1994 Burr-Brown Corporation

PDS-1228B

Printed in U.S.A. January, 1994

FPO

70%

FEATURES

PHOTODIODE SIZE: 0.090 x 0.090 inch
(2.29 x 2.29mm)

FEEDBACK RESISTOR

HIGH RESPONSIVITY: 0.47A/W

(650nm)

IMPROVED UV RESPONSE

LOW DARK ERRORS: 2mV

BANDWIDTH: 4kHz

WIDE SUPPLY RANGE:

2.25 to

18V

LOW QUIESCENT CURRENT: 400

HERMETIC TO-99

APPLICATIONS

MEDICAL INSTRUMENTATION

LABORATORY INSTRUMENTATION

POSITION AND PROXIMITY SENSORS

PHOTOGRAPHIC ANALYZERS

SMOKE DETECTORS

DESCRIPTION

The OPT301 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 FET-
input 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 de-
signs such as leakage current errors, noise pick-up and
gain peaking due to stray capacitance.

The OPT301 operates over a wide supply range (

2.25

18V) and supply current is only 400

A. It is

packaged in a hermetic TO-99 metal package with a
glass window, and is specified for the 40

C to 85

temperature range.

INTEGRATED PHOTODIODE

AND AMPLIFIER

OPT301

40pF

V+

OPT301

SPECTRAL RESPONSIVITY

Voltage Output (V/ľW)

Wavelength (nm)

100

200

300

400 500

600

700 800

900 1000 1100

0.5

0.4

0.3

0.2

0.1

0.5

0.4

0.3

0.2

0.1

Photodiode Responsivity (A/W)

Infrared

Blue

Green

Yellow

Red

Ultraviolet

Using Internal
1M

Resistor

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Internet: http://www.burr-brown.com/ ˇ FAXLine: (800) 548-6133 (US/Canada Only) ˇ Cable: BBRCORP ˇ Telex: 066-6491 ˇ FAX: (520) 889-1510 ˇ Immediate Product Info: (800) 548-6132

OPT301

OPT301M

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

RESPONSIVITY
Photodiode Current

650nm

0.47

A/W

Voltage Output

650nm

0.47

vs Temperature

200

ppm/

Unit-to-Unit Variation

650nm

Nonlinearity

(1)

FS Output = 10V

0.01

% of FS

Photodiode Area

(0.090 x 0.090in)

0.008

(2.29 x 2.29mm)

5.2

DARK ERRORS, RTO

(2)

Offset Voltage, Output

0.5

vs Temperature

vs Power Supply

2.25V to

18V

100

V/V

Voltage Noise

Measured BW = 0.1 to 100kHz

160

Vrms

RESISTOR--1M

Internal

Resistance

Tolerance

0.5

vs Temperature

ppm/

FREQUENCY RESPONSE
Bandwidth, Large or Small-Signal, 3dB

kHz

Rise Time, 10% to 90%

Settling Time, 1%

FS to Dark

240

0.1%

FS to Dark

350

0.01%

FS to Dark

900

Overload Recovery Time

100% overdrive, V

15V

240

100% overdrive, V

500

100% overdrive, V

2.25V

1000

OUTPUT
Voltage Output

= 10k

(V+) 1.25

(V+) 0.65

= 5k

(V+) 2

(V+) 1

Capacitive Load, Stable Operation

Short-Circuit Current

POWER SUPPLY
Specified Operating Voltage

Operating Voltage Range

2.25

Quiescent Current

= 0

0.4

0.5

TEMPERATURE RANGE
Specification

+85

Operating/Storage

+125

Thermal Resistance,

200

C/W

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

SPECIFICATIONS

ELECTRICAL

At T

= +25

C, V

15V,

= 650nm, internal 1M

feedback resistor, unless otherwise noted.

PHOTODIODE SPECIFICATIONS

At T

= +25

C, unless otherwise noted.

Photodiode of OPT301

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Photodiode Area

(0.090 x 0.090in)

0.008

(2.29 x 2.29mm)

5.1

Current Responsivity

650nm

0.47

A/W

Dark Current

= 0V

(1)

500

vs Temperature

doubles every 10

Capacitance

= 0V

(1)

4000

NOTE: (1) Voltage Across Photodiode.

OPT301

SPECIFICATIONS

(CONT)

ELECTRICAL

Op Amp Section of OPT301

(1)

At T

= +25

C, V

15V, unless otherwise noted.

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.

