®
Mobile
AMD-K6
Processor
®
Power Supply
Design
Application Note
Publication # 22495
Rev: C
Issue Date: May 1999
Amendment/0
© 1999 Advanced Micro Devices, Inc. All rights reserved.
The contents of this document are provided in connection with Advanced Micro
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Other product names used in this publication are for identification purposes only and may be trademarks of their
respective companies.
22495C/0—May 1999
Mobile AMD-K6® Processor Power Supply Design
Contents
Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Mobile AMD-K6® Processor Family Power Requirements. . . . . . . . . 3
Voltage Planes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Power Supply Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Selecting a Power Supply Design . . . . . . . . . . . . . . . . . . .
Switching Regulator . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
6
6
7
Decoupling and Layout Recommendations . . . . . . . . . . . . . . . . . . . . 11
Power Distribution . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Current Transient Response . . . . . . . . . . . . . . . . . . . . . .
Output Voltage Response Measurement Techniques . . . . . .
Output Voltage Response Measurement Utility. . . . . .
Decoupling Capacitance and Component Placement. . . . . . .
Bulk Decoupling for the I/O Supply. . . . . . . . . . . . . . . .
High-Frequency Decoupling . . . . . . . . . . . . . . . . . . . . . .
Power Sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
12
18
19
20
24
25
29
Power Supply Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Digital-to-Analog Converter (DAC) . . . . . . . . . . . . . . . .
Elantech EL7571 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Linear Technology LT1435 . . . . . . . . . . . . . . . . . . . . . . .
Maxim MAX798 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
31
33
35
38
Voltage Regulator Vendor Information . . . . . . . . . . . . . . . . . . . . . . . 40
Contents
iii
Mobile AMD-K6® Processor Power Supply Design
iv
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Contents
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
List of Figures
Figure 1. 321-Pin CPGA VCC and Ground Pins Location . . . . . . . . . 4
Figure 2. 360-Pin CBGA VCC and Ground Pins Location . . . . . . . . . 5
Figure 3. Linear and Switching Voltage Regulators. . . . . . . . . . . . . 7
Figure 4. Basic Asynchronous Design. . . . . . . . . . . . . . . . . . . . . . . . . 8
Figure 5. Basic Synchronous Design . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Figure 6. Power Distribution Model . . . . . . . . . . . . . . . . . . . . . . . . . 11
Figure 7. Load Current Step versus Output Voltage Response. . . 14
Figure 8. Bulk Decoupling versus Output Voltage Response
for a 1.8V Processor Core @ 6.25 amps . . . . . . . . . . . . . . 16
Figure 9. Bulk Decoupling versus Output Voltage Response
for a 2.0V Processor Core @ 6.0 amps . . . . . . . . . . . . . . . 17
Figure 10. Bulk Decoupling versus Output Voltage Response
for a 2.2V Processor Core @ 8.5 amps . . . . . . . . . . . . . . . 18
Figure 11. Via Layout For Low Inductance . . . . . . . . . . . . . . . . . . . . 21
Figure 12. CPGA Suggested Component Placement. . . . . . . . . . . . . 22
Figure 13. CBGA Suggested Component Placement. . . . . . . . . . . . . 23
Figure 14. 0.1µF (c1) and 0.01 µF (c2) X7R Capacitor
Impedance vs. Frequency . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 15. Decoupling Inductance . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Figure 16. Power Sequencing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Figure 17. Elantech EL7571 Switching Power Supply Design. . . . . 33
Figure 18. Linear LT1435 2.0V Switching Power Supply Design . . 36
Figure 19. Maxim MAX798 Switching Power Supply Design . . . . . 38
List of Figures
v
Mobile AMD-K6® Processor Power Supply Design
vi
22495C/0—May 1999
List of Figures
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
List of Tables
Table 1.
Voltage Error Budget . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Table 2.
Representative ESR Values. . . . . . . . . . . . . . . . . . . . . . . . 20
Table 3.
Inductance Contributions of Components . . . . . . . . . . . . 21
Table 4.
Decoupling Capacitor Values . . . . . . . . . . . . . . . . . . . . . . 24
Table 5.
Capacitor Recommendations . . . . . . . . . . . . . . . . . . . . . . 24
Table 6.
Voltage Output VID Codes . . . . . . . . . . . . . . . . . . . . . . . . 31
Table 7.
Mobile Voltage Output VID Codes . . . . . . . . . . . . . . . . . . 32
Table 8.
Elantec EL 7571 Bill of Materials. . . . . . . . . . . . . . . . . . . 34
Table 9.
Linear LT1435 Bill Of Materials . . . . . . . . . . . . . . . . . . . . 37
Table 10. Maxim MAX798 Bill of Materials . . . . . . . . . . . . . . . . . . . 39
List of Tables
vii
Mobile AMD-K6® Processor Power Supply Design
viii
22495C/0—May 1999
List of Tables
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Revision History
Date
Rev
Description
Jan 1999
A
Initial published release.
Apr 1999
B
Revised “Output Voltage Response Measurement Utility” on page 19 to reflect the latest
recommended utility.
May 1999
C
Changed title and added first sentence on page 1 to reflect that the information in this document
applies to the mobile AMD-K6® processor family.
May 1999
C
Revised the Introduction section.
May 1999
C
Added Example 3 on page 14, Figure 9 on page 17, and Figure 10 on page 18.
May 1999
C
Added “Bulk Decoupling for the I/O Supply” on page 24.
May 1999
C
Added new vendor to “Voltage Regulator Vendor Information” on page 40.
Revision History
ix
Mobile AMD-K6® Processor Power Supply Design
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Revision History
22495C/0—May 1999
Mobile AMD-K6® Processor Power Supply Design
Application Note
Mobile AMD-K6
®
Processor Power Supply
Design
Unless otherwise noted, the information in this application
note pertains to all mobile processors in the AMD-K6® family,
which includes the Mobile AMD-K6 processor, the Mobile
AMD-K6-2 processor, and the Mobile AMD-K6-III-P processor.
Introduction
This application note is intended to guide the board designer
through the process of developing a reliable power supply for
the mobile AMD-K6 processor family. AMD encourages
designers to support adjustable voltage by using regulators
with VID inputs. This programmable voltage feature facilitates
t h e t ra n s i t i o n t o t h e n e x t g e n e ra t i o n o f p ro c e s s o rs .
Additionally, as mobile processors are pushed for higher
performance and faster clock speeds, the current requirements
will continue to rise. Higher currents will require more
decoupling capacitors, and can be planned for by including
pads on the board today even if they are not populated. Designs
that support higher currents will extend the life of a mobile
system.
This application note also provides basic guidelines on circuit
decoupling for reduction of noise generated by fast current
transients.
Introduction
1
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
For power supply design information for desktop AMD-K6
processors, see the AMD-K6 ® Processor Power Supply Design
Application Note, order# 21103.
This document contains the following sections:
■
■
■
■
2
Mobile AMD-K6® Processor Family Power Requirements—
Lists the power requirements for the mobile AMD-K6
processor family with an overview of power supply design
considerations. This section describes the basic elements of
a power supply and the constraints of different design
approaches.
