2000 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA
www.infineon.com/opto • 1-888-Infineon (1-888-463-4636)
OSRAM Opto Semiconductors GmbH & Co. OHG • Regensburg, Germany
www.osram-os.com • +49-941-202-7178 1 April 3, 2000-14
FEATURES
Couples AC and DC signals
0.01% Servo Linearity
Wide Bandwidth, >200 kHz
High Gain Stability,
±
0.05%/C
Low Input-Output Capacitance
Low Power Consumption, < 15 mw
Isolation Test Voltage, 5300 V
RMS
,
1.0 sec.
Internal Insulation Distance, >0.4 mm
for VDE
Underwriters Lab File #E52744
VDE Approval #0884 (Available with
Option 1, Add -X001 Suffix)
IL300G Replaced by IL300-X006
APPLICATIONS
Power Supply Feedback Voltage/Current
Medical Sensor Isolation
Audio Signal Interfacing
Isolate Process Control Transducers
Digital Telephone Isolation
DESCRIPTION
The IL300 Linear Optocoupler consists of an
AlGaAs IRLED irradiating an isolated feed-
back and an output PIN photodiode in a
bifurcated arrangement. The feedback pho-
todiode captures a percentage of the LED's
flux and generates a control signal (IP
1
) that
can be used to servo the LED drive current.
This technique compensates for the LED's
non-linear, time, and temperature character-
istics. The output PIN photodiode produces
an output signal (IP
2
) that is linearly related
to the servo optical flux created by the LED.
The time and temperature stability of the
input-output coupler gain (K3) is insured by
using matched PIN photodiodes that accu-
rately track the output flux of the LED.
A typical application circuit (Figure 1) uses
an operational amplifier at the circuit input to
drive the LED. The feedback photodiode
sources current to R1 connected to the
inverting input of U1. The photocurrent, IP1,
will be of a magnitude to satisfy the relation-
ship of (IP1=
V
IN
/R1).
V
DE
DESCRIPTION
(continued)
The magnitude of this current is directly proportional to the feedback transfer
gain (K1) times the LED drive current (
V
IN
/R1=K1 •
I
F
). The op-amp will supply
LED current to force sufficient photocurrent to keep the node voltage (Vb) equal
to Va.
The output photodiode is connected to a non-inverting voltage follower amplifier.
The photodiode load resistor, R2, performs the current to voltage conversion. The
output amplifier voltage is the product of the output forward gain (K2) times the
LED current and photodiode load, R2 (
V
O
=
I
F
• K2 • R2).
Therefore, the overall transfer gain (V
O
/V
IN
) becomes the ratio of the product of
the output forward gain (K2) times the photodiode load resistor (R2) to the prod-
uct of the feedback transfer gain (K1) times the input resistor (R1). This reduces
to
V
O
/
V
IN
=(K2 • R2)/(K1 • R1). The overall transfer gain is completely indepen-
dent of the LED forward current. The IL300 transfer gain (K3) is expressed as the
ratio of the output gain (K2) to the feedback gain (K1). This shows that the circuit
gain becomes the product of the IL300 transfer gain times the ratio of the output
to input resistors [
V
O
/
V
IN
=K3 (R2/R1)].
Figure 1. Typical application circuit
1
2
3
4
8
7
6
5
K2K1
Pin 1 ID. .240 (6.096)
.260 (6.604)
3
4
.380 (9.652)
.400 (10.16)
10°
.300 Typ.
(7.62) Typ.
.021 (0.527)
.035 (0.889)
1
2
.280 (7.112)
.330 (8.382)
.016 (.406)
.020 (.508 )
.130 (3.302)
.150 (3.810)
.040 (1.016)
.050 (1.270 )
.100 (2.540)
4°
.010 (0.254) REF.
.050 (1.270)
3°
9
.110 (2.794)
.130 (3.302)
.010 (0.254) REF.
6
5
8
7
.020 (0.508) REF.