OPT301 Op Amp

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

INPUT
Offset Voltage

0.5

vs Temperature

vs Power Supply

2.25V to

18V

V/V

Input Bias Current

vs Temperature

doubles every 10

NOISE
Input Voltage Noise
Voltage Noise Density, f=10Hz

nV/

f=100Hz

nV/

f=1kHz

nV/

Current Noise Density, f=1kHz

0.8

fA/

INPUT VOLTAGE RANGE
Common-Mode Input Range

14.4

Common-Mode Rejection

106

INPUT IMPEDANCE
Differential

||3

||pF

Common-Mode

||3

||pF

OPEN-LOOP GAIN
Open-Loop Voltage Gain

120

FREQUENCY RESPONSE
Gain-Bandwidth Product

380

kHz

Slew Rate

0.5

Settling Time 0.1%

0.01%

OUTPUT
Voltage Output

= 10k

(V+) 1.25

(V+) 0.65

= 5k

(V+) 2

(V+) 1

Short-Circuit Current

POWER SUPPLY
Specified Operating Voltage

Operating Voltage Range

2.25

Quiescent Current

= 0

0.4

0.5

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

OPT301

ELECTROSTATIC
DISCHARGE SENSITIVITY

This integrated circuit can be damaged by ESD. Burr-Brown
recommends that all integrated circuits be handled with ap-
propriate 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.

Feedback

Common

Output

V+

NOTE: Metal package is internally connected to common (Pin 8).

Photodiode
Area

PIN CONFIGURATION

Top View

PACKAGE INFORMATION

PACKAGE DRAWING

PRODUCT

PACKAGE

NUMBER

(1)

OPT301M

8-Pin TO-99

001-1

NOTE: (1) For detailed drawing and dimension table, please see end of data
sheet, or Appendix C of Burr-Brown IC Data Book.

Supply Voltage ...................................................................................

18V

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

Output Short-Circuit (to ground) ............................................... Continuous
Operating Temperature ................................................... 55

C to +125

Storage Temperature ...................................................... 55

C to +125

Junction Temperature .................................................................... +125

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

ABSOLUTE MAXIMUM RATINGS

OPT301

TYPICAL PERFORMANCE CURVES

At T

= +25

C, V

15V,

= 650nm, unless otherwise noted.

NORMALIZED SPECTRAL RESPONSIVITY

Normalized Current or Voltage Output

Wavelength (nm)

100

200

300

400 500

600

700 800

900 1000 1100

1.0

0.8

0.6

0.4

0.2

650nm

(0.47A/W)

(0.52A/W)

VOLTAGE RESPONSIVITY vs RADIANT POWER

Radiant Power (ľW)

Output Voltage (V)

0.01

0.1

100

0.1

0.01

0.001

= 1M

= 100k

= 10k

= 10M

= 650nm

VOLTAGE RESPONSIVITY vs IRRADIANCE

Irradiance (W/m

)

Output Voltage (V)

0.001

0.01

100

0.1

0.01

0.001

= 1M

= 100k

= 10k

= 10M

= 650nm

DISTRIBUTION OF RESPONSIVITY

Units (%)

Responsivity (A/W)

0.45

0.46

0.47

0.48

0.49

0.5

Distribution Totals

100%

= 650nm

Laboratory Test

Data

RESPONSE vs INCIDENT ANGLE

Relative Response

Incident Angle (°)

1.0

0.8

0.6

0.4

0.2

ą20

ą40

ą60

ą80

1.0

0.8

0.6

0.4

0.2

VOLTAGE OUTPUT RESPONSIVITY vs FREQUENCY

Responsivity (V/ľW)

Frequency (Hz)

100

0.1

0.01

0.001

10k

100k

= 10M

= 3.3M

= 1M

= 330k

EXT

= 30pF

= 100k

EXT

= 90pF

= 33k

EXT

= 180pF

= 10k

EXT

= 350pF

= 650nm

OPT301

TYPICAL PERFORMANCE CURVES

At T

= +25

C, V

15V,

= 650nm, unless otherwise noted.

SMALL-SIGNAL DYNAMIC RESPONSE

LARGE-SIGNAL DYNAMIC RESPONSE

20mV/div

2V/div

100

s/div

100

s/div

QUIESCENT CURRENT vs TEMPERATURE

Quiescent Current (mA)

Temperature (°C)

0.6

0.5

0.4

0.3

0.2

0.1

100

125

= ą15V

= ą2.25V

Dice

OUTPUT NOISE VOLTAGE

vs MEASUREMENT BANDWIDTH

Measurement Bandwidth (Hz)

Noise Voltage (ľVrms)

10k

100k

100

1000

100

0.1

= 10M

= 1M

= 100k

EXT

= 90pF

= 100M

= 10k

EXT

= 350pF

Dotted lines show

noise beyond the

signal bandwidth.

NOISE EFFECTIVE POWER

vs MEASUREMENT BANDWIDTH

Measurement Bandwidth (Hz)

Noise Effective Power (W)

10k

100k

100

Dotted lines indicate
noise measured beyond
the signal bandwidth.

= 650nm

= 100M

= 10M

= 1M

= 100k

= 10k

OPT301

APPLICATIONS INFORMATION

Figure 1 shows the basic connections required to operate the
OPT301. 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.