Decoupling and Layout Recommendations—Describes the
decoupling and layout recommendations of the power
supply design. Proper decoupling is required in order to
deliver a reliable power source across the power planes and
to reduce the noise generated from the fast current
transients.
Power Supply Solutions—Describes several voltage
regulator circuits that are developed by voltage regulator
vendors. These circuits can be used to generate the proper
core and I/O voltages for the mobile AMD-K6 processors.
AMD recommends that board designers consult with the
voltage regulator vendors to obtain the most updated
information.
For more information about the mobile AMD-K6 processor
family, refer to the following:
• Mobile AMD-K6® Processor Data Sheet, order# 21049
• Mobile AMD-K6®-2 Processor Data Sheet, order# 21896
• Mobile AMD-K6®-III-P Processor Data Sheet, order# 22655
Introduction
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Mobile AMD-K6® Processor Family Power Requirements
Voltage Planes
Two separate supply voltages are required to support the
mobile AMD-K6 processors—VCC2 and VCC3. VCC2 provides the
core voltage for the processor and V CC3 provides the I/O
voltage.
The power supply pin assignments for the mobile AMD-K6
processors 321-pin CPGA package (See Figure 1 on page 4) are
as follows:
VCC2
(Core):
A-07, A-09, A-11, A-13, A-15, A-17, B-02, E-15, G-01,
J-01, L-01, N-01, Q-01, S-01, U-01, W-01, Y-01, AA-01,
AC-01, AE-01, AG-01, AJ-11, AN-09, AN-11, AN-13,
AN-15, AN-17, AN-19
VCC3
(I/O):
A-19, A-21, A-23, A-25, A-27, A-29, E-21, E-27, E-37,
G-37, J-37, L-33, L-37, N-37, Q-37, S-37, T-34, U-33,
U-37, W-37, Y-37, AA-37, AC-37, AE-37, AG-37,
AJ-19, AJ-29, AN-21, AN-23, AN-25, AN-27, AN-29
The power supply pin assignments for the Mobile AMD-K6 and
the Mobile AMD-K6-2 processor 360-pin CBGA package (See
Figure 2 on page 5) are as follows:
VCC2
(Core):
F04, F05, F06, F07, G06, G07, H08, H09, H12, H13,
J04, J05, J08, J09, J10, J11, J12, J13, K04, K05, K06,
K07, K10, K11, L04, L05, L08, L09, L10, L11, L12,
L13, M08, M09, M12, M13, N06, N07, P04, P05, P06,
P07
VCC3
(I/O):
D07, D08, D09, D12, D13, E07, E08, E09, E12, E13,
F10, F11, F14, G10, G11, G14, G15, G16, H14, H15,
H16, K17, M14, M15, M16, N10, N11, N14, N15, N16,
P10, P11, P14, R07, R08, R09, R12, R13, T07, T08,
T09, T12, T13
Note: The Mobile AMD-K6-III-P processor is not available in the
CBGA package.
Mobile AMD-K6® Processor Family Power Requirements
3
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Figure 1. 321-Pin CPGA VCC and Ground Pins Location
4
Mobile AMD-K6® Processor Family Power
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
1
2 3 4
5 6
Other
VCC3 Pins
VSS Pins
VCC2 Pins
7
8 9 10 11 12 13 14 15 16 17 18 19
W
V
U
T
R
P
N
M
W
V
U
T
R
P
N
M
L
K
J
H
G
F
E
D
C
B
A
L
K
J
H
G
F
E
D
C
B
A
1 2 3 4
5 6
7
8 9 10 11 12 13 14 15 16 17 18 19
Bottom View
Figure 2. 360-Pin CBGA VCC and Ground Pins Location
Mobile AMD-K6® Processor Family Power Requirements
5
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Power Supply Specification
The maximum current used for power calculations is based on
maximum VCC whereas the current used for maximum thermal
power calculations is based on nominal V CC . Refer to the
Thermal Solution Design Application Note, order# 21085 for
more details on thermal calculations
For voltage and current specifications of the mobile AMD-K6
processor family, refer to their respective data sheets at
http://www.amd.com/K6/k6docs/.
Selecting a Power
Supply Design
Most PC platforms today require DC-to-DC voltage conversion
circuits to supply lower voltages to the processor core and I/O.
Two types of regulators are used—linear and switching. Figure
3 shows the linear and switching regulators.
A linear regulator provides excellent dynamic-load response in
the low-voltage, high-current environment. It also contributes
to simplified design and lower cost. However, the efficiency loss
and heat generated by a linear regulator should be addressed
by board designs. Although most desktop system designs can
tolerate the efficiency loss, mobile designs cannot. In a
high-current model, the power dissipation from the linear
regulator can be as much as that of the processor itself. In order
for the voltage regulator thermal solution to meet the case
temperature requirement, the linear regulator requires a larger
heatsink. Linear regulators are not recommended for mobile
designs because of the heat and low efficiency.
A switching regulator meets the efficiency and size limitations
of mobile board designs. Switching regulators are found in most
notebook computers that require both low-profile design and
power-dissipation reduction. The switching regulator uses a
series switch in conjunction with the output capacitor (CO) to
control the ON/OFF ratio in order to obtain an average output
voltage. Because the switch turns off frequently, only a small
amount of power is lost during conversion.
6
Mobile AMD-K6® Processor Family Power
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
+
+
VIN
Control
–
Feedback
RL
VOUT
–
Linear Regulator
Efficiency =
VOUT
VIN
LO
+
+
VIN
CO
RL
VOUT
–
–
Switching Regulator
Figure 3. Linear and Switching Voltage Regulators
Switching Regulator
A switching regulator varies the switch duty cycle (ON/OFF
ratio) according to the output feedback. A large output
capacitor (C O ) is used in the switching design to achieve a
constant average output. The switching regulator delivers
higher efficiency than a linear regulator, but the tradeoffs are
higher ripple voltages (noise) and slower transient current
response time. A series inductor is used to supply current to the
load during the switch OFF time, adding complexity to the
design. In addition, the inductor and the output capacitor
increase the overall cost of the switching regulator design
relative to a linear regulator design.
The power supply design must account for a minimized current
(I CC2 and I CC3 ) drain when the mobile AMD-K6 processors
enter the Stop Grant state. The power supply must ensure the
minimal current drain does not cause any adverse side effects
(drift out of regulation, over-compensation, or shutdown) that
could corrupt or damage the functionality of the processor.
The mobile AMD-K6 processors voltage tolerance requirement
on both core and I/O voltage pins can be handled by commonly
available linear and switching regulators. This application note
describes several high-accuracy designs (starting on page 31)
Mobile AMD-K6® Processor Family Power Requirements
7
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
that provide the processor with accurate and stable voltage
supplies.
In the basic asynchronous circuit design shown in Figure 4, Q1
turns on to charge Cout and builds up the magnetic field in L1.
