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www.intel.com
or call 1-800-548-4725
4Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide
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1Introduction
This document provides design guidelines for developing systems based on the Intel® Celeron®
Processor – Low Power or Ultra Low Power or Intel® Pentium® III - Low Power in a BGA2
packageandtheIntel
presented. Likely design errors have been listed here in a checklist format. These are
recommendations only.
These design guidelines and recommendations have been simulated and validated and strongly
recommended to meet the timing and signal quality specifications. It is recommended that
simulations be performed to meet design-specific requirements.
Note: The system bus speed supported by the design is based on the capabilities ofthe processor,
chipset, and clock driver.
® 815E chipset. Special design recommendations and concerns are
Introduction
1.1Audience
This document is intended to be used by Intel® Celeron® or Intel® Pentium® III –
LP/ULP/815E system developers.
Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide5
Introduction
1.2Notation and Terminology
This section describes someof the terms used in this document.
TermDescription
AGPAcceleratedGraphics Port
GTL+Refers to processor bus signals that are implemented open drain GTL+ interface
signal.
Bus AgentA componentor group of compo nents that, whencombined, representasingle load on
the AGTL bus.
CrosstalkThe reception o na victim network of asignal impose dby aggressor network(s) through
• Backward Crosstalk–coupling that creates asignal in avictim network that travels in
the opposite direction as theaggressor signal.
• Forward Crosstalk–coupling that creates a signal in a victim network that travels in
the same direction as the aggressor signal.
• Even ModeCrosstalk–coupling from single or multipleaggressors when all the
aggressors switch in thesa m edirection that thevictim is switching.
• Odd Mode Crosstalk–coupling from single or multipleaggressors when all the
aggressorsswitchin theoppositedirection thatthe victim isswitching.
R
GMCHGraphics and MemoryController Hub. A component o f theIntel®815chipsetplatform
for use withIntel
Power
ICH2Intel®82801BA I/O Controller Hub component.
ISIInter-symbol interferenceis theeffect of a previo us signal(o rtra nsition)on the
interconnect dela y. For example ,when asignal is transmitted dow na line and the
reflections due tothetransition have not completelydissipated,thefollowing data
transition launched onto thebus is affected. ISI is dependent upon frequency,time
delay of the line, and the reflection coefficient at the driver and receiver. ISI can impact
both timing andsignalintegrity.
Network LengthThe distance between agent 0 pins and the agent pins at the far end of the bus.
PadThe electrical contact pointof a semiconductor dietothe package substrate. A padis
onlyobservablein simulation.
PinThe contact point of acomponent packageto the traces on asubstrate such as the
motherboard. Signal qualityand timings can be measured at the pin.
RingbackThe voltage thata signal rings back to after achiev ingits maximumabsolute value .
Ringback maybedue to reflections, drive roscillations, or other transmission line
phenome na.
Setup WindowThe time between thebeginning of Setup to Clock (T
clock edge. This windowmay bedifferent for ea ch type of bus agent in the system.
®
Pentium III-Low Power an dIntel®Celeron-Ultra Low Power/Low
) and the arrival of a valid
SU_MIN
6Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide
Introduction
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TermDescription
SSOSimultaneous Switching Output (SSO) Effects refers to the difference in electrical
timing parameters and degradation in signalquality causedbymultiple signal outputs
simultaneously switching voltage levels (e.g., high-to-low) in the opposite direction from
a single signal (e .g.,low-to-high) or inthesamedirection (e.g., high-to-low). These are
respectivelycalled odd-modeswitching and even-modeswitching. This simultaneous
switching of multiple outputs creates highercurrent swings that ma ycause additional
propagation delay (or “push-out”), or a decrease in propagation delay (or “pull-in”).
These SSO effects may impact the setup and/or hold times and are not always taken
into account bysimulations. Systemtimingbudgets need toinclude ma rginfor SSO
effects.
StubThe branch from the bus trunk terminatingat the pa dof an agent.
SystemBusThesystembus isthe processorbus.
TrunkThe mainconnection, ex cluding inte rconnect branches, from one end agentpad to the
other end agent pad.
UndershootMinimum voltage observed for a signal to extend below VSSat the device pad.
VictimA network that receives a coupled crosstalk signal from another network is called the
victim network.
In this document, a ‘#’ symbol after a signal name identifies the signal as active low; that is, a
signal that is in the active state, based on the name of the signal, when dr iven to a low level. For
example, when FLUSH# is low, a flush has been requested. When NMI is high, a non-maskable
interrupt has occurred. When a signal name does not imply an active state, a # symbol indicates
that th e signal is inverted. For example, D[3:0] = ‘HLHL’ refers to a hex ‘A’, and D[3:0]# =
‘LHLH’ also refers to a hex ‘A’ (H= High logic level, L= Low logic level).
The term “BGA2-based processor(s)” refers to the Intel® Celeron® processor-Ultra Low Power
and Low Power in a BGA2 package and th e Intel® Pentium® III processor-Low Power in a
BGA2 package.
Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide7
Introduction
1.3Reference Documents
The reader of this document needs to be familiar with the material and concepts presented in th e
following documents.
