ACPL-782T-500E 查看數據表（PDF） - Avago Technologies
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ACPL-782T-500E Datasheet PDF : 18 Pages
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Voltage sensing for DC rail measurement
2
ACPL-782T is a suitable device to measure the DC rail
voltage over different potentials. In a DC rail voltage
1.5
sensing application, the Line1 and Line2 in Figure 21 are
the DC lines to be measured.
Dividing ratio error due to the tolerances of the resistors
1
Dividing error when 1% resistors are used(%)
From a differential calculation, the error in the voltage
divider of Ra and Rb is expressed as
0.5
'A/A = Ra/(Ra + Rb) * ('Rb/Rb – 'Ra/Ra) (1)
Where A is the ratio of the resistor divider consisting of Ra
and Rb.
0
0.5
0.6
0.7
0.8
0.9
1.0
Ra/(Ra+Rb)
Since the errors of the resistors, 'Rb/Rb and 'Ra/Ra are
independent to each other, we need to take absolute
values in equation (1) to know the maximum possible
gain error of the divider and it gives
Figure 22: Divider Error % Vs Resistors Divider
'A/A = Ra/(Ra + Rb) * ( |'Rb/Rb| + |'Ra/Ra|) (2)
Figure 22 is the plot of the equation (2) when the resistors
have 1% tolerance expressing the relationship between
the ratio of Ra to (Ra+Rb) and the possible maximum error
of the dividing ratio.
150 pF
Semitec
EC2F103A2-40113
Thermistor
IGBT attaching type
+ SUPPLY
+5 V
TH
78L05
IN
+5 V
OUT
0.1 PF
0.1 PF
1
ACPL-782T
8
0.1 PF
2
7
2.0 k:
R1 R2
RL = R1//(R2+R3)
39:
3
6
2.0
4
5
k:
1 PF
R3
150 pF
Note on the thermistor and the RL:
Vdd x [RL/(Rth + RL)] x [ R3/(R2 + R3)] <= 200 mV, assuming R2+R3 >> R1
Rth: Resistance of thermistor
RL: Linearizing resistor value = R1//(R2+R3)
Figure 23. Recommended circuit for temperature sensing application.
10.0 k:
+15 V
0.1 PF
68
-
7
+
5 4 TL032A
VOUT
0.1 PF
10.0 k:
-15 V
17
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