.008 (0.203)
.012 (0.305)
Dimensions in inches (mm)
8
7
6
5
K1
1
2
3
4
K2
R1 R2
IL300
Vb
Va +
-
U1
Vin
lp 1
-
U2
+
lp 2
Vout
VCC
VCC
VCC
VCC
IF
Vc
+
IL300
Linear Optocoupler
2000 Inneon Technologies Corp. Optoelectronics Division San Jose, CA IL300
www.inneon.com/opto 1-888-Inneon (1-888-463-4636)
OSRAM Opto Semiconductors GmbH & Co. OHG Regensburg, Germany
www.osram-os.com +49-941-202-7178 2 April 3, 2000-14
IL300 Terms
KIServo Gain
The ratio of the input photodiode current (I
P1
) to the LED cur-
rent (
I
F
). i.e., K1 = I
P1
/
I
F
.
K2Forward Gain
The ratio of the output photodiode current (I
P2
) to the LED
current (
I
F
), i.e., K2 = I
P2
/
I
F
.
K3Transfer Gain
The Transfer Gain is the ratio of the Forward Gain to the Servo
gain, i.e., K3 = K2/K1.
K3Transfer Gain Linearity
The percent deviation of the Transfer Gain, as a function of
LED or temperature from a specic Transfer Gain at a xed
LED current and temperature.
Photodiode
A silicon diode operating as a current source. The output cur-
rent is proportional to the incident optical ux supplied by the
LED emitter. The diode is operated in the photovoltaic or pho-
toconductive mode. In the photovoltaic mode the diode func-
tions as a current source in parallel with a forward biased
silicon diode.
The magnitude of the output current and voltage is depen-
dent upon the load resistor and the incident LED optical ux.
When operated in the photoconductive mode the diode is
connected to a bias supply which reverse biases the silicon
diode. The magnitude of the output current is directly propor-
tional to the LED incident optical ux.
LED
(Light Emitting Diode)
An infrared emitter constructed of AlGaAs that emits at 890
nm operates efciently with drive current from 500 µA to 40
mA. Best linearity can be obtained at drive currents between
5.0 mA to 20 mA. Its output ux typically changes by
0.5%/
°
C over the above operational current range.
Absolute Maximum Ratings
Symbol Min. Max. Unit
Emitter
Power Dissipation
(
T
A
=25
°
C)
P
LED
160 mW
Derate Linearly from 25
°
C——2.13 mW/
°
C
Forward Current
l
F
60 mA
Surge Current
(Pulse width <10
µ
s)
l
pk
250 mA
Reverse Voltage
V
R
5.0 V
Thermal Resistance
R
th
470 K/W
Junction Temperature
T
J
100
°
C
Detector
Power Dissipation
P
DET
50 mA
Derate linearly from 25
°
C——0.65 mW/
°
C
Reverse Voltage
V
R
50 V
Junction Temperature
T
J
100
°
C
Thermal Resistance
R
th
1500 K/W
Coupler
Total Package
Dissipation at 25
°
C
P
T
210 mW
Derate linearly from 25
°
C——2.8 mW/
°
C
Storage Temperature
T
S
55 150
°
C
Operating Temperature
T
OP
55 100
°
C
Isolation Test Voltage 5300 V
RMS
Isolation Resistance
V
IO
=500 V,
T
A
=25
°
C
V
IO
=500 V,
T
A
=100
°
C
10
12
10
11
2000 Inneon Technologies Corp. Optoelectronics Division San Jose, CA IL300
www.inneon.com/opto 1-888-Inneon (1-888-463-4636)
OSRAM Opto Semiconductors GmbH & Co. OHG Regensburg, Germany
www.osram-os.com +49-941-202-7178 3 April 3, 2000-14
Characteristics
T
A
=25
°
C
Symbol Min. Typ. Max. Unit Test Condition
LED Emitter
Forward Voltage
V
F
1.25 1.50 V
I
F
=10 mA
V
F
Temperature Coefficient
V
F
/
°
C—–2.2 mV/
°
C
Reverse Current
I
R
1.0 10
µ
A
V
R
=5.0 V
Junction Capacitance
C
J
15 pF
V
F
=0 V, f=1.0 MHz
Dynamic Resistance
V
F
/
I
F
6.0
I
F
=10 mA
Switching Time
t
r
t
f
1.0
1.0
µ
s
µ
s
I
F
=2.0 mA, I
F
q
=10 mA
I
F
=2.0 mA, I
F
q
=10 mA
Detector
Dark Current
I
D
1.0 25 nA V
det
=-15 V,
I
F
=0
µ
A
Open Circuit Voltage
V
D
500 mV
I
F
=10 mA
Short Circuit Current
I
SC
70
µ
A
I
F
=10 mA
Junction Capacitance