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DocumentDocument Number /
Intel®815 Chipset Family: 82815 Graphics and Memory Controll erHub (GMCH) for
use with the Universal Socket 370 Datasheet
Communication Network Riser Specification, Revision 1.1http://dev eloper.intel.co
Universal Serial Bus, Revision1.0 Specification
Location
298351
290687
290689
m/pcsupp/platform/ac97/inde
x.htm.
http://dev eloper.intel.co
m
http://dev eloper.intel.co
m
m/technology /cnr/
8Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide
General Design Considerations
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2General Design Considerations
This section documents the example of a nominal board stack up for BGA2-based processor with
the 815E platform.
Make sure the impedance for all signal layers is 60 Ω±15%. That is, the impedance of the trace
when not subjected to fields created by changing current in neighboring traces. When calculating
flight times, it is important to consider the minimum and maximum impedance of a trace, based
on the switching of neighboring traces. The use of wider spaces between the tr aces can minimize
this trace-to-trace coupling. In addition, th ese wider spaces reduce crosstalk and settling time.
Coupling between two traces is a function of the coupled length, the distance separating th e
traces, the signal edge rate, and the degree of mutual capacitance and inductance. To minimize
the effects of trace-to-trace coupling, follow the routing guidelines documented in this section.
The routing guidelines in this design guide have been created using a PCB stack-up similar to
that in Figure 1. When this stack-up is not used, thorough simulations of every interface must be
completed. Using a thicker dielectric (prepreg) makes routing very difficult or impossible.
2.1Nominal Board Stack-up
The BGA2-based processor/815E platform requires a board stack-up yielding a target impedance
of 60 Ω ± 15% with a 5 mil nominal trace width. Figure 1 shows an example stack-up achieving
this. It is a 6-layer printed circuit board (PCB) construction using 53%-resin FR4 material.
Figure 1. Board Construction Example for 60 ΩΩΩΩ Nominal Stack-up
Signal/Powerplane layer ½ozCu., 1ozPlating
Prepreg = 3mils
GroundLayer1ozCu.
Core = 6 mils
Signal layer 1 oz Cu.
Prepreg = 34 mils
Signal layer 1 oz Cu.
Core = 6 mils
Ground layer 1 oz Cu.
Prepreg =3 mils
Signal/Powerlayer ½ oz Cu., 1ozPlating
Dieletric Constant for FR4 = 4.2
4 mils tr ace width for outer layers gives a 50 Ω signal impedance.
5 mils tr ace width for inner layers gives a 60 Ω signal impedance
Total thickness:
62 mils
Additional guidelines on board stack-up, placement, and layout include the following.
− The board impedance (Z) is 60 Ω ± 15%.
− The dielectric process variation in the PCB fabrication is minimized.
− The ground plane is not split on the ground plane layer.
− Keep vias for decoupling capacitors as close to the capacitor pads as possible.
Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide9
Processor Host Bus Design
3Processor Host Bus Design
This section documents the layout and routing guidelines using the BGA2-based processor with
the Intel® 815E chipset platform. The solution covers system bus speeds of 100 MHz only. The
Ω
processor must also be configured to 56.2
discuss the functional aspect of any bus or the layout guideline for an add-in device.
When the guidelines listed in this document are not followed, it is very important that thorough
signal integrity and timing simulations be completed for each design. Even when the guidelines
are followed, simulate critical signals to ensure proper signal integrity and flight time. As bus
speeds increase, it is imperative that the guidelines documented are followed precisely. Simulate
any deviation from these guidelines.
3.1Initial Timing Analy s is
To determine the available flight time window, perform an initial timing analysis. Analysis of
setup and hold conditions determine the minimum and maximum flight time bounds for the
system bus. Use the following equations to establish th e system flight time limits.
± 1% on-die termination. The document does not
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Table 1.System Timing Equations
T
T
flight,min
flight,max
>= T
hold–Tco,min+Tskew
<= T
cycle–Tco,max–Tsu–Tskew–Tjit–Tadj
Table 2.System Timing Terms
TermDescription
T
cycle
T
flight,min
T
flight,max
T
co,max
T
co,min
T
su
System cycle time, defined as th e reciprocal of the frequency.
Minimum system flight time.
Maximum system flight time.
Maximum driver delay from input clock to output data.
Minimum driver delay from input clock to output data.
Minimum setup time. Defined as the time for which the input data must be valid
prior to the input clock.
T
hold
Minimum hold time. Defined as the time for which the input data must remain
valid after the input clock.
T
skew
Clock generator skew. Defined as the maximum delay variation between output
clock signals from the system clock generator, the maximum delay variation
between clock signals due to system board variation and chipset loading variation.
T
jit
T
adj
Clock jitter. Defined as maximum edge to edge variation in a given clock signal.
Multi-bit timing adjustment factor. This term accounts for the additional delay
that occurs in the network when multiple data bits switch in the same cycle. The
adjustment factor includes such mechanisms as package and PCB crosstalk, high
inductance current return paths, and simultaneous switching noise.
Equation
10Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide
Processor Host Bus Design
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Table 3 lists the GTL+ component timings of the processors and GMCHdefined at the pins for
the Intel® 815E platform.
Note: These timings are for r eference only. Obtain the processor specifications from respective
processor datasheet and chipset values from the appropriate Intel® 815E chipset datasheet.
Table 3.Intel® Celeron® - Ultra Low Power and 82815E GMCH GTL+ Parameters for
Example Calculations
IC ParametersIntel®Celeron®-Ultra
Clock to Output maximum(T
Clock to Output minimum (T
Setup time(T
Holdtime (T
NOTES:
1. All time in nanoseconds
2. Numbers in table are for reference only. These timing parameters are subject to change. Check the
appropriatecomponent documentatio nfor validtimingparamete rvalues.