When the feedback from the sense input is too high, the
controller turns Q1 off. Current is supplied to the load by the
collapsing magnetic field in L1 and the discharge of Cout. When
the sense feedback detects a drop in the load voltage, the
controller turns on Q1 to recharge the circuit. CR2 supplies a
return path for L1 when it is supplying current.
L1
Q1
Sense
Controller
CR2
Cout
RL
Figure 4. Basic Asynchronous Design
The operation of the basic synchronous circuit design shown in
Figure 5 is essentially the same as the asynchronous design. Q1
turns on to charge Cout and builds up the magnetic field in L1.
When the feedback from the sense input is too high, the
controller turns Q1 off. Current is supplied to the load by the
collapsing magnetic field in L1 and the discharge of Cout. When
the sense feedback detects a drop in the load voltage, the
controller turns on Q1 to recharge the circuit. Q2 supplies a
return path for L1 when it is supplying current. When Q1 is on,
Q2 is off and when Q1 is off, Q2 is on. The main reason the
synchronous design is more efficient than the asynchronous
design is because the power dissipated in Q2 is lower than the
power dissipated in CR2.
8
Mobile AMD-K6® Processor Family Power
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Q1
Vout
L1
Sense
Controller
Q2
Cout
RL
Figure 5. Basic Synchronous Design
Another consideration is power dissipation in the lower
MOSFET Q2 (synchronous) or diode CR2 (asynchronous). As
the output voltage decreases, the power dissipation in CR2 (Q2)
increases. The higher power dissipation may require using a
different package type or adding a heat sink to dissipate the
additional power.
To determine if the transistors or the diode need a heat sink,
use the following equation:
P = I2R
•
duty cycle (Q1)
P = I2R
•
(1– duty cycle) (Q2)
Duty cycle ~ Vout/Vin
Compare these calculations with the specifications of the
device used.
Other specifications to consider are the input-voltage range and
the number of outputs provided. The input-voltage range must
be matched to the batteries and charger. Ensure that the
charger voltage does not exceed the input-voltage range of the
regulator when the battery is removed. Generally, the battery
stack consists of 5 to 12 NiCd cells or 2 to 3 Li-Ion cells.
Some parts supply multiple outputs. These devices can save
critical space in a mobile design. However, these devices limit
some of the voltage and current options, and should be
evaluated based on the total requirements of the end product.
Mobile AMD-K6® Processor Family Power Requirements
9
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Mobile systems typically require 12 V, 5 V, 3.3 V, and the
specified CPU core voltage for the AMD-K6 processor Models 7,
8 and 9. Each of these voltages can be generated directly from
the battery (a technique called distributed power). The more
common approach involves producing a 5 V main supply and
generating the other voltages from this 5 V source. This
technique is less efficient, yielding a shorter battery life. For
example, assume a 90% efficiency to generate 5 V from the
battery and 90% efficiency to generate 3.3 V from 5 V. This
yields an overall efficiency of 81% between the battery and the
3.3V supply. Efficiency is very important because it contributes
directly to battery life. To achieve high efficiency at low
currents, many converters have a pulse-skipping mode. Some
companies call this hysteretic mode or burst mode. All of the
examples starting on page 33 use synchronous converter
designs because they are the most efficient (90%–95%). The
additional Schottky diode in some designs provides an
additional efficiency improvement at low currents.
Space and weight are also important considerations for mobile
designs. Some solutions listed use fewer components than
others. Some use more expensive components. The size of the
inductor can be reduced by running the controller at a higher
frequency.
When choosing a vendor, pick one that meets all the needs of
the end product. The product lines of some vendors include
battery charger circuits and backlight inverters for the display.
In addition, locate the supply as close as possible to the CPU.
This placement reduces the distance current transients must
travel in the VCC and GND planes, thereby reducing EMI.
10
Mobile AMD-K6® Processor Family Power
Mobile AMD-K6® Processor Power Supply Design
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Decoupling and Layout Recommendations
Power Distribution
In order to maintain a stable voltage supply during fast
transients, power planes with high frequency and bulk
decoupling capacitors are required. Figure 6 shows a power
distribution model for the power supply and the processor. The
bulk capacitors (C B ) are used to minimize ringing, and the
processor decoupling capacitors (CF) are spread evenly across
the circuit to maintain stable power distribution.
Power
PCB Trace
+
VOUT
CB
Plane
+
CF
Processor
RL
–
Equivalent Circuit
Power
Plane
PCB Trace
RTRACE
Processor
LTRACE
ESR
+
VOUT
CB
ESL
CF
CL
RL
–
Figure 6. Power Distribution Model
Decoupling and Layout Recommendations
11
Mobile AMD-K6® Processor Power Supply Design
Current Transient
Response
22495C/0—May 1999
In the power distribution model shown in Figure 6, C B
represents bulk capacitors for the power supply and C F
represents high-frequency capacitors for processor decoupling.
The bulk capacitors supply current to the processor during
sudden excessive current demands that cannot be supplied by
the voltage regulator (for example, transistioning from the Stop
Grant state to normal mode). The required CB can be calculated
by the following equation (ideal case):
C ≥
∆I
∆V
•
∆t
Where:
■
■
■
Example 1
∆I is the maximum processor current transient
∆V is the tolerance times the nominal processor voltage
∆t is the voltage regulator response time
Assuming the maximum processor current transient is 6A, the
voltage tolerance of the processor is 100 mV, and the voltage
regulator response time is 10µs, the minimum capacitance for
the bulk decoupling is:
CB ≥ (6A/0.100V)
•
10µs = 600µF
ESR (equivalent series resistance) and ESL (equivalent series
inductance) are introduced in the model shown in Figure 6. CB
contains ESR and ESL, which cause voltage drop during current
transient activity (See Figure 7). The resistive and inductive
effect of the capacitors must be taken into account when
designing processor decoupling. Low ESL and ESR capacitors
should be used to obtain better voltage and current output
characteristics. The voltage error budget for ESL is shown in
Table 1 on page 15. Taking into account the ESR, the following
equation is used to calculate CB:
C ≥
12
∆I
(∆V – (∆I
•
ESR))
•
∆t
Decoupling and Layout Recommendations
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Example 2
Example 1 assumes the maximum processor current transient is
6A, the voltage tolerance of the processor is less than 100mV,
and the voltage regulator response time is 10µs.
Assuming five tantalum capacitors with 55-mΩ ESR (the
parallel resistance is 11 mΩ) are used as bulk capacitors, the
minimum bulk capacitance is:
CO ≥ ((6A/(0.100V – [6A
•
11mΩ]))
•
10µs = 1764µF
In Example 2, the effect of the ESR requires the addition of
more capacitance than the ideal shown in Example 1.
In order to achieve more margin, the total error budget should
be distributed between set point tolerance, ESL, and ESR as
shown in Figure 7 on page 14 and Table 1 on page 15. Although
the drop from ESL is a small factor, it is not negligible. If
aluminum electrolytic capacitors are used instead of tantalum
capacitors, the ESL drop is larger.
