Datasheets opt209 Datasheet

®

FPO
70%

PHOTODIODE

WITH ON-CHIP AMPLIFIER

OPT209

FEATURES

● PHOTODIODE SIZE: 0.090 x 0.090 inch

(2.29 x 2.29mm)

● 1MΩ FEEDBACK RESISTOR

● HIGH RESPONSIVITY: 0.45A/W

(650nm)

● LOW DARK ERRORS: 2mV

● BANDWIDTH: 16kHz

● WIDE SUPPLY RANGE:

● LOW QUIESCENT CURRENT: 400

±2.25 to ±18V

µA

● TRANSPARENT 8-PIN DIP

APPLICATIONS

● MEDICAL INSTRUMENTATION

● LABORATORY INSTRUMENTATION

● POSITION AND PROXIMITY SENSORS

● PHOTOGRAPHIC ANALYZERS

● SMOKE DETECTORS

2

1MΩ

10pF

λ

1

83

V+

V–

175Ω

OPT209

4

5

V

O

DESCRIPTION

The OPT209 is an opto-electronic integrated circuit
containing a photodiode and transimpedance
amplifier on a single dielectrically isolated chip. The
transimpedance amplifier consists of a precision FET­input op amp and an on-chip metal film resistor. The

0.09 x 0.09 inch photodiode is operated at zero bias for
excellent linearity and low dark current.

The integrated combination of photodiode and
transimpedance amplifier on a single chip eliminates
the problems commonly encountered in discrete de­signs such as leakage current errors, noise pick-up and
gain peaking due to stray capacitance.

The OPT209 operates over a wide supply range (±2.25
to ±18V) and supply current is only 400µA. It is
packaged in a transparent plastic 8-pin DIP, specified
for the 0°C to 70°C temperature range.

SPECTRAL RESPONSIVITY

Ultraviolet

0.5

0.4

0.3

0.2

Voltage Output (V/µW)

0.1

0

100 200 300 400 500 600 700 800 900 1000 1100

Using Internal
1MΩ Resistor

Blue

Wavelength (nm)

Green

Yellow

Red

Infrared

0.5

0.4

0.3

0.2

0.1

Photodiode Responsivity (A/W)

0

International Airport Industrial Park • Mailing Address: PO Box 11400, Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd., Tucson, AZ 85706 • Tel: [phone] • Twx: 910-952-1111

Internet: http://www.burr-brown.com/ • FAXLine: [phone] (US/Canada Only) • Cable: BBRCORP • Telex: 066-6491 • FAX: [phone] • Immediate Product Info: [phone]

©

1994 Burr-Brown Corporation PDS-1232D Printed in U.S.A. March, 1997

SPECIFICATIONS

ELECTRICAL

At TA = +25°C, VS = ±15V, λ = 650nm, internal 1MΩ feedback resistor, unless otherwise noted.

OPT209P
PARAMETER CONDITIONS MIN TYP MAX UNITS
RESPONSIVITY

Photodiode Current 650nm 0.45 A/W
Voltage Output 650nm 0.45 V/µW

vs Temperature 100 ppm/°C
Unit-to-Unit Variation 650nm ±5%
Nonlinearity
Photodiode Area (0.090 x 0.090in) 0.008 in

DARK ERRORS, RTO

Offset Voltage, Output ±0.5 ±2mV
vs Temperature ±10 µV/°C
vs Power Supply V
Voltage Noise Measured BW = 0.1 to 100kHz 350 µVrms

RESISTOR—1MΩ Internal

Resistance 1MΩ
Tolerance ±0.5 ±2%
vs Temperature 50 ppm/°C

FREQUENCY RESPONSE

Bandwidth, Large or Small-Signal, –3dB 16 kHz
Rise Time, 10% to 90% 22 µs
Settling Time, 1% FS to Dark 60 µs

Overload Recovery Time (to 1%) 100% 0verdrive, V

OUTPUT

Voltage Output R

Capacitive Load, Stable Operation 1nF
Short-Circuit Current ±18 mA

POWER SUPPLY

Specified Operating Voltage ±15 V
Operating Voltage Range ±2.25 ±18 V
Quiescent Current V

TEMPERATURE RANGE

Specification, Operating 0 +70 °C
Storage –25 +85 °C
Thermal Resistance,

NOTES: (1) Deviation in percent of full scale from best-fit straight line. (2) Referred to Output. Includes all error sources.

