AD AD637 High precision, wideband rms-to-dc converter Datasheet

High Precision, Wideband
RMS-to-DC Converter
AD637
FEATURES
FUNCTIONAL BLOCK DIAGRAM
BUFF IN
BUFF
OUT
25kΩ
VIN
DEN INPUT
ABSOLUTE
VALUE
SQUARER/
DIVIDER
RMS OUT
CAV
25kΩ
dB OUTPUT
OUTPUT
OFFSET
BIAS
COMMON
AD637
CS
00788-001
High accuracy
0.02% maximum nonlinearity, 0 V to 2 V rms input
0.10% additional error to crest factor of 3
Wide bandwidth
8 MHz at 2 V rms input
600 kHz at 100 mV rms
Computes
True rms
Square
Mean square
Absolute value
dB output (60 dB range)
Chip select/power-down feature allows
Analog three-state operation
Quiescent current reduction from 2.2 mA to 350 μA
14-lead SBDIP, 14-lead low cost CERDIP, and 16-lead SOIC_W
Figure 1.
GENERAL DESCRIPTION
The AD637 is a complete, high accuracy, monolithic rms-to-dc
converter that computes the true rms value of any complex
waveform. It offers performance that is unprecedented in
integrated circuit rms-to-dc converters and comparable to
discrete and modular techniques in accuracy, bandwidth, and
dynamic range. A crest factor compensation scheme in the
AD637 permits measurements of signals with crest factors of
up to 10 with less than 1% additional error. The wide bandwidth of the AD637 permits the measurement of signals up to
600 kHz with inputs of 200 mV rms and up to 8 MHz when the
input levels are above 1 V rms.
As with previous monolithic rms converters from Analog
Devices, Inc., the AD637 has an auxiliary dB output available to
users. The logarithm of the rms output signal is brought out to a
separate pin, allowing direct dB measurement with a useful
range of 60 dB. An externally programmed reference current
allows the user to select the 0 dB reference voltage to correspond to
any level between 0.1 V and 2.0 V rms.
A chip select connection on the AD637 permits the user to
decrease the supply current from 2.2 mA to 350 μA during periods
when the rms function is not in use. This feature facilitates the
addition of precision rms measurement to remote or handheld
applications where minimum power consumption is critical. In
addition, when the AD637 is powered down, the output goes to a
high impedance state. This allows several AD637s to be tied
together to form a wideband true rms multiplexer.
The input circuitry of the AD637 is protected from overload
voltages in excess of the supply levels. The inputs are not
damaged by input signals if the supply voltages are lost.
The AD637 is available in accuracy Grade J and Grade K for
commercial temperature range (0°C to 70°C) applications, accuracy
Grade A and Grade B for industrial range (−40°C to +85°C) applications, and accuracy Grade S rated over the −55°C to +125°C
temperature range. All versions are available in hermetically sealed,
14-lead SBDIP, 14-lead CERDIP, and 16-lead SOIC_W packages.
The AD637 computes the true root mean square, mean square,
or absolute value of any complex ac (or ac plus dc) input
waveform and gives an equivalent dc output voltage. The true
rms value of a waveform is more useful than an average
rectified signal because it relates directly to the power of the
signal. The rms value of a statistical signal is also related to the
standard deviation of the signal.
The AD637 is laser wafer trimmed to achieve rated performance
without external trimming. The only external component
required is a capacitor that sets the averaging time period. The
value of this capacitor also determines low frequency accuracy,
ripple level, and settling time.
The on-chip buffer amplifier can be used either as an input
buffer or in an active filter configuration. The filter can be used
to reduce the amount of ac ripple, thereby increasing accuracy.
Rev. K
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rights of third parties that may result from its use. Specifications subject to change without notice. No
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DOCUMENTATION
DESIGN COLLABORATION COMMUNITY
AD637: Military Data Sheet
AN-653: Improving Temperature, Stability, and Linearity of High
Dynamic Range RMS RF Power Detectors
AN-268: RMS-to-DC Converters Ease Measurement Tasks
RMS-to-DC Application Guide
- Section I: RMS-DC Conversion - Theory
- Section II: RMS-DC Conversion - Basic Design Considerations
- Section III: RMS Application Circuits
- Appendix A: Testing the Critical Parameters of RMS Converters
- Appendix B: Input Buffer Amplifier Requirements
- Appendix C: Computer Programs for Determining Computational
Errors, Output Ripple, and 1% Settling Time of RMS Converter
- Appendix D: New Products Appendix to the RMS-to-DC Conversion
Application Guide
- Download the entire guide in .zip format
Introduction to Analog RMS-to-DC Technology: Converters and
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AD637
TABLE OF CONTENTS
Features .............................................................................................. 1
Choosing the Averaging Time Constant....................................9
Functional Block Diagram .............................................................. 1
Frequency Response .................................................................. 11
General Description ......................................................................... 1
AC Measurement Accuracy and Crest Factor ........................ 12
Revision History ............................................................................... 2
Connection for dB Output........................................................ 12
Specifications..................................................................................... 3
dB Calibration............................................................................. 13
Absolute Maximum Ratings............................................................ 5
Low Frequency Measurements................................................. 14
ESD Caution.................................................................................. 5
Vector Summation ..................................................................... 14
Pin Configurations and Function Descriptions ........................... 6
Evaluation Board ............................................................................ 16
Functional Description .................................................................... 7
Outline Dimensions ....................................................................... 19
Standard Connection ................................................................... 8
Ordering Guide .......................................................................... 20
Chip Select..................................................................................... 8
Optional Trims for High Accuracy ............................................ 8
REVISION HISTORY
2/11—Rev. J to Rev. K
Changes to Figure 15...................................................................... 11
Changes to Figure 16...................................................................... 12
Changes to Evaluation Board Section and Figure 23................. 16
Added Figure 24; Renumbered Sequentially .............................. 17
Changes to Figure 25 Through Figure 29.................................... 17
Changes to Figure 30...................................................................... 18
Added Figure 31.............................................................................. 18
Deleted Table 6; Renumbered Sequentially ................................ 18
Changes to Ordering Guide .......................................................... 20
4/07—Rev. I to Rev. J
Added Evaluation Board Section ................................................. 16
Updated Outline Dimensions ....................................................... 20
10/06—Rev. H to Rev. I
Changes to Table 1............................................................................ 3
Changes to Figure 4.......................................................................... 7
Changes to Figure 7.......................................................................... 9
Changes to Figure 16, Figure 18, and Figure 19 ......................... 12
Changes to Figure 20...................................................................... 13
4/05—Rev. F to Rev. G
Updated Format..................................................................Universal
Changes to Figure 1...........................................................................1
Changes to General Description .....................................................1
Deleted Product Highlights .............................................................1
Moved Figure 4 to Page ....................................................................8
Changes to Figure 5...........................................................................9
Changes to Figure 8........................................................................ 10
Changes to Figure 11, Figure 12, Figure 13, and Figure 14....... 11
Changes to Figure 19...................................................................... 14
Changes to Figure 20...................................................................... 14
Changes to Figure 21...................................................................... 16
Updated Outline Dimensions....................................................... 17
Changes to Ordering Guide .......................................................... 18
3/02—Rev. E to Rev. F
Edits to Ordering Guide ...................................................................3
12/05—Rev. G to Rev. H
Updated Format..................................................................Universal
Changes to Figure 1.......................................................................... 1
Changes to Figure 11...................................................................... 10
Updated Outline Dimensions ....................................................... 16
Changes to Ordering Guide .......................................................... 17
Rev. K | Page 2 of 20
AD637
SPECIFICATIONS
At 25°C and ±15 V dc, unless otherwise noted. 1
Table 1.