Decoupling and Layout Recommendations
13
Mobile AMD-K6® Processor Power Supply Design
Example 3
22495C/0—May 1999
This example assumes the maximum processor current
transient is 8.5A, the voltage tolerance of the processor is less
than 100mV, and the voltage regulator response time is 10µs.
Assuming seven tantalum capacitors with 55-mΩ ESR (the
parallel resistance is 8 mΩ) are used as bulk capacitors, the
minimum bulk capacitance is:
CO ≥ ((8.5A/(0.100V – [8.5A
•
8mΩ]))
•
10µs = 2656µF
In order to achieve more margin, the total error budget should
be distributed between set point tolerance, ESL, and ESR as
shown in Figure 7 and Table 1 on page 15. Although the drop
from ESL is a small factor, it is not negligible. If aluminum
electrolytic capacitors are used instead of tantalum capacitors,
the ESL drop is larger.
Note: For additional higher current calculations, see the
AMD-K6® Power Supply Design Application Note, order#
21103.
The high-frequency decoupling capacitors (C F ), which are
typically smaller in capacitance and ESL, maintain the voltage
output during average load change until C B can react. See
“ H i g h -Fre q u e n cy D e c o u p l i n g ” o n p a g e 2 5 f o r m o re
information.
Load
Current
(Max)
ICC
(Min)
(Max)
Output
Voltage
VCC
Response
ESR x ∆I
ESL x
∆I
∆t
∆I = ∆V
C ∆t
Voltage Regulator Response
(Min)
Figure 7. Load Current Step versus Output Voltage Response
14
Decoupling and Layout Recommendations
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Allocation of the voltage error budget can be determined from
Figure 7. Given a total error budget of 100mV and using good
capacitors (five 470-µ F capacitors with a 55-mΩ ESR are
assumed), voltage drops can be allocated as shown in Table 1.
Table 1.
Voltage Error Budget
Error Budget
Component
V (Set Point)
V (ESR)
V (ESL)
Calculations*
1%
11mΩ x 5.6A
(11mΩ = 55mΩ/5)
0.24nH x (6A/100nsec)
{0.24nH = (0.6nH + 0.6nH via)/5}
Total
Budgeted
Drop
0.020V
0.062V
0.014V
0.096V
Note:
*
Calculations assume 5 capacitors
Decoupling and Layout Recommendations
15
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Figure 8 shows the voltage drop as a function of bulk
decoupling. The graph was calculated using 55-mΩ ESR 470-µF
capacitors, and gives the designer a visual representation of
how much bulk decoupling is required. For example, at 1880 µF,
the voltage is 1.72V (6A current transient), leaving little margin
for DC-tolerance errors. At 2820 µF, the voltage is 1.75 V,
allowing 0.05V for set point tolerance.
Output Volta ge vs. Ca pa cita nce
1.8
1.75
1.7
Voltage
1.65
1.6
1.55
V olts
1.5
1.45
1.4
1.35
1.3
470
940
1410
1880
2350
2820
3290
3760
C ap acitan ce in u F
Figure 8. Bulk Decoupling versus Output Voltage Response for a 1.8V
Processor Core @ 6.25 amps
16
Decoupling and Layout Recommendations
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Similarly, Figure 9 shows the voltage drop as a function of bulk
decoupling. The graph was calculated using 55-mΩ ESR 470-µF
capacitors, and gives the designer a visual representation of
how much bulk decoupling is required. For example, at 1880 µF,
the voltage is 1.92V (6A current transient), leaving little margin
for DC-tolerance errors. At 2820 µF, the voltage is 1.95 V,
allowing 0.05V for set point tolerance.
Output Voltage vs. Capacitance
2
1.95
1.9
1.85
Voltage
1.8
1.75
Volts
1.7
1.65
1.6
1.55
1.5
470
940
1410
1880
2350
2820
3290
3760
Capacitance in uF
Figure 9. Bulk Decoupling versus Output Voltage Response for a 2.0V
Processor Core @ 6.0 amps
Decoupling and Layout Recommendations
17
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Similarly, Figure 10 shows the voltage drop as a function of bulk
decoupling. The graph was calculated using 55-mΩ ESR 470-µF
capacitors, and gives the designer a visual representation of
how much bulk decoupling is required. For example, at 2350 µF,
the voltage is 2.11V (8.5 A current transient), leaving little
margin for DC-tolerance errors. At 3760 µF, the voltage is 2.14V,
allowing 0.04V for set point tolerance.
Output Voltage vs. Capacitance
2.2
2.15
2.1
2.05
Voltage
2
1.95
Volts
1.9
1.85
1.8
1.75
1.7
0
470
940 1410 1880 2350 2820 3290 3760 4230 4700
Capacitance in uF
Figure 10. Bulk Decoupling versus Output Voltage Response for a 2.2V
Processor Core @ 8.5 amps
Output Voltage Response Measurement Techniques
To measure output voltage response, run a program such as DOS
EDIT and toggle STPCLK# every 40 µs or slower. (AMD has
developed the Maxpwr99.exe utility. See “Output Voltage
Response Measurement Utility” for more information.)
Measure the voltage at the back of the board right under the
processor. Use a scope probe with a ground connection next to
the tip. The 3 inch to 6 inch ground leads that come off the side
of a scope probe have too much inductance for this type of
measurement. The scope bandwidth can be limited to 20MHz,
18
Decoupling and Layout Recommendations
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
giving a clear indication of the power supplied. While limiting
the scope bandwidth for bulk decoupling verification gives a
clear indication of the low frequency issues, AMD recommends
rechecking with at least a 250-MHz bandwidth for verifying the
high-frequency decoupling.
AMD used a Tektronix 684B scope with 6245 probes and an
HP54720 with 54701 probes. (There was no significant
difference between these two instruments.) The data was taken
over a 40-second window with the scope set to infinite
persistence. AMD made measurements running Winstone ®
under the Windows® 95 operating system, running DOS EDIT
pull dow n, and running Maxpwr99. exe w hile t oggling
STPCLK#. The latter case created the worst measured-case
current transient. In addition, this is the case that requires the
maximum decoupling capacitance.
The table “Voltage Regulator Vendor Information” on page 40
lists some possible power supply solutions. The listed regulators
a re o n e s t h a t A M D b e l i eve s c a n m e e t t h e p ro c e s s o r
requirements (with proper decoupling). AMD has not tested
any of the mobile power supplies.
Output Voltage
Response
Measurement Utility
AMD has developed the Maxpwr99.exe utility to assist in
designing systems that comply with the AMD-K6 processors
power and thermal requirements. This utility can verify that
the supply voltage remains stable during a transition to a
higher power/current consumption level.
This utility is DOS based. For systems based on the Windows 95
or Windows 98 operating systems, re-boot in DOS mode or boot
from a bootable DOS floppy disk that contains the utility. For
systems based on the Windows NT® and OS/2 operating systems,
boot from a bootable DOS floppy disk that contains the utility.
The command line for this utility is as follows: (Note: Do not
execute the utility in a DOS window or with a memory manager
loaded.)
c:\>Maxpwr99.exe
The Maxpwr99.exe utility is available under a non-disclosure
a g re e m e n t . C o n t a c t yo u r l o c a l A M D s a l e s o f f i c e fo r
information.