(1)

FS Output = 10V 0.01 % of FS

(2.29 x 2.29mm) 5.2 mm

(2)

= ±2.25V to ±18V 10 100 µV/V

S

0.1% FS to Dark 85 µ s

0.01% FS to Dark 100 µs
= ±15V 44 µs

100% 0verdrive, V

100% 0verdrive, V

θ

JA

S

= ±5V 100 µs

S

= ±2.25V 240 µs

S

= 10kΩ (V+) – 1.25 (V+) – 1 V

L

R

= 5kΩ (V+) – 2 (V+) – 1.5 V

L

= 0 ±400 ±500 µA

O

100 °C/W

2

2

PHOTODIODE SPECIFICATIONS

At TA = +25°C, unless otherwise noted.

Photodiode of OPT209

PARAMETER CONDITIONS MIN TYP MAX UNITS

Photodiode Area (0.090 x 0.090in) 0.008 in

Current Responsivity 650nm 0.45 A/W
Dark Current V

vs Temperature doubles every 10°C

Capacitance V

NOTE: (1) Voltage Across Photodiode.

®

OPT209

(2.29 x 2.29mm) 5.1 mm

(1)

= 0V

D

= 0V

D

(1)

500 fA

600 pF

2

2

2

SPECIFICATIONS (CONT)

ELECTRICAL Op Amp Section of OPT209

At TA = +25°C, VS = ±15V, unless otherwise noted.

OPT209 Op Amp
PARAMETER CONDITIONS MIN TYP MAX UNITS
INPUT

Offset Voltage ±0.5 mV

vs Temperature ±5 µV/°C
vs Power Supply V

Input Bias Current 1pA

vs Temperature doubles every 10°C

NOISE

Input Voltage Noise
Voltage Noise Density, f=10Hz 30 nV/√Hz

f=100Hz 25 nV/√Hz
f=1kHz 15 nV/√Hz

Current Noise Density, f=1kHz 0.8 fA/√Hz

INPUT VOLTAGE RANGE

Common-Mode Input Range ±14.4 V
Common-Mode Rejection 106 dB

INPUT IMPEDANCE

Differential 10
Common-Mode 10

OPEN-LOOP GAIN

Open-Loop Voltage Gain 120 dB

FREQUENCY RESPONSE

Gain-Bandwidth Product 4 MHz
Slew Rate 6V/µs
Settling Time 0.1% 4 µs

0.01% 5 µs

OUTPUT

Voltage Output R

Short-Circuit Current ±18 mA

POWER SUPPLY

Specified Operating Voltage ±15 V
Operating Voltage Range ±2.25 ±18 V
Quiescent Current I

NOTE: (1) Op amp specifications provided for information and comparison only.

= ±2.25V to ±18V 10 µV/V

S

12

||3 Ω||pF

12

||3 Ω||pF

= 10kΩ (V+) – 1.25 (V+) – 1 V

L

R

= 5kΩ (V+) – 2 (V+) – 1.5 V

L

= 0 ±400 ±500 µA

O

(1)

The information provided herein is believed to be reliable; however, BURR-BROWN assumes no responsibility for inaccuracies or omissions. BURR-BROWN assumes
no responsibility for the use of this information, and all use of such information shall be entirely at the user’s own risk. Prices and specifications are subject to change
without notice. No patent rights or licenses to any of the circuits described herein are implied or granted to any third party. BURR-BROWN does not authorize or warrant
any BURR-BROWN product for use in life support devices and/or systems.

3

OPT209

®

PIN CONFIGURATION

ELECTROSTATIC

TOP VIEW

V+

–In

V–

1MΩ Feedback

1
2

(1)

3
4

NOTE: (1) Photodiode location.

8
7
6
5

Common
NC
NC
Output

ABSOLUTE MAXIMUM RATINGS

Supply Voltage................................................................................... ±18V

Input Voltage Range (Common Pin) .................................................... ±V

Output Short-Circuit (to ground)............................................... Continuous

Operating Temperature..................................................... –25°C to +85°C

Storage Temperature........................................................ –25°C to +85°C

Junction Temperature ...................................................................... +85°C

Lead Temperature (soldering, 10s)................................................ +300°C

(Vapor-Phase Soldering Not Recommended)

S

PACKAGE INFORMATION

PRODUCT PACKAGE NUMBER

OPT209P 8-Pin DIP 006-1
OPT209P-J 8-Lead Surface Mount

NOTE: (1) For detailed drawing and dimension table, please see end of data
sheet, or Appendix C of Burr-Brown IC Data Book. (2) 8-Pin DIP with leads
formed for surface mounting.