C
J
12 pF
V
F
=0 V, f=1.0 MHz
Noise Equivalent Power NEP 4 x 10
14
W/
Hz V
det
=15 V
Coupled Characteristics
K1, Servo Gain (I
P1
/
I
F
) K1 0.0050 0.007 0.011
I
F
=10 mA, V
det
=-15 V
Servo Current, see Note 1, 2
I
P
170
µ
A
I
F
=10 mA, V
det
=-15 V
K2, Forward Gain (I
P2
/
I
F
) K2 0.0036 0.007 0.011
I
F
=10 mA, V
det
=-15 V
Forward Current
I
P
270
µ
A
IF=10 mA, Vdet=-15 V
K3, Transfer Gain (K2/K1)
See Note 1, 2 K3 0.56 1.00 1.65 K2/K1 IF=10 mA, Vdet=-15 V
Transfer Gain Linearity K3 ±0.25 %IF=1.0 to 10 mA
Transfer Gain Linearity K3 ±0.5 %IF=1.0 to 10 mA, TA=0°C to 75°C
Photoconductive Operation
Frequency Response BW (3 db) 200 kHz IFq=10 mA, MOD=±4.0 mA, RL=50 Ω,
Phase Response at 200 kHz ——45 Deg. Vdet=15 V
Rise Time tr1.75 µs
Fall Time tf1.75 µs
Package
Input-Output Capacitance CIO 1.0 pF VF=0 V, f=1.0 MHz
Common Mode Capacitance Ccm 0.5 pF VF=0 V, f=1.0 MHz
Common Mode Rejection Ratio CMRR 130 dB f=60 Hz, RL=2.2 K
Notes
1. Bin Sorting:
K3 (transfer gain) is sorted into bins that are ±6%, as follows:
Bin A=0.5570.626
Bin B=0.6200.696
Bin C=0.6900.773
Bin D=0.7650.859
Bin E=0.8510.955
Bin F=0.9451.061
Bin G=1.0511.181
Bin H=1.1691.311
Bin I=1.2971.456
Bin J=1.4421.618
K3=K2/K1. K3 is tested at IF=10 mA, Vdet=15 V.
2. Bin Categories: All IL300s are sorted into a K3 bin, indicated by an
alpha character that is marked on the part. The bins range from A
through J.
The IL300 is shipped in tubes of 50 each. Each tube contains only
one category of K3. The category of the parts in the tube is marked
on the tube label as well as on each individual part.
3. Category Options: Standard IL300 orders will be shipped from the
categories that are available at the time of the order. Any of the ten
categories may be shipped. For customers requiring a narrower
selection of bins, four different bin option parts are offered.
IL300-DEFG: Order this part number to receive categories
D,E,F,G only.
IL300-EF: Order this part number to receive categories E, F only.
IL300-E: Order this part number to receive category E only.
IL300-F: Order this part number to receive category F only.
2000 Inneon Technologies Corp. Optoelectronics Division San Jose, CA IL300
www.inneon.com/opto 1-888-Inneon (1-888-463-4636)
OSRAM Opto Semiconductors GmbH & Co. OHG Regensburg, Germany
www.osram-os.com +49-941-202-7178 4 April 3, 2000-14
Figure 2. LED forward current vs. forward voltage
Figure 3. LED forward current vs. forward voltage
Figure 4. Servo photocurrent vs. LED current and
temperature
Figure 5. Servo photocurrent vs. LED current
and temperature
1.41.31.21.11.0
0
5
10
15
20
25
30
35
VF - LED Forward Voltage - V
IF - LED Current - mA
1.0 1.1 1.2 1.3 1.4
.1
1
10
100
VF - LED Forward Voltage - V
IF - LED Current - mA
0°C
25°C
50°C
75°C
VD = 15 V
.1 1 10 100
300
250
200
150
100
50
0
IF - LED Current - mA
IP1 - Servo Photocurrent - µA
.1 1 10 100
1000
100
10
1
IF - LED Current - mA
IP1 - Servo Photocurrent - µA
VD=–15 V
0°C
25°C
50°C
75°C
Figure 6. Normalized servo photocurrent vs. LED
current and temperature
Figure 7. Normalized servo photocurrent vs. LED
current and temperature
Figure 8. Servo gain vs. LED current and temperature
Figure 9. Normalized servo gain vs. LED current
and temperature
0 5 10 15 20 25
3.0
2.5
2.0
1.5
1.0
0.5
0.0
IF - LED Current - mA
Normalized Photocurrent
Normalized to: IP1@ IF=10 mA,
TA=25°C,
VD=15 V
0°C
25°C
50°C
75°C
.1 1 10 100
10
1
.1
.01
IF - LED Current - mA
0°C
25°C
50°C
75°C
IP1 - Normalized Photocurrent
