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