Decoupling and Layout Recommendations
19
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Decoupling Capacitance and Component Placement
The high-frequency decoupling capacitors (C5–C31 in Figure 12
on page 22) should be located as close to the processor power
and ground pins as possible. To minimize resistance and
inductance in the lead length, the use of surface mounted
capacitors is recommended. When possible, use traces to
connect capacitors directly to the processor’s power and ground
pins. The decoupling capacitors can be placed in the Socket 7
cavity on the same side of the processor (component side) or the
opposite side (bottom side).
Suggested component placement for the decoupling capacitors
are shown in Figure 12 on page 22 for CPGA packages and in
Figure 13 on page 23 for CBGA packages. The values of the
capacitors are specified in Table 4 on page 24. Capacitor
recommendations are shown in Table 5 on page 24. The split
voltage planes should be isolated if they are in the same layer of
the circuit board. To separate the two power planes, an isolation
region with a minimum width of 0.254 mm is recommended. The
ground plane should never be split.
These recommendations are based on single-sided component
assembly and space constraints. The designer should assume
these are minimum requirements. If double-sided component
assembly is used, it is preferable to use more capacitors of a
smaller value, which reduces the total ESR and total ESL of the
capacitors. For example, instead of four 470-µF capacitors, use
ten 47-µF capacitors. (Check the device specifications shown in
Table 2 on page 20. Occasionally a lower value capacitance has
a higher ESR.) As the effective ESR is lowered, the total
required capacitance is reduced. The breakdown voltage and
case size both affect the ESR value.
Table 2.
20
Representative ESR Values
Capacitance
Device 1
Device 2
470 µF
55 mΩ
100 mΩ
270 µF
70 mΩ
100 mΩ
100 µF
90 mΩ
100 mΩ
68 µF
95 mΩ
100 mΩ
47 µF
120 mΩ
250 mΩ
Decoupling and Layout Recommendations
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Via inductance can be reduced when using double-sided
component assembly. Components can share vias on the top
side and bottom side. This technique reduces the effective via
inductance.
Figure 11 shows another way to reduce via inductance —
parallel vias. This technique is usually used on bulk decoupling
capacitors. The inductance contribution numbers shown in
Table 3 indicate that a poor layout can negate a good
component.
Pad
Capacitor
Dual Vias
No Trace between Via and Pad
Figure 11. Via Layout For Low Inductance
Table 3.
Inductance Contributions of Components
Component
Induction
Comment
Capacitor
0.6nH (approximately) ESL
Via
0.7nH (approximately) –
100 mil Trace
1.6nH (approximately) 10 mil wide trace
Decoupling and Layout Recommendations
21
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
C17
C20
C19
C21
C1
C2
C8
CC4
+
+
CC5
CC6
C9
C10
VCC3 (I/O) Plane
C26
+
+
+
C22
C23
C24
C25
CC8
CC3
C29
C27
C30
C28
C31
CC7
C7
C15
C6
C16
C18
C5
CC9
C14
CC10
0.254mm (min.) for
isolation region
VCC2 (Core) Plane
Figure 12. CPGA Suggested Component Placement
22
Decoupling and Layout Recommendations
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Other
VCC3 Pins
VSS Pins
VCC2 Pins
C1
CC9
CC8
CC7
CC6
CC5
CC4
CC3
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
W
V
U
T
R
P
N
M
L
K
J
H
G
F
E
D
C
B
A
W
V
U
T
R
P
N
M
L
K
J
H
G
F
E
D
C
B
A
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
CC10
0.254mm (min.) for
isolation region
C2
Bottom View
Note: High-frequency capacitor placement is very layout dependent and is not shown in this figure.
Figure 13. CBGA Suggested Component Placement
Decoupling and Layout Recommendations
23
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Table 4 lists the recommended capacitor values.
Table 4.
Decoupling Capacitor Values
Item
Qty
Location
Value
1
2
C1, C2
47µF
2
8
CC3–
CC10
470µF
3
24
C5–C31
0.1µF
Footprint
Description
AVX
Surface tantalum capacitor, AVX part number
Size V
AVX
Size V
Note
TPSV476*025R0300 or equivalent
Surface tantalum capacitor, AVX part number
TPSV477*006R0100 or equivalent
0805
VCC3 Decoupling
VCC2 Decoupling
C5–C10 for VCC3
–
C14–C31 for VCC2
Table 5 lists recommended capacitor types.
Table 5.
Capacitor Recommendations
Manufacturer
Type
Comment
Web
AVX
TPS
exceptional
/www.avxcorp.com
Vishay Sprague
594D
exceptional
/vishay.com/vishay/sprague
Sanyo
SA/SG
excellent
/www.sanyovideo.com
Chem-con
LVX
good
/www.chemi-con.com
Mallory
T495
good
/www.nacc-mallory.com
Nemco
SLR series
good
/www.nemcocaps.com
Panasonic
EEF
good
/www.panasonic.com/pic
Panasonic
FA
good
/www.panasonic.com/pic
Vishay Sprague
593D
good
/vishay.com/vishay/sprague
Elna
RJH/RJJ
good
/www.elna-america.com
The recommendations in Table 5 are not the only possibilities.
Based on parts availability and the controller chosen, many
solutions exist. The intent of these recommendations is to give
insight into the requirements, and not to specify a particular
solution. Many vendors prefer to use aluminum electrolytics
instead of tantalum capacitors. This approach is acceptable as
long as good quality, low-ESR parts are used.
Bulk Decoupling for
the I/O Supply
24
The data sheet specifies the VCC3 current at about 0.6 amps.
This number only specifies the maximum current consumed by
the processor without any load. To calculate the peak demand
on the I/O supply, consider what happens when all 64 data bus
Decoupling and Layout Recommendations
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
lines switch from low to high. A typical PC board trace
impedance appears as 50 Ω during the switching time.
Therefore, the theoretically computed current demand is
I = 3.3 V/50 Ω = 66 mA. If this is multiplied by 64 drivers, the
result is 4.22 A. However, the driver acts as a constant current
source/sink of about 20 mA for the first 200 psec then it
b e h ave s a s a 4 0 m A c u r re n t s o u rc e / s i n k u n t i l i t i s
approximately 1 volt from VCC3 when driving high, or 1 volt
from ground when driving low. From this point the current
linearly decreases to zero. Thus instead of a maximum of
4.22 A, the current is limited to 64 • 40 mA = 2.56 A current
demand to charge the bus. Using the same techniques as the
previous core, the bulk decoupling for the I/O can be computed
as follows:
This example assumes a maximum processor I/O current
transient of 2.6A, the voltage tolerance of the processor is less
than 145 mV, and the voltage regulator response time is 1µs. A
linear regulator is assumed in this example to have a 1µs
response time.
