Low Power, Low Cost
a
FEATURES
Low Quiescent Current: 250 A Max
Laser Trimmed to High Accuracy:
2.5 V ⴞ5 mV Max (AN, AR Grade)
Trimmed Temperature Coefficient:
20 ppm/ⴗC Max (AN, AR Grade)
Low Noise: 8 V p-p from 0.1 Hz to 10 Hz
250 nV/√Hz Wideband
Temperature Output Pin (N, R Packages)
Available in Three Package Styles:
8-Lead Plastic DIP, 8-Lead SOIC and 3-Pin TO-92
PRODUCT DESCRIPTION
The AD680 is a bandgap voltage reference that provides a fixed
2.5 V output from inputs between 4.5 V and 36 V. The architecture of the AD680 enables the reference to be operated at a
very low quiescent current while still realizing excellent dc
characteristics and noise performance. Trimming of the high
stability thin-film resistors is performed for initial accuracy and
temperature coefficient, resulting in low errors over temperature.
The precision dc characteristics of the AD680 make it ideal for
use as a reference for D/A converters which require an external
precision reference. The device is also ideal for A/D converters
and, in general, can offer better performance than the standard
on-chip references.
Based upon the low quiescent current of the AD680, which
rivals that of many incomplete two-terminal references, the
AD680 is recommended for low power applications such as
hand-held battery equipment.
A temperature output pin is provided on the 8-lead package
versions of the AD680. The temperature output pin provides an
output voltage that varies linearly with temperature and allows
the AD680 to be configured as a temperature transducer while
providing a stable 2.5 V output.
The AD680 is available in five grades. The AD680AN is specified
for operation from –40°C to +85°C, while the AD680JN is
specified for 0°C to 70°C operation. Both the AD680AN and
AD680JN are available in 8-lead plastic DIP packages. The
AD680AR is specified for operation from –40°C to +85°C,
while the AD680JR is specified for 0°C to 70°C operation. Both
are available in an 8-lead Small Outline IC (SOIC) package.
The AD680JT is specified for 0°C to 70°C operation and is
available in a 3-pin TO-92 package.
2. 5 V Reference
AD680*
CONNECTION DIAGRAMS
1
TP*
2
IN
3
4
AD680
TOP VIEW
(Not to Scale)
+V
TEMP
* TP DENOTES FACTORY TEST POINT.
NO CONNECTIONS SHOULD BE MADE
TO THESE PINS.
8
TP*
7
TP*
6
V
OUT
5
NCGND
PRODUCT HIGHLIGHTS
1. The AD680 bandgap reference operates on a very low quiescent
current which rivals that of many two-terminal references.
This makes the complete, higher accuracy AD680 ideal for
use in power sensitive applications.
2. Laser trimming of both initial accuracy and temperature
coefficients results in low errors over temperature without the
use of external components. The AD680AN and AD680AR
have a maximum variation of 6.25 mV between –40°C
and +85°C.
3. The AD680 noise is low, typically 8 µV p-p from 0.1 Hz to
10 Hz. Spectral density is also low, typically 250 nV/√Hz.
4. The temperature output pin on the 8-lead package versions
enables the AD680 to be configured as a temperature
transducer.
5. Plastic DIP packaging provides machine insertability, while
SOIC packaging provides surface mount capability. TO-92
packaging offers a cost effective alternative to two-terminal
references, offering a complete solution in the same package
in which two-terminal references are usually found.
AD680
BOTTOM VIEW
(Not to Scale)
32
+V
V
IN
OUT
1
GND
*Protected by U.S. Patent Nos. 4,902,959; 4,250,445; and 4,857,862.
REV. D
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 2001
AD680–SPECIFICATIONS
(TA = 25ⴗC, VIN = 5 V, unless otherwise noted.)