Normalized to: IP1@ IF=10 mA,
TA=25°C,
VD=15 V
.1 1 10 100
IF - LED Current - mA
NK1 - Normalized Servo Gain
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0°C
25°C
50°C
75°C
85°C
.1 1 10 100
IF - LED Current - mA
NK1 - Normalized Servo Gain
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0°C
25°C
50°C
75°C
100°C
Normalized to:
IF=10 mA, TA=25°C
2000 Inneon Technologies Corp. Optoelectronics Division San Jose, CA IL300
www.inneon.com/opto 1-888-Inneon (1-888-463-4636)
OSRAM Opto Semiconductors GmbH & Co. OHG Regensburg, Germany
www.osram-os.com +49-941-202-7178 5 April 3, 2000-14
Figure 10. Transfer gain vs. LED current and temperature
Figure 11. Normalized transfer gain vs. LED current
and temperature
Figure 12. Amplitude response vs. frequency
Figure 13. Amplitude and phase response vs. frequency
0 5 10 15 20 25
1.010
1.005
1.000
0.995
0.990
IF - LED Current - mA
K3 - Transfer Gain - (K2/K1)
0°C
25°C
50°C
75°C
0 5 10 15 20 25
1.010
1.005
1.000
0.995
0.990
IF - LED Current - mA
K3 - Transfer Gain - (K2/K1)
0°C
25°C
50°C
75°C
Normalized to:
IF=10 mA,
TA=25°C
104105106
5
0
-5
-10
-15
-20
F - Frequency - Hz
Amplitude Response - dB
RL=1.0 K
RL=10 K
IF=10 mA, Mod=±2.0 mA (peak)
dB
PHASE
Ø - Phase Response - °
103104105106107
5
0
-5
-10
-15
-20
45
0
-45
-90
-135
-180
F - Frequency - Hz
Amplitude Response - dB
IFq=10 mA
Mod=±4.0 mA
TA=25°C
RL=50
Figure 14. Common mode rejection
Figure 15. Photodiode junction capacitance vs. reverse
voltage
Application Considerations
In applications such as monitoring the output voltage from a
line powered switch mode power supply, measuring bioelectric
signals, interfacing to industrial transducers, or making oating
current measurements, a galvanically isolated, DC coupled
interface is often essential. The IL300 can be used to construct
an amplier that will meet these needs.
The IL300 eliminates the problems of gain nonlinearity and drift
induced by time and temperature, by monitoring LED output
ux.
A PIN photodiode on the input side is optically coupled to the
LED and produces a current directly proportional to ux falling
on it. This photocurrent, when coupled to an amplier, provides
the servo signal that controls the LED drive current.
The LED ux is also coupled to an output PIN photodiode. The
output photodiode current can be directly or amplied to sat-
isfy the needs of succeeding circuits.
Isolated Feedback Amplier
The IL300 was designed to be the central element of DC cou-
pled isolation ampliers. Designing the IL300 into an amplier
that provides a feedback control signal for a line powered
switch mode power is quite simple, as the following example
will illustrate.
See Figure 17 for the basic structure of the switch mode supply
using the Inneon TDA4918 Push-Pull Switched Power Supply
Control Chip. Line isolation and insulation is provided by the
high frequency transformer. The voltage monitor isolation will
be provided by the IL300.
10 100 1000 10000 100000 1000000
-130
-120
-110
-100
-90
-80
-70
-60
F - Frequency - Hz
CMRR - Rejection Ratio - dB
0
2
4
6
8
10
12
14
0246810
Voltage - Vdet
Capacitance - pF
2000 Inneon Technologies Corp. Optoelectronics Division San Jose, CA IL300
www.inneon.com/opto 1-888-Inneon (1-888-463-4636)
OSRAM Opto Semiconductors GmbH & Co. OHG Regensburg, Germany
www.osram-os.com +49-941-202-7178 6 April 3, 2000-14
Figure 16. Isolated control amplier
For best input offset compensation at U1, R2 will equal R3. The
value of R1 can easily be calculated from the following.