Parameter
TRANSFER FUNCTION
Min
AD637J/AD637A
Typ
Max
VOUT =
avg × (VIN )2
CONVERSION ACCURACY
Total Error, Internal Trim 2
(Figure 5)
TMIN to TMAX
vs. Supply
+VIN = 300 mV
vs. Supply
−VIN = −300 mV
DC Reversal
Error at 2 V
Nonlinearity 2 V Full Scale 3
Nonlinearity 7 V Full Scale
Total Error, External Trim
ERROR VS. CREST FACTOR 4
Crest Factor 1 to 2
Crest Factor = 3
Crest Factor = 10
AVERAGING TIME CONSTANT
INPUT CHARACTERISTICS
Signal Range, ±15 V Supply
Continuous RMS Level
Peak Transient Input
Signal Range, ±5 V Supply
Continuous RMS Level
Peak Transient Input
Maximum Continuous
Nondestructive
Input Level
(All Supply Voltages)
Input Resistance
Input Offset Voltage
FREQUENCY RESPONSE 5
Bandwidth for 1%
Additional Error
(0.09 dB)
VIN = 20 mV
VIN = 200 mV
VIN = 2 V
±3 dB Bandwidth
VIN = 20 mV
VIN = 200 mV
VIN = 2 V
Min
AD637K/AD637B
Typ
Max
VOUT =
avg × (VIN )2
Max
Unit
avg × (VIN )2
VOUT =
±1 ± 0.5
±0.5 ± 0.2
±1 ± 0.5
mV ±% of
reading
±3.0 ± 0.6
±2.0 ± 0.3
±6 ± 0.7
30
150
30
150
30
150
mV ± % of
reading
μV/V
100
300
100
300
100
300
μV/V
% of
reading
% of FSR
% of FSR
mV ± % of
reading
0.25
0.1
0.25
0.04
0.05
0.02
0.05
0.04
0.05
±0.5 ± 0.1
±0.25 ± 0.05
±0.5 ± 0.1
Specified accuracy
±0.1
Specified accuracy
±0.1
Specified accuracy
±0.1
±1.0
±1.0
±1.0
25
25
25
0 to 7
0 to 7
±15
0 to 4
±6
±15
8
0 to 7
±15
0 to 4
6.4
AD637S
Typ
Min
9.6
±0.5
6.4
8
±15
V rms
V p-p
±6
±15
V rms
V p-p
V p-p
9.6
±0.5
kΩ
mV
0 to 4
±6
±15
9.6
±0.2
6.4
8
% of
reading
% of
reading
ms/μF CAV
11
66
200
11
66
200
11
66
200
kHz
kHz
kHz
150
1
8
150
1
8
150
1
8
kHz
MHz
MHz
Rev. K | Page 3 of 20
AD637
Parameter
OUTPUT CHARACTERISTICS
Offset Voltage
vs. Temperature
Voltage Swing,
±15 V Supply, 2 kΩ Load
Voltage Swing,
±3 V Supply, 2 kΩ Load
Output Current
Short-Circuit Current
Resistance
Chip Select High
Resistance
Chip Select Low
dB OUTPUT
Error, VIN 7 mV to 7 V rms,
0 dB = 1 V rms
Scale Factor
Scale Factor Temperature
Coefficient
Min
IREF for 0 dB = 1 V rms
IREF Range
BUFFER AMPLIFIER
Input Output
Voltage Range
Input Offset Voltage
Input Current
Input Resistance
Output Current
Short-Circuit Current
Small Signal Bandwidth
Slew Rate 6
DENOMINATOR INPUT
Input Range
Input Resistance
Offset Voltage
CHIP SELECT (CS)
RMS On Level
RMS Off Level
IOUT of Chip Select
CS Low
CS High
On Time Constant
Off Time Constant
POWER SUPPLY
Operating Voltage Range
Quiescent Current
Standby Current
5
1
AD637J/AD637A
Typ
Max
0 to 12.0
±0.05
13.5
0 to 2
2.2
±1
±0.089
0 to 12.0
±0.04
13.5
0 to 2
2.2
Min
AD637S
Typ
0 to 12.0
±0.04
13.5
0 to 2
2.2
V
±0.5
±0.056
Max
Unit
±1
±0.07
mV
mV/°C
V
20
0.5
20
0.5
20
0.5
mA
mA
Ω
100
100
100
kΩ
±0.5
±0.3
±0.5
dB
−3
+0.33
−3
+0.33
−3
+0.33
mV/dB
% of
reading/°C
dB/°C
μA
μA
6
6
−0.033
20
80
100
−VS to (+VS − 2.5 V)
±0.8
±2
108
−0.13
5
1
−0.033
20
±0.5
±2
108
±2
±10
+5
0 to 10
25
±0.2
6
80
100
−VS to (+VS − 2.5 V)
−0.13
20
1
5
20
AD637K/AD637B
Typ
Max
Min
−0.033
20
5
1
−VS to (+VS − 2.5 V)
±0.8
±2
108
±1
±5
+5
−0.13
20
1
5
30
±0.5
20
0 to 10
25
±0.2
80
100
V
±2
±10
+5
20
1
5
30
±0.5
0 to 10
25
±0.2
20
30
±0.5
Open or 2.4 V < VC < +VS
VC < 0.2 V
VC < 0.2 V
Open or 2.4 V < VC < +VS
VC < 0.2 V
Open or 2.4 V < VC < +VS
10
0
10 + ((25 kΩ) × CAV)
10 + ((25 kΩ) × CAV)
10
0
10 + ((25 kΩ) × CAV)
10 + ((25 kΩ) × CAV)
10
0
10 + ((25 kΩ) × CAV)
10 + ((25 kΩ) × CAV)
±3.0
2.2
350
±18
3
450
±3.0
2.2
350
1
±18
3
450
±3.0
2.2
350
±18
3
450
mV
nA
Ω
mA
mA
MHz
V/μs
V
kΩ
mV
μA
μA
μs
μs
V
mA
μA
Specifications shown in bold are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels.
