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参数资料
| 型号： | AN-242 |
| 厂商： | National Semiconductor Corporation |
| 英文描述： | LJT 18C 18#20 SKT RECP |
| 中文描述： | 应用新的精密运算放大器 |
| 文件页数： | 15/16页 |
| 文件大小： | 267K |
| 代理商： | AN-242 |
Temperature sensing is done with a bridge, one leg of which
is formed by an IC temperature sensor, S1, and a reference
diode, D1. Frequency stabilization is done with C2 providing
a lag that is finally broken out by C1. If the control transistor,
Q2, is put inside the oven for maximum heating efficiency,
some level of regulation is suggested for the heater supply
when precise control is required. With Q2 in the oven, ab-
rupt supply changes will alter heating, which must be com-
pensated for by the loop. This takes time, causing a small
temperature transient.
Because the input bias current of the LM11 does not in-
crease with temperature, it can be installed inside the oven
for best performance. In fact, when an oven is available in a
piece of equipment, it would be a good idea to put all critical
LM11s inside the oven if the temperature is less than 100
§
C.
ac amplifier
Figure 26 shows an op amp used as an AC amplifier. It is
unusual in that DC bootstrapping is used to obtain high input
resistance without requiring high-value resistors. In theory,
this increases the ouput offset because the op amp offset
voltage is multiplied by the resistance boost.
But when conventional resistor values are used, it is practi-
cal to include R5 to eliminate bias-current error. This gives
less output offset than if a single, large resistor were used.
C1 is included to reduce noise.
standard cell buffer
The accuracy and lifetime of a standard cell deteriorate with
loading. Further, with even a moderate load transient, re-
covery is measured in minutes, hours or even days. The
circuit inFigure 27 not only buffers the standard cell but also
disconnects it in the event of malfunction.
The fault threshold is determined by the gate turn-on volt-
age of Q1. As the voltage on the gate approaches the
threshold either because of low battery voltage or excessive
output loading, the MOS switch will begin to turn off. At the
turn off threshold, the output voltage can rise because of
amplifier bias current flowing through the increasing switch
resistance. Therefore, a LED indicator is included that extin-
R
IN
e
R1
#
1
a
R2
R3
J
;
A
V
e
R2
a
R3
a
R4
R2
a
R3
TL/H/7479–28
Figure 26. A high input impedance AC amplifier for a piezoelectric transducer. Input resistance of 880 M
X
and gain of
10 is obtained.
TL/H/7479–29
*
cannot have gate protection diode; V
TH
l
V
OUT
Figure 27. Battery powered buffer amplifier for standard cell has negligible loading and disconnects cell for low
supply voltage or overload on output. Indicator diode extinguishes as disconnect circuitry is activated.
15
相关PDF资料 |
PDF描述 |
|---|---|
| AN-40 | Application Note 40 |
| AN-5002 | LJT 18C 18#20 SKT WALL RECP |
| AN-5025 | Applications Using the GTLP10B320 |
| AN-5026 | Circular Connector; No. of Contacts:19; Series:MS27656; Body Material:Aluminum; Connecting Termination:Crimp; Connector Shell Size:15; Circular Contact Gender:Pin; Circular Shell Style:Wall Mount Receptacle; Insert Arrangement:15-19 RoHS Compliant: No |
| AN-5031 | GTLP Power Configuration |
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