)1.202.651,2
SU_MIN
)1.200.101
HOLD
)3.404.101,2
CO_MAX
)0.201.051,2
CO_MIN
Low Power processor
core at 100 MHz
System Bus
82815E GMCHNotes
Table 4 provides an exampleGTL+ initial maximum flight time and Table 5 is an example
minimum flight time calculation for a 100 MHz, uni-processor system using the Intel®
Celeron® -Ultra Low Power processor/Intel
®
815E chipset system bus. Note that assumed values
for clock skew and clock jitter were used. Clock skew and clock jitter values are dependent on
the clock components and distribution method chosenfor a particular design and must be
budgeted into the initial timing equations as appropriate for each design.
Table4andTable5arederivedassuming:
SKEW = 0.20 ns (Note: Assumes clock driver pin-to-pin skew is reduced to 50 ps by
• CLK
tying two host clock outputs together (“ganging”) at clock driver output pins, and the PCB
clock routing skew is 150 ps. System timing budget must assume 0.175 ns of clock driver
skew and 150 ps PCB clock routing skew if outputs are not tied together and a clock driver
that meets the CK815E Clock Synthesizer/ Driver Specification is being used.)
JITTER = 0.250 ns
• CLK
See the appropriateIntel
®
815E chipset documentation, and CK815E Clock Synthesizer/DriverSpecification for details on clock skew and jitter specifications. Exact details of host clock
routing topology are provided with the platform design guideline.
The flight times in Table 4 include margin to account for the following phenomena that Intel
observed when multiple bits are switching simultaneously. These multi-bit effects can adversely
affect the flight time and signal quality and sometimes are not accounted for durin g simulation.
Accordingly, the maximum flight times depend on the baseboard design, an d additional
adjustment factors or margins are recommended.
• SSO push-out or pull-in
• Rising or falling edge rate degradation at the receiver caused by inductance in the
current return path, requiring extrapolation that causes additional delay
• Crosstalk on the PCB and inside the package which can cause variation in the signals
Additional effects exist that may not necessarily be covered by the multi-bit adjustment factor
and need to be budgeted as appropriate to the baseboard design. These effects are included as
in th e examplecalculations in Table 4. Examples include:
T
ADJ
• The effective board propagation constant (SEFF), which is a function of:
FLT_MIN
Calculations (Frequency Independent)
FLT_MIN
T
ε
-Dielectric constant (
)ofthePCBmaterial
r
-Type oftraceconnecting the components (stripline or microstrip)
-Length of the trace an d the load of the components on the trace. Note that the board
propagation constant multiplied by the trace length is a component of the flight time,
but not necessarily equal to the flight time.
12Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide
Processor Host Bus Design
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3.2General Topology and Layout Guidelines
Figure 2. Topology for BGA2 Designs with Single-Ended Termination (SET)
1. Reference a ll GTL+ bus signals to the ground pla nefor thee ntireroute.
2. Use an intragroupGTL+ spacing : line width : dielectric thickness ratio of at least 2:1:1 for microstrip
geometry. If
mils spacing, 5 mils trace width, and a 5 mils prepreg between the signal layer and the plane it references
(assuming a 6-layer board design)
3. The recomme nde dtrace widthis 5 mils, but not grea ter than 6 mils.
ε
= 4.5, this limits coupling to3.4%. Fo re xample ,intragro upGTL+ routing could use10
r
%1560±Ω=
1, 2, 3
3.3Simulation Methodology
3.3.1Pre-Layout Simulation
Analog simulations are recommended for high-speed system bus designs. Start simulations prior
to layout. Pre-layout simulations provide a detailed picture of the working “solution space” that
meets flight time and signal qualityrequirements. By basing board layout guidelines on the
solution space, the iterations between layout and post-layout simulations can be r educed.
3.505.00
Intel recommends running simulations at the device pads for signal quality and at the device pins
for timing analysis. However, simulation results at the device pins may be used later to correlate
simulation performance against actual system measurements.
The BGA2-based processor and 815E I/O buffer models are available from Intel through your
Intel representative.
Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide13
Processor Host Bus Design
T
3.3.2Post-Layout Simulation
From the following layout, extract the traces and run simulations to verifythat the layout meets
timing and noise requirements. A small amount of trace “tuning” may be required, but
experience at Intel has shown that a sensitivity analysis significantlyreduces the amount of
tuning required.
Take into account the expected variation for all interconnect parameters for the post layout
simulations. Intel recommends runn ing simulations at the device pads for signal qualityand at
the device pins for timing analysis. However, simulation results at the device pins may be used
later to correlate simulation performance against actual system measurements.
3.4Layout Rules for GTL+ Signals
Ground Reference
It is strongly recommended that GTL+ signals be routed on the signal layer n ext to the ground
layer (referenced to ground). It is important to provide an effectivesignal r eturn path with low
inductance. The best signal routing is directly adjacent to a solid GND plane with no splits or
cuts. Eliminate parallel tr aces between layers not separated bya power or ground plane. Routing
signals between two signals layers not separated by ground plan need to be implemented as
showninFigure3.
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Figure 3. Top view of a PCB layout
0
90
Traces in layer A
races in layer B
When a signal has to go through routing layers, the recommendations are:
Note: Following these layout rules is critical for GTL+ signal integrity, particularly for
0.18 micron and smaller process technology.
