DRAFT IBIS Rev 2.0, part 3

Text item: Text_1

$|==============================================================================
$| Keyword: [GND Clamp Reference]
$| Required: Yes, if the [Voltage Range] keyword is not present.
$|Description: Defines a power supply rail other than 0v as the reference
$| voltage for the [GND Clamp] V/I data. If this keyword is not
$| present, the voltage data points in the [GND Clamp] V/I table
$| are referenced to 0v.
$|Usage Rules: Provide actual voltages (not percentages) in the usual typ, min,
$| max format. "NA" is allowed for the min and max values only.
$|Other Notes: Power Supplies: It is intended that standard TTL and CMOS
$| devices be specified using only the [Voltage Range] keyword.
$| However, in cases where the output characteristics of a device
$| depend on more than a single supply and ground, or a pullup,
$| pulldown, or clamp structure is referenced to something other
$| than the default supplies, use the additional 'reference'
$| keywords.
$|
$| If the [Voltage Range] keyword is not present, then all four of
$| the other keywords must be present. If the [Voltage Range]
$| keyword is present, the other keywords are optional and may or
$| may not be used as required. It is legal (although redundant)
$| for an optional keyword to specify the same voltage as specified
$| by the [Voltage Range] keyword.
$|---------------------------------------------------------------------------
$| variable typ min max
$[GND Clamp Reference] 0V 0V 0V
$|
|==============================================================================
| Keywords: [Pulldown], [Pullup], [GND Clamp], [POWER Clamp]
| Required: Yes, if they exist in the device
| Description: The data points under these keywords define the V/I curves of
| the pulldown and pullup structures of an output buffer and the
| V/I curves of the clamping diodes connected to the GND and the
$| POWER pins, respectively. Currents are considered positive
$| when their direction is into the component.
$|
| Usage Rules: In each of these sections, the first column contains the
| voltage value, and the three remaining columns hold the
| typical, minimum, and maximum current values. The four
| entries, Voltage, I(typ), I(min), and I(max) must be placed on
| a single line and must be separated by at least one white
| space or tab character.
|
| All four columns are required under these keywords. However,
| data is only required in the typical column. If minimum
| and/or maximum current values are not available, the reserved
| word "NA" must be used. "NA" can be used for currents in the
| typical column, but numeric values MUST be specified for the
| first and last voltage points on any V/I curve. Each V/I
| curve must have at least 2, but not more than 100, voltage
| points.
|
| Other Notes: The V/I curve of the [Pullup] and the [POWER Clamp] structures
$| are 'Vcc relative', meaning that the voltage values are
$| referenced to the Vcc pin. (Note: Under these keywords, all
$| references to 'Vcc' refer to the voltage rail defined by the
$| [Voltage range], [Pullup Reference], or [POWER Clamp Reference]
$| keywords, as appropriate.) The voltages in the data tables are
| derived from the equation: Vtable = Vcc - Voutput.
|
| Therefore, for a 5V component, -5 V in the table actually
| means 5 V above Vcc, which is +10 V with respect to ground;
| and 10 V means 10 V below Vcc, which is -5 V with respect to
| ground. Vcc-relative data is necessary to model a pullup
| structure properly, since the output current of a pullup
| structure depends on the voltage between the output and Vcc
| pins and not the voltage between the output and ground pins.
| Note that the [GND Clamp] V/I curve can include quiescent
| input currents, or the currents of a 3-stated output, if so
| desired.
|
$| When tabulating data for ECL devices, the data in the pulldown
$| table is measured with the output in the 'logic low' state.
$| In other words, the data in the table represents the V-I
$| characteristics of the output when the output is at the most
$| negative of its two logic levels. Likewise, the data in the
$| pullup table is measured with the output in the 'logic one'
$| state and represents the V-I characteristics when the output
$| is at the most positive logic level. Note that in BOTH of
$| these cases, the data is referenced to the Vcc supply voltage,
$| using the equation Vtable = Vcc - Voutput.