Using three tantalum capacitors with 100-mΩ ESR (the parallel
resistance is 33 mΩ) as bulk capacitors, the minimum bulk
capacitance is calculated as:
CO ≥ ((2.6A/(0.145V – [2.6A
•
33mΩ])) • 1µs = 44µF
Three 22 µF tantalum capacitors with 100-mΩ ESR meet this
requirement. However, if the regulator response time is 10 µs
then 440 µF would be required. It is difficult to find a 22 µF
tantalum capacitors with an ESR this low. Therefore, it is
necessary to use a much larger value of capacitance to get this
low of an ESR. Two 470 µF, 55 mΩ ESR parts would meet the
requirement. Three 100 µF capacitors with an ESR of 100 mΩ
would also work.
High-Frequency
Decoupling
Inductance is also a concern for the high-frequency decoupling
capacitors. Case size can be a significant factor affecting
c a p a c i t o r i n d u c t a n c e . Fo r e x a m p l e , a 0 6 0 3 c a s e h a s
significant ly more inductance than a 0612 case. AMD
recommends the 0612, 1206, 0805, and 0603 case in order of
best to worst. Inductance can also be reduced by directly
connecting the capacitor to the power pin of the processor. In
order to minimize its inductance, this trace must be short and as
wide as possible. This technique effectively removes two via
Decoupling and Layout Recommendations
25
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
inductances between the capacitor and the processor as shown
in Figure 15 on page 28. The dotted line shows that connecting
the capacitor directly to the processor eliminates two series
inductances. However, this trace also has inductance—if it is
too long or too narrow it can be worse than the vias.
Figure 14 on page 28 shows the effect of the inductance at
higher frequencies. (The numbers outside the X and Y axis
indicate the minimum and maximum values plotted). The
inductance used is 1.8 nH (0.7nH for each of the two vias and
0.4 nH for the capacitor itself). The capacitor is a 0.1-µF X7R
multilayer Ceramic MLC. The inductance of a capacitor is a
function of the case type. An 0612 case is assumed here.
The following steps show how the number of required
capacitors is calculated:
1. Decide what to allow as a ripple voltage budget. In this
example calculation the ripple-voltage budget (dv) is 30 mV.
2. The measured AC transient current is 0.75A. This transient
current has a typical duration (dt) of 2.5 nsec. The amount
of capacitance required can now be determined using the
following equation:
I = C (dv/dt)
C = I (dt/dv) = 0.75A (2.5nsec/30mV) = 0.625µF
This equation indicates that if the capacitors didn't have
inductance, only six 0.1-µF capacitors would be required.
3. Determine the number of capacitors required based on the
inductance of the capacitor. Use the following formula:
V = L (di/dt) = L • (0.75A/2.5nsec) = 30mV
Solving for L, the allowed budget is 100pH.
4. The inductance of the capacitor and via = 1.8nH (0.7nH for
each of the two vias and 0.4nH from the capacitor itself).
Because each capacitor usually has two vias (one on each
end), the effective via inductance must be:
2 • 0.7nH + 0.4nH = 1.8nH
26
Decoupling and Layout Recommendations
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
5. Solving the following equations for N:
1.8nH/N = 100pH
N = 1.8nH/100pH = 18
The number of capacitors required is 18.
The following steps repeat the calculation for I/O decoupling:
1. Determine the amount of capacitance required using the
following equation:
I = C (dv/dt)
C = I (dt/dv) = 0.5 (2.5nsec/145mV) = 0.0086 µF
This equation indicates that if the capacitors didn’t have
inductance, only one 0.1-µF capacitor would be required.
2. Using 0.5A as a typical ICC3 value, repeat the calculations to
account for inductance:
Note: The ripple budget is 145mV because the I/O drivers are
not as sensitive to supply variations as the core and the
current transient is smaller.
L = V (dt/di) = 0.145 (2.5nsec/.5A) = 725pH
Solving for L, the allowed budget is 725pH.
The number of capacitors = 1.8nH/725pH = 2.5. Therefore,
only three capacitors are required on the I/O. AMD
recommends six capacitors.
Decoupling and Layout Recommendations
27
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
15.9312 100
10
Zo( c2, L , r , w )
Zo( c1, L , r , w )
1
0.191752
0.1
6
1 10
7
1 10
1e+006
8
1 10
9
1 10
w
1e+009
Figure 14. 0.1µF (c1) and 0.01 µF (c2) X7R Capacitor Impedance vs. Frequency
Pad
A
Capacitor
C
Via to VCC
Via to GND
B
D
CPU via to VCC
Cc
Via
C
CPU via to GND
Processor
A
Via
B
D
VCC Plane
GND Plane
Figure 15. Decoupling Inductance
28
Decoupling and Layout Recommendations
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Power Sequencing
Although the mobile AMD-K6 processor requires dual power
supply voltages, there are no special power sequencing
requirements. The best procedure is to minimize the time
between which VCC2 and VCC3 are either both on or both off
(See Figure 16). However, a good design practice ensures VCC3
is always greater than VCC2.
Volt
VCC3
VCC2
Minimize Time
Figure 16. Power Sequencing
Decoupling and Layout Recommendations
29
Mobile AMD-K6® Processor Power Supply Design
30
22495C/0—May 1999
Decoupling and Layout Recommendations
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Power Supply Solutions
The solutions provided in this section are not all-inclusive.
Obtain additional circuit diagrams and application assistance
from the manufacturers. The manufacturers can customize
designs to an OEM’s requirements. The schematics shown in
this document have not been tested by AMD and are provided
as examples only.
Digital-to-Analog
Converter (DAC)
Table 6.
Voltage Identification (VID) codes provide a way to program
the Digital-to-Analog Converter (DAC) to supply a reference for
d if f e re n t o u t pu t vo l t a g e s . M a ny m a nu fa ct u re rs h ave
DAC-controlled devices, however, some do not follow the VID
defined codes. The devices listed in the table “Voltage
Regulator Vendor Information” on page 40 use the VID codes.
Table 6 shows the codes and corresponding voltages.
Voltage Output VID Codes
D4
D3
D2
D1
D0
Output
Voltage
D4
D3
D2
D1
D0
Output
Voltage
1
0
0
0
0
3.50V
0
0
0
0
0
2.05V
1
0
0
0
1
3.40V
0
0
0
0
1
2.00V
1
0
0
1
0
3.30V
0
0
0
1
0
1.95V
1
0
0
1
1
3.20V
0
0
0
1
1
1.90V
1
0
1
0
0
3.10V
0
0
1
0
0
1.85V
1
0
1
0
1
3.00V
0
0
1
0
1
1.80V
1
0
1
1
0
2.90V
0
0
1
1
0
1.75V
1
0
1
1
1
2.80V
0
0
1
1
1
1.70V
1
1
0
0
0
2.70V
0
1
0
0
0
1.65V
1
1
0
0
1
2.60V
0
1
0
0
1
1.60V
1
1
0
1
0
2.50V
0
1
0
1
0
1.55V
1
1
0
1
1
2.40V
0
1
0
1
1
1.50V
1
1
1
0
0
2.30V
0
1
1
0
0
1.45V
1
1
1
0
1
2.20V
0
1
1
0
1
1.40V
1
1
1
1
0
2.10V
0
1
1
1
0
1.35V
1
1
1
1
1
OFF
0
1
1
1
1
1.30V
Power Supply Solutions
31
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
To meet the special requirements of Mobile parts new VID
codes separate from the desktop controllers are used. These
new mobile VID codes are defined in Table 7.