AD680AN/AR AD680JN/JR AD680JT
Model Min Typ Max Min Typ Max Min Typ Max Unit
OUTPUT VOLTAGE
Output Voltage, V
Initial Accuracy, V
O
OERR
2.495 2.500 2.505 2.490 2.500 2.510 2.490 2.500 2.510 V
–5 +5 –10 +10 –10 +10 ±mV
–0.20 +0.20 –0.40 +0.40 –0.40 +0.40 %
OUTPUT VOLTAGE DRIFT
1
0°C to 70°C 10 10 25 10 30 ppm/°C
–40°C to +85°C202525
LINE REGULATION
4.5 V ≤ +VIN ≤ 15 V 40 40 40 µV/V
(@ T
MIN
15 V ≤ +V
(@ T
MIN
to T
≤ 36 V 40 40 40
IN
to T
)404040
MAX
)404040
MAX
LOAD REGULATION
0 < I
(@ T
< 10 mA 80 100 80 100 80 100 µV/mA
OUT
MIN
to T
) 80 100 80 100 80 100
MAX
QUIESCENT CURRENT 195 250 195 250 195 250 µA
(@ T
MIN
to T
) 280 280 280
MAX
POWER DISSIPATION 1 1.25 1 1.25 1 1.25 mW
OUTPUT NOISE
0.1 Hz to 10 Hz 8 10 8 10 8 10 µV p-p
Spectral Density, 100 Hz 250 250 250 nV/√Hz
CAPACITIVE LOAD 50 50 50 nF
LONG TERM STABILITY 25 25 25 ppm/1000 hr
SHORT CIRCUIT CURRENT
TO GROUND 25 50 25 50 25 50 mA
TEMPERATURE PIN
Voltage Output @ 25°C 540 596 660 540 596 660 mV
Temperature Sensitivity 2 2 mV/°C
Output Current –5 +5 –5 +5 µA
Output Resistance 12 12 kΩ
TEMPERATURE RANGE
Specified Performance –40 +85 0 70 0 70 ° C
Operating Performance
NOTES
1
Maximum output voltage drift is guaranteed for all packages.
2
The operating temperature range is defined as the temperature extremes at which the device will still function. Parts may deviate from their specified performance
outside their specified temperature range.
Specifications subject to change without notice.
Specifications in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels. All min and
max specifications are guaranteed.
2
–40 +85 –40 +85 –40 +85 °C
–2–
REV. D
AD680
ABSOLUTE MAXIMUM RATINGS*
VIN to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 V
Power Dissipation (25°C) . . . . . . . . . . . . . . . . . . . . . 500 mW
Storage Temperature . . . . . . . . . . . . . . . . . . –65°C to +125°C
Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . . 300°C
Package Thermal Resistance
(All Packages) . . . . . . . . . . . . . . . . . . . . . . . . 120°C/W
θ
JA
Output Protection: Output safe for indefinite short to ground
and momentary short to V
*Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those indicated in the operational
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
.
IN
8-Lead Plastic DIP
and
8-Lead SOIC Packages
1
TP*
2
+V
TEMP
* TP DENOTES FACTORY TEST POINT.
NO CONNECTIONS SHOULD BE MADE
TO THESE PINS.
AD680
IN
TOP VIEW
3
(Not to Scale)
4
NC = NO CONNECT
8
TP*
7
TP*
6
V
OUT
5
NCGND
TO-92 Package
AD680
BOTTOM VIEW
(Not to Scale)
32
+V
IN
1
V
GND
OUT
Figure 1. Connection Diagrams
THEORY OF OPERATION
Bandgap references are the high-performance solution for low
supply voltage operation. A typical precision bandgap will consist of a reference core and buffer amplifier. Based on a new,
patented bandgap reference design (Figure 2), the AD680
merges the amplifier and the core bandgap function to produce
a compact, complete precision reference. Central to the device
is a high gain amplifier with an intentionally large Proportional
To Absolute Temperature (PTAT) input offset. This offset is
controlled by the area ratio of the amplifier input pair, Q1 and
Q2, and is developed across resistor R1. Transistor Q12’s base
emitter voltage has a Complementary To Absolute Temperature
(CTAT) characteristic. Resistor R2 and the parallel combination of R3 and R4 “multiply” the PTAT voltage across R1.
Trimming resistors R3 and R4 to the proper ratio produces a
temperature invariant 2.5 V at the output. The result is an
accurate, stable output voltage accomplished with a minimum
number of components.
