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參數(shù)資料
| 型號： | EL5486CU |
| 元件分類： | 比較器 |
| 英文描述： | Quad 4ns High Speed Comparators |
| 中文描述： | 四4ns的高速比較器 |
| 文件頁數(shù)： | 2/12頁 |
| 文件大?。?/td> | 119K |
| 代理商： | EL5486CU |
10
EL5485C, EL5486C - Preliminary
Quad 4ns High Speed Comparators
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4
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5
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P
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m
in
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ry
Select the threshold voltage VTH and calculate R1 and
R2. The current through R1/R2 bias string must be many
times greater than the input bias current of the
comparator:
Let the hysteresis be VH, and calculate R3:
where:
VO=VSD-0.8V (swing of the output)
Recalculate R2 to maintain the same value of VTH:
Non inverting comparator with hysteresis:
R3 adds a portion of the output to the positive input.
Note that the current through R3 should be much greater
than the input bias current in order to minimize errors.
The calculation of the resistor values as follows:
Pick the value of R1. R1 should be small (less than 1k)
in order to minimize the propagation delay time.
Choose the hysteresis VH and calculate R3:
Check the current through R3 and make sure that it is
much greater than the input bias current as follows:
The above two methods will generate hysteresis of up to
a few hundred millivolts. Beyond that, the impedance of
R3 is low enough to affect the bias string and adjustment
of R1 may be required.
Power Dissipation
When switching at high speeds, the comparator's drive
capability is limited by the rise in junction temperature
caused by the internal power dissipation. For reliable
operation, the junction temperature must be kept below
TJMAX (125°C).
An approximate equation for the device power dissipa-
tion is as follows. Assume the power dissipation in the
load is very small:
where:
VS is the analog supply voltage from VS+ to VS-
IS is the analog quiescent supply current per comparator
VSD is the digital supply voltage from VSD to ground
ISD is the digital supply current per comparator
ISD strongly depends on the input switching frequency.
Please refer to the performance curve to choose the input
driving frequency. Having obtained the power dissipa-
tion, the maximum junction temperature can be
determined as follows:
where:
TMAX is the maximum ambient temperature
θJA is the thermal resistance of the package
Threshold Detector
The inverting input is connected to a reference voltage
and the non-inverting input is connected to the input. As
the input passes the VREF threshold, the comparator's
V
TH
V
REF
R
1
R
1
R
2
+
-------------------
×
=
R
3
V
O
V
H
--------
R
1
(
R
2 )
||
×
=
R
2 1VREF
(
V
TH )
V
TH
R
1
-----------
÷
–
V
TH
0.5V
SD
–
R
3
-------------------------------------
+
=
+
-
R3
VIN
VREF
R1
R
3
V
(
SD
0.8
)
R
1
V
H
--------
×
–
=
I
0.5V
SD
V
REF
–
R
3
----------------------------------------
=
P
DISS
V
S
I
S
V
SD
I
SD )
×
+
×
(
=
T
JMAX
T
MAX
Θ
JA
P
DISS
×
+
=
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| EL5486CU-T13 | 制造商:ELANTEC 制造商全稱:ELANTEC 功能描述:Quad 4ns High Speed Comparators |
| EL5492ACL | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Operational Amplifier |
| EL5492ACL-T13 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Operational Amplifier |
| EL5492ACL-T7 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Operational Amplifier |
| EL5492CS | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:Operational Amplifier |
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