DC065A - Demo Manual

DEMO MANUAL DC065A
NO DESIGN SWITCHER
Power Validator Test Fixture
Demo Board
U
DESCRIPTIO
Providing power for the Pentium® microprocessor family
is not a trivial task by any means. There are currently
several different voltage specifications for different
versions of the µP. Future upgrades will further challenge
the power supply. In an effort to promote flexible,
upgradable power supplies for their current and future
microprocessors, Intel has defined a specification for a
modularized power system for the CPU. This demo board
is designed to accept modules built to the Intel specification and also accept an Intel Power Validator module. The
Power Validator generates the fast load transients characteristic of the current generation of Pentium processors.
In addition, there is a 5V to 3.3V at 7A, LT ®1584 based
regulator (DC065A-A) included onboard which meets the
needs of a 75MHz, 3.3V ±5% Pentium processor. An
LT1585 version (DC065A-B) is available which is capable
of only 4.6A* but in all other respects is identical to the
LT1584 design. Either regulator may be disabled if desired, permitting installation of a plug-in module on the
30-pin header provided.
, LTC and LT are registered trademarks of Linear Technology Corporation.
Pentium is a registered trademark of Intel Corporation.
*There is also a 5A version, the LT1585A available. Contact a Linear Technology Corporation sales
representative for details.
D BOARD PHOTOS
Component Side
1
DEMO MANUAL DC065A
NO DESIGN SWITCHER
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W
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PACKAGE A D SCHE ATIC DIAGRA S
3.3V
LT1584CT
LT1585CT
VCORE
12V
JMP1
FRONT VIEW
J1
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
3
IN
2
OUT
1
ADJ
T PACKAGE
3-LEAD TO-220
DISABLE
E11
1
NOTES: UNLESS OTHERWISE SPECIFIED.
1. ALL RESISTOR VALUES OHMS, 5%, CHIP-1206.
2. ALL CERAMIC CAPACITORS 20%, 50V, CHIP-1206.
3. ALL POLARIZED CAPACITORS TANTALUM, 20%, SMT.
4. ALL 330 µF POLARIZED CAPACITORS SANYO 0S-CON.
5. REMOVE JMP2-7 BEFORE USING POWER MODULE SOCKET J1.
6. VERSION DC065A-A HAS LT1584. VERSION DCO65A-B HAS LT1585.
7. C7-C10 OPTIONAL.
VCORE_GOOD
E10
1
HEADER_15X2 POWER MODULE
5V
SEE NOTE 5
AT-CONNECTORS
12V
5V
J9
1
1
2
3
4
5
6
5V
+
E4 –5V
1
J8
3.3V
+
C24
330µF
6.3V
PENTIUM
VALIDATOR
SOCKET
PROTOTYPE
AREA
VSS
1
J3
BNC
R1
51
E1
VCORE
VCORE
E8 –12V
1
+
C22
330µF
6.3V
VCORE
TEST
POINT
E2
GND
E9 GND
INSIDE POWER VALIDATOR SOCKET CAVITY (SEE NOTE 7)
VCORE
+
+
+
+
+
+
+
+
+
+
C1-C10
100µF
10V
C11-C20
1µF
25V
5V
1
1
1
JP2
JP3
JP4
VCORE
LT1584/LT1585 POWER SUPPLY
(SEE NOTE 6)
2
3
2
IN
2
+
C26
220µF
10V
+
C27
220µF
10V
+
C28
220µF
10V
U1
2
LT1584/LT1585 OUT
ADJ
1
R3
189
0.5%
1
1
R2
110
0.5%
1
+
C32
0.33
16V
Figure 1. Power Validator Motherboard
2
C21
330µF
6.3V
VCORE
1
E7 12V
1
+
C23
330µF
6.3V
VCORE
E6 PWR_GOOD
1
5V
J7
5V
+
C25
47µF
16V
VCORE
1
E12
3.3V
