AN-1106: An Improved Topology for Creating Split Rails from a Single Input Voltage (Rev. A) PDF

AN-1106
APPLICATION NOTE
One Technology Way • P.O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel: 781.329.4700 • Fax: 781.461.3113 • www.analog.com
An Improved Topology for Creating Split Rails from a Single Input Voltage
by Kevin Tompsett
INTRODUCTION
combination results in two supplies that track each other
very well under all but a 100% load mismatch.
An analysis of the converter’s operation and implementation
using the Analog Devices, Inc., ADP161x demonstrates the
versatility of this topology. In addition, a revolutionary new
design tool is introduced, providing a quick path to implementing a SEPIC-Ćuk in user applications.
One solution to this problem is to use two different converters;
one to provide the positive rail and one to provide the negative
rail. This can be expensive and, as this application note shows,
unnecessary. Another solution is using a flyback; however, the
supplies tend not to track each other very well with differential
loading, it requires a large and expensive transformer, and it
tends to be inefficient.
A better solution is a SEPIC-Ćuk converter. This topology
consists of an unregulated Ćuk converter tied to the same
switching node as a regulated SEPIC converter. This
VIN
L2a
L2b
–VOUT
C2
Q3
L1a
COUT2
Q2
+VOUT
C1
CIN
Q1
L1b
COUT1
09556-001
Even with the widespread use of rail-to-rail single supply op
amps, there is still often the requirement for dual rails (for
example, ±15 V) to be generated from a single (positive) input
power rail to power different parts of the analog signal chain.
These are often low current (such as 10 mA to 500 mA) with
relatively well-matched loads on the positive and negative
supplies.
Figure 1. Schematic of the SEPIC-Ćuk Converter
Rev. A | Page 1 of 12
AN-1106
Application Note
TABLE OF CONTENTS
Introduction ...................................................................................... 1
Power Component Stress .............................................................6
Revision History ............................................................................... 2
Output Filter ..................................................................................8
Description of Topology .................................................................. 3
ADP161x Design Tool ......................................................................9
Limits to the Coupling Coefficient ............................................ 4
Lab Results....................................................................................... 10
Differential Load and Output Voltage Tracking ...................... 4
References.................................................................................... 10
Small-Signal Analysis and Loop Compensation ...................... 5
Conclusion .................................................................................. 10
REVISION HISTORY
7/13—Rev. 0 to Rev. A
Changes to Figure 8 .......................................................................... 6
7/11—Revision 0: Initial Version
Rev. A | Page 2 of 12
Application Note
AN-1106
DESCRIPTION OF TOPOLOGY
Initially, the SEPIC-Ćuk appears to be a complicated converter
with four different inductors and switches. Fortunately, it can be
broken down into its two constituent converters, simplifying the
analytical problem. For a SEPIC or Ćuk converter, the Q1 and
Q2 switches operate in the opposite phase from one another.
Figure 2 shows the current flow diagram for the two different
switch states in a SEPIC converter.
L1b
COUT1
Q1
SN2
Q2
L1b
Figure 2. Current Flow in a SEPIC Converter
It is not immediately obvious, but the transfer capacitor
(C1) voltage is approximately constant VIN (with
small ripple).
Figure 4 shows the idealized waveforms for a SEPIC converter.
When Q1 is on, the voltage at SN2 is equal to −VIN. Thus,
during the time that Q1 is on (Q2 is off), the voltage across
both L1a and L1b is VIN and when Q1 is off (Q2 is on), then
the voltage across both L1a and L1b is −VOUT. Applying the
principles of inductor-volt second balance, the equilibrium dc
conversion ratio as shown in Equation 1 can be calculated. D
is the converter’s duty cycle (the fraction of the switching cycle
that Q1 is on).
VIN
D