The value of R5 depends upon the IL300 Transfer Gain (K3). K3
is targeted to be a unit gain device, however to minimize the
part to part Transfer Gain variation, Inneon offers K3 graded
into % bins. R5 can determined using the following equation,
Or if a unity gain amplier is being designed
(VMONITOR=VOUT, R1=0), the equation simplies to:
+
-
Voltage
Monitor
R1
R2
To Control
Input
ISO
AMP
+1
R1R2VMONITOR
Va
--------------------------- 1


=
5±
R5VOUT
VMONITOR
--------------------------- R3R1R2+()
R2K3
-----------------------------------
=
R5R3
K3
-------=
The isolated amplier provides the PWM control signal which is
derived from the output supply voltage. Figure 16 more closely
shows the basic function of the amplier.
The control amplier consists of a voltage divider and a non-
inverting unity gain stage. The TDA4918 data sheet indicates
that an input to the control amplier is a high quality opera-
tional amplier that typically requires a +3.0 V signal. Given
this information, the amplier circuit topology shown in Figure
18 is selected.
The power supply voltage is scaled by R1 and R2 so that there
is +3.0 V at the non-inverting input (Va) of U1. This voltage is
offset by the voltage developed by photocurrent owing
through R3. This photocurrent is developed by the optical ux
created by current owing through the LED. Thus as the scaled
monitor voltage (Va) varies it will cause a change in the LED
current necessary to satisfy the differential voltage needed
across R3 at the inverting input.
The rst step in the design procedure is to select the value of
R3 given the LED quiescent current (IFq) and the servo gain
(K1). For this design, IFq=12 mA. Figure 4 shows the servo
photocurrent at IFq is found to be 100 µA. With this data R3 can
be calculated.
R3Vb
IPl
------ 3V
100µA
------------------
== 30K=
Figure 17. Switch mode power supply
Figure 18. DC coupled power supply feedback amplier
SWITCH XFORMER
SWITCH
MODE
REGULATOR
TDA4918
ISOLATED
FEEDBACK
CONTROL
110/
220
MAIN
DC OUTPUT
AC/DC
RECTIFIER AC/DC
RECTIFIER
8
7
6
5
100 pF
4
3
1
2
8
6
7
K1
VCC
VCC
1
2
3
4
K2
VCC
Vmonitor
R1
20 K
R2
30 K
R3
30 K
R4
100
Vout To
control
input
R5
30 K
IL300
Vb
Va +
-
U1
LM201
2000 Inneon Technologies Corp. Optoelectronics Division San Jose, CA IL300
www.inneon.com/opto 1-888-Inneon (1-888-463-4636)
OSRAM Opto Semiconductors GmbH & Co. OHG Regensburg, Germany
www.osram-os.com +49-941-202-7178 7 April 3, 2000-14
Table 1 gives the value of R5 given the production K3 bins.
Table 1, R5 selection
The last step in the design is selecting the LED current limiting
resistor (R4). The output of the operational amplier is targeted
to be 50% of the VCC, or 2.5 V. With an LED quiescent current
of 12 mA the typical LED (VF) is 1.3 V. Given this and the oper-
ational output voltage, R4 can be calculated.
The circuit was constructed with an LM201 differential opera-
tional amplier using the resistors selected. The amplier was
compensated with a 100 pF capacitor connected between
pins 1 and 8.
The DC transfer characteristics are shown in Figure 19. The
amplier was designed to have a gain of 0.6 and was mea-
sured to be 0.6036. Greater accuracy can be achieved by
adding a balancing circuit, and potentiometer in the input
divider, or at R5. The circuit shows exceptionally good gain lin-
earity with an RMS error of only 0.0133% over the input voltage
range of 4.0 V6.0 V in a servo mode; see Figure 20.
Bins Min. Max.
3
Typ.