$|
$| V/I table data is allowed to be non-monotonic in one axis.
$| To be monotonic, the V/I table data must meet any one of the
$| following 8 criteria:
$| 1- The CURRENT axis either increases or remains constant as
$| the voltage axis is increased.
$| 2- The CURRENT axis either increases or remains constant as
$| the voltage axis is decreased.
$| 3- The CURRENT axis either decreases or remains constant as
$| the voltage axis is increased.
$| 4- The CURRENT axis either decreases or remains constant as
$| the voltage axis is decreased.
$|
$| 5- The VOLTAGE axis either increases or remains constant as
$| the current axis is increased.
$| 6- The VOLTAGE axis either increases or remains constant as
$| the current axis is decreased.
$| 7- The VOLTAGE axis either decreases or remains constant as
$| the current axis is increased.
$| 8- The VOLTAGE axis either decreases or remains constant as
$| the current axis is decreased.
$|
$| It is assumed that the simulator sums the clamp curves
$| together with the appropriate pullup or pulldown curve when a
$| buffer is driving high or low, respectively. From this
$| assumption and the nature of 3-statable buffers, it follows
$| that the data in the clamping curve sections are handled as
$| constantly present curves and the pullup and pulldown curves
$| are used only when needed in the simulation.
$|
$| The clamp curves of an input or I/O buffer can be measured
$| directly with a curve tracer, with the I/O buffer 3-stated.
$| However, sweeping enabled buffers results in curves that are
$| the sum of the clamping curves and the output structures.
$| Based on the assumption outlined above, the pullup and
$| pulldown curves of an IBIS model must represent the difference
$| of the $3-stated and the enabled buffer's curves. (Note that
$| the resulting difference curve can demonstrate a non-monotonic
$| shape.) This requirement enables the simulator to sum the
$| curves, without the danger of double counting, and arrive at
$| an accurate model in both the 3-stated and enabled conditions.
$|
$| Since in the case of a non 3-statable buffer, this difference
$| curve cannot be generated through lab measurements (because
$| the clamping curves cannot be measured alone), the pullup and
$| pulldown curves of an IBIS model can contain the sum of the
$| clamping characteristics and the output structure. In this
$| case, the clamping curves must contain all zeroes, or the
$| keywords must be omitted.
|------------------------------------------------------------------------------
[Pulldown]
| Voltage I(typ) I(min) I(max)
|
   -5.0V -40.0m -34.0m -45.0m
   -4.0V -39.0m -33.0m -43.0m
| .
| .
    0.0V 0.0m 0.0m 0.0m
| .
| .
    5.0V 40.0m 34.0m 45.0m
   10.0V 45.0m 40.0m 49.0m
|
[Pullup]
|
| Voltage I(typ) I(min) I(max)
|
   -5.0V 32.0m 30.0m 35.0m
   -4.0V 31.0m 29.0m 33.0m
| .
| .
    0.0V 0.0m 0.0m 0.0m
| .
| .
    5.0V -32.0m -30.0m -35.0m
   10.0V -38.0m -35.0m -40.0m
|
[GND Clamp]
|
| Voltage I(typ) I(min) I(max)
|
   -5.0V -3900.0m -3800.0m -4000.0m
   -0.7V -80.0m -75.0m -85.0m
   -0.6V -22.0m -20.0m -25.0m
   -0.5V -2.4m -2.0m -2.9m
   -0.4V 0.0m 0.0m 0.0m
    5.0V 0.0m 0.0m 0.0m
|
[POWER Clamp]
|
| Voltage I(typ) I(min) I(max)
|
   -5.0V 4450.0m NA NA
   -0.7V 95.0m NA NA
   -0.6V 23.0m NA NA
   -0.5V 2.4m NA NA
   -0.4V 0.0m NA NA
    0.0V 0.0m NA NA
|
$|==============================================================================
$| Keywords: [Rgnd], [Rpower], [Rac], [Cac]
$| Required: Yes, if they exist in the device
$| Description: The data for these keywords define the resistance values of
$| Rgnd and Rpower connected to GND and the POWER pins,
$| respectively.