+V
IN
R5
TEMP
GND
Q9
Q10
R6
R7
Q2
Q3
Q8
8ⴛ
Q1
1ⴛ
Q6
Q4
Q11
V
Q5
R1
C1
R2
Q12
Q7
OUT
R3
R4
Figure 2. Schematic Diagram
An additional feature with this approach is the ability to minimize
the noise while maintaining very low overall power dissipation
for the entire circuit. Frequently it is difficult to independently
control the dominant noise sources for bandgap references:
bandgap transistor noise and resistor thermal noise. By properly
choosing the operating currents of Q1 and Q2 and separately
sizing R1, low wideband noise is realized while maintaining
1 mW typical power dissipation.
ORDERING GUIDE
Output Initial Temperature No. of Temperature
Voltage Accuracy Coefficient Package Package Parts Range
Model V
O
mV % ppm/ⴗC Description Option per Reel ⴗC
AD680AN 2.5 5 0.20 20 Plastic N-8 48 –40 to +85
AD680AR 2.5 5 0.20 20 SOIC R-8A 98 –40 to +85
AD680JN 2.5 10 0.40 25 Plastic N-8 48 0 to 70
AD680JR 2.5 10 0.40 25 SOIC R-8A 98 0 to 70
AD680JT 2.5 10 0.40 30 TO-92 TO-92 100 0 to 70
REV. D
–3–
AD680
APPLYING THE AD680
The AD680 is simple to use in virtually all precision reference
applications. When power is applied to +V
is tied to ground, V
provides a 2.5 V output. The AD680
OUT
and the GND pin
IN
typically requires less than 250 µA of current when operating
from a supply of 4.5 V to 36 V.
To operate the AD680, the +V
pin must be bypassed to the
IN
GND pin with a 0.1 µF capacitor tied as close to the AD680 as
possible. Although the ground current for the AD680 is small
(typically 195 µA), a direct connection should be made between
the AD680 GND pin and the system ground plane.
Reference outputs are frequently required to handle fast transients caused by input switching networks, as are commonly
found in ADCs and measurement instrumentation equipment.
Many of the dynamic problems associated with this situation
can be minimized with a few simple techniques. Using a series
resistor between the reference output and the load will tend to
“decouple” the reference output from the transient source. Or a
relatively large capacitor connected from the reference output to
ground can serve as a charge storage element to absorb and
deliver charge as is required by the dynamic load. A 50 nF
capacitor is recommended for the AD680 in this case; this is
large enough to store the required charge, but small enough so
as not to disrupt the stability of the reference.
The 8-lead plastic DIP and SOIC packaged versions of the
AD680 also provide a temperature output pin. The voltage on
this pin is nominally 596 mV at 25°C. This pin will provide an
output linearly proportional to temperature with a characteristic
of 2 mV/°C.
Noise in a 300 kHz bandwidth is approximately 800 µV p-p.
Figure 4 shows the broadband noise of a typical AD680.
50s
500V
500V
100
90
10
0%
Figure 4. Broadband Noise at 300 kHz
TURN-ON TIME
Upon application of power (cold start), the time required for the
output voltage to reach its final value within a specified error
band is defined as the turn-on settling time. Two components
normally associated with this are: the time for the active circuits
to settle, and the time for the thermal gradients on the chip
to stabilize. Figure 5 shows the turn-on settling time of the
AD680 to be about 20 µs to 0.025% of its final value.
5V
100
V
IN
90
1mV
10s
NOISE PERFORMANCE
The noise generated by the AD680 is typically less than 8 µV p-p
over the 0.1 Hz to 10 Hz band. Figure 3 shows the 0.1 Hz to
10 Hz noise of a typical AD680. The noise measurement is
made with a bandpass filter made of a 1-pole high-pass filter
with a corner frequency at 0.1 Hz and a 2-pole low-pass filter
with a corner frequency at 12.6 Hz to create a filter with a
9.922 Hz bandwidth.
1s
5V
100
90
10
0%
Figure 3. 0.1 Hz to 10 Hz Noise
V
OUT
10
0%
Figure 5. Turn-On Settling Time
The AD680 thermal settling characteristic benefits from its
compact design. Once initial turn-on is achieved, the output
linearly approaches its final value; the output is typically within
0.01% of its final value after 25 ms.