PACKAGE DRAWING

(2)

(1)

006-4

DISCHARGE SENSITIVITY

This integrated circuit can be damaged by ESD. Burr-Brown
recommends that all integrated circuits be handled with ap­propriate precautions. Failure to observe proper handling and
installation procedures can cause damage.

ESD damage can range from subtle performance degradation
to complete device failure. Precision integrated circuits may
be more susceptible to damage because very small parametric
changes could cause the device not to meet its published
specifications.

MOISTURE SENSITIVITY

AND SOLDERING

Clear plastic does not contain the structural-enhancing fillers
used in black plastic molding compound. As a result, clear
plastic is more sensitive to environmental stress than black
plastic. This can cause difficulties if devices have been stored
in high humidity prior to soldering. The rapid heating during
soldering can stress wire bonds and cause failures. Prior to
soldering, it is recommended that devices be baked-out at
85°C for 24 hours.

The fire-retardant fillers used in black plastic are not compat­ible with clear molding compound. The OPT209 cannot meet
flammability test, UL-94.

®

OPT209

4

RESPONSE vs INCIDENT ANGLE

Relative Response

Incident Angle (°)

0

1.0

0.8

0.6

0.4

0.2

0

±20 ±40 ±60 ±80

θ

Y

θ

X

θ

Y

θ

X

1.0

0.8

0.6

0.4

0.2

0

TYPICAL PERFORMANCE CURVES

VOLTAGE RESPONSIVITY vs RADIANT POWER

Radiant Power (µW)

Output Voltage (V)

0.01 0.1 10 100 1k1

10

1

0.1

0.01

0.001

R

F

= 1MΩ

R

F

= 100kΩ

R

F

= 10MΩ

λ = 650nm

At TA = +25°C, VS = ±15V, λ = 650nm, unless otherwise noted.

1.0

NORMALIZED SPECTRAL RESPONSIVITY

0.8
650nm

(0.45A/W)

0.6

0.4

0.2

Normalized Current or Voltage Output

0

100 200 300 400 500 600 700 800 900 1000 1100

Wavelength (nm)

VOLTAGE RESPONSIVITY vs IRRADIANCE

10

1

= 10MΩ

F

0.1

Output Voltage (V)

0.01

R

= 1MΩ

F

R

= 100kΩ

F

R

λ = 650nm

0.001

0.001 0.01 1 10 1000.1
Irradiance (W/m

2

)

(0.48A/W)

VOLTAGE OUTPUT RESPONSIVITY vs FREQUENCY

10

1

0.1

Responsivity (V/µW)

0.01
RF = 33kΩ C

0.001
100

RF = 10MΩ

RF = 3.3MΩ

λ = 650nm

RF = 1MΩ

RF = 100kΩ, C

= 25pF

EXT

1k 10k 100k 10M

1M

EXT

= 9pF

Frequency (Hz)

60

DISTRIBUTION OF RESPONSIVITY

50

40

30

Units (%)

20

10

0

0.43

0.44 0.45 0.46 0.47 0.48
Responsivity (A/W)

λ = 650nm
Distribution Totals

100%

Laboratory Test

Data

®

5

OPT209

TYPICAL PERFORMANCE CURVES (CONT)

At TA = +25°C, VS = ±15V, λ = 650nm, unless otherwise noted.

0.6

0.5

0.4

0.3

0.2

Quiescent Current (mA)

0.1

0

20mV/div

QUIESCENT CURRENT vs TEMPERATURE

–50 –25 0 25 50 75 100 125

–75

SMALL-SIGNAL RESPONSE

VS = ±2.25V

Temperature (°C)

VS = ±15V

Dice

1000

Dotted lines show

noise beyond the

signal bandwidth.