(1  D)
COUT2
(Q1 IS OPEN, Q2 IS CLOSED)
L2a SN1 C2 SN2 L2b –V
OUT
Q1
Q2
COUT1
The idealized waveforms for a Ćuk converter are shown in
Figure 4. Applying the principles of inductor-volt second
balance and capacitor charge balance, the voltage across C2 is
VIN + VOUT. Therefore, the SN2 switch node switches between
GND, when Q2 is closed, and −(VIN + VOUT). The voltage across
both L2a and L2b while Q1 is on (Q2 is off), is VIN and, while
Q1 is off (Q2 is on), the voltage across both L2a and L2b
is −VOUT.
VOUT
COUT1
Q2
Figure 3. Current Flow in a Ćuk Converter
09556-002
L1a SN1 C1
Q1
Comparing the waveforms in Figure 4 and Figure 5, note that
the voltages across the inductors in a Ćuk are identical to those
for the SEPIC. Thus, the duty cycle equation for a Ćuk is simply
negative the duty cycle for the SEPIC,` as shown in Equation 2.
NODE VOLTAGES
VIN + VOUT
–VIN
(1)
The Ćuk converter operates in a similar manner to the SEPIC
converter, however, in this case, Switch Q2 is connected
to ground rather than the output and the Inductor L2b is
connected to the output instead of ground. Figure 3 shows a
current flow diagram for the Ćuk converter during both switch
positions.
SN1
SN2
COMPONENT CURRENTS
IL1a
IL1b
IOUT (IQ2)
IOUT/(1 – D)
D × IOUT (1 – D)
IOUT
The Ćuk is a negative output converter, so current flowing out
of the load is actually delivering power to the output.
Rev. A | Page 3 of 12
ON TIME
OFF TIME
ON TIME
Figure 4. Idealized Waveforms SEPIC
OFF TIME
09556-003
Q1
CIN
VOUT SEPIC
VIN
CIN
(Q1 IS OPEN; Q2 IS CLOSED)
VIN
CIN
(Q1 IS CLOSED; Q2 IS OPEN)
L1a SN1 C1 SN2 Q2
VOUT
CIN
(Q1 IS CLOSED, Q2 IS OPEN)
L2a SN1 C1 SN2 L2b –V
OUT
09556-004
VIN
VIN
AN-1106
Application Note
NODE VOLTAGES
LIMITS TO THE COUPLING COEFFICIENT
SN1
SN2
Even though coupling the inductors has distinct advantages, it
is undesirable for the coupling to be tight enough for there to
be significant energy transfer through the core. To avoid this
situation, the designer must ensure that the magnitude of the
complex impedance of C1 (and C2) at the switching frequency
is less than a tenth that of the impedance of the leakage
inductance (LLKG) plus the DCR of a single winding.
VIN + VOUT
–VIN – VOUT
COMPONENT CURRENTS
IL1a
IL1b
IQ2
This inequality is designated in Equation 5. The leakage
inductance (Ll) can be calculated using Equation 6 and
the coupling coefficient (K) generally found on coupled
inductor data sheets. Lm is the measured self-inductance that
appears in the data sheet. Note that in Equation 5, the x in Cx
and Lx refers to either C1 or C2 or L1 or L2.
–IOUT/(1 – D)
D × IOUT (1 – D)
OFF TIME
ON TIME
OFF TIME
09556-005
ON TIME
–IOUT
| Z Cx
Figure 5. Idealized Waveforms Ćuk
VOUT Cuk
VIN

D
(1  D)
(2)
The fact that the duty cycles are equal and opposite, the switch
node (SN1) voltages are identical, and the inductor currents
are identical is what makes it possible to simply attach the two
converters together at Node SN1. The combined converter is
shown in Figure 1.
Q2 and Q3 have been replaced by diodes because these supplies
are generally lower power analog supplies where an asynchronous controller makes good sense. In addition, two inductors
(L1a and L2a) are in parallel. The reason for this is that L1a and
L1b, and L2a and L2b, are coupled together using two separate
coupled inductors. This has multiple advantages.
Coupling the inductors reduces current ripple in the inductors
by a factor of two (see the Ćuk-Middlebrook paper cited in the
References section). In addition, it significantly reduces the
complexity of the small signal model and enables higher bandwidth by eliminating the SEPIC and Ćuk resonances located
according to Equation 3 and Equation 4. This enables the use of
a wide variety of off-the-shelf parts since there are not many
three winding 1:1:1 inductors available.
f SEPIC resonance 
f Cuk resonance 
1
2
L1a  L1b C1
1
2
L 2a  L 2b C 2
(3)