• For signals going from a ground reference to a power reference, add capacitors between
ground and power near the vias to providean AC return path. Use one capacitor for every
three signal lines that change reference layers. Capacitor requirements are as follows:
C=100nF, ESR=80mΩ,ESL=0.6nH.
• For signals going from one ground reference to another, separate ground reference, add vias
between the two ground planes to provide a better return path.
14Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide
Processor Host Bus Design
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Reference Plane Splits
Splits in r eference planes disrupt signal return paths and increase overshoot/undershoot due to
significantlyincreased inductance. Eliminate routing signal across split/cut plane. When a signal
has to route across split plane, add capacitors between the split planes to ground.
Important note: It is strongly recommended NOT to route GTL+ signals across split/cut plane
or changing reference plane resulted bytraversinglayers.
Processor Breakout
It is strongly recommended that GTL+ signals do n ot traverse multiple signal layers. Intel
recommends breaking out all signals from the processor on the same layer. When r outing is
tight, break outfrom the processor on the opposite routinglayer over a ground reference and
cross over to main signal layer near the processor.
Minimizing Crosstalk
The following general rules minimize the impact of crosstalk in a high-speed GTL+ bus design:
• Maximizethe space between traces. Where possible, maintain a minimum of 10 mils
(assuming a 5 mil trace) between trace edges. It maybe necessary to use tighter spacing
when routing between component pins. When traces must be close and parallel to each
other, minimize th e distancethat they are close together and maximize the distance between
the sections when the spacing restrictions are relaxed.
• Avoid parallelism between signals on adjacent layers, when there is no AC reference plane
between th em. As a rule of thumb, route adjacent layers orthogonally.
• SinceGTL+ is a low-signal-swing technology, it is important to isolate GTL+ signals from
other signals by at least 25 mils. This avoids coupling from signals that have larger voltage
swings (e.g., 5 V PCI).
• GTL+ signals must be well isolated from system memory signals. GTL+ signal trace edges
must be at least 30 mils from system memory trace edges within 100 mils of the ball of the
Intel® 82815 GMCH.
• Select a board stack-up that minimizes th e coupling between adjacent signals. Minimize the
nominal characteristic impedance within the GTL+ specification. This can be done by
minimizing the height of the trace from its reference plane, which minimizes crosstalk.
• Route GTL+ address, data, and control signals in separate groups to minimize crosstalk
between groups. Keep at least 15 mils between each gr oup of signals.
• Minimize the dielectric used in the system. This makes the traces closer to their r eference
plane and thus reduces the crosstalk magnitude.
• Minimize the dielectric process variation used in the PCB fabrication.
• Minimize the cross-sectional area of the traces. This can be done bymeans of narrower
traces and/or by using thinner copper, but the trade-off for this smaller cross-sectional area is
higher tr ace resistivity, which can reduce the falling-edge noise margin becauseof the I*R
loss along the trace.
Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide15
Processor Host Bus Design
3.5Layout Rules for Non-GTL+ (CMOS) Signals
Table 7.Routing Guidelines for Non-GTL+ Signals
SignalTrace WidthSpacing to Other TracesTrace Length
A20M#5 mils10 mils1” to9”
FERR#5 mils10 mils1” to 9”
FLUSH#5 mils10 mils1” to 9”
IERR#5 mils10 mils1” to 9”
IGNNE#5 mils10mils1” to 9”
INIT#5mils10 mils1” to 9”
LINT[0] (INTR)5 mils10 mils1” to 9”
LINT[1] (NMI)5 mils10 mils1” to 9”
PICD[1:0]5m ils10 mils1” to 9”
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PREQ#5 mils10m ils1” to 9”
PWRGOOD5 mils10mils1” to 9”
SLP#5 mils10 mils1” to 9”
SMI#5 mils10 mils1” to 9”
STPCLK5 mils10 mils1” to9”
NOTE:Route these signals on any layer or combination of layers.
3.5.1Additional Routing and Placement Considerations
• Distribute VTTwith a wide trace. A 0.050 inch minimum trace is recommended to minimize
DC losses. Route the V
trace to all components on the h ost bus. Be sure to include
TT
decoupling capacitors.
• The V
voltage need to be 1.25 V ± 3% for static conditions, and 1.25 V ± 9% for worst-
TT
case transient conditions.
• Place resistor divider pair for V
generation at the GMCHcomponent. V
REF
REF
delivered to the processor.
3.6Undershoot/Overshoot Requirements
Overshoot (or undershoot) is the absolute value of the maximum voltage above the nominal high
voltage or below V
fast signal edge rates. The processor can be damaged by repeated overshoot events on buffers
when the charge is large enough (i.e. when the overshoot is great enough). Determining the
impact of an overshoot/undershoot condition requires knowledge ofthe magnitude, the pulse
direction an d the activityfactor (AF). Permanent damage to the pr ocessor is the likelyresult of
excessive overshoot/undershoot. Violating the overshoot/undershoot guideline also makes
satisfying the ringback specification difficult.
. The overshoot guideline limits transitions beyond VCCor VSSdue to the
SS
also is
16Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide
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When performing simulations to determine impact of overshoot and undershoot, ESD diodes
must be properlycharacterized. ESD protection diodes do not act as voltage clamps and do not
provide overshoot or undershoot protection. Refer to Intel® Celeron® Processor Low
Power/Ultra LowPower and Intel® Pentium® III – Low Power datasheet for detailed
undershoot/overshoot requirements.