100

RF = 100MΩ

10

1

Noise Voltage (µVrms)

0.1
1 10 1k 10k 100k100

2V/div

OUTPUT NOISE VOLTAGE

vs MEASUREMENT BANDWIDTH

RF = 10MΩ

RF = 100kΩ

RF = 1MΩ

1M

Frequency (Hz)

LARGE-SIGNAL RESPONSE

®

OPT209

50µs/div

–8

10

–9

10

–10

10

–11

10

–12

10

Noise Effective Power (W)

–13

10

–14

10

NOISE EFFECTIVE POWER

vs MEASUREMENT BANDWIDTH

Dotted lines show
noise beyond the
signal bandwidth.

RF = 100kΩ

RF = 1MΩ

1 10 1k 10k 100k100

50µs/div

RF = 10MΩ

RF = 100MΩ

1M

Frequency (Hz)

6

APPLICATIONS INFORMATION

Figure 1 shows the basic connections required to operate the
OPT209. Applications with high-impedance power supplies
may require decoupling capacitors located close to the
device pins as shown. Output is zero volts with no light and
increases with increasing illumination.

2

1MΩ

R

F

4

I

ID is proportional
to light intensity
(radiant power).

λ

I

D

(0V)

10pF

1

83

0.1µF 0.1µF

D

175Ω

OPT209

5

V

O

VO = ID R

F

metal, and differential stages are cross-coupled. Furthermore,
the photodiode area is very large relative to the op amp input
circuitry making these effects negligible.

If your light source is focused to a small area, be sure that
it is properly aimed to fall on the photodiode. If a narrowly
focused light source were to miss the photodiode area and
fall only on the op amp circuitry, the OPT209 would not
perform properly. The large (0.090 x 0.090 inch) photodiode
area allows easy positioning of narrowly focused light sources.
The photodiode area is easily visible—it appears very dark
compared to the surrounding active circuitry.

The incident angle of the light source also affects the
apparent sensitivity in uniform irradiance. For small incident
angles, the loss in sensitivity is simply due to the smaller
effective light gathering area of the photodiode (proportional
to the cosine of the angle). At a greater incident angle, light
is diffused by the side of the package. These effects are
shown in the typical performance curve “Response vs Incident
Angle.”

–15V+15V

FIGURE 1. Basic Circuit Connections.

Photodiode current, ID, is proportional to the radiant power
or flux (in watts) falling on the photodiode. At a wavelength
of 650nm (visible red) the photodiode Responsivity, RI, is
approximately 0.45A/W. Responsivity at other wavelengths
is shown in the typical performance curve “Responsivity vs
Wavelength.”

The typical performance curve “Output Voltage vs Radiant
Power” shows the response throughout a wide range of
radiant power. The response curve “Output Voltage vs
Irradiance” is based on the photodiode area of 5.23 x 10

–6m2

The OPT209’s voltage output is the product of the photodiode
current times the feedback resistor, (I

). The internal

DRF

feedback resistor is laser trimmed to 1MΩ ±2%. Using this
resistor, the output voltage responsivity, RV, is approximately

0.45V/µW at 650nm wavelength.
An external resistor can be connected to set a different

voltage responsivity. Best dynamic performance is achieved
by connecting R

< 1MΩ), with the internal resistor as shown in

(for R

F

in series (for RF > 1MΩ), or in parallel

EXT

Figure 2. These connections take advantage of on-chip
capacitive guarding of the internal resistor, which improves
dynamic performance. For values of R
external capacitor, C
with R

(see Figure 2). This capacitor eliminates gain

F

, should be connected in parallel

EXT

peaking and prevents instability. The value of C

less than 1MΩ, an

F

can be

EXT

read from the table in Figure 2.

LIGHT SOURCE POSITIONING

The OPT209 is 100% tested with a light source that uniformly
illuminates the full area of the integrated circuit, including
the op amp. Although all IC amplifiers are light-sensitive to
some degree, the OPT209 op amp circuitry is designed to
minimize this effect. Sensitive junctions are shielded with

For R

> 1MΩ

F

2

1MΩ

λ

V+

.

For R

< 1MΩ

F

RF = R

2

EXT

3pF

|| 1MΩ

1MΩ

λ

1

83

V+

EQUIVALENT RFC

100MΩ

10MΩ

1MΩ
330kΩ
100kΩ 9pF

33kΩ 25pF

≤20kΩ

NOTES: (1) No C
Not recommended due to possible
op amp instability.

