DataSheet8.cn


PDF ( 数据手册 , 数据表 ) LOG100

零件编号 LOG100
描述 Precision LOGARITHMIC AND LOG RATIO AMPLIFIER
制造商 Burr-Brown Corporation
LOGO Burr-Brown Corporation LOGO 


1 Page

No Preview Available !

LOG100 数据手册, 描述, 功能
® LOG100
Precision
LOGARITHMIC AND LOG RATIO AMPLIFIER
FEATURES
q ACCURACY
0.37% FSO max Total Error
Over 5 Decades
q LINEARITY
0.1% max Log Conformity
Over 5 Decades
q EASY TO USE
Pin-selectable Gains
Internal Laser-trimmed Resistors
q WIDE INPUT DYNAMIC RANGE
6 Decades, 1nA to 1mA
q HERMETIC CERAMIC DIP
DESCRIPTION
The LOG100 uses advanced integrated circuit tech-
nologies to achieve high accuracy, ease of use, low
cost, and small size. It is the logical choice for your
logarithmic-type computations. The amplifier has guar-
anteed maximum error specifications over the full six-
decade input range (1nA to 1mA) and for all possible
combinations of I1 and I2. Total error is guaranteed so
that involved error computations are not necessary.
The circuit uses a specially designed compatible thin-
film monolithic integrated circuit which contains am-
plifiers, logging transistors, and low drift thin-film
9
–VCC
1
I1
Q1
A1
Q2
14
I2
6
+VCC
10
Com
VOUT = K LOG
I1
I2
APPLICATIONS
q LOG, LOG RATIO AND ANTILOG
COMPUTATIONS
q ABSORBANCE MEASUREMENTS
q DATA COMPRESSION
q OPTICAL DENSITY MEASUREMENTS
q DATA LINEARIZATION
q CURRENT AND VOLTAGE INPUTS
resistors. The resistors are laser-trimmed for maxi-
mum precision. FET input transistors are used for the
amplifiers whose low bias currents (1pA typical) per-
mit signal currents as low as 1nA while maintaining
guaranteed total errors of 0.37% FSO maximum.
Because scaling resistors are self-contained, scale
factors of 1V, 3V or 5V per decade are obtained
simply by pin selections. No other resistors are re-
quired for log ratio applications. The LOG100 will
meet its guaranteed accuracy with no user trimming.
Provisions are made for simple adjustments of scale
factor, offset voltage, and bias current if enhanced
performance is desired.
A2
270
220
7.5k
24k
7
VOUT
3
K=1
4
K=3
5
K=5
39k
Scale
Factor
2 Trim
Resistor values nominal only;
laser-trimmed for precision gain.
International Airport Industrial Park • Mailing Address: PO Box 11400 • Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd. • Tucson, AZ 85706
Tel: (520) 746-1111 • Twx: 910-952-1111 • Cable: BBRCORP • Telex: 066-6491 • FAX: (520) 889-1510 • Immediate Product Info: (800) 548-6132
© 1981 Burr-Brown Corporation
PDS-437E
Printed in U.S.A. January, 1995







LOG100 pdf, 数据表
–VCC 10k+VCC
–VCC
R1
100k
9
1
2
7
+
I1
LOG100
VOUT
14 10
6 543
I2
–VCC
9
LOG100
6
+VCC
I1 = I2
+VCC
CC
FIGURE 7. Output Offset Nulling.
FIGURE 8. Reverse Polarity Protection.
techniques should be used to avoid damage caused by low
energy electrostatic discharge (ESD).
ADJUSTMENTS OF SCALE FACTOR K
The value of K may be changed by increasing or decreasing
the voltage divider resistor normally connected to the out-
put, pin 7. To increase K put resistance in series between pin
7 and the appropriate scaling resistor pin (3, 4 or 5). To
decrease K place a parallel resistor between pin 2 and either
pin 3, 4 or 5.
APPLICATION INFORMATION
WIRING PRECAUTIONS
In order to prevent frequency instability due to lead induc-
tance of the power supply lines, each power supply should
be bypassed. This should be done by connecting a 10µF
tantalum capacitor in parallel with a 1000pF ceramic capaci-
tor from the +VCC and –VCC pins to the power supply
common. The connection of these capacitors should be as
close to the LOG100 as practical.
CAPACITIVE LOADS
Stable operation is maintained with capacitive loads of up to
100pF, typically. Higher capacitive loads can be driven if a
22carbon resistor is connected in series with the LOG100’s
output. This resistor will, of course, form a voltage divider
with other resistive loads.
LOG RATIO
One of the more common uses of log ratio amplifiers is to
measure absorbance. A typical application is shown in
Figure 9.
Absorbance of the sample is A = log λ1'
λ1
(22)
If λ2 = λ1 and D1 and D2 are matched A K log
I1
I
. (23)
2
Sample
λ1 λ1
Light λ2
Source
–VCC
I1 1
9
7
D1
I2 14
D2
LOG100
6 54
CC
10
3
+VCC
FIGURE 9. Absorbance Measurement.
+
VOUT
CIRCUIT PROTECTION
The LOG100 can be protected against accidental power
supply reversal by putting a diode (1N4001 type) in series
with each power supply line as shown in Figure 8. This
precaution is necessary only in power systems that momen-
tarily reverse polarity during turn-on or turn-off. If this
protection circuit is used, the accuracy of the LOG100 will
be degraded slightly by the voltage drops across the diodes
as determined by the power supply sensitivity specification.
The LOG100 uses small geometry FET transistors to achieve
the low input bias currents. Normal FET handling
DATA COMPRESSION
In many applications the compressive effects of the logarith-
mic transfer function is useful. For example, a LOG100
preceding an 8-bit analog-to-digital converter can produce
equivalent 20-bit converter operation.
SELECTING OPTIMUM VALUES OF I2 AND K
In straight log applications (as opposed to log ratio), both K
and I2 are selected by the designer. In order to minimize
errors due to output offset and noise, it is normally best to
®
LOG100
8














页数 9 页
下载[ LOG100.PDF 数据手册 ]


分享链接

Link :

推荐数据表

零件编号描述制造商
LOG100Precision LOGARITHMIC AND LOG RATIO AMPLIFIERBurr-Brown Corporation
Burr-Brown Corporation
LOG100Precision Logarithmic and Log Ratio AmplifierTexas Instruments
Texas Instruments
LOG100JPPrecision LOGARITHMIC AND LOG RATIO AMPLIFIERBurr-Brown Corporation
Burr-Brown Corporation
LOG101Precision LOGARITHMIC AND LOG RATIO AMPLIFIERBurr-Brown Corporation
Burr-Brown Corporation

零件编号描述制造商
STK15C88256-Kbit (32 K x 8) PowerStore nvSRAMCypress Semiconductor
Cypress Semiconductor
NJM4556DUAL HIGH CURRENT OPERATIONAL AMPLIFIERNew Japan Radio
New Japan Radio
EL1118-G5 PIN LONG CREEPAGE SOP PHOTOTRANSISTOR PHOTOCOUPLEREverlight
Everlight


DataSheet8.cn    |   2020   |  联系我们   |   搜索  |  Simemap