DYNAMIC PERFORMANCE
The output stage of the amplifier is designed to provide the
AD680 with static and dynamic load regulation superior to less
complete references.
–4–
REV. D
AD680
Figure 6 displays the characteristics of the AD680 output amplifier driving a 0 mA to 10 mA load. Longer settling times will
result if the reference is forced to sink any transient current.
In some applications, a varying load may be both resistive and
capacitive in nature, or the load may be connected to the
AD680 by a long capacitive cable.
+V
IN
V
0.1F
AD680
OUT
V
V
OUT
249⍀
V
OUT
L
0V
Figure 6a. Transient Load Test Circuit
100
90
V
L
V
OUT
10
0%
5s50mV2V
Figure 7 displays the output amplifier characteristics driving a
1000 pF, 0 mA to 10 mA load.
+V
IN
V
0.1F
AD680
OUT
C
L
1000pF
V
V
OUT
249⍀
V
OUT
L
0V
Figure 7a. Capacitive Load Transient Response Test
Circuit
100
90
V
L
V
OUT
10
0%
5s5mV2V
Figure 7b. Output Response with Capacitive Load
Figure 6b. Large-Scale Transient Response
100
90
V
IN
V
OUT
10
0%
5s5mV2V
Figure 6c. Fine Scale Settling for Transient Load
LOAD REGULATION
Figure 8 shows the load regulation characteristics of the AD680.
100
90
V
L
V
OUT
10
0%
100s1mV1V
Figure 8. Typical Load Regulation Characteristics
REV. D
–5–
AD680
TEMPERATURE PERFORMANCE
The AD680 is designed for reference applications where temperature performance is important. Extensive temperature
testing and characterization ensures that the device’s performance is maintained over the specified temperature range.
Some confusion exists in the area of defining and specifying
reference voltage error over temperature. Historically, references
have been characterized using a maximum deviation per degree
centigrade, i.e., ppm/°C. However, because of nonlinearities in
temperature characteristics which originated in standard Zener
references (such as “S” type characteristics), most manufacturers now use a maximum limit error band approach to specify
devices. This technique involves the measurement of the output
at three or more different temperatures to specify an output
voltage error band.
2.501
2.500
2.499
2.498
–50 6002040
–10–30 80 100
TEMPERATURE – ⴗC
SLOPE = TC
– V
V
MAX
=
(T
– T
MAX
=
(85ⴗC – (–40ⴗC)) ⴛ 2.5V ⴛ 10
= 9.6ppm/ⴗC
MIN
) ⴛ 2.5V ⴛ 10
MIN
2.501 – 2.498
–6
–6
Figure 9. Typical AD680AN/AP Temperature Drift
Figure 9 shows a typical output voltage drift for the AD680AN/AR
and illustrates the test methodology. The box in Figure 9 is
bounded on the sides by the operating temperature extremes,
and on the top and bottom by the maximum and minimum
output voltages measured over the operating temperature range.
The maximum height of the box for the appropriate temperature range and device grade is shown in Table I. Duplication of
these results requires a combination of high accuracy and stable
temperature control in a test system. Evaluation of the AD680
will produce a curve similar to that in Figure 9, but output
readings may vary depending upon the test equipment utilized.
Table I. Maximum Output Change in mV
Maximum Output Change (mV)
Device Grade 0⬚C to 70⬚C –40⬚C to +85⬚C
AD680JN/JR 4.375 ––
AD680JT 5.250 ––
AD680AN –– 6.250
TEMPERATURE OUTPUT PIN
The 8-lead packaged versions of the AD680 provide a temperature output pin on Pin 3 of each device. The output of Pin 3
(TEMP) is a voltage that varies linearly with temperature. V
TEMP
at 25°C is 596 mV, and the temperature coefficient is 2 mV/°C.
Figure 10 shows the output of this pin over temperature.