FIGURE 2. Using External Feedback Resistor.

EXT

175Ω

OPT209

V–

C

EXT

R

EXT

175Ω

OPT209

V–

EXT

(1)
(1)
(1)

(1)

pF

(2)

required. (2)

= R

R

4

5

4

5

+ 1MΩ

F

EXT

R

EXT

V

= ID R

O

F

V

= ID R

O

F

®

7

OPT209

DARK ERRORS

The dark errors in the specification table include all sources.
The dominant error source is the input offset voltage of the
op amp. Photodiode dark current and input bias current of
the op amp are in the 2pA range and contribute virtually no
offset error at room temperature. Dark current and input bias
current double for each 10°C above 25°C. At 70°C, the error
current can be approximately 100pA. This would produce a
1mV offset with R

= 10MΩ. The OPT209 is useful with

F

feedback resistors of 100MΩ or greater at room temperature.
The dark output voltage can be trimmed to zero with the
optional circuit shown in Figure 3.

When used with very large feedback resistors, tiny leakage
currents on the circuit board can degrade the performance of
the OPT209. Careful circuit board design and clean assembly
procedures will help achieve best performance. A “guard
ring” on the circuit board can help minimize leakage to the
critical non-inverting input (pin 2). This guard ring should
encircle pin 2 and connect to Common, pin 8.

2

100µA

1/2 REF200

100Ω

100Ω

100µA

1/2 REF200

V+

V–

λ

83

500Ω

0.01µF

Adjust dark output for 0V.

Trim Range: ±7mV

1MΩ

10pF

1

V+

V–

175Ω

OPT209

4

5

V

FIGURE 3. Dark Error (Offset) Adjustment Circuit.

simple R/C circuit with a –3dB cutoff frequency of 16kHz.
This yields a rise time of approximately 22µs (10% to 90%).
Dynamic response is not limited by op amp slew rate. This
is demonstrated by the dynamic response oscilloscope
photographs showing virtually identical large-signal and
small-signal response.

Dynamic response will vary with feedback resistor value as
shown in the typical performance curve “Voltage Output
Responsivity vs Frequency.” Rise time (10% to 90%) will
vary according to the –3dB bandwidth produced by a given
feedback resistor value—

0.35

tR≈

f

C

where:

t

is the rise time (10% to 90%)

R

is the –3dB bandwidth

f

C

NOISE PERFORMANCE

Noise performance of the OPT209 is determined by the op
amp characteristics in conjunction with the feedback
components and photodiode capacitance. The typical
performance curve “Output Noise Voltage vs Measurement
Bandwidth” shows how the noise varies with R
bandwidth (1Hz to the indicated frequency). The signal
bandwidth of the OPT209 is indicated on the curves. Noise
can be reduced by filtering the output with a cutoff frequency
equal to the signal bandwidth.

O

Output noise increases in proportion to the square-root of the
feedback resistance, while responsivity increases linearly
with feedback resistance. So best signal-to-noise ratio is
achieved with large feedback resistance. This comes with
the trade-off of decreased bandwidth.

The noise performance of a photodetector is sometimes
characterized by Noise Effective Power (NEP). This is the
radiant power which would produce an output signal equal
to the noise level. NEP has the units of radiant power
(watts). The typical performance curve “Noise Effective
Power vs Measurement Bandwidth” shows how NEP varies

and measurement bandwidth.

with R

F

and measured

F

(1)

LINEARITY PERFORMANCE

Current output of the photodiode is very linear with radiant
power throughout a wide range. Nonlinearity remains below
approximately 0.01% up to 100µA photodiode current. The
photodiode can produce output currents of 10mA or greater
with high radiant power, but nonlinearity increases to several
percent in this region.

This very linear performance at high radiant power assumes
that the full photodiode area is uniformly illuminated. If the
light source is focused to a small area of the photodiode,
nonlinearity will occur at lower radiant power.

DYNAMIC RESPONSE

Using the internal 1MΩ resistor, the dynamic response of
the photodiode/op amp combination can be modeled as a

®

OPT209

2

1MΩ

R

F

4

10pF

175Ω

Gain Adjustment

+50%; –0%

5

λ

OPT209

1

83

V+

FIGURE 4. Responsivity (Gain) Adjustment Circuit.

