high is specified, then S_overshoot_high is | necessary for testing beyond the static limit. Similarly, if | D_overshoot_low is specified, then S_overshoot_low is | necessary for testing beyond the static limit. with the new text with changes shown: | | S_overshoot_high, S_overshoot_low rules: | | The static overshoot subparameters provide the DC voltage | values for which the model is no longer guaranteed to function |* correctly. Often these voltages are given as absolute maximum |* ratings. However, if any lower overshoot_high or higher |* overshoot_low limit for functional specification compliance |* exits, that limit should be used. | | D_overshoot_high, D_overshoot_low, D_overshoot_time rules: | | The dynamic overshoot values provide a time window during | which the overshoot may exceed the static overshoot limits |* but be below the dynamic overshoot limits and still guarantee |* functional specification compliance. D_overshoot_time | is required for dynamic overshoot testing. In addition, if | D_overshoot_high is specified, then S_overshoot_high is | necessary for testing beyond the static limit. Similarly, if | D_overshoot_low is specified, then S_overshoot_low is | necessary for testing beyond the static limit. ****************************************************************************** ANALYSIS PATH/DATA THAT LED TO SPECIFICATION With the old formulation the user have no means to know if the parameters specified as overshoot requirements are for function or destruction. Similarly the model creator can with the old formulation not clearly know which values to put into the model. BIRD109.1 The following change in BIRD109 was removed in BIRD109.1: Replace the following text, of the [Model Spec] keyword in section 6: (from the 4.2 spec) | | The minimum and maximum values are used for specifications | subparameter values that may track the min and max operation | conditions of the [Model]. For example, some subparameter | values might change with the [Voltage Range] settings for each | column. | with: | | The minimum and maximum values are used for specifications | subparameter values that may track the min and max operation | conditions of the [Model]. For example, some subparameter | values might change with the [Voltage Range] settings for each |* column. Unless otherwise noted, all voltage values are with |* respect to 0.0 V. | since we could not resolve the global reference text terminology. ***************************************************************************** ANY OTHER BACKGROUND INFORMATION: ******************************************************************************