3.7Processor Reset Requirements
The BGA2-based processor designs must route the GTL+ reset signalfrom the chipset to the
processor as well as to the debug port connector. The A6 (RESET) signal is connected to this pin
for the Intel® Pentium® III processor (CPUID=068xh), Intel® Celeron® processor
(CPUID=068xh)
Note: The GTL+ reset signal must always terminate to VTT on th e motherboard.
Designs that do not support the debug port will not utilize the 240 Ω series resistor or the
connection of RESET# to the debug port connector.
Processor Host Bus Design
The routing rules for the GTL+ reset signal a re shown in Figure 4.
Figure 4. RESET# Routing Guidelines
VTT
L2L0
ProcessorGMCH
Table 8. RESET# Routing Guidelines (see Figure 4)
ParameterMinimum (in)Maximum (in)
L02.04.1
L10.51.5
Ω
86
L1
L20.91.5
L0+L23.55.0
Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide17
Processor Host Bus Design
3.8Debug Port Routing Guidelines
The Test Access Port (TAP) interface is an implementation of the IEEE 1149.1 (“JTAG”)
standard. Due to voltage levels supported bythe TAP interface, Intel recommends that the Intel®
Celeron® Processor-LP/ULP and Intel® Pentium® III Processor-LP and the other 1.5V JTAG
specification compliant devices be last in the JTAG chain after an y devices with 3.3 V or 5 V
JTAG interfaces within th e system. A translation buffer needs to be used to reducethe TDO
output voltage of the last 3.3/5 V device down to the 1.5 V range that the processors can tolerate.
Multiple copies of TMS and TRST# must be provided, one for each voltage level.
A Debug Port an d connector may be placed at the start and end of the JTAG chain containing the
processor, with TDI tothe first component coming from theDebug Port and TDO from the last
component going to the Debug Port. There are no requirements for placing the Intel® Celeron®
Processor-ULP/LP and Intel® Pentium® III Processor-LP in the JTAG chain, except for those
that ar e dictated by voltage requirements ofthe TAP signals.
The 1.5 V connector is a mirror image of the older 2.5 V connector. Either connector will fit into
the same printed circuit board layout. Only the pin numbers change (Figure 5). Also required,
along with the newconnector, is an In-Target Probe* (ITP) that is capable of communicating
with the TAP at the appropriate logic levels.
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Figure 5. TAP Connector Comparison
2.5 V connector,AMP 104068-3 vertical plug, top view
24681012141618202224262830
RESET#
RESET#
1357911131517192123252729
1.5 V connector,AMP 104078-4 vertical receptacle, topview
1357911131517192123252729
24681012141618202224262830
sys_bus_TAP_conn
Caution:The Intel® Pentium® III processor (CPUID=068xh) and Intel® Celeron® processor
(CPUID=068xh) require an in-target probe (ITP) compatible with 1.5 V signal levels on the
TAP. Previous ITPs were designed to work with higher voltages and may damage the processor
when connected to any of these specified processors.
See the processor datasheet for more information regarding the debug port.
18Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide
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3.9PLL Filter Recommendations
It is h igh ly critical that phase lock loop power delivery to the processor meets Intel requirements.
A low pass filter is required for power deliveryto pins PLL1 and PLL2. This serves as an
isolated, decoupled power source for the internal PLL.
3.9.1Topology
The general desired topology for these PLLs is shown in Figure 6. Not shown are the parasitic
routing and local decoupling capacitors. Excluded from the external circuitry are parasitic
associated with each component.
The following tables contain examples of components that meet Intel recommendations when
configured in the topology of Figure6.
1 Ω10%1/16 WResistor may beimplemented with trace resistance, in
which case a discrete R is not needed. See Figure.
To satisfydamping requirements, total series resistance in the filter (from VTTto the top plate of
the capacitor) must be at least 0.35 Ω. This resistor can be in the form of a discrete component or
routing or both. For example, if the chosen inductor has minimum DCR of 0.25 Ω,thena
routing resistance of at least 0.10 Ω is required. Be careful not to exceed the maximum resistance
rule(2Ω). For example, if using discrete R1 (1 Ω±1%), the maximum DCR of the L (tra ce plus
inductor) is less than 2.0 – 1.1 = 0.9 Ω, which precludes the use of some inductors and sets a
max. trace length.
Current
DCR (Typical)
Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide19
Processor Host Bus Design
Other routing requirements:
• The capacitor (C) is close to the PLL1 and PLL2 pins, < 0.1 Ω per route. These routes do not
count towards the min imum damping R requirement.
• The PLL2 route is parallel and next to the PLL1 route (i.e., minimize loop area).
R
• The inductor (L) is close to C. Any routing resistance is inserted between V
• Anydiscrete resistor (R) is in serted between V
Figure 6. Example PLL Filter Using a Discrete Resistor
V
TT
LR
<0.1Ω route
Discrete resistor
C
<0.1Ω route
Figure 7. Example PLL Filter Using a Buried Resistor
TT
and L.
PLL1
PLL2
TT
Processor
and L.
PLL_filter_1
V
TT
Trace resistance
LR
<0.1Ω route
C
PLL1
Processor
PLL2
<0.1Ω route
PLL_filter_2
20Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide
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3.9.2Filter Specification
The function of the filter is to protect the PLL from external noise thr ough low-pass attenuation.