8

V–

5kΩ

10kΩ

V

O

2

1MΩ

OPT209

10pF

175Ω

2

83

5

4

1

R

1

1kΩ

–15V

λ

+15V

R

F

I

D

IO ≤ 5mA

IO = ID 1 +

R

F

R

1

1MΩ

OPT209

10pF

175Ω

2

83

5

4

1

NC

λ

R

F

1MΩ

OPT209

10pF

175Ω

2

83

5

4

1

V

O

V–

λ

V+

R

F

8

This OPT209 used
as photodiode, only.

NC

VO = (I

D2 – ID1) RF

I

D1

I

D2

1MΩ

R

F

4

10pF

175Ω

λ

OPT209

1

83

V+

Advantages: High gain with low resistor values.
Less sensitive to circuit board leakage.

Disadvantage: Higher offset and noise than by using high

value for R

V–

.

F

FIGURE 5. “T” Feedback Network.

2

1MΩ

R

F1

10pF

175Ω

λ

OPT209

1

83

V+

Max linear
input voltage
(V+) –0.6V typ

V–

R1 + R

= ID R

V

O

R

5

R

1

19kΩ

R

2

1kΩ

4

5

= I

D1 RF1

+ I

V

O

2

D2 RF2

2

F

Bandwidth is reduced to
11kHz due to additional
photodiode capacitance.

FIGURE 7. Differential Light Measurement.

2

1MΩ

R

F2

4

λ

FIGURE 6. Summing Output of Two OPT209s.

10pF

175Ω

1

83

V+

V–

5

OPT209

= I

V

O

D2 RF2

FIGURE 8. Current Output Circuit.

®

9

OPT209

C

2

2

1MΩ

R

F

4

0.1µF
R

1MΩ

2

10pF

175Ω

5

λ

OPT209

1

83

(1)

V

Z

3.3V

FIGURE 9. Single Power Supply Operation.

5kΩ

0.1µF

V+

NOTE: (1) Zener diode or other shunt regulator.

2

1MΩ

R

F1

4

10pF

+

= IDR

V

O

F

–

V

Z

(pesudo-ground)

A

1

R

3

100kΩ

R

1

2

1MΩ

1MΩ

4

C

0.1µF

1

10pF

175Ω

5

λ

V

O

OPT209

8

See AB-061 for details.

20dB/decade

f

–3dB

=

2πR2R3C

R

= 16Hz

FIGURE 10. DC Restoration Rejects Unwanted Steady-

State Background Light.

INA106

10kΩ

2

100kΩ

5

Difference Measurement

1

2

175Ω

5

λ

OPT209

1

8

83

V+

V–

2

1MΩ

R

F2

4

10pF

175Ω

5

λ

OPT209

1

83

V+

FIGURE 11. Differential Light Measurement.

®

OPT209

V–

= I

V

O1

D1 RF1

= I

V

O2

D2 RF2

10

3

100kΩ

100kΩ

10kΩ

14

G = 10

1

100kΩ

LOG100

= 10 (V

V

O

6

O2

– VO1)

1

Log of Ratio Measurement

(Absorbance)

7
10

V

O

= K log

V

O1

V

O2

3

1nF

C

C

+15V

2

REF102

4

10V
6

10kΩ

100kΩ

FIGURE 12. LED Output Regulation Circuit.

3.3nF

OPA627

0.03µF11kΩ

LED

270Ω

IN4148

Glass Microscope Slide

≈ 8%

OPT209

2

LED

λ

83

Approximately
92% light
available for application.

1MΩ

10pF

1

+15V

–15V

R

F

175Ω

OPT209

4

5

1/2

REF200

100µA

2

10pF

λ

83

R

1

22.5kΩ

Values shown provide a dark output of 4mA.
Output is 20mA at a photodiode current of

. Values shown are for I

I

D max

FIGURE 13. 4-20mA Current-Loop Transmitter.

D max

1MΩ

OPT209

max = 1µA.

1

4

175Ω

2N2222

5

IN4148

R1 = – 994,000Ω

(1 – 2500 I

R2 = – 26,000Ω

(1 – 2500 I

R

2

65Ω

1.014 X 10

26,000

D max

D max

100µA

1/2

REF200

10V to 36V

20kΩ

4-20mA

(4mA Dark)

6

)

)

11

®

OPT209