All minimum and maximum specifications are guaranteed, although only those shown in boldface are tested on all production units.
2
Accuracy specified 0 V rms to 7 V rms dc with AD637 connected, as shown in Figure 5.
3
Nonlinearity is defined as the maximum deviation from the straight line connecting the readings at 10 mV and 2 V.
4
Error vs. crest factor is specified as additional error for 1 V rms.
5
Input voltages are expressed in volts rms. Percent is in % of reading.
6
With external 2 kΩ pull-down resistor tied to −VS.
Rev. K | Page 4 of 20
AD637
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
ESD Rating
Supply Voltage
Internal Quiescent Power Dissipation
Output Short-Circuit Duration
Storage Temperature Range
Lead Temperature (Soldering 10 sec)
Rated Operating Temperature Range
AD637J, AD637K
AD637A, AD637B
AD637S, 5962-8963701CA
Rating
500 V
±18 V dc
108 mW
Indefinite
−65°C to +150°C
300°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent 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
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
ESD CAUTION
0°C to 70°C
−40°C to +85°C
−55°C to +125°C
Rev. K | Page 5 of 20
AD637
PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS
14
BUFF OUT
NC 2
13
VIN
12
NC
COMMON 3
AD637
BUFF IN 1
COMMON 3
TOP VIEW 11 +VS
(Not to Scale)
10 –VS
CS 5
OUTPUT OFFSET 4
OUTPUT OFFSET 4
CS 5
9
RMS OUT
dB OUTPUT 7
8
CAV
DEN INPUT 6
dB OUTPUT 7
00788-002
DEN INPUT 6
NC = NO CONNECT
16 BUFF OUT
NC 2
NC 8
15 VIN
AD637
14 NC
13 +VS
TOP VIEW
(Not to Scale) 12 –VS
11 RMS OUT
10 CAV
9
NC
NC = NO CONNECT
Figure 2. 14-Lead SBDIP/CERDIP Pin Configuration
00788-003
BUFF IN 1
Figure 3. 16-Lead SOIC_W Pin Configuration
Table 3. 14-Lead SBDIP/CERDIP Pin Function Descriptions
Table 4. 16-Lead SOIC_W Pin Function Descriptions
Pin No.
1
2, 12
3
4
5
6
7
8
9
10
11
13
14
Pin No.
1
2, 8, 9, 14
3
4
5
6
7
10
11
12
13
15
16
Mnemonic
BUFF IN
NC
COMMON
OUTPUT OFFSET
CS
DEN INPUT
dB OUTPUT
CAV
RMS OUT
−VS
+VS
VIN
BUFF OUT
Description
Buffer Input
No Connection
Analog Common
Output Offset
Chip Select
Denominator Input
dB Output
Averaging Capacitor Connection
RMS Output
Negative Supply Rail
Positive Supply Rail
Signal Input
Buffer Output
Rev. K | Page 6 of 20
Mnemonic
BUFF IN
NC
COMMON
OUTPUT OFFSET
CS
DEN INPUT
dB OUTPUT
CAV
RMS OUT
−VS
+VS
VIN
BUFF OUT
Description
Buffer Input
No Connection
Analog Common
Output Offset
Chip Select
Denominator Input
dB Output
Averaging Capacitor Connection
RMS Output
Negative Supply Rail
Positive Supply Rail
Signal Input
Buffer Output
AD637
FUNCTIONAL DESCRIPTION
FILTER/AMPLIFIER
BUFF OUT 14
1
BUFFER
AMPLIFIER
A5
24kΩ
A4
I4
I1
24kΩ
Q4
Q1
ABSOLUTE VALUE VOLTAGE TO
CURRENT CONVERTER
6kΩ
Q2
6kΩ
Q5
Q3
BIAS
I3
A3
12kΩ
125Ω
CAV
11
+VS
9
RMS
OUT
7
dB
OUTPUT
3
COMMON
5
CS
6
DEN
INPUT
4
OUTPUT
OFFSET
10
–VS
24kΩ
A2
VIN 13
8
AD637
A1
00788-004
BUFF IN
ONE QUADRANT
SQUARER/DIVIDER
Figure 4. Simplified Schematic
The AD637 embodies an implicit solution of the rms equation
that overcomes the inherent limitations of straightforward rms
computation. The actual computation performed by the AD637
follows the equation
⎡ V 2 ⎤
V rms = Avg ⎢ IN ⎥
⎣⎢ V rms ⎦⎥
Figure 4 is a simplified schematic of the AD637, subdivided
into four major sections: absolute value circuit (active rectifier),
squarer/divider, filter circuit, and buffer amplifier. The input
voltage (VIN), which can be ac or dc, is converted to a unipolar
current I1 by the active rectifiers A1 and A2. I1 drives one input
of the squarer/divider, which has the transfer function
2
I4 =
I1
I3
To compute the absolute value of the input signal, the averaging
capacitor is omitted. However, a small capacitance value at the
averaging capacitor pin is recommended to maintain stability;
5 pF is sufficient for this purpose. The circuit operates identically
to that of the rms configuration, except that I3 is now equal to
I4, giving
I4 =
I 12
I4
I4 = |I1|
The denominator current can also be supplied externally by
providing a reference voltage (VREF) to Pin 6. The circuit operates
identically to the rms case, except that I3 is now proportional to
VREF. Therefore,
I 4 = Avg
The output current of the squarer/divider I4 drives A4, forming
a low-pass filter with the external averaging capacitor. If the RC
time constant of the filter is much greater than the longest period
of the input signal, then the A4 output is proportional to the
average of I4. The output of this filter amplifier is used by A3
to provide the denominator current I3, which equals Avg I4 and
is returned to the squarer/divider to complete the implicit rms
computation
I 12
I3
and
VOUT =
VIN 2
VDEN
This is the mean square of the input signal.