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 OPT301 would not
perform properly. The large (0.090

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 reflected and scattered by the side of the package. These
effects are shown in the typical performance curve
"Response vs Incident Angle."

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 approximately 2pA 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

= 10M

. The OPT301 is

useful with feedback resistors of 100M

or greater at room

temperature. The dark output voltage can be trimmed to
zero with the optional circuit shown in Figure 3.

FIGURE 1. Basic Circuit Connections.

Photodiode current, I

, is proportional to the radiant power

or flux (in watts) falling on the photodiode. At a wavelength
of 650nm (visible red) the photodiode Responsivity, R

, 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

The OPT301's voltage output is the product of the photodiode
current times the feedback resistor, (I

). The internal

feedback resistor is laser trimmed to 1M

2%. Using this

resistor, the output voltage responsivity, R

, is approximately

0.45V/

W at 650nm wavelength.

An external resistor can be used to set a different voltage
responsivity. For values of R

less than 1M

, an external

capacitor, C

EXT

, should be connected in parallel with R

(see

Figure 2). This capacitor eliminates gain peaking and prevents
instability. The value of C

EXT

can be read from the table in

Figure 2.

LIGHT SOURCE POSITIONING

The OPT301 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 OPT301 op amp circuitry is designed to
minimize this effect. Sensitive junctions are shielded with
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.

FIGURE 2. Using External Feedback Resistor.

EXTERNAL R

EXT

100M

(1)

10M

(1)

330k

30pF

100k

130pF

33k

180pF

10k

350pF

NOTE: (1) No C

EXT

required.

is proportional

to light intensity
(radiant power).

OPT301

40pF

15V

+15V

0.1ľF 0.1ľF

= I

(0V)

NOTE: Metal package
is internally connected
to common (Pin 8).

OPT301

40pF

= I

V+

EXT

OPT301

When used with very large feedback resistors, tiny leakage
currents on the circuit board can degrade the performance of
the OPT301. Careful circuit board design and clean assembly
procedures will help achieve best performance. A "guard
trace" 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.

DYNAMIC RESPONSE

Using the internal 1M

resistor, the dynamic response of

the photodiode/op amp combination can be modeled as a
simple R/C circuit with a 3dB cutoff frequency of 4kHz.
This yields a rise time of approximately 90

s (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--

where:

is the rise time (10% to 90%)

is the 3dB bandwidth

LINEARITY PERFORMANCE

Current output of the photodiode is very linear with radiant
power throughout a wide range. Nonlinearity remains below

approximately 0.02% up to 100

A photodiode current. The

photodiode can produce output currents of 1mA or greater
with high radiant power, but nonlinearity increases to several
percent in this region.

This excellent linearity 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.

NOISE PERFORMANCE

Noise performance of the OPT301 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

and measured

bandwidth (1Hz to the indicated frequency). The signal
bandwidth of the OPT301 is indicated on the curves. Noise
can be reduced by filtering the output with a cutoff frequency
equal to the signal bandwidth.

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
with R

and measurement bandwidth.

0. 35

(1)

FIGURE 3. Dark Error (Offset) Adjustment Circuit.

OPT301

40pF

V+

0.01ľF

500

V+

100ľA

1/2 REF200

100

100ľA

1/2 REF200

Adjust dark output for 0V.

Trim Range: ą7mV

FIGURE 4. Responsivity (Gain) Adjustment Circuit.

OPT301

40pF

V+

10k

Gain Adjustment

+50%; 0%

OPT301

FIGURE 5. "T" Feedback Network.

FIGURE 7. Differential Light Measurement.

FIGURE 8. Current Output Circuit.

Bandwidth is reduced to
2.8kHz due to additional
photodiode capacitance.

FIGURE 6. Summing Output of Two OPT301s.

OPT301

40pF

V+

19k

= I

+ R

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

OPT301

40pF

15V

+15V

5mA

= I

1 +

OPT301

40pF

OPT301

40pF

V+

This OPT301 used
as photodiode, only.

= (I

)

OPT301

40pF

= I

+ I

V+

OPT301

40pF

= I

V+

Max linear
input voltage
(V+) 0.6V typ

OPT301

FIGURE 9. Single Power Supply Operation.

FIGURE 10. Output Filter to Reduce Noise.

FIGURE 11. Differential Light Measurement.

OPT301

40pF

= I

V+

0.1ľF

(pesudo-ground)

(1)

3.3V

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

OPT301

40pF

V+

10nF

Output filter reduces
output noise from
250ľV to 195ľV.

OPT301

40pF

= I

V+

OPT301

40pF

= I

V+

100k

INA106

= 10 (V

)

100k

10k

G = 10

Difference Measurement

= K log

LOG100

Log of Ratio Measurement

(Absorbance)

100k

1nF

Part Number OPT301