J4
GND
E5 5V
12V
1
2
3
4
5
6
J6
3.3V
J5
12V
E3 GND
1
1
C29
220µF
10V
+
C30
220µF
10V
+
JP5
JP6
JP7
2
2
2
C31
220µF
10V
DC065A • TA01
DEMO MANUAL DC065A
NO DESIGN SWITCHER
PARTS LIST
REFERENCE
DESIGNATOR
C1-C6
QUANTITY
6
PART NUMBER
DESCRIPTION
VENDOR
TELEPHONE
TPSD107M010R0100
Cap., Tantalum, 100µF, 10V, 20%
AVX
(803) 946-0690
C7-C10
4
C11-C20
10
12063G105ZAT2A
Optional
Cap., Y5V, 1µF, 25V
AVX
(803) 946-0362
C21-C24
4
6SA330M
Cap., OS-CON, 330µF, 6.3V, 20%
SANYO
(619) 661-6835
C25
1
TPSD476M016R0150
Cap., Tantalum, 47µF, 16V, 20%
AVX
(803) 946-0690
C26-C28
3
TPSE227M010R0100
Cap., Tantalum, 220µF, 10V, 20%
AVX
(803) 946-0690
C29-C31
3
Optional
C32
1
1206YC334KAT2A
Cap., X7R, 0.33, 16V, 10%
AVX
(803) 946-0362
E1-E12
12
1502-2
Terminal, 2-Turret, 0.092"
KEYSTONE
(718) 956-8900
JMP1-JMP7
7
TSW-102-07-G-S
Jumper, 0.100", 2-Pin
SAMTEC
(800) 726-8329
J1
1
1-102567-3
Header, Shrouded, 15 x 2, 30-Pin
AMP
(717) 564-0100
J2
1
916560-2
Socket, PGA, ZIF, 320-Pin
AMP
(717) 564-0100
J3
1
227699-3
Con., PC-MNT, BNC, 50Ω
AMP
(717) 564-0100
J4-J7
4
575-4
Jack, Banana, .175-ID, Low Profile
KEYSTONE
(718) 956-8900
J8, J9
2
15-48-0406
Header, 6-Pin, Std-AT
MOLEX
(408) 946-4700
R1
1
CR32-510J-T
Res., Chip, 51, 1/8W, 5%
AVX
(803) 946-0524
R2
1
CR32-1100F-T
Res., Chip, 110, 1/8W, 1%
AVX
(803) 946-0524
R3
1
CR32-1820F-T
Res., Chip, 182, 1/8W, 1%
AVX
(803) 946-0524
U1*
1
LT1584CT
IC, +VREG, LT1584
LTC
(408) 432-1900
7
SNT-100-BK-T
Shunt, 0.100cc
SAMTEC
(800) 726-8329
Standoff, #4-40 x 1/2", F/F, Plastic
ANY
Screw, #4-40, 3/8", Pan Hd, Phil
ANY
Heat Sink, for LT1584
THERMALLOY
8
8
**
1
7021B-MT
(214) 243-4321
* U1 may be substituted with an LT1585CT for 4.6A design, version DC065A-B.
** Heat sink may be substituted with a 7020B-MT for 4.6A design.
3
DEMO MANUAL DC065A
NO DESIGN SWITCHER
U
OPERATIO
PENTIUM POWER DEMANDS
The supply voltage for these processors is clock frequency
dependent. The standard Pentium processor has a
supply requirement of 3.3V ±5%, while the Pentium VR
processor has a supply spec of 3.3V +5%/–0%. The
Pentium VRE processor requires 3.525V ±75mV. In all
cases, the CPU can cycle from a standby condition which
consumes approximately 200mA to a full load current of
approximately 4.0A in 2 clocks or as little as 20ns. The
supply must remain within the appropriate voltage limitations at all times, even during these large load transients.
Disabling the stop clock modes will not relieve the
designer of the need to handle the fast transients. Events
such as an “L1 cache miss” will generate transients of
similar magnitude during normal operation. As may be
imagined, the decoupling network supplying power to the
CPU is critical in maintaining a clean voltage supply.
DECOUPLING CAPACITOR NETWORK REQUIREMENTS
For the Pentium VR processor spec, the supply must be
designed using a set point of 3.38V with a ±2.5% tolerance. The Pentium VRE processor spec is even tighter.