The temperature pin has an output resistance of 12 kΩ and is
capable of sinking or sourcing currents of up to 5 µA without
disturbing the reference output, enabling the temp pin to be
buffered by any of a number of inexpensive operational amplifiers that have bias currents below this value.
760
720
680
640
600
560
TEMP PIN VOLTAGE – mV
520
480
440
–50
–40 –30 –20 –10 0 10 304050 60708090
20
TEMPERATURE – ⴗC
Figure 10. Temp Pin Transfer Characteristic
DIFFERENTIAL TEMPERATURE TRANSDUCER
Figure 11 shows a differential temperature transducer that
can be used to measure temperature changes in the AD680’s
environment. This circuit operates from a 5 V supply. The
temperature dependent voltage from the TEMP pin of the
AD680 is amplified by a factor of 5 to provide wider full-scale
range and more current sourcing capability. An exact gain of 5
can be achieved by adjusting the trim potentiometer until the
output varies by 10 mV/°C. To minimize resistance changes
with temperature, resistors with low temperature coefficients,
such as metal film resistors, should be used.
5V
0.1F
V
IN
TEMP
AD680
GND
R
100⍀
R
B
BP
OP90
1.69k⍀
1%
5V
⌬V
OUT
= 10mV/ ⴗC
⌬T
R
F
6.98k⍀
1%
Figure 11. Differential Temperature Transducer
LOW POWER, LOW VOLTAGE REFERENCE FOR DATA
CONVERTERS
The AD680 has a number of features that make it ideally suited
for use with A/D and D/A converters. The low supply voltage
required makes it possible to use the AD680 with today’s converters that run on 5 V supplies without having to add a higher
supply voltage for the reference. The low quiescent current
(195 µA), combined with the completeness and accuracy of the
AD680 make it ideal for low power applications such as handheld,
battery-operated meters.
–6–
REV. D
AD680
OP90
AD680
V
OUT
V
IN
GND
0.1F
R2
2.5k⍀
1%
0.1F
CF
R3
1k⍀
OUT
V–
V+
+IN
–IN
R4
3.57k⍀
CC
3.3F
2N2907A
4.7V TO 15V
+C1
10F
C2
0.1F
R1
2k⍀
1%
R5
3.9⍀
OP20
AD680
V
OUT
V
IN
GND
R1
402k⍀
1%
402k⍀
1%
R2
+
+
68F
TANT
C1
1000F
ELECT
C2
LEAD-ACID
BATTERY
6V
CHARGER
INPUT
+
0.1F
R3
510k⍀
TEMP
IRF9530
One such ADC that the AD680 is well suited for is the AD7701.
Figure 12a shows the AD680 used as the reference for this
converter. The AD7701 is a 16-bit A/D converter with on-chip
digital filtering intended for the measurement of wide dynamic
range, low frequency signals such as those representing chemical, physical or biological processes. It contains a charge balancing
(sigma-delta) ADC, calibration microcontroller with on-chip
static RAM, a clock oscillator and a serial communications port.
This entire circuit runs on ±5 V supplies. The power dissipation
of the AD7701 is typically 25 mW and, when combined with
the power dissipation of the AD680 (1 mW), the entire circuit
consumes just 26 mW of power.
+5V
ANALOG
SUPPLY
CALIBRATE
0.1F
RANGE
SELECT
ANALOG
INPUT
ANALOG
GND
–5V
ANALOG
SUPPLY
0.1F10F
V
AD680
GND
0.1F
0.1F10F
AV
DD
DV
IN
V
V
OUT
REF
AD7701
BP/UP
CAL
A
IN
AGND
AV
SS
SLEEP
MODE
DRDY
CS
SCLK
SDATA
CLKIN
CLKOUT
SC1
SC2
DGND
DV
DD
0.1F
DATA READY
READ (TRANSMIT)
SERIAL CLOCK
SERIAL DATA
0.1F
SS
Figure 12a. Low Power, Low Voltage Supply Reference
for the AD7701 16-Bit A/D Converter
Figure 12b shows the AD680 connected to the AD773 high
speed 8-bit ADC. The low-pass filter shown minimizes the
AD680’s wideband noise.