1

|= ESRC x 2 + 
2
C
f


C x sw

DCR L x 2  2L L
lkg
2
| Z Llkg |


Lx

 
10


Lx
10
Llkg  Lm (1  K )
(5)
(6)
DIFFERENTIAL LOAD AND OUTPUT VOLTAGE
TRACKING
By nature, the Ćuk (negative) output of the SEPIC-Ćuk is
unregulated; thus, there is some amount of load variation with
changes in output current and, particularly with load mismatch,
compared to the SEPIC (positive) output. Note that the tracking
is much better than a similarly configured flyback converter,
especially in the case of a transient or a load mismatch. This is
because the coupling between channels is a direct connection
rather than through the transformer with its inherent leakage
inductance.
Figure 6 shows a 30 mA transient applied to the Ćuk (−VOUT)
output of a SEPIC-Ćuk converter, while a constant 100 mA
remains on the SEPIC output. It shows that both outputs
respond to the transient load. This is the worst-case transient
because the Ćuk output is unregulated. Interestingly, most of
the deviation shown on the −VOUT rail is actually dc regulation
shift caused by the mismatch between the loads applied to the
two rails (IOUT+, IOUT−).
(4)
A six winding part, such as found in Coilcraft’s Hexapath line
product line, or a custom three winding transformer could also
be used.
Rev. A | Page 4 of 12
Application Note
AN-1106
ADP161x part in SEPIC-Ćuk and may not be accurate for other
parts made by Analog Devices or the company’s competitors.
VOUT+
C1
The small-signal model for a SEPIC-ĆUK looks very similar to
a SEPIC converter with no attached Ćuk as long as a few design
requirements are met. It is assumed that identical inductors are
used on the SEPIC-Ćuk rails. This requirement makes sense
because both outputs are designed for the same voltage and
current.
VOUT–
C3
C4
IOUT+
IOUT–
C1 F BWL AC1M
5.00mV/DIV
15.100mV
C2 F BWL DC
50.0mA/DIV
–199.00mA
TIMEBASE 0.00ms
500µs/DIV
500kS
100MS/s
C3 F BWL AC1M
5.00mV/DIV
2.900mV
C4 I F B DC
50.0mA/DIV
–50.00mV
TRIGGER
C3 DC
STOP
300µV
EDGE
POSITIVE
09556-006
C2
Figure 6. Transient Response from a 30 mA Step Load Applied
to the Negative (Ćuk) Output
With an identical load on both supplies, at steady state, the
most significant error terms are a mismatch in the DCR of the
inductors and the forward voltage of the diodes, both of which
can be made quite small relative to the output voltage.
With substantial load mismatch, the error grows as shown in
Figure 7. Therefore, in some applications it may be necessary to
put a small dummy load on one or both of the channels to keep
both supplies in their regulation window. Note that, in general,
analog chips, like op amps, are largely insensitive to dc changes
in their power supplies as long as there is sufficient head room
available.
2.0
LOAD ON VOUT+ = 0.1A
LOAD ON VOUT+ = 0.01A
LOAD ON VOUT+ = 0.051A
LOAD ON VOUT+ = 0.0016A
1.5
VOUT/VIN (%)
0.5
0
–0.5
–1.0
–2.0
0.02
0.03 0.04 0.05 0.06 0.07
IOUT NEGATIVE SUPPLY (A)
0.08
0.09
0.10
09556-007
–1.5
0.01
The first step in compensating a SEPIC Ćuk is to choose an
achievable target crossover frequency. Like most boost and
buck-boost topologies, the SEPIC-Ćuk has a right half plane
zero (RHP) located according to Equation 7. An RHP has the
dual effect of adding gain, like a zero, and subtracting phase,
like a pole. Therefore, the converter must be compensated for
a crossover frequency a maximum of one fifth of the frequency
of the RHP (fRHP).
The SEPIC-Ćuk has an additional resonance caused by the
leakage inductance (Llkg ) and transfer capacitance (C1) that
occurs at Fres. This resonance is generally well damped by the
DCR of the inductors, but can introduce significant phase lag;
therefore, it is good to crossover at least a decade before it. In
addition, a current mode controller with standard Type II
compensation is used, thus, the maximum achievable crossover
frequency is approximately one-tenth the switching frequency.
Target fu should, therefore, be chosen as the minimum of these
three constraints, as shown in Equation 9.
1.0
0
In their paper, Ćuk and Middlebrook (see the References
section) show that a coupled inductor, from both a small signal
and a large signal, behaves like an inductor with twice its
single winding inductance value, without the SEPIC or Ćuk
resonances. Therefore, analysis in this application note is shown
using the effective inductance, that is, twice the single winding
inductance value that appears on coupled inductor data sheets.
The analysis assumes identical resistive loads, though the
converter remains stable with significant load imbalance. The
two transfer capacitances (C1 and C2) should be nearly the
same value, erring on the side of having C2 slightly larger than
C1. These are assumed to be ceramic capacitors and, thus, the
designer needs to take into account the differences in their dc
bias value when calculating their effective capacitances.
Figure 7. Relative Voltage Regulation Between Rails with
Differential Loading
f RHP =
f res =
SMALL-SIGNAL ANALYSIS AND LOOP
COMPENSATION
A complete small-signal analysis of the SEPIC-Ćuk converter
is beyond the scope of this paper; however, the equations
provided in this application note should allow the designer to
correctly compensate their design. The ADP161x SEPIC-Ćuk
design tool uses a more complete model which is more accurate,
but much more complicated. The equations shown refer to the
Rev. A | Page 5 of 12
R LOAD D Q2 1.5
L  D Q1
1
2π L lkg C 1
f fsw 
f
f

