IBIS BIRD50 - Add Model Bus Hold

Dear IBIS folks:

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

Bob Ross
Interconnectix/Mentor Graphics

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BIRD ID#: 50
ISSUE TITLE: Add Model Dynamic Clamps
REQUESTER: Neven Orhanovic, Bob Ross, Mentor G., Arpad Muranyi, Intel
DATE SUBMITTED: 4/2/98
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:
|
| The bus hold functionality is defined by the Model_type 'Bus_hold'. The
| [Pullup] and [Pulldown] tables both are used to define a weak internal
| buffer that is triggered to be set in the opposite state of the signal.
| The transistion is defined normally by a [Ramp] keyword, but, the [Rising
| Waveform] and [Falling Waveform] keywords also may be used.
|
| 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 stage 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
| changes 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
| change 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 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.

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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 Apr 2 14:05:03 1998