R5
Resistor
K
1%
K
A 0.560 0.623 0.59 50.85 51.1
B 0.623 0.693 0.66 45.45 45.3
C 0.693 0.769 0.73 41.1 41.2
D 0.769 0.855 0.81 37.04 37.4
E 0.855 0.950 0.93 32.26 32.4
F 0.950 1.056 1.00 30.00 30.0
G 1.056 1.175 1.11 27.03 27.0
H 1.175 1.304 1.24 24.19 24.0
I 1.304 1.449 1.37 21.90 22.0
J 1.449 1.610 1.53 19.61 19.4
R4Vopamp VF
IFq
-------------------------------- 2.5V1.3V
12mA
------------------------------ 1 0 0 ===
Figure 19. Transfer gain
Figure 20. Linearity error vs. input voltage
The AC characteristics are also quite impressive offering a -
3.0 dB bandwidth of 100 kHz, with a 45° phase shift at 80 kHz
as shown in Figure 21.
Figure 21. Amplitude and phase power supply control
The same procedure can be used to design isolation ampliers
that accept bipolar signals referenced to ground. These ampli-
ers circuit congurations are shown in Figure 22. In order for the
amplier to respond to a signal that swings above and below
ground, the LED must be prebiased from a separate source by
using a voltage reference source (Vref1). In these designs, R3
can be determined by the following equation.
6.05.55.04.54.0
2.25
2.50
2.75
3.00
3.25
3.50
3.75
Vin - Input Voltage - V
Vout - Ooutput Voltage - V
Vout = 14.4 mV + 0.6036 x Vin
LM 201 Ta = 25°C
6.05.55.04.54.0
-0.015
-0.010
-0.005
0.000
0.005
0.010
0.015
0.020
0.025
Vin - Input Voltage - V
Linearity Error - %
LM201
dB
PHASE
Phase Response - °
103104105106
2
0
-2
-4
-6
-8
45
0
-45
-90
-135
-180
F - Frequency - Hz
Amplitude Response - dB
R3Vref1
IP1
-------------Vref1
K1IFq
---------------=
=
2000 Inneon Technologies Corp. Optoelectronics Division San Jose, CA IL300
www.inneon.com/opto 1-888-Inneon (1-888-463-4636)
OSRAM Opto Semiconductors GmbH & Co. OHG Regensburg, Germany
www.osram-os.com +49-941-202-7178 8 April 3, 2000-14
These ampliers provide either an inverting or non-inverting
transfer gain based upon the type of input and output ampli-
er. Table 2 shows the various congurations along with the
specic transfer gain equations. The offset column refers to the
calculation of the output offset or Vref2 necessary to provide a
zero voltage output for a zero voltage input. The non-inverting
input amplier requires the use of a bipolar supply, while the
inverting input stage can be implemented with single supply
operational ampliers that permit operation close to ground.
For best results, place a buffer transistor between the LED and
output of the operational amplier when a CMOS opamp is
used or the LED IFq drive is targeted to operate beyond 15
mA. Finally the bandwidth is inuenced by the magnitude of
the closed loop gain of the input and output ampliers. Best
bandwidths result when the amplier gain is designed for unity.
Figure 22. Non-inverting and inverting ampliers
Table 2. Optolinear ampliers
Amplier Input Output Gain Offset
Non-Inverting Inverting Inverting
Non-Inverting Non-Inverting
Inverting Inverting Non-Inverting
Non-Inverting Inverting
Vcc
20pF
4
1
2
3
4
8
7
6
5
+Vref2
R5
R6
7
2
4
3Vo
R4
R3
Vref1
Vin
R1 R2
37
6
+
+Vcc
100
6
IL300
2Vcc
Vcc
Vcc
Vcc
+
Vcc
Vcc
20pF
4
1
2
3
4
8
7
6
5
+Vref2
7
24
3
Vout
R4
R3
+Vref1
Vin
R1 R2
37
6
+
+Vcc
100
6
2Vcc Vcc
Vcc
+
Vcc
Non-Inverting Input Non-Inverting Output
Inverting Input Inverting Output
IL300
Vcc
VOUT K3 R4 R2
VIN R3 (R1+R2)
=Vref1 R4 K3
R3
Vref2=
VOUT K3 R4 R2 (R5+R6)
VIN R3 R5 (R1 +R2)
=
Vref1 R4 (R5+R6) K3
R3 R6
Vref2=
VOUT K3 R4 R2 (R5+R6)
VIN R3 R5 (R1 +R2)
=Vref1 R4 (R5+R6) K3
R3 R6
Vref2=
VOUT K3 R4 R2
VIN R3 (R1 +R2)
=Vref1 R4 K3
R3
Vref2=