The low-pass specification, with input at VCC
as follows:
• < 0.2 dB gain in pass band
• < 0.5 dB attenuation in pass band (see DC drop in next set of requirements)
• > 34 dB attenuation from 1 MHz to 66 MHz
• > 28 dB attenuation from 66 MHz to core frequency
The filter specification is graphically shown in Figure 8.
Processor Host Bus Design
and output measured across the capacitor, is
CORE
Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide21
Processor Host Bus Design
Figure 8. Filter Specification
R
0.2dB
0dB
-0.5 dB
Forbidden
Zone
Forbidden
Zone
-28dB
-34dB
1MHz66MHzfcorefpeak1HzDC
passband
NOTES:
1. Diagram not to scale.
2. No specification for frequencies beyond
3.
fpeak is less than 0.05 MHz .
fcore.
high frequency
band
Other requirements:
• Use shielded-type inductor to minimize magnetic pickup.
• Filter supports DC current > 30 mA.
• DC voltage drop from VCC to PLL1 is < 60 mV, which in practice implies series
R<2Ω. This alsomeans pass-band (from DC to 1 Hz) attenuation < 0.5 dB for V
V, and < 0.35 dB for V
=1.5V.
CC
filter_spec
CC
=1.1
22Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide
Processor Host Bus Design
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3.10Decoupling Guidelines for BGA2-based Processors
The amount of bulk decoupling required on the VCCand V
planes to met the voltage tolerance
CCT
requirements for th e Intel® Celeron® Processor – Low Power or Ultra Low Power and Intel®
Pentium® III Processor – Low Power are a strong function of the power supply design. Contact
your Intel Field Sales Representative for tools to help determine h ow much bulk decoupling is
required.
For 700 MHz processors, the following decoupling is recommended. The processor core power
plane (V
) has fifteen 0.68µF 0603 ceramic capacitors (using X7R dielectric for thermal
CC
reasons) placed directly under the package using two vias for power and two vias for ground to
reduce the trace inductance. Also to minimize inductance, traces to those vias are 22 mils (in
width) from the capacitor pads to match the via-pad size (assuming 22-mil pad size). Twenty-
µ
four 2.2
die as flex solution allows. The system bus buffer power plane (V
F 0805, X5R mid-frequency decoupling capacitors placed around the die as close to the
) has twenty 0.1µFhigh-
CCT
frequency decoupling capacitors around the die.
For 500 and 400 MHz processors, the processor core power plane (V
frequency decoupling capacitors placed underneath the die an d twenty 0.1
)haseight0.1µFhigh-
CC
µ
F mid-frequency
decoupling capacitors placed around the die as close to the die as flex solution allows. The
system bus buffer power plane (V
) has twenty 0.1µF high-frequencydecoupling capacitors
CCT
around the die.
For 300 MHz processors, the processor core powe r plane (V
decoupling capacitors placed underneath the die and twenty 0.1
)haseight0.1µF high-frequency
CC
µ
F mid-frequency decoupling
capacitors placed around the die as close to the die as flex solution allows. The system bus buffer
power plane (V
) has twenty 0.1µF high-frequencydecoupling capacitors around the die.
CCT
3.11Catastrophic Thermal Protection
The Intel® Celeron® Processor – Low Power / Ultra Low Power and Intel® Pentium® III
Processor – LowPower does not support catastrophic thermal protection or the THERMTRIP#
signal. An external thermal sensor must be used to protect the processor and the system against
excessive temperatures.
Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide23
Clocking
4Clocking
4.1General Clocking Considerations
The host bus clock signals are critical signals for the BGA2-based processor an d 815E platform.
The signal integrity and timing of these signals needs to be carefullyevaluated and simulated.
In general, the following layout recommendation needs to be followed for the host bus clocks:
• It is recommended that system bus clocksbe routed on the signal layer next to the
ground layer (referenced toground)
• It is strongly recommended that system bus clocks do not traverse multiple signal layers.
R
• System clock routing over power plane splits need to be eliminated.
• When necessary, grounded guard band traces can be routed next to clock traces to
reduce cross talk to other signals.
4.2Single-Ended Host Bus Clocking Routing
The BGA2-based processor and 815E platforms have support for using single-ended host bus
clock driver. When using this clocking method, the BCLK signal is used as th e single-ended
clock input to the BGA2-based processor. The CLKREF signal is used as a reference voltage and
must be connected to the appropriate filter circuit described in section 4.2.1
Figure 9 shows the topology recommended for the BGA2-based processor and 815E clock traces.
Please note that section 1, section 2 and section 3 r efer to tra ce length between the illustrated
components. Table 12 contains the r ecommended length and component values for this topology.
24Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide
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Figure 9 Single-Ended Clocking Topology
Clocking
Table 12 Recommended Length for Single-Ended Clocking Topology
Destination
ProcessorBCLK<0.1”<0.5”A + 5.2”N.A.
GMCH HCLKN.A.<0.5”N.A.A +8”
NOTES:
1. Length “A” has bee nsimulated upto6 inches. The length must bem a tchedbetween SDRAM MCLK lines
±100 mils.
by
2. All length specific in inches
Clock Decoupling
Several general layout guidelines need to be followed when laying out the power planes for the
CK815 clock generator, as follows:
• Isolate power planes to each of the clock groups.