f u = minimum RHP , res ,
10 10 
 5
(7)
(8)
(9)
AN-1106
Application Note
Ac is the magnitude of the open-loop converter gain at the
crossover frequency fu.
POWER STAGE AND
INNER CURRENT LOOP
–VOUT
L2a
C2
D2
L1a
VIN
GCS
C1
Q1 L1b
L2b
RESR 3
COUT3
RLOAD
D1
+VOUT
RESR1
RLOAD
COUT1
CLK
R
RI
+
M c  1
–
RF1
VC
CC1
CC2
GM
VREF
V REF 2 G m 2 Ac 2
4π 2 VOUT 2
 1
1


 f p2 fu 2

09556-008
2


 C 2  1  fu
C2

 2 f p2






 D off M c

 D
on

(16)
Acs  13.5 (ADP1612/ADP1613)
(17)
VOUT I OUT
V IN
I pkLxa  I I N 




0.45
C out1  C out3  C 2 R LOAD
(12)
(into each inductor L1a and L2 a)
I L  0.3I IN
where:
fp is the dominant pole for the current mode converter with
some correction factors to account for ramp compensation and
finite current gain.
fp 
(15)
V RAMP  0.1 (ADP1612/ADP1613)
I IN 
(11)
2
(14)
As is often the case, a 30% ripple in the inductors generally
results in a reasonable value (see Equation 19). However, with
large step down ratios it can be more optimal to increase this
ripple percentage in the input inductor to 50% or 60%.
(10)
1
2f p C C1
VRAMP f sw L1 Acs
2 V IN
POWER COMPONENT STRESS
The compensation values in Figure 8 can be calculated as
follows. Since it is assumed ceramic output capacitors will be
used, CC2 can be selected as 10 pf.
(1  D off ) 0.25
(13)
Vramp and Acs are fixed constants within the chip.
RF2
RC1
Figure 8. Block Diagram Showing Power Stage and
Compensation Components
Rc 
2
Lf sw Acs
4 M c V IN
Fm 
FEEDBACK AND COMPENSATION
C C1  C C2 
f 
1  u 
 fp 
 
2
Mc and Fm are terms derived from Ridley’s thesis (see the
References section) on current mode control.
RAMP
Q S
Fm
 F V (1  D ) 
2D on D off 1  m out 2 on 

D on D off Rload 

Ac 
 f 
1  u 
 f rhp 


(19)
I L
2
I pkLxb  I OUT 
L1 
(18)
I L
2
V I N VOUT
(V IN  VOUT ) f sw I L
(20)
(21)
(22)
The currents in the FET Switch Q1 and the two diode switches,
Q2 and Q3, are shown in Figure 9. The dc components of the
switch current are also shown in Figure 9. Note that Q1 carries
the current for both the SEPIC and the Ćuk rails. The peak
currents depend on the ripple chosen in Equation 19.
Rev. A | Page 6 of 12
Application Note
AN-1106
IQ1
IQ2 = IQ3
2 × IOUT/(1 – D)
The peak-to-peak output voltage ripple on the SEPIC (positive)
output is (ΔVripple SEPIC) and is approximated by
4 × ∆I
I OUT D ON
ΔVripple SEPIC 
ON TIME
OFF TIME
09556-009
IOUT/(1 – D)
ON TIME OFF TIME
f sw C OUT 1
 ESRCOUT 1  I OUT (1  D ON )
(23)
The value of the current through the capacitor (IRMS Cout SEPIC) is
Figure 9. Idealized Waveforms for SEPIC-Ćuk
I D
1  I 1  DON  
 (24)
 OUT ON 1    L