.
Table 7.
32
Mobile Voltage Output VID Codes
D4
D3
D2
D1
D0
Output
Voltage
D4
D3
D2
D1
D0
Output
Voltage
1
0
0
0
0
1.275V
0
0
0
0
0
2.00V
1
0
0
0
1
1.250V
0
0
0
0
1
1.95V
1
0
0
1
0
1.225V
0
0
0
1
0
1.90V
1
0
0
1
1
1.200V
0
0
0
1
1
1.85V
1
0
1
0
0
1.175V
0
0
1
0
0
1.80V
1
0
1
0
1
1.150V
0
0
1
0
1
1.75V
1
0
1
1
0
1.125V
0
0
1
1
0
1.70V
1
0
1
1
1
1.100V
0
0
1
1
1
1.65V
1
1
0
0
0
1.075V
0
1
0
0
0
1.60V
1
1
0
0
1
1.050V
0
1
0
0
1
1.55V
1
1
0
1
0
1.025V
0
1
0
1
0
1.50V
1
1
0
1
1
1.000V
0
1
0
1
1
1.45V
1
1
1
0
0
0.975V
0
1
1
0
0
1.40V
1
1
1
0
1
0.950V
0
1
1
0
1
1.35V
1
1
1
1
0
0.925V
0
1
1
1
0
1.30V
1
1
1
1
1
OFF
0
1
1
1
1
OFF
Power Supply Solutions
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Elantech EL7571
The EL7571 switching regulator is a flexible, high-efficiency,
PWM controller that includes a 5-bit DAC adjustable output.
This regulator employs synchronous rectification to deliver up
to 15A at efficiencies greater than 85% over a supply voltage
range of 4.5V to 12.6V. (Efficiencies up to 92% can be achieved
at 10A.) Figure 17 shows an EL7571 reference design. The VID
code allows the output to be set between 1.3 V and 2.05 V (in
50mV increments) and 2.1V and 3.5 V (in 100mV increments)
with a 1% accuracy. Table 8 on page 34 shows the bill of
materials for the EL7571.
10Ω
D1
C6
VHI 20
1 OTEN
ENABLE
R2
1.5uH
220pF
C3
C4
0.1uF
2 CSLOPE
HSD 19
C1
Q1
0.1uF
L2
4.5V to
12.6V
660uF x3
LX 18
3 COSC
220pF
1.4V
C5
0.1uF
VIN 17
4 REF
L2
R1
VOUT
1.3V to 3.5V
C7
5 PWRGD
POWER
GOOD
VINP 16
5uH
0.1uF
IC1
7.5mΩ
C2
D2
6 VID0
LSD 15
7 VID1
GNDP 14
8 VID2
GND 13
9 VID3
CS 12
10 VID4
FB 11
660uF x6
Q2
Voltage
I.D.
(VID[0:4])
Figure 17. Elantech EL7571 Switching Power Supply Design
Power Supply Solutions
33
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Contact Information.
Elantec Corporation
675 Trade Zone Blvd.
Milpitas, CA 95035-1323
Tel: (408) 945-1323
Fax: (408) 945-9305
www.elantec.com
Table 8.
Elantec EL 7571 Bill of Materials
Reference
Description
Part Number
Manufacturer
C1, C2
680µF
LXF16VB681M10X20LL
United Chem-Con
C3, C4
220pF
Chip capacitor
any
C5, C6, C7
0.1µF
Chip capacitor
any
D1
Diode
BAV99
Motorola, et-al
D2
Diode
32CTQ030
International Rectifier
IC1
Controller
EL 7571CM
Elantec
L1
5.1µH
PE-53700
Pulse Engineering
L2
1.5µH
T30-26 7T AWG #20
Micro Metals
R1
15mΩ
WSL-2512
Dale
R2
10Ω
Chip resistor
any
R3
10Ω
Chip resistor
any
Q1, Q2
MOSFET
Si4410
Siliconix
34
Power Supply Solutions
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Linear Technology
LT1435
The LT1435 is designed to be configured as a synchronous buck
converter with a minimum of external components. The input
voltage can range from 4.5 V to 24 V (limited by the external
MOSFETs). The circuit highlights the capabilities of the
LTC1435, which uses a current mode, constant frequency
architecture to switch a pair of N-channel power MOSFETs
while providing 99 % m aximum dut y cycle. Opera t ing
efficiencies exceeding 90% are obtained. Figure 18 on page 36
shows an LT1435 reference design that can deliver up to 6 A.
Vout = 1.19 (1 + R1/R2). Table 9 on page 37 shows the bill of
materials for the LT1435.
Contact Information.
Linear Technology Corporation
1630 McCarthy Blvd.
Milpitas, CA 95035-7417
Tel: (408) 432-1900
Fax: (408) 434-0507
www.linear.com
Power Supply Solutions
35
E9
C8
0.1uF
C7
0.1uF
42.2K 1 %
R8
46.4K 1 %
R7
52.3K 1 %
R6
1 0 0 pF
5 1 pF
CC2
C1
10K
RC
C S S 0.1uF
J1
8
7
6
5
LTC1435
SENSE+
SENSE-
VOSENS
SGND
SFB
ITH
RUN/SS
COSC
U2
EXTVCC
PGND
BG
INTVCC
VIN
SW
BOOST
TG
9
10
11
12
13
14
15
16
C3
4.7uF
16V
M B R S 1 40
D1
0.1uF
C4
4
Q2
SI4410DY
2uH
L2
4
R1
C6
1 0 0 pF
1%
0.033
RSENSE1
0.033
RSENSE2
35.7K
D3
M B R S 3 40
1 0 uH
L1
Q1
SI4410DY
CIN1
2 2 0uF
35V
CIN3
2 2 0uF
35V
CIN4
2 2 0 uF
35V
CIN5
2 2 0 uF
35V
C O UT2
1 0 0 uF
10V
C O UT3
1 0 0 uF
10V
AVX TPS LOW ESR
COUT
1 0 0uF
10V
C O UT4
1 0 0 uF
10V
C O UT5
1 0 0uF
10V
C11
0.1µF
2.0V @ 6A
MV-GX ALUMINIUM ELECTROLITIC
CIN
2 2 0uF
35V
C5
1 0 00pF
SANYO
C10
0.1uF
22uF AVX TPS LOW ESR CAN BE
Figure 18. Linear LT1435 2.0V Switching Power Supply Design
2.2V
J3
2.1V
J2
3
2
3 3 0 pF 4
2V
CC
1
C O SC 1 0 0pF
C2
0.1uF
OPTIONAL EMI FILTER
SGND CONNECTION ARE CONNECTED TO GROUND OF OUTPUT CAPS
4.5V TO 24V
5
6
7
8
1
2
3
5
6
7
8
1
2
3
36
SUBSTITUTED FOR CURRENT INPUT CAPS
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Power Supply Solutions
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Table 9.