⎡I 2 ⎤
I 4 = Avg ⎢ 1 ⎥ = I 1 rms
⎣ I4 ⎦
and
VOUT = VIN rms
Rev. K | Page 7 of 20
AD637
20
AD637
1 BUFF IN
2 NC
+VS
4.7kΩ
(OPTIONAL)
SQUARER/
DIVIDER
+VS
5 CS
25kΩ
–VS
DEN
6 INPUT 25kΩ
11
10
9
+VS
–VS
VOUT = VIN2
+ CAV
CAV 8
00788-005
7 dB OUTPUT
5
0
±3
±5
±10
±15
SUPPLY VOLTAGE – DUAL SUPPLY (V)
±18
CHIP SELECT
VIN
NC 12
BIAS
10
Figure 6. Maximum VOUT vs. Supply Voltage
VIN 13
3 COMMON
15
0
BUFF
OUT 14
NC
ABSOLUTE
VALUE
OUTPUT
4 OFFSET
MAX VOUT (Volts 2kΩ Load)
The AD637 is simple to connect for a majority of rms
measurements. In the standard rms connection shown in Figure 5,
only a single external capacitor is required to set the averaging
time constant. In this configuration, the AD637 computes the
true rms of any input signal. An averaging error, the magnitude
of which is dependent on the value of the averaging capacitor,
is present at low frequencies. For example, if the filter capacitor,
CAV, is 4 μF, the error is 0.1% at 10 Hz and increases to 1% at
3 Hz. To measure ac signals, the AD637 can be ac-coupled by
adding a nonpolar capacitor in series with the input, as shown
in Figure 5.
00788-006
STANDARD CONNECTION
The AD637 includes a chip select feature that allows the user
to decrease the quiescent current of the device from 2.2 mA to
350 μA. This is done by driving CS, Pin 5, to below 0.2 V dc.
Under these conditions, the output goes into a high impedance
state. In addition to reducing the power consumption,
the outputs of multiple devices can be connected in parallel
to form a wide bandwidth rms multiplexer. Tie Pin 5 high to
disable the chip select.
OPTIONAL TRIMS FOR HIGH ACCURACY
Figure 5. Standard RMS Connection
The performance of the AD637 is tolerant of minor variations
in the power supply voltages; however, if the supplies used
exhibit a considerable amount of high frequency ripple, it is
advisable to bypass both supplies to ground through a 0.1 μF
ceramic disc capacitor placed as close to the device as possible.
The output signal range of the AD637 is a function of the
supply voltages, as shown in Figure 6. The output signal can be
used buffered or nonbuffered, depending on the characteristics
of the load. If no buffer is needed, tie the buffer input (Pin 1) to
common. The output of the AD637 is capable of driving 5 mA
into a 2 kΩ load without degrading the accuracy of the device.
The AD637 includes provisions for trimming out output offset
and scale factor errors resulting in significant reduction in the
maximum total error, as shown in Figure 7. The residual error is
due to a nontrimmable input offset in the absolute value circuit
and the irreducible nonlinearity of the device.
Referring to Figure 8, the trimming process is as follows:
• Offset trim: Ground the input signal (VIN) and adjust R1 to
give 0 V output from Pin 9. Alternatively, R1 can be adjusted
to give the correct output with the lowest expected value of VIN.
• Scale factor trim: Resistor R4 is inserted in series with the
input to lower the range of the scale factor. Connect the
desired full-scale input to VIN, using either a dc or a calibrated ac
signal, and trim Resistor R3 to give the correct output at Pin 9
(that is, 1 V dc at the input results in a dc output voltage of
l.000 V dc). A 2 V p-p sine wave input yields 0.707 V dc at the
output. Remaining errors are due to the nonlinearity.
Rev. K | Page 8 of 20
AD637
5.0
EO
IDEAL
EO
AD637K MAX
DC ERROR = AVERAGE OF OUTPUT – IDEAL
2.5
INTERNAL TRIM
0
DOUBLE-FREQUENCY
RIPPLE
00788-009
ERROR (mV)
AVERAGE ERROR
AD637K
EXTERNAL TRIM
TIME
Figure 9. Typical Output Waveform for a Sinusoidal Input
–2.5
AD637K: 0.5mV ± 0.2%
0.25mV ± 0.05%
EXTERNAL
0
0.5
1.0
INPUT LEVEL (V)
1.5
2.0
00788-007
–5.0
This ripple can add a significant amount of uncertainty to the
accuracy of the measurement being made. The uncertainty can
be significantly reduced through the use of a postfiltering
network or by increasing the value of the averaging capacitor.
Figure 7. Maximum Total Error vs.
Input Level AD637K Internal and External Trims
AD637
1 BUFF IN
2 NC
OUTPUT
OFFSET
TRIM
+VS
R1
50kΩ
–VS
BUFF
OUT
ABSOLUTE
VALUE
3 COMMON
R2
1MΩ
+VS
OUTPUT
4 OFFSET
4.7kΩ
SQUARER/
DIVIDER
5 CS
R4
13 147Ω VIN
NC
12
–VS
25kΩ
DEN
6 INPUT 25kΩ
1
in % of reading
0.16 + 6.4 τ2 f 2
14
NC
VIN
+VS
BIAS
The dc error appears as a frequency dependent offset at the
output of the AD637 and follows the relationship
11
10
9
Because the averaging time constant, set by CAV, directly sets
the time that the rms converter holds the input signal during
computation, the magnitude of the dc error is determined only
by CAV and is not affected by postfiltering.