(1  DON )
2 I OUT
 3 

2
I rms _ COUT _ SEPIC
Calculating the switching loss in the primary Switch Q1 is
beyond the scope of this application note. Note that, in many
cases, the switching loss can be quite large since the voltage
swing the switch sees is large (~VIN + VOUT) and so are the
currents (see Figure 9).
The peak-to-peak output voltage ripple on the Ćuk (negative)
output (ΔVripple Ćuk) is approximated by
Vripple Cuk 
The ADP1612/ADP1613 work to reduce this loss by switching
very quickly. The FET chosen must be rated to withstand at
least VIN + VOUT and good engineering allows some margin for
switch node ringing due to stray inductances, in addition to
thermal stress from RDS on loss and switching losses.
I L D ON
 ESR COUT3  I L
8 f sw C OUT3
(25)
The I rms value of the current into the COUT on the Ćuk
(negative) output (ΔVrip Ćuk) is approximated by
I rms _ COUT _ Cuk 
I L
3
(26)
The ripple on C1 and C2 should be chosen for around 5% of
VIN. As stated earlier, they should have similar values despite the
difference in dc voltage across them.
Vripple _ Cx 
1  DON I IN
f sw C 1
 I IN ESRC x
(27)
It is important to consider I rms ratings when choosing C1 and
C2 since the current through them is quite large.
Vripple _ Cx
1 DON  I
 pk _ Lxa 2  I pk _ Lxa

1  DON I IN

 I IN ESRCx
f sw C 1
I rms _ C  C 
1
2
3

I IN 
I L
2

 I IN 
   
I L 2 
2

DON
3
I pk _ L
xb
2 I



I L
I L 2 

pk _ L xb I OUT  2  I OUT  2

(28)
(29)
Rev. A | Page 7 of 12
AN-1106
Application Note
I DC _ diode _ current _ rating 
2
I IN  I OUT  I L 
3
(30)
OUTPUT FILTER
The SEPIC-Ćuk as a dual rail converter is typically used for
analog power supplies, which often require very low output
ripple. Low output ripple (down to 1 mV) is generally easily
achieved on the Ćuk (negative) output rail simply by using
ceramic output capacitors because the output current is
continuous like the output current of a buck converter.
RFILT
Q2
LFILT
COUT1
+VOUT
COUT2
09556-010
Since Q2 and Q3 are generally diodes, there are several things
to consider when choosing a component. Vds max must be rated
to at least VIN + VOUT. The continuous current should be at
least 1/3 the peak current to be seen. Interestingly, because of
the phase relationship between the output voltage ripple of the
two supplies, the SEPIC diode actually receives the full switch
for some amount of time before the current achieves a more
even split. As expected though, the average current through
both diodes is the same, IOUT. In addition, the package must
be able to handle the IOUT in the thermal environment of the
application.
Figure 10. Schematic of the Output Filter
Although this filter affects the small-signal model in new
and interesting ways, this issue is not fully discussed in this
application note. As long as the damping resistor is chosen
according to the Equation 31 and Equation 32, and the
converter is designed to crossover at a tenth of ωo or less,
no instability should be caused by the pi filter.
COUT1 should be chosen for around 2% output ripple and COUT2
should be chosen to match the output capacitor of the Ćuk
output using the equations in the power components stress
section. A good value for Lfilt is generally 1 μH, and Qo should
be set to 1.
o 
On the SEPIC (positive) rail, the output current is discontinuous like the input current of a buck converter. This results
in a step change in the current into the output capacitors.
These switching spikes are not well attenuated even by ceramic
capacitors because of their inductance. Therefore, it is often
necessary to put a small, damped output pi filter on the output
of the SEPIC winding.
Rev. A | Page 8 of 12
R filt
2C OUT 1  C OUT 2 
L
filt C OUT 1
C OUT 2