Linear LT1435 Bill Of Materials
Reference
Description
Part Number
Manufacturer
CC
330pF 50V 10% NPO chip capacitor
08055A331KAT1A
AVX
CC2
51pF 50V 10% NPO chip capacitor
08055A510KAT1A
AVX
CIN, CIN1, 3, 4, 5
220µF 35V 20% Alum Elec. capacitor MV-GX
Sanyo
COUT1–5
100µF 10V 20% tantalum capacitor
TPSD107M010R0080
AVX
C1, C6, Cosc
100pF 50V 10% NPO chip capacitor
08055A101KAT1A
AVX
C2, C4, CSS, C7–8,
0.1µF 50V 10% Y5V chip capacitor
C10–11
08055G104KAT1A
AVX
C3
4.7µF 16V 20% tantalum capacitor
TAJB475M016
AVX
C5
1000pF 50V 10% X7R chip capacitor
08055C102KAT1A
AVX
D1
BVR = 40V – 1 A Schottky diode
MBRS150
Motorola
D2
BVR = 40V – 3 A Schottky diode
MBRS340T3
Motorola
JP1
2mm pin header
2802S-03-G2
Comm Con
JP2
2mm pin header
2802S-10-G2
Comm Con
L1
10µH inductor
BI HM77-25006
PE53663
BI Tech
Pulse Engineering
L2
2µH inductor EMI filter (optional)
DO3316P-222
Coil Craft
Q1, Q2
N-Channel MOSFET
Si4410DY
Siliconix
R1
35.7k 1/10W 1% chip resistor
CR21-3572F-T
AVX
R6
52.3k 1/10W 1% chip resistor
CR21-5232F-T
AVX
R7
46.4k 1/10W 1% chip resistor
CR21-4642F-T
AVX
R8
42.2k 1/10W 1% chip resistor
CR21-4222F-T
AVX
RC
10k 1/10W 5% chip resistor
CR21-103J-T
AVX
RSENSE
33 milli Ω 1/2W 1% resistor
LR2010-01-R033-F
IRC
U1
16-Lead narrow small outline IC
LTC1435CS
LTC
Jumper
CCIJ2mm-138-G
Comm Con
Power Supply Solutions
37
Mobile AMD-K6® Processor Power Supply Design
Maxim
MAX798
22495C/0—May 1999
The MAX798 current-mode converter shown in Figure 19
converts the input voltage (from the wall adapter or the battery
pack) down to the desired 1.8 V. The MAX798 can achieve
efficiencies up to 96% and has an input-voltage rage of 4.5V to
30V. The input voltage is switched by the MOSFETs N1 and N2.
This switched voltage is filtered by the LC filter, consisting of
L1, C4, and C5. R1 and R2 divide the 1.8 V output voltage to
1.6V for the feedback reference (Vout = 1.6V · (1 + R1/R2). The
values in the bill of material (See Table 10 on page 39) provide
1.8 V at 5.6 A. The 560-pF capacitor improves stability by
increasing the loop phase at crossover, which increases the
phase margin. Maxim’s MAX1710/11 has VID inputs.
Vin
C1
C2
C3
C6
C8 C12
VL
V + BS T
D1
SKIP
C7
N1
DH
L1
R3
Vout
LX
C4
SHDN
N2
C5
D2
DL
U1
C9
C10
PGND
MAX798
C11
CS H
SS
R1
CS L
REF
FB
SYNC
GND
R2
Figure 19. Maxim MAX798 Switching Power Supply Design
38
Power Supply Solutions
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Contact Information.
Maxim Integrated Products
120 San Gabriel Drive
Sunnyvale, CA 92841
Tel: (408) 737-7600
Fax: (408) 737-7194
www.maxim-ic.com
Table 10. Maxim MAX798 Bill of Materials
Reference
Description
Part Number
Manufacturer
C1–C3
10µF 30V Os-Con capacitor
30SA10
Sanyo
C4, C5
470µF 4V low ESR capacitor
594D477X0004R2T
Sprague
C6, C7
0.1µF ceramic capacitor
any
any
C8
4.7µF 16V Low ESR Tantalum capacitor 595D475X0016A2B
Sprague
C9
0.01µF ceramic capacitor
any
any
C10
0.33µF ceramic capacitor
any
any
C11
560pF ceramic capacitor
any
any
C12
1.0µF ceramic capacitor
any
any
DS1
Schottky Diode, 100mA, 30V
CMPSH-3
Central Semi
DS2
Schottky Diode, 1A, 30V
MBRS130LT3
Motorola
L1
4.7µH inductor
CDRH127-4R7MC
Sumida
N1, N2
N-Channel MOSFET 30V
Si4412DY
Siliconix
R1
4.22k, 0.1% resistor
any
any
R2
16.9k, 0.1% resistor
any
any
R3
13mΩ 1% Current sense resistor *
WSL-2512-R013F
Dale
U1
DC-DC converter
MAX798ESE
Maxim
Note:
*
2.0 V at 6A.
Power Supply Solutions
39
Mobile AMD-K6® Processor Power Supply Design
22495C/0—May 1999
Voltage Regulator Vendor Information
Company Name and Contact
Part Number
Type
Remarks*
Cherry
Contact: George Shuline
(401)886-3821
CS5156
Switching Regulator
a) 5 bit VID 1.3 V min
Elantech
Contact: Steve Sacarisen
(408) 945-1323 x 345
EL7571
Switching Regulator
a) 5 bit VID 1.3 V min
Linear Technology Corporation
Contact: Mike Gillespie
(408) 428-2060
LT1435/36/37
LT1439/1339
LTC1538/39
Switching Regulator
Switching Regulator
Switching Regulator
a) Voltage set by resistors
b) Voltage set by resistors
c) Voltage set by resistors
Maxim Integrated Products
Contact: Nancie George-Adeh
(408) 737-7600
MAX798
MAX1630/31/32
MAX1710/11
Switching Regulator
Switching Regulator
Switching Regulator
a) Voltage set by resistors
b) Voltage set by resistors
c) 4bit/bit DAC 0.925V min
Micro Linear
Contact: Doyle Slack
(408) 433-5200
ML4880
Switching Regulator
Semtech Corporation
Contact: Alan Moore
(805) 498-2111
SC1401
Switching Regulator
STMicroelectronics
20041 Agrate Brianza -Italy
Via C. Olivetti, 2
Contact: Nicola Tricomi
Tel. +39 039 6036512
L4992
L5955
Switching Regulator
Switching Regulator
a) Voltage set by resistors
b) 4bit/bit DAC 1.35V min., 2.0V max.
Unitrode
Contact: John O’Connor
(603) 429-8504
www.unitrode.com
UCC3870-1
Switching Regulator
Voltage set by resistors or external
DAC—input range 4–36 volts
Voltage set by resistors
Note:
*
40
These regulators all have a wide input-voltage range
Voltage Regulator Vendor Information