With only ±2% total deviation from the ideal voltage
allowed, the magnitude of the transients must be carefully
controlled. Some of the error budget must remain for
the static tolerances such as line and load regulation,
temperature variation and initial set point. Realistically,
approximately 45mV peak transient response is obtainable. To achieve this, a large number of low ESR tantalum
capacitors must be installed as close to the processor as
possible. The microprocessor socket cavity is the best
place for these capacitors.
As an absolute minimum, use 6 pieces of a 100µF,
10V AVX type TPS tantalum for a Pentium VR or VRE
processor supply. If more height is available, such as with
a ZIF socket, it is preferred to use 6 each, 220µF, 10V parts
instead. When using the 100µF parts there is very little
margin in the design. Do not reduce the quantity of the
capacitors if larger values are used. The ESR specs are the
same for the 100µF, 220µF and 330µF capacitors. The
reason for paralleling 6 caps is to reduce the ESR as well
as providing bulk capacitance. In standard 3.3V ±5%
applications, a slightly larger transient can be tolerated, so
4
somewhat less capacitance may be used. It is recommended that you use at least 4 each of the 100µF AVX
tantalums. Intel recommends 24 each, 1µF ceramic capacitors in addition to the tantalum bulk decoupling. These
additional ceramics have little effect on the transient
response but do effect the amount of high frequency clock
noise reflected back onto the supply by the CPU.
DEMO BOARD CHARACTERISTICS
This demo board has provisions for a pair of standard “AT”
style power entry connectors for 5V and 12V power input.
Also, along the top of the board are provisions for banana
plug inputs for 3.3V, 5V and 12V power. The 3.3V is
provided in accordance with the Intel module specification
and will only be needed for future upgrade designs. It is not
connected to the 3.3V output of the onboard regulator or
any of the LTC plug-in modules currently available. All
input supplies have onboard decoupling capacitors to
reduce the effects of long distribution cables. There are
also test points for all input and output voltages as well
as access to optional “power good” monitor functions.
A BNC type connector is provided for monitoring the
CPU supply during testing. This line is terminated into
50Ω and it allows measurement of the “core voltage” at
one of the socket pins. This point should be connected to
an oscilloscope input with a 50Ω BNC cable. It is not
necessary to terminate the oscilloscope end at 50Ω as the
edge rates are slow enough not to cause any reflections or
unusual perturbations.
The onboard LT1584 with its associated heat sink is set up
to provide 3.3V at up to 7.0A. The regulator used is an
adjustable device with an external divider. The lower
resistor of the divider is bypassed with a 0.33µF capacitor
to speedup the regulator transient response time. Fixed
3.3V regulators are available from LTC. However, due to
the inability to add a large value speedup capacitor to the
internal feedback divider, there is a substantial increase in
the transient response time (approximately 2X). A corresponding increase in the number of decoupling capacitors
is required. The addition of the 2 divider resistors and the
0.33µF ceramic capacitor required by the adjustable
regulator more than pay for themselves due to the reduction in bulk capacitance that results compared to the
fixed voltage parts.
DEMO MANUAL DC065A
NO DESIGN SWITCHER
U
OPERATIO
The board utilizes 6 each, 100µF tantalums and 10 each,
1µF ceramics on planes located in the processor socket
cavity. Also, an area is provided to the right of the socket
for additional capacitors, if it is desired to further reduce
the transient magnitude. Jumpers JP-2 thru JP-7 permit
disabling the onboard regulator if a plug-in module is to
be used. The resistance of the jumpers causes a slight
degradation of the load regulation as measured at the CPU.
TEST SETUP
Install the power validator in the socket and connect a 5V
“silver box” supply to the input connectors. Be sure to
observe the proper connector orientation. The connectors
are not configured the same as on a normal motherboard.
Test points adjacent to the connectors correspond to the
supply voltages at those pins. The oscilloscope should be
connected to the board with a BNC cable. Be careful of
potential ground loop problems. In general it is best to use
an isolation transformer for the oscilloscope or use isolated probes. This will eliminate several measurement
errors that are likely to exist otherwise. For safety reasons,
be sure to keep the off-line case grounded. Voltmeters
should be connected to the input and output test points.