+VS
–VS
VOUT = VIN2
100
SCALE FACTOR TRIM
R3
1kΩ
Figure 8. Optional External Gain and Offset Trims
CHOOSING THE AVERAGING TIME CONSTANT
The AD637 computes the true rms value of both dc and ac
input signals. At dc, the output tracks the absolute value of the
input exactly; with ac signals, the AD637 output approaches the
true rms value of the input. The deviation from the ideal rms
value is due to an averaging error. The averaging error
comprises an ac component and a dc component. Both
components are functions of input signal frequency f and the
averaging time constant τ (τ: 25 ms/μF of averaging capacitance).
Figure 9 shows that the averaging error is defined as the peak
value of the ac component (ripple) and the value of the dc error.
The peak value of the ac ripple component of the averaging
error is defined approximately by the relationship
50
in % of reading where (τ > 1 f )
6.3 τf
10
PEAK RIPPLE
1.0
DC ERROR
0.1
10
100
1k
SINE WAVE INPUT FREQUENCY (Hz)
10k
00788-010
8
00788-008
CAV
7 dB OUTPUT
DC ERROR OR RIPPLE (% of Reading)
+ CAV
Figure 10. Comparison of Percent DC Error to the Percent Peak Ripple over
Frequency Using the AD637 in the Standard RMS Connection with a 1 × μF CAV
The ac ripple component of averaging error is greatly reduced
by increasing the value of the averaging capacitor. There are two
major disadvantages to this: the value of the averaging capacitor
becomes extremely large and the settling time of the AD637
increases in direct proportion to the value of the averaging
capacitor (TS = 115 ms/μF of averaging capacitance). A preferable
method of reducing the ripple is by using the postfilter network,
as shown in Figure 11. This network can be used in either a 1pole or 2-pole configuration. For most applications, the 1-pole
filter gives the best overall compromise between ripple and
settling time.
Rev. K | Page 9 of 20
AD637
REQUIRED CAV (µF)
+ CAV
1
FOR A SINGLE-POLE
FILTER SHORT RX
AND REMOVE C3
00788-011
C2
24kΩ
100
1k
INPUT FREQUENCY (Hz)
100
*%dc ERROR + %RIPPLE (PEAK)
ACCURACY ±20% DUE TO
COMPONENT TOLERANCE
REQUIRED CAV (AND C2)
C2 = 3.3 × CAV
1
1
0.1
0.01
1
10
100
1k
INPUT FREQUENCY (Hz)
0.1
10k
0.01
100k
100
100
10
10
R
RO
R
ER
O
%
R
01
ER OR
0.
R
R
ER RO
ER
1
1
1%
0.
5%
REQUIRED CAV (AND C2 + C3)
C2 = C3 = 2.2 × CAV
Figure 13. Values of CAV, C2, and 1% Settling Time for Stated % of Reading
Averaging Error* for 1-Pole Post Filter (see * in Figure)
1%
Figure 14 can be used to determine the required value of CAV,
C2, and C3 for the desired level of ripple and settling time.
R
O
R
R
ER
O
R
%
01
R
ER
0.
O
R
1%
R
0.
ER RO
ER
For applications that are extremely sensitive to ripple, the 2-pole
configuration is suggested. This configuration minimizes capacitor
values and the settling time while maximizing performance.
10
5%
The symmetry of the input signal also has an effect on the
magnitude of the averaging error. Table 5 gives the practical
component values for various types of 60 Hz input signals.
These capacitor values can be directly scaled for frequencies
other than 60 Hz—that is, for 30 Hz, these values are doubled,
and for 120 Hz they are halved.
10
100
1%
Figure 13 shows the relationship between the averaging error,
signal frequency settling time, and averaging capacitor value.
Figure 13 is drawn for filter capacitor values of 3.3× the
averaging capacitor value. This ratio sets the magnitude of the
ac and dc errors equal at 50 Hz. As an example, by using a 1 μF
averaging capacitor and a 3.3 μF filter capacitor, the ripple for
a 60 Hz input signal is reduced from 5.3% of the reading using
the averaging capacitor alone to 0.15% using the 1-pole filter.
This gives a factor of 30 reduction in ripple, and yet the settling
time only increases by a factor of 3. The values of filter
Capacitor CAV and Filter Capacitor C2 can be calculated for
the desired value of averaging error and settling time by using
Figure 13.
0.01
100k
Figure 12. Values for CAV and 1% Settling Time for Stated % of Reading Averaging
Error* Accuracy Includes ±2% Component Tolerance (see * in Figure)
Figure 11. 2-Pole Sallen-Key Filter
Figure 12 shows values of CAV and the corresponding averaging
error as a function of sine wave frequency for the standard rms
connection. The 1% settling time is shown on the right side of
Figure 12.
10k
FOR 1% SETTLING TIME IN SECONDS
MULTIPLY READING BY 0.400
RX
24kΩ
10
00788-012
*%dc ERROR + %RIPPLE (PEAK)
0.01
+
FOR 1% SETTLING TIME IN SECONDS
MULTIPLY READING BY 0.115
0.1
00788-013
CAV 8
0.1
0.1
0.01
0.1
*%dc ERROR + %RIPPLE (PEAK)
ACCURACY ±20% DUE TO
COMPONENT TOLERANCE
1
10
100
1k
INPUT FREQUENCY (Hz)
10k
FOR 1% SETTLING TIME IN SECONDS
MULTIPLY READING BY 0.365
7 dB OUTPUT
1.0
0.01
100k
Figure 14. Values of CAV, C2, and C3 and 1% Settling Time for Stated % of
Reading Averaging Error* for 2-Pole Sallen-Key Filter (see * in Figure)
Rev. K | Page 10 of 20
00788-014
9
–VS
R
DEN
6 INPUT 25kΩ
R
10
1.0
R
–VS
25kΩ
+VS
R
+VS 4.7kΩ 5 CS
11
RO
ER
+VS
O
R
ER
BIAS
C3
10
RO
ER
NC 12
SQUARER/
DIVIDER
10
+
%
10
OUTPUT
4 OFFSET
VIN
1%
3 COMMON
RO
ER
VIN 13
ABSOLUTE
VALUE
RMS OUT
%
01
0.
