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參數(shù)資料
| 型號(hào)： | ICL8048BCJE |
| 廠商： | INTERSIL CORP |
| 元件分類： | 運(yùn)動(dòng)控制電子 |
| 英文描述： | Log Amplifier |
| 中文描述： | LOG OR ANTILOG AMPLIFIER, CDIP16 |
| 封裝： | FRIT SEALED, CERDIP-16 |
| 文件頁(yè)數(shù)： | 6/7頁(yè) |
| 文件大小： | 85K |
| 代理商： | ICL8048BCJE |
6
To determine the maximum error over the operating
temperature range, the 0
o
C to 70
o
C absolute error values
given in the table of electrical specifications should be used.
For intermediate temperatures, assume a linear increase in
the error between the 25
o
C value and the 70
o
C value.
It is important to note that the ICL8048 requires positive
values of I
REF
, and the input current must also be positive.
Application of negative I
IN
to the ICL8048 or negative I
REF
will cause malfunction, and if maintained for long periods,
would lead to device degradation. Some protection can be
provided by placing a diode between pin 7 and ground.
Setting Up the Reference Current
The input current reference pin (I
REF
) is not a true virtual
ground. For the ICL8048, a fraction of the output voltage is
seen on Pin 16 (Figure 7). This does not constitute an
appreciable error provided V
REF
is much greater than this
voltage. A 10V or 15V reference satisfies this condition.
Alternatively, I
REF
can be provided from a true current
source. One method of implementing such a current source
is shown in Figure 12.
Log of Ratio Circuit, Division
The ICL8048 may be used to generate the log of a ratio by
modulating the I
REF
input. The transfer function remains the
same, as defined by Equation 7:
Clearly it is possible to perform division using just one
ICL8048, followed by an antilog amplifier. For multiplication,
it is generally necessary to use two log amps, summing their
outputs into an antilog amp.
To avoid the problems caused by the I
REF
input not being a
true virtual ground (discussed in the previous section), the
circuit of Figure 12 is again recommended if the I
REF
input is
to be modulated.
Definition of Terms
In the definitions which follow, it will be noted that the various
error terms are referred to the output of the log amp, and to
the input of the antilog amp. The reason for this is explained
on the previous page.
Dynamic Range.
The dynamic range of the ICL8048 refers
to the range of input voltages or currents over which the
device is guaranteed to operate.
Error, Absolute Value.
The absolute error is a measure of
the deviation from the theoretical transfer function, after
performing the offset and scale factor adjustments as
outlined, (ICL8048). It is expressed in mV and referred to the
linear axis of the transfer function plot. Thus, in the case of
the ICL8048, it is a measure of the deviation from the
theoretical output voltage for a given input current or voltage.
The absolute error specification is guaranteed over the
dynamic range.
Error, % of Full Scale.
The error as a percentage of full
scale can be obtained from the following relationship:
Temperature Coefficient of V
OUT
.
For the ICL8048 the
temperature coefficient refers to the drift with temperature of
V
OUT
for a constant input current.
Power Supply Rejection Ratio.
The ratio of the voltage
change in the linear axis of the transfer function (V
OUT
for
the ICL8048) to the change in the supply voltage, assuming
that the log axis is held constant.
Wideband Noise.
For the ICL8048, this is the noise
occurring at the output under the specified conditions.
Scale Factor.
For the log amp, the scale factor (K) is the
voltage change at the output for a decade (i.e., 10:1) change
at the input. See Equation 5.
Application Notes
For further applications assistance, see A007 “The
ICL8048/8049 Monolithic Log-Antilog Amplifiers”.
INPUT CURRENT (A)
10
-10
10
-9
10
-8
10
-7
10
-6
10
-5
10
-4
10
-3
-6
-8
-4
-2
0
2
4
6
8
O
I
REF
= 1nA
I
REF
= 1
μ
A
I
REF
= 1mA
Actual output will lie
within shaded area for
ICL8048BC at 25
o
C
30mV
30mV
TRANSFER FN
THEORETICAL
FIGURE 11. TRANSFER FUNCTION FOR CURRENT INPUTS
+15V
+15V
+
-
741
2N2609
2N2219
10k
V
REF
I
REF
R
1
I
REF
= V
REF
/R
1
(TO PIN 16 ON ICL8048)
FIGURE 12.
VOUT
Klog
–
10
--------------
=
(EQ. 7)
Error, % of Full Scale
-----------------------------------------------------------------------
=
ICL8048
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| ICL8048 | Log Amplifier |
| ICL8069CCZQ | Low-Voltage Reference |
| ICL8069DCZQ | Low-Voltage Reference |
| ICL8069DESA | Low-Voltage Reference |
| ICL8069CCSA | Low-Voltage Reference |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ICL8048C | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog IC |
| ICL8048C/D DIE | 制造商:Harris Corporation 功能描述: |
| ICL8048CJE | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Analog IC |
| ICL8049 | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:N-CHANNEL JFET |
| ICL8049BCJE | 制造商:INTERSIL 制造商全稱:Intersil Corporation 功能描述:Antilog Amplifier |
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