The power validator should be powered up and set according to the instructions provided by Intel. If the demo
board’s onboard regulator is to be used, be sure jumpers
JMP2 through JMP7 are installed. If you plan to use a
plug-in power supply module, remove these jumpers to
isolate the LT1584. Also, a fan which provides approximately 100 linear feet per minute of air flow should be
aimed at the LT1584 heat sink or the plug-in module.
Jumper JMP1 connects the CPU core and I/O power pins
on the power module header together. Leave this jumper
installed if the CPU you intend to use only requires a single
supply voltage. At this point it should be safe to power up
the off-line supply.
TEST RESULTS
raised from 200mA to 3.2A and the load delta held constant at 3.8A, the waveform remains essentially unchanged.
The transient droop measures approximately 44mV pk.
and is nearly symmetrical. Note the offset voltage between
the high load and low load condition on the output waveform. This is the load regulation of the regulator including
any distribution (I)(R) drops. When using the socketed
modules the additional resistance of the connector pins
makes the use of remote sense desirable to ensure that the
(I)(R) drops are kept under control.
The photo in Figure 3 shows the same transient at 2µs/div.
There is a fast leading edge droop followed by one short
ring. The output then begins to slowly recover toward
its final value. The layout techniques utilized here keep
VOUT =
50mV/DIV
IOUT =
2A/DIV
200µs/DIV
Figure 2. Transient Response
VOUT =
50mV/DIV
IOUT =
2A/DIV
The results should look like Figure 2. The test conditions
were as follows:
VIN = 5.0V, VOUT = 3.30V. Load steps from 200mA to 4.0A.
It should be noted that as the minimum load current is
2µs/DIV
Figure 3. Transient Response
5
DEMO MANUAL DC065A
NO DESIGN SWITCHER
U
OPERATIO
ringing to a minimum. To appreciate the effects of
parasitic inductance, try connecting a 100µF tantalum
capacitor to the area on the right side of the socket and
note the difference in transient amplitude, especially the
leading edge spike. Now remove the capacitor and solder
a couple of inches of 24AWG wire to the capacitor and
reconnect it to the power planes. The difference in performance is quite noticeable.
AVAILABLE PLUG-INS
Several additional boards are available for use with the
Power Validator demo board. Both linear and switching
regulators have been designed and built to comply with
the Intel module specification. We anticipate developing
additional designs as technology improvements warrant.
Contact Linear Technology for further details.
W
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PCB LAYOUT A D FIL
6
Component Side Copper
Solder Side Copper
Component Side Solder Mask
Solder Side Solder Mask
DEMO MANUAL DC065A
NO DESIGN SWITCHER
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PCB LAYOUT A D FIL
Component Side Silkscreen
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PC FAB DRAWI G
7.000
H
K
K
K
NOTES: UNLESS OTHERWISE SPECIFIED.
1. FINISHED MATERIAL IS FR4, 0.062" THICK, 2-OZ COPPER.
2. PCB WILL BE DOUBLE-SIDED WITH PLATED THROUGH HOLES.
3. PTH SIZES AFTER PLATING, 0.001" MIN WALL THICKNESS.
4. USE PADMASTER PROCESS.
5. SOLDER MASK BOTH SIDES USING PC-401 OR EQUIVALENT.
6. SILKSCREEN COMPONENT SIDE USING WHITE NONCONDUCTIVE INK.
7. ALL DIMENSIONS IN INCHES, ±0.005".
8. ALL HOLE SIZES AFTER PLATING, ±0.003" MAX.
H
K
D
A
B (8x)
G
H
H
C (30x)
C
E
C
G
HOLE CHART
A (64x)
5.500
A
G
A (5x)
G G
B (320x)
G
H
C
H
C
HH
H
D
H H
H
NUMBER
OF HOLES
SYMBOL
DIAMETER
A
0.020
71
B
0.030
328
44
C
0.040
D
0.045
8
E
0.075
14
G
0.094
12
H
0.120
12
K
0.210
4
TOTAL HOLES
493
0.200
DC065A • PCB01
0.200
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
7
DEMO MANUAL DC065A
NO DESIGN SWITCHER
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0595
8
Linear Technology Corporation
BA/GP 0895 100 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7487
(408) 432-1900 ● FAX: (408) 434-0507 ● TELEX: 499-3977
 LINEAR TECHNOLOGY CORPORATION 1995
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