BUFF
OUT 14
1%
0.
2 NC
100
100
AD637
1 BUFF IN
AD637
Table 5. Practical Values of CAV and C2 for Various Input Waveforms
Input Waveform
and Period
Absolute Value
Circuit Waveform
and Period
1/2T
T
A
Minimum R × CAV
Time Constant
1/2T
Recommended Standard Values for CAV and C2
for 1% Averaging Error @ 60 Hz with T = 16.6 ms
C2 (μF)
CAV (μF)
0.47
1.5
1% Settling
Time
181 ms
T
0.82
2.7
325 ms
10 (T − T2)
6.8
22
2.67 sec
10 (T − 2T2)
5.6
18
2.17 sec
0V
Symmetrical Sine Wave
T
T
B
0V
Sine Wave with dc Offset
T
C
T
T2
T2
0V
Pulse Train Waveform
T
T
D
T2
0V
T2
FREQUENCY RESPONSE
10
7V RMS INPUT
2V RMS INPUT
To take full advantage of the wide bandwidth of the AD637,
care must be taken in the selection of the input buffer amplifier.
To ensure that the input signal is accurately presented to the
converter, the input buffer must have a −3 dB bandwidth that is
wider than that of the AD637. Note the importance of slew rate
in this application. For example, the minimum slew rate required
for a 1 V rms, 5 MHz, sine wave input signal is 44 V/μs. The user is
cautioned that this is the minimum rising or falling slew rate
and that care must be exercised in the selection of the buffer
amplifier, because some amplifiers exhibit a two-to-one
difference between rising and falling slew rates. The AD845 is
recommended as a precision input buffer.
Rev. K | Page 11 of 20
1V RMS INPUT
1
1%
0.1
0.01
10%
±3dB
100mV RMS INPUT
10mV RMS INPUT
1k
10k
100k
INPUT FREQUENCY (Hz)
1M
Figure 15. Frequency Response
10M
00788-015
VOUT (V)
The frequency response of the AD637 at various signal levels is
shown in Figure 15. The dashed lines show the upper frequency
limits for 1%, 10%, and ±3 dB of additional error. For example,
note that for 1% additional error with a 2 V rms input, the
highest frequency allowable is 200 kHz. A 200 mV signal can
be measured with 1% error at signal frequencies up to 100 kHz.
AD637
1.5
AC MEASUREMENT ACCURACY AND CREST
FACTOR
INCREASE IN ERROR (%)
1.0
Crest factor is often overlooked in determining the accuracy of
an ac measurement. Crest factor is defined as the ratio of the peak
signal amplitude to the rms value of the signal (CF = VP/V rms).
Most common waveforms, such as sine and triangle waves, have
relatively low crest factors (≤2). Waveforms that resemble low
duty cycle pulse trains, such as those occurring in switching
power supplies and SCR circuits, have high crest factors. For
example, a rectangular pulse train with a 1% duty cycle has
0.5
0
–0.5
POSITIVE INPUT PULSE
CAV = 22µF
–1.0
–1.5
Vp
100µs
e0
eIN(RMS) = 1 V RMS
1
MAGNITUDE OF ERROR (% of RMS Level)
INCREASE IN ERROR (%)
CAV = 22µF
1
CF = 10
0.1
5
6
7
CREST FACTOR
8
9
10
11
1.8
1.6
1.4
1.2
1000
00788-017
CF = 3
Figure 17. AD637 Error vs. Pulse Width Rectangular Pulse
Figure 18 is a curve of additional reading error for the AD637
for a 1 V rms input signal with crest factors from 1 to 11.
A rectangular pulse train (pulse width 100 μs) is used for this
test because it is the worst-case waveform for rms measurement
(all the energy is contained in the peaks). The duty cycle and
peak amplitude were varied to produce crest factors from l to 10
while maintaining a constant 1 V rms input amplitude.
CF = 10
1.0
0.8
CF = 7
0.6
0.4
0.2
0
10
100
PULSE WIDTH (µs)
4
2.0
10
1
3
Figure 18. Additional Error vs. Crest Factor
Figure 16. Duty Cycle Timing
0.01
2
CF = 3
0
0.5
1.0
VIN (V RMS)
1.5
2.0
00788-019
0
100µs
η = DUTY CYCLE =
T
CF = 1/ η
00788-016
T
00788-018
a crest factor of 10 (CF = 1 η ).
Figure 19. Error vs. RMS Input Level for Three Common Crest Factors
CONNECTION FOR dB OUTPUT
Another feature of the AD637 is the logarithmic, or decibel,
output. The internal circuit that computes dB works well over
a 60 dB range. Figure 20 shows the dB measurement connection.
The user selects the 0 dB level by setting R1 for the proper 0 dB
reference current, which is set to cancel the log output current
from the squarer/divider circuit at the desired 0 dB point. The
external op amp is used to provide a more convenient scale and to
allow compensation of the +0.33%/°C temperature drift of the
dB circuit. The temperature resistor R3, as shown in Figure 20,
is available from Precision Resistor Co., Inc., in Largo, Fla.
(Model PT146). Consult its website for additional information.
Rev. K | Page 12 of 20
AD637
dB CALIBRATION
Refer to Figure 20:
• Set VIN = 1.00 V dc or 1.00 V rms
• Adjust R1 for 0 dB out = 0.00 V
• Set VIN = 0.1 V dc or 0.10 V rms
• Adjust R2 for dB out = −2.00 V
Any other dB reference can be used by setting VIN and R1
accordingly.