L


 R load L filt C OUT 1  C OUT 2   filt 

Q o  o 

R load C OUT 1  C OUT 2 
 L filt C OUT 1
Qoo
(31)
(32)
Application Note
AN-1106
ADP161X DESIGN TOOL
If the View Solution button is pressed, the design tool outputs
a complete, optimized design. This includes a costed BOM with
compensation values, an accurate, tested efficiency plot across load,
a plot of power loss across load, a full load bode plot, performance
parameters, component stresses, and power dissipation for every
component. In addition, the Build Your Design tab provides the
same BOM, but with the components arranged to fit on the blank
demo board (ADP161x-BL3-EVZ) and any extra components
required to configure the demo board .
09556-012
The ADP161x SEPIC-Ćuk design tool is a fully integrated
Excel®-based designer for the ADP161x chips in a SEPIC-Ćuk
configuration. Once the user has enabled macros (which may
require a change of the security settings in Excel), the Enter
Inputs dialog box appears, or can be found by pressing the
Find Solution button. In the dialog box, enter the voltages
and currents required for the design and choose whether to
optimize for cost, loss, or size.
Figure 12. Advanced inputs Dialog Box
One of the most powerful features of this tool are the
component buttons found on the User Interface tab. This
functionality gives the user the ability to individually change
each component to fully customize the design.
09556-011
Each of the components in the drop-down list have been
preselected from a database of thousands of components to
produce a functional design, and sorted according to the
optimization chosen in the Enter Inputs dialog box. The
components must be selected in order, from top to bottom,
since there are dependencies between the different components.
Figure 11. Basic Inputs Dialog Box
Additional customization tools are available in the Advanced
Settings dialog box. Here the user can select parameter
specifications for output voltage ripple, current, transient
response, optional output filter usage, an external UVLO, and
more. A more in-depth description of the functionality of these
options is provided in the Program Details dialog box available
by clicking the Program Details button found on the Enter
Inputs dialog box.
Rev. A | Page 9 of 12
AN-1106
Application Note
LAB RESULTS
REFERENCES
To demonstrate the efficacy of the design tool, a design was
done using the tool for 5 VIN, ±5 VOUT at 50 mA with the
advanced specifications shown in Figure 11 and Figure 12.
In addition, the diode was changed for slightly lower loss.
The jagged efficiency line at around 10 mA is caused by the
converter going into discontinuous mode. Once both the
switches have turned off, the switch node rings causing zero
voltage switching at specific load currents. A schematic for the
circuit is shown in Figure 14.
Ridley, Dr. Ray. 1990. “A New Continuous-Time Model for
Current-Mode Control.” Brandenton, FL: Ridley Engineering.
Ćuk, Slobodan and R.D. Middlebrook. 1983. “CoupledInductor and Other Extensions of a New Optimum Topology
Switching DC-DC Converter.” Advances in Switched-Mode
Power Conversion, Volumes I and II. Irvine, CA: Tesla Co.
CONCLUSION
In conclusion, the SEPIC-Ćuk provides an inexpensive and
robust way to create dual rails using only one controller. The
ADIsimPOWER™ design tool allows complete customization of
the design and can be relied on to create robust SEPIC-Ćuk
designs quickly.
0.9
0.7
0.6
PREDICTED EFFICIENCY
MEASURED EFFICIENCY
0.5
0
0.01
0.02
IOUT (A)
0.03
0.04
Figure 13. Efficiency Verification
VOUT–
COUT3
2× 10µF, 6.3V, 0805
D2
b
a
LPD4012-153
C2
1µF, 16V, 0805
b
D1
VIN
a
LPD4012-153
CIN1
1µF, 6.3V, 0603
ENABLE
RB0
10Ω
C1
1µF, 16V, 0805
1µH
ME3220-102MLB
COUT1
1µF, 6.3V, 0603
VOUT+
COUT2
2× 10µF
6.3V, 0805
U1
ADP1613
CC1
15nF
CC2
10pF
RC1
27.4kΩ
COMP
FB
EN
GND
SS
RT
IN
SW
CV5
1µF, 6.3V, 0603
RF2
16.5kΩ
CSS
10nF
RF1B
49.9kΩ
09556-014
0.4
09556-013
EFFICIENCY (POUT/PIN)
0.8
Figure 14. Schematic of Test Circuit
Rev. A | Page 10 of 12
Application Note
AN-1106
NOTES
Rev. A | Page 11 of 12
AN-1106
Application Note
NOTES
©2011–2013 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
AN09556-0-7/13(A)
Rev. A | Page 12 of 12
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