V
IN
AD680
V
GND
OUT
22⍀
6
10F
0.1F
REF IN
AD773
input can be driven from one low cost, low power reference.
The high impedance input allows multiple AD773s to be driven
from one AD680 thus minimizing drift errors.
4.5 V REFERENCE FROM A 5 V SUPPLY
The AD680 can be used to provide a low power, 4.5 V reference as shown in Figure 13. In addition to the AD680, the
circuit uses a low power op amp and a transistor in a feedback
configuration that provides a regulated 4.5 V output for a power
supply voltage as low as 4.7 V. The high quality tantalum 10 µF
capacitor (C1) in parallel with the ceramic 0.1 µF capacitor
(C2) and the 3.9 Ω resistor (R5) ensure a low output impedance
up to around 50 MHz.
Figure 13. 4.5 V Reference Running from a Single 5 V
Supply
VOLTAGE REGULATOR FOR PORTABLE EQUIPMENT
The AD680 is ideal for providing a stable, low cost and low
power reference voltage in portable equipment power supplies.
Figure 14 shows how the AD680 can be used in a voltage regulator that not only has low output noise (as compared to a
switch mode design) and low power, but also a very fast recovery after current surges. Some precaution should be taken in the
selection of the output capacitors. Too high an ESR (effective
series resistance) could endanger the stability of the circuit. A
solid tantalum capacitor, 16 V or higher, and an aluminum
electrolytic capacitor, 10 V or higher, are recommended for C1 and
C2, respectively. Also, the path from the ground side of C1 and
C2 to the ground side of R1 should be kept as short as possible.
REF GND
Figure 12b. AD680 to AD773 Connection
The AD773’s high impedance reference input allows direct
connection to the AD680. Unlike the resistor ladder requirements
of a flash converter the AD773’s single pin, high impedance
REV. D
Figure 14. Voltage Regulator for Portable Equipment
–7–
AD680
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Lead Plastic DIP 8-Lead SOIC 3-Pin TO-92
PIN 1
0.210
(5.33)
MAX
0.160 (4.06)
0.115 (2.93)
0.022 (0.558)
0.014 (0.356)
0.430 (10.92)
0.348 (8.84)
8
0.100 (2.54)
5
14
BSC
0.070 (1.77)
0.045 (1.15)
0.325 (8.25)
0.300 (7.62)
0.015 (0.381)
0.008 (0.204)
0.280 (7.11)
0.240 (6.10)
0.060 (1.52)
0.015 (0.38)
0.130
(3.30)
SEATING
PLANE
0.195 (4.95)
0.115 (2.93)
MIN
0.1574 (4.00)
0.1497 (3.80)
PIN 1
0.0098 (0.25)
0.0040 (0.10)
SEATING
0.0098 (0.25)
0.0075 (0.19)
0.1968 (5.00)
0.1890 (4.80)
85
0.0500 (1.27)
PLANE
41
BSC
0.0192 (0.49)
0.0138 (0.35)
0.0196 (0.50)
0.0099 (0.25)
8ⴗ
0ⴗ
0.0500 (1.27)
0.0160 (0.41)
0.2440 (6.20)
0.2284 (5.80)
0.102 (2.59)
0.094 (2.39)
ⴛ 45ⴗ
SEATING
PLANE
0.105 (2.66)
0.095 (2.42)
0.105 (2.66)
0.080 (2.42)
0.105 (2.66)
0.080 (2.42)
0.135
(3.43)
MIN
0.500
(12.70)
MIN
123
BOTTOM VIEW
0.205 (5.20)
0.175 (4.96)
0.210 (5.33)
0.170 (4.38)
0.050
(1.27)
MAX
0.019 (0.482)
0.016 (0.407)
SQUARE
0.055 (1.39)
0.045 (1.15)
0.165 (4.19)
0.125 (3.94)
C00813a–0–7/01(D)
AD680–Revision History
Location Page
Data Sheet changed from REV. C to REV. D.
Changes to SPECIFICATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Changes to ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Table I added . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
–8–
REV. D
PRINTED IN U.S.A.
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