R2
33.2kΩ
SIGNAL
INPUT
dB SCALE
FACTOR
ADJUST
5kΩ
+VS
BUFFER
AD637
1 BUFF IN
R3
1kΩ*
BUFF
OUT 14
60.4Ω
2 NC
ABSOLUTE
VALUE
3 COMMON
OUTPUT
4 OFFSET
+VS
4.7kΩ
BIAS
SECTION
3
+VS
25kΩ
5 CS
–VS
+VS
10
9
7 dB OUTPUT
8
–VS
VOUT
+
FILTER
4
6
COMPENSATED
dB OUTPUT
+ 100mV/dB
–VS
11
DEN
6 INPUT 25kΩ
7
AD707JN
VIN 13
NC 12
SQUARER/DIVIDER
2
1µF
CAV
10kΩ
NC = NO CONNECT
+VS
R1
500kΩ
+2.5 V
AD508J
00788-020
0dB ADJUST
*1kΩ + 3500ppm
SEE TEXT
Figure 20. dB Connection
Rev. K | Page 13 of 20
AD637
V+
1µF
3.3MΩ
BUFFER
2 NC
3 COMMON
+VS
OUTPUT
OFFSET 50kΩ
ADJUST
VIN 13
AD548JN
2
4
6
FILTERED
V RMS OUTPUT
V–
SIGNAL
INPUT
6.8MΩ
NC 12
BIAS
SECTION
OUTPUT
4 OFFSET
1MΩ
+VS
–VS
ABSOLUTE
VALUE
7
3
1µF
BUFF
OUT 14
AD637
1 BUFF IN
3.3MΩ
SQUARER/DIVIDER
25kΩ
5 CS
4.7kΩ
+VS
–VS
25kΩ
11
10
+
FILTER
CAV 8
–VS
VOUT
9
6 DEN
INPUT
7
dB OUTPUT
1000pF
+VS
100µF
VIN2
V RMS
499kΩ 1%
R
CAV1
3.3µF
00788-021
NOTES
1. VALUES CHOSEN TO GIVE 0.1% AVERAGING ERROR @ 1Hz.
2. NC = NO CONNECT.
Figure 21. AD637 as a Low Frequency RMS Converter
LOW FREQUENCY MEASUREMENTS
VECTOR SUMMATION
If the frequencies of the signals to be measured are below 10 Hz,
the value of the averaging capacitor required to deliver even 1%
averaging error in the standard rms connection becomes
extremely large. Figure 21 shows an alternative method of
obtaining low frequency rms measurements. The averaging
time constant is determined by the product of R and CAV1, in
this circuit, 0.5 sec/μF of CAV. This circuit permits a 20:1
reduction in the value of the averaging capacitor, permitting the
use of high quality tantalum capacitors. It is suggested that the
2-pole, Sallen-Key filter shown in Figure 21 be used to obtain a
low ripple level and minimize the value of the averaging
capacitor.
Vector summation can be accomplished through the use of two
AD637s, as shown in Figure 22. Here, the averaging capacitors
are omitted (nominal 100 pF capacitors are used to ensure
stability of the filter amplifier), and the outputs are summed as
shown. The output of the circuit is
If the frequency of interest is below 1 Hz, or if the value of the
averaging capacitor is still too large, the 20:1 ratio can be
increased. This is accomplished by increasing the value of R.
If this is done, it is suggested that a low input current, low offset
voltage amplifier, such as the AD548, be used instead of the
internal buffer amplifier. This is necessary to minimize the
offset error introduced by the combination of amplifier input
currents and the larger resistance.
VOUT = VX 2 + VY 2
This concept can be expanded to include additional terms by
feeding the signal from Pin 9 of each additional AD637 through
a 10 kΩ resistor to the summing junction of the AD711 and
tying all of the denominator inputs (Pin 6) together.
If CAV is added to IC1 in this configuration, then the output is
VX 2 + VY 2
If the averaging capacitor is included on both IC1 and IC2, the
output is
V X 2 + VY 2
This circuit has a dynamic range of 10 V to 10 mV and is
limited only by the 0.5 mV offset voltage of the AD637.
The useful bandwidth is 100 kHz.
Rev. K | Page 14 of 20
AD637
EXPANDABLE
BUFFER
1
BUFF IN
IC1
AD637
ABSOLUTE
VALUE
2 NC
3 COMMON
14
VXIN 13
NC 12
BIAS
SECTION
OUTPUT
4 OFFSET
SQUARER/DIVIDER
25kΩ
5 CS
+VS
–VS
11
10
4.7kΩ
VOUT
25kΩ
6
DEN
INPUT
7
+VS
–VS
9
100pF
FILTER
dB OUTPUT
BUFFER
1 BUFF IN
2 NC
IC2
AD637
ABSOLUTE
VALUE
3 COMMON
+VS
BIAS
SECTION
DEN
6 INPUT
BUFF
OUT
14
VYIN
AD711K
13
10kΩ
NC 12
SQUARER/DIVIDER
25kΩ
5 CS
4.7kΩ
CAV
10kΩ
10kΩ
OUTPUT
4 OFFSET
5pF
8
+VS
–VS
25kΩ
11
+VS
10
9
20kΩ
–VS
VOUT
100pF
7
dB OUTPUT
FILTER
8
VOUT =
Figure 22. Vector Sum Configuration
Rev. K | Page 15 of 20
VX2 + VY2
00788-022
+VS
BUFF
OUT
AD637
EVALUATION BOARD
amp, and is configured on the AD637-EVALZ as a low-pass
Sallen-Key filter whose fC < 0.5 Hz. Users can connect to the
buffer by moving the FILTER switch to the on position.
DC_OUT is still the output of the AD637, and the test loop,
BUF_OUT, is the output of the buffer. The R2 trimmer adjusts
the output offset voltage.
Referring to the schematic in Figure 30, the input connector
RMS_IN is capacitively coupled to Pin 15 (VIN of SOIC package) of
the AD637. The DC_OUT connector is connected to Pin 11,
RMS OUT, with provisions for connections to the output buffer
between Pin 1 and Pin 16. The buffer is an uncommitted op
The LPF frequency is changed by changing the component
values of CF1, CF2, R4, and R5. See Figure 24 and Figure 30 to
locate these components. Note that a wide range of capacitor
and resistor values can be used with the AD637 buffer amplifier.
00788-123
Figure 23 shows a digital image of the AD637-EVALZ, an
evaluation board specially designed for the AD637. It is
available at www.analog.com and is fully tested and ready for
bench testing after connecting power and signal I/O. The circuit
is configured for dual power supplies, and standard BNC
connectors serve as the signal input and output ports.