• Place local decoupling as close as possible to power pins, and connect with short, wide traces
and copper.
• Connect pins to appropriate power plane with power vias (larger than signal vias).
• Bulk decoupling needs to be connected to a plane with 2 or more power vias.
• Minimize clock signal routing over plane splits.
• Donot route any signals underneath the clock generator on the component side of the board.
• An example signal via is a 14 mils finished hole with a 24 mils to 26 mils pad. An example
power via is an 18 mils finished h ole with a 33 mils to 38 mils pad. For large decoupling or
power planes with large current transients, a larger power via is recommended
Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide25
Clocking
4.2.1CLKREF Filter Implementation
When using single-ended clocking mode, the CLKREF signal on the BGA2-based processor
serves as a reference voltage to the clock input. To provide a steady reference voltage, a filter
circuit must be implemented and attached to this pin. Figure 10 shows the recommended
CLKREF filter implementation. The CLKREF filter n eed to be placed as close as possible (less
than 1.0 inch) to the processor CLKREF pin.
Figure 10. Examples for CLKREF Divider Circuit
R
Table 13. CLKREF Component Values
R1 (Ω
Ω) ± 1%R2 (ΩΩΩΩ) ± 1%CLKREF Voltage (V)
ΩΩ
1k1k1.25
26Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide
The BGA2-based processor and 815E platform is using single-ended clocking that only support
100 MHz system bus. In order to implement the 100 MHz system bus, BSEL0 needs to be pulled
up to 1.5 V through a 1.5 KΩ 5% resistor and BSEL1 needs to be pulled down to GND. This
strapping configures the clock generator to output 100 MHz clock to support a 100 MHz capable
processor. Figure 11 shows a diagram of this implementation.
Figure 11. BSEL[1:0] Circuit Implementation for LP CopperMine processor
Designs
Clocking
.2k
4.2.3Clock Driver Decoupling and Power Delivery
The decoupling and power delivery requirements of the system clock driver are dependent on the
clock driver and chipset used in the system implementation. Because ofthis, no specific
information can be provided in this document. However, since proper decoupling and n oise-free
power deliveryare critical to the clock driver operation, Intel encourages system implementers to
carefully followthe chipset and clock driver vendor recommendations in these areas. An
incorrect implementation of these circuits can easily cripple clock driver recommendations in
these areas and its abilityto produce reliable clock signals and lead to system instability. Please
refer to the appropriate clock driver and chipset vendor information for more details.
Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide27
Processor Host Bus Design Checklist
5P rocessor Host Bus Design
Checklist
5.1Introduction
This checklist highlights design considerations that n eed to be reviewed prior to manufacturing a
motherboard. This design checklist only provides the processor host bus signals design
recommendation. It is not a complete list and does not guarantee that a design functions
properly. Besides the items in the following text, refer to most recent version of the Intel® 815EChipset Platform For Use with Universal Socket 370 Design Guide for more detailed instruction.
This checklist is to be revised, as new information is available.
R
5.2GTL+ Checklist
Table 14. GTL+ signals checklist
Checklist itemsRecommendations
A[35:3]#Connect to A[31:3]# to 815 GMCH. LeaveA[35:32]# as N/C.
BNR#, BPRI#,
BREQ0#10Ωpull down toground.
RESET#Connect to8 1 5GMCH. Pull up to VCCT withan 86Ω1%resistor.Connect to
Connect to 815 GMCH.
resistor, and placed within 150 mils of 815 GMCH
Leave as N/C.
ITP with 240
Ω
series resistor near to ITP if ITP is used.
Ω
28Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide
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5.2.1CMOS (Non-GTL+) Checklist
Table 15. CMOS (Non-GTL+) signals checklist
Checklist itemsRecommendations
A20M#, IGNNE#,
INTR,INIT#,NMI,
SMI#, STPCLK#
FERR#, SLP#,Conne cttoICH2. Pull up toVCCT with a 1.5KΩresistor.
FLUSH#, IERR#,
PREQ#
PWRGOODPull up to2.5V with 1.5KΩresistor.
PICD[1:0]Connect to ICH2. Pull up to VCCT with a 150Ωresistor.
Connect toICH2.
Pull up toVCCT with 1.5 KΩresistor.
Processor Host Bus Design Checklist
5.3TAP Checklist
Table 16. TAP signals checklist
Checklist itemsRecommendations
TCK,TMSConnecttoITP with47Ωseriesresistor.Pull upto VCCT with1KΩresistor
TDI, TDOCo n n ect toITP. Pullu pto VCCT with a 150Ωresistor.
TRST#Connect to ITP. Pull down with1 KΩresistor to ground.
PRDY#Connect to ITP with 240Ωseriesresistor.Pull upto VCCT with56.2
resistor.
PRDY1#,PRDY2#,
PRDY3#
Pull up to 1.5 V VCCT through 1 KΩresistor.
Ω
Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide29
Processor Host Bus Design Checklist
5.3.1Miscellaneous Checklist
Table 17. Miscellaneous signal checklist
BCLKConnect to CK815 clock generator with 33Ωserie sresistor(mayvary
depends onsimulatio n). Tie bo thhost clock outputs (to the processor and to
the chipset) at the clock gene ra to rbe forerouting outtoprocessor andGMCH.
BSEL0Pullupto VCCT with 1.5 KΩ5% resistor (100 MHz PSB only).
BSEL1Tie toground (100 MHz PSBonly).