$| Usage Rules: For each of these keywords, the three columns hold the
$| typical, minimum, and maximum resistance values. The three
$| entries for R(typ), R(min), and R(max), or the three entries
for
$| C(typ), C(min), and C(max) must be placed on a single line and
$| must be separated by at least one white space or tab character.
$| All three columns are required under these keywords. However,
$| data is only required in the typical column. If minimum
$| and/or maximum values are not available, the reserved word
$| "NA" must be used indicating the R(typ) or C(typ) value by
$| default.
$| Other Notes: It should be noted that [Rpower] is connected to 'Vcc' and
$| [Rgnd] is connected to 'GND'. However, [GND Clamp Reference]
$| voltages, if defined, apply to [Rgnd]. [POWER Clamp Reference]
$| voltages, if defined, apply to [Rpower]. Either or both [Rgnd]
$| and [Rpower] may be defined and may coexist-exist with [GND
Clamp]
$| and [POWER Clamp] structures. If an AC terminator is
$| specified, then both [Rac] and [Cac] are required. When
$| [Rgnd], [Rpower], or [Rac] and [Cac] are specified, the
$| Model_type must be Terminator.
$|
$| |<-------------TERMINATOR Model--------------->|
$|
$| VOLTAGE RANGE or
$| POWER_CLAMP REF
$| o
$| |
$| POWER_ |---o---|
$| CLAMP | |
$| |--o--| \
$| | | /
$| | VI | \ RPOWER PACKAGE Keyword
$| Parameters
$| |--o--| | |<----------------->|
$| | |
$| | | PIN
$| o-----o-------o-----o-----/\/\/\--UUUUUU---o--o
$| | |GND_ | | R_PKG L_PKG |
$| | |CLAMP | | |
$| | |--o--| | | |
$| | | | \ | |
$| | | VI | /RGND | |
$| | | | \ \ |
$| | |--o--| / / RAC |
$| | | | \ |
$| | |---o---| / |
$| | | | |
$| C_COMP --- o --- CAC C_PKG ---
$| --- GND or --- ---
$| | GND_CLAMP REF | |
$| | | |
$| |-------------------o----------------------|
$| |
$| o
$| GND
$|------------------------------------------------------------------------------
$| variable R(typ) R(min) R(max)
$|
$[Rgnd] 330Ohm 300Ohm 360Ohm | Parallel Terminator
$[Rpower] 220Ohm 200Ohm NA
$|
$[Rac] 30Ohm NA NA
$|
$| variable C(typ) C(min) C(max) | AC terminator
$|
$[Cac] 50pF NA NA
$|
|==============================================================================
| Keyword: [Ramp]
| Required: Yes, except for inputs
| Description: Defines the rise and fall times of a buffer.
$| Sub-Params: dV/dt_r, dV/dt_f, R_load
$| Usage Rules: These parameters describe an ideal slope and can be expressed
$| as a ratio of any reasonable voltage and time values as shown
$| in the examples. The [Ramp] values can to use "NA" for the
$| min and max values only. The R_load sub-parameter is optional
$| if the preferred 50 ohm load is used. It is required if a non-
$| standard load is used.
$|------------------------------------------------------------------------------
[Ramp]
| variable typ min max
dV/dt_r 4.2/1.8n 3.5/2.5n 5.0/1.1n
dV/dt_f 2.5/1.5n 2.0/2.3n 3.0/0.8n
$R_load = 300ohms
$|
$|==============================================================================
$| Keywords: [Rising waveform], [Falling waveform]
$| Required: No
$| Description: Describes the shape of the rising and falling edge
$| waveforms of a driver.
