IBIS BIRD50.1 Add Model Bus Hold

Dear IBIS Folks:

BIRD50 describes a bus hold extension which is also useful for other similar
structures.

BIRD50.1 is issued with these changes:

  The title is corrected.
  [Add Model Spec] is required for bus hold models
  Add_model_mode is illustrated
  Any other minor editorial correction

Changes occurred or are documemented in the |* lines.

Bob Ross
Interconnectix/Mentor Graphics

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BIRD ID#: 50.1
ISSUE TITLE: Add Model Bus Hold
REQUESTER: Neven Orhanovic, Bob Ross, Mentor G., Arpad Muranyi, Intel
DATE SUBMITTED: 4/2/98, 5/21/98
DATE ACCEPTED BY IBIS OPEN FORUM: Pending

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STATEMENT OF THE ISSUE:

New devices incorporate bus hold or other latching mechanisms to hold the
input at a particular state using some active pullup and pulldown components.

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STATEMENT OF THE RESOLVED SPECIFICATIONS:

The Bus Hold functionality is added in the new Section 6a:

| Bus Hold:
|
|* When the Model_type subparameter under the [Model] keyword is set to
|* Bus_hold, the added model describes the bus hold functionality. This
|* section introduces the dynamic clamp add model functionality.
|
|* Existing keywords and subparameters are used to describe bus hold models.
|* The [Pullup] and [Pulldown] tables both are used to define a weak internal
|* buffer that is triggered switch to its opposite state. This switching
|* transition is specified by a [Ramp] keyword or by the [Rising Waveform]
|* and [Falling Waveform] keywords.
|*
|* For bus hold models, the [Add Model Spec] and V_trigger_r and V_trigger_f
|* subparameters are required.
|
| The transition is triggered by action at the die using the [Add Model Spec]
| V_trigger_r and V_trigger_f subparameters as follows:
|
|* If the starting voltage is below V_trigger_f, then the bus_hold model is
|* set to the low state causing additional pulldown current. If the starting
|* voltage is above V_trigger_r, the bus hold model is set to the high
| state for additional pullup current. When the input passes though
| V_trigger_f during a high-to-low transition at the die, the bus hold output
|* switches to the low state. Similarly, when the input passes though
|* V_trigger_r during a low-to_high transition at the die, the bus hold output
|* switches to the high state.
|
| No additional keywords are needed for this functionality.

|------------------------------------------------------------------------------
|
| Complete Bus_hold Model Example:
|
[Model] Bus_hold_1
Model_type Bus_hold
C_comp 0 0 0
|
|* Add Model_Mode added to the example in the next three lines:
Add_Model_Mode Non-Driving | Illustrates constraining this additional
                                   | functionalily to non-driving modes of
                                   | operation
[Add Model Spec]
| Subparameter typ min max
|
V_trigger_f 1.3 1.2 1.4 | Falling edge trigger
V_trigger_r 3.1 2.6 4.6 | Rising edge trigger
|
[Pulldown]
|
-5V -100uA -80uA -120uA
-1V -30uA -25uA -40uA
0V 0 0 0
1V 30uA 25uA 40uA
3V 50uA 45uA 50uA
5V 100uA 80uA 120uA
10v 120uA 90uA 150uA
|
[Pullup]
|
-5V 100uA 80uA 120uA
-1V 30uA 25uA 40uA
0V 0 0 0
1V -30uA -25uA -40uA
3V -50uA -45uA -50uA
5V -100uA -80uA -120uA
10v -120uA -90uA -150uA
|
|****************************************************************************
|
[Ramp]
| typ min max
dV/dt_r 2.0/0.50n 2.0/0.75n 2.0/0.35n
dV/dt_f 2.0/0.50n 2.0/0.75n 2.0/0.35nn
|
|****************************************************************************

|==============================================================================

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ANALYSIS PATH/DATA THAT LED TO SPECIFICATION:

A weak driver can be added using the [Add Model] keyword.

BIRD50.1 adds the statement that [Add Model Spec] and its V_trigger_r and
V_trigger_f subparameters are required. This is because [Add Model Spec]
may not be required for other added models.

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ANY OTHER BACKGROUND INFORMATION:

This proposal is based on a conversation with Bob Ross, Chris Reid, and
Arpad Muranyi on March 11, 1998.

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Received on Thu May 21 15:48:25 1998