Figure 23. AD637-EVALZ
Rev. K | Page 16 of 20
00788-124
00788-127
AD637
Figure 27. Evaluation Board—Secondary Side Copper
00788-125
00788-128
Figure 24. AD637-EVALZ Assembly
Figure 25. Component Side Silkscreen
00788-129
00788-126
Figure 28. Evaluation Board—Internal Power Plane
Figure 29. Evaluation Board—Internal Ground Plane
Figure 26. Evaluation Board—Component Side Copper
Rev. K | Page 17 of 20
AD637
–VS
GND1 GND2 GND3 GND4
C1
10µF
25V
+VS
+ C2
10µF
25V
+
–VS
+VS
FILTER
BUF_IN
4
1
2
OUT
5
3
6
1
IN
BUFF OUT
BUFF IN
16
2
3
+VS
R1
1MΩ
R2
50kΩ
+VS
4
R3
4.7kΩ 5
–VS
6
7
NC
Z1
AD637
COMMON
NC
OUTPUT
OFFSET
+VS
CS
–VS
DEN INPUT
dB OUTPUT
DB_OUT
8
VIN
RMS OUT
CAV
NC
NC
R4
24.3kΩ
15
+
RMS_IN
14
CIN
22µF
16V
RMS_IN
13
12
11
BUF_OUT
C3
0.1µF
C4
0.1µF
+VS
–VS
DC_OUT
DC_OUT
+ CAV
10
22µF
16V
9
+ CF1
R5
24.3kΩ
47µF
25V
00788-130
+ CF2
47µF
25V
Figure 30. Evaluation Board Schematic
AC OR DC INPUT SIGNAL SOURCE
FROM PRECISION CALIBRATOR
OR FUNCTION GENERATOR
PRECISION DMM TO
MONITOR VOUT
Figure 31. AD637-EVALZ Typical Bench Configuration
Rev. K | Page 18 of 20
00788-131
POWER
SUPPLY
AD637
OUTLINE DIMENSIONS
0.005 (0.13) MIN
0.080 (2.03) MAX
8
14
1
PIN 1
0.310 (7.87)
0.220 (5.59)
7
0.100 (2.54)
BSC
0.765 (19.43) MAX
0.200 (5.08)
MAX
0.200 (5.08)
0.125 (3.18)
0.023 (0.58)
0.014 (0.36)
0.060 (1.52)
0.015 (0.38)
0.320 (8.13)
0.290 (7.37)
0.150
(3.81)
MIN
SEATING
PLANE
0.070 (1.78)
0.030 (0.76)
0.015 (0.38)
0.008 (0.20)
CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
Figure 32. 14-Lead Side-Brazed Ceramic Dual In-Line Package [SBDIP]
(D-14)
Dimensions shown in inches and (millimeters)
0.005 (0.13) MIN
14
1
PIN 1
0.098 (2.49) MAX
8
0.310 (7.87)
0.220 (5.59)
7
0.100 (2.54) BSC
0.785 (19.94) MAX
0.200 (5.08)
MAX
0.200 (5.08)
0.125 (3.18)
0.023 (0.58)
0.014 (0.36)
0.320 (8.13)
0.290 (7.37)
0.060 (1.52)
0.015 (0.38)
0.150
(3.81)
MIN
SEATING
0.070 (1.78) PLANE
0.030 (0.76)
15°
0°
0.015 (0.38)
0.008 (0.20)
CONTROLLING DIMENSIONS ARE IN INCHES; MILLIMETER DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF INCH EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
Figure 33. 14-Lead Ceramic Dual In-Line Package [CERDIP]
(Q-14)
Dimensions shown in inches and (millimeters)
Rev. K | Page 19 of 20
AD637
10.50 (0.4134)
10.10 (0.3976)
9
16
7.60 (0.2992)
7.40 (0.2913)
10.65 (0.4193)
10.00 (0.3937)
8
1.27 (0.0500)
BSC
0.30 (0.0118)
0.10 (0.0039)
COPLANARITY
0.10
0.75 (0.0295)
45°
0.25 (0.0098)
2.65 (0.1043)
2.35 (0.0925)
SEATING
PLANE
0.51 (0.0201)
0.31 (0.0122)
8°
0°
0.33 (0.0130)
0.20 (0.0079)
COMPLIANT TO JEDEC STANDARDS MS-013-AA
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN.
1.27 (0.0500)
0.40 (0.0157)
03-27-2007-B
1
Figure 34. 16-Lead Standard Small Outline Package [SOIC_W]
Wide Body (RW-16)
Dimensions shown in millimeters and (inches)
ORDERING GUIDE
Model 1
5962-8963701CA
AD637AQ
AD637AR
AD637ARZ
AD637BQ
AD637BR
AD637BRZ
AD637JD
AD637JDZ
AD637JQ
AD637JR
AD637JR-REEL
AD637JR-REEL7
AD637JRZ
AD637JRZ-RL
AD637JRZ-R7
AD637KD
AD637KDZ
AD637KQ
AD637KRZ
AD637SD
AD637SD/883B
AD637SQ/883B
AD637-EVALZ
1
2
Notes
2
Temperature Range
−55°C to +125°C
−40°C to +85°C
−40°C to +85°C
−40°C to +85°C
−40°C to +85°C
−40°C to +85°C
−40°C to +85°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
0°C to 70°C
−55°C to +125°C
−55°C to +125°C
−55°C to +125°C
Package Description
14-Lead CERDIP
14-Lead CERDIP
16-Lead SOIC_W
16-Lead SOIC_W
14-Lead CERDIP
16-Lead SOIC_W
16-Lead SOIC_W
14-Lead SBDIP
14-Lead SBDIP
14-Lead CERDIP
16-Lead SOIC_W
16-Lead SOIC_W
16-Lead SOIC_W
16-Lead SOIC_W
16-Lead SOIC_W
16-Lead SOIC_W
14-Lead SBDIP
14-Lead SBDIP
14-Lead CERDIP
16-Lead SOIC_W
14-Lead SBDIP
14-Lead SBDIP
14-Lead CERDIP
Evaluation Board
Z = RoHS Compliant Part.
A standard microcircuit drawing is available.
©2007–2011 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D00788-0-2/11(K)
Rev. K | Page 20 of 20
Package Option
Q-14
Q-14
RW-16
RW-16
Q-14
RW-16
RW-16
D-14
D-14
Q-14
RW-16
RW-16
RW-16
RW-16
RW-16
RW-16
D-14
D-14
Q-14
RW-16
D-14
D-14
Q-14