CLKREFConnect to voltage divider circuitry on 2.5 V to create 1.25 V reference.
Decouple using 0.1
EDGECTRLPPull down with 110Ωresistor 1% to ground.
PICCLKConnect to CK815E clock genera to r with33Ωserie sresistor(mayvary
depends onsimulatio n).
PLL1, PLL2Connect to PLL lowpass filter circuit.
RTTIMPEDPPull down with 56.2Ωresistor 1% to ground.
THERMDA,
THERMDC
CMOSREFConnect to voltage divider circuitry on 2.5 V to create 1V reference. Decouple
VID[4:0]Connect 100Ωresistorto GND.
VREF[7:0]Connect to v oltag edivider circuit toVCCT with 2/3 ratio(75Ωand 150Ω,1%
VCC_COREProcessor coresupply.Se enotes 1 and 2
VCCT1.5 V supply.
VSSGround.
A15, A16, A17, C14,
If thermalsensor isused, connecttothermal sensor. Else,leaveas NC.
using two 0.1
resistors). Decouple with four 0.1
to 815 GMCH GTLREF[A,B] with two0.1
Noconnect.
µF capacitors.
R
µF capacitor
µF capacitors near processor. Also connect
µF decoupling capacitors at GMCH.
NOTES:
1. Refer to
2. Refer to
Intel® Pentium®IIIProcessor – Low Power 700Mhz, 500Mhz and 400Mhz Processors in BGA2
Package
Processor in a BGA2 Package
for power supplyde co upling require ment.
Intel® Celeron® Processor – Low Power/Ultra Low Power 300MHz (ULP) and 400AMHz (LP)
for power supplyde co upling require ment.
30Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide
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6Reference Schematic
This section providethe reference schematic for Intel ® Celeron® Processor – Low Power or
Ultra Low Power or Intel ® Pentium® III - Low Power in a BGA2 package and th e Intel
chipset platform.
Reference Schematic
® 815E
Intel®Pentium®III and Intel Celeron®– Low Power/Ultra Low Power / 815E Design Guide31
COVER SHEET
<Doc>0.5
Low Power Intel® Celeron®/Pemtium® III with 815E
Title
Size Document NumberRev
of
134Wednesday, March 27, 2002
Date:Sheet
The Intel® Celeron(tm) processor and Intel® 815E chipset may contain design defects
or errors known as errata which may cause the product to deviate from published
specifications. Current characterized errata are available on request.
Copyright (c) Intel Corporation 2001.
THESE SCHEMATICS ARE PROVIDED "AS IS" WITH NO WARRANTIES
WHATSOEVER, INCLUDING ANY WARRANTY OF MERCHANTABILITY, FITNESS
FOR ANY PARTICULAR PURPOSE, OR ANY WARRANTY OTHERWISE ARISING
OUT OF PROPOSAL, SPECIFICATION OR SAMPLES.
Information in this document is provided in connection with Intel products. No license,
express or impl ied, by estoppel or otherwise, to any intellectual property rights is
granted by this document. Except as provided in Intel's Terms and Conditions of Sale
for such products, Intel assumes no liability whatsoever, and Intel disclaims any
express or implied warranty, relating to sale and/or use of Intel products including
liability or warranties relating to fitness for a particular purpose, merchantability, or
infringement of any patent, copyright or other intellectual property right. Intel products
A
** Please note these schematics are subject to change.
are not intended for use in medical, life saving or life sustaining applications.
Intel may make changes to specifications and product descriptions at any time,
without notice.
* Third-party brands and names are the property of their respective owners.
A
REVISION 0.5
INTEL® PENTIUM® III LOW POWER & INTEL®
UNIPROCESSOR CUSTOMER REFERENCE SCHEMATICS
CELERON (TM) ULTRA-LOW POWER
PROCESSOR (BGA2) / INTEL® 815E CHIPSET
1
TitlePage
Cover Sheet
5CPU Decoupling
3, 4
2
Low Power Intel® Celeron®/Pemtium® III BGA2
Clock Synthesizer6
Block Diagram
7, 8, 91011, 12
82815E
Display Cache
System Memory
13, 141516
17, 18
19202122232425
ICH2
FWH & UDAM 100 IDE1-2
Super I/O
PCI Connectors
USB Connectors
AC97 CODEC
Serial and Parallel Ports
Audio I/O
Kybrd / Mse / F. Disk / Gme Connectors
Digital Video Out
29, 30
26
27, 283132, 33
Video Connectors
LAN on Motherboard
ATX Power & H/W Monitor
Voltage Regulators
System Configuration
34
Pullup Resistors and Unused Gates
Power Plane Decoupling Capacitors
AA
PCI CONN 4
BLOCK DIAGRAM
Title
Low Power Intel® Celeron®/Pemtium® III with 815E
Size Document NumberRev
of
234Wednesday, March 27, 2002
<Doc>0.5
Date:Sheet
PCI CONN 3
PCI CONN 2
A
PCI CONN 1
Serial 2
A
Serial 1
Clock
2 DIMM
Modules
FloppyParallel
PCI BUS
DATA
DATA
SIO
LPC Bus
Mouse
Keyboard
Game Port
CTRL
CTRL
ADDR
GTL BUS
ADDR
815E
GMCH
ICH2
FirmWare
Hub
Block Diagram
Low Power Intel® Celeron®/Pemtium® III BGA2 Processor