$| Sub-params: R_fixture, V_fixture, C_fixture, L_fixture,
$| R_dut, L_dut, C_dut
$| Usage Rules: Each [Rising waveform] and [Falling waveform] keyword
$| introduces a table of time vs. voltage points that
$| describe the shape of an output waveform. These
$| time/voltage points are taken under the conditions
$| specified in the R/L/C/V_fixture and R/L/C_dut
$| sub-parameters. The table itself consists of
$| one column of time points, then three columns of
$| voltage points in the standard typ, min, and max format.
$| The four entries must be placed on a single line and
$| must be separated by at least one white space or tab
$| character. All four columns are required. However, data
$| is only required in the typical column. If minimum
$| or maximum data is not available, use the reserved word
$| "NA". The first value in the time column need not be `0'.
$| Time values must increase as one parses down the table.
$| The waveform table can contain a maximum of 100 data
$| points. A maximum of 100 waveform tables are allowed per
$| model. Note that for backwards compatibility, the existing
$| [Ramp] keyword is still required.
$|
$| A waveform table must include the entire waveform;
$| i.e., the first entry (or entries) in a voltage column
$| must be the DC voltage of the output before switching
$| and the last entry (or entries) of the column must be
$| the final DC value of the output after switching.
$|
$| A [Model] specification can contain more than one rising
$| edge or falling edge waveform table. However, each new
$| table must begin with the appropriate keyword and sub-
$| parameter list as shown below. If more than one rising or
$| falling edge waveform table is present, then the data in
$| each of the respective tables must be time correlated.
$| In other words, the rising (falling) edge data in each
$| of the rising (falling) edge waveform tables must be
$| entered with respect to a common reference point on the
$| input stimulus waveform.
$|
$| The 'fixture' sub-parameters specifies the loading
$| conditions under which the waveform is taken. The R_dut,
$| C_dut, and L_dut Sub-params are analogous to the
$| package parameters R_pkg, C_pkg and L_pkg and are used
$| if the waveform includes the effects of pin
$| inductance/capacitance. The diagram below shows the
$| interconnection of these elements.
$|
$| PACKAGE | TEST FIXTURE
$| _________
$| | DUT | L_dut R_dut | L_fixture R_fixture
$| | die |__@@@@@__/\ /\______|__@@@@_______/\ /\_____ V_fixture
$| | | \/ | | | \/
$| |_________| | |
$| | |
$| C_dut === | === C_fixture
$| | |
$| | |
$| gnd | gnd
$|
$| Only the R_fixture and V_fixture sub-parameters are
$| required, the rest of the sub-parameters are optional.
$| If a sub-parameter is not used, its value defaults to
$| zero. The sub-parameters must appear in the text after
$| the keyword and before the first row of the waveform
$| table.
$|------------------------------------------------------------------------------
$[Rising waveform]
$R_fixture = 500
$V_fixture = 5.0
$C_fixture = 50p
$L_fixture = 2n
$C_dut = 7p
$R_dut = 1m
$L_dut = 1n
$|Time V(typ) V(min) V(max)
$ 0.0ns 0.3 0.5 NA
$ 0.5ns 0.3 0.5 NA
$ 1.0ns 0.6 0.7 NA
$ 1.5ns 0.9 0.9 NA
$ 2.0ns 1.5 1.3 NA
$ 2.5ns 2.1 1.7 NA
$ 3.0ns 3.0 2.7 NA
$ 3.5ns 3.2 3.0 NA
$|
$[Falling waveform]
$R_fixture = 50
$V_fixture = 0
$|Time V(typ) V(min) V(max)
$ 10.0ns 3.2 3.0 NA
$ 10.5ns 3.0 2.7 NA
$ 11.0ns 2.1 1.7 NA
$ 11.5ns 1.5 1.3 NA
$ 12.0ns 0.9 0.9 NA
$ 12.5ns 0.6 0.7 NA
$ 13.0ns 0.3 0.5 NA
$ 13.5ns 0.3 0.5 NA
|
------------------------------ end of part 3 ---------------------------------
Received on Wed May 25 00:33:18 1994