TC815CBU 查看數據表（PDF） - Microchip Technology
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TC815CBU
Microchip Technology
TC815CBU Datasheet PDF : 26 Pages
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TC815
FIGURE 3-1:
RATIOMETRIC RESISTANCE MEASUREMENT FUNCTIONAL DIAGRAM
R5/1638500Ω
39
R4/163850Ω 38
R3/16385Ω 37
R2/1638.5Ω 36
R1/163.85Ω
35
S29
S30
S31
S32
S33
÷10k ÷1k ÷100 ÷10 ÷1
VSSD
30
Ohms
VA
Ω • HIΩ
~1.5kΩ
Low Ohms
Ω • LO
VCC
10kΩ
~1.5kV
9V
57 VSSA
VCC
28
30
R18
24kΩ
REFHI
34
5kΩ
Voltage
S24 S25 S26 S27 S28
Reference
29
R8
220Ω
33
CREF
S23 DE • Ω
≈ VCC - 2.8V +
S20
DE S19
DE + Ω –
VCC - 2.6V
Analog
Common
0.1µF 32
31 50
R6/100kΩ
S18
DE
S21 DE • Ω
DE
Buffer
TC815
R7/100k Ω 50 S12
RX Unknown
V•
1
1
S13
INT • (Ω + DC)
S35
S37 Ω Ω
Integrator
Comparator
S36
Ω
S34
Ω
RΩBUF 54 55
49
RVIBUF
150kΩ
220kΩ
CAZ
47
0.1µF
CINT
0.1µF
FIGURE 3-2:
RS
16.385k
Unknown
RESISTANCE MEASUREMENT ACCURACY SET BY EXTERNAL
STANDARD RESISTOR
VA
0.64V for Ohms
0.32V for LO Ohms
Example: 200kΩ Full Scale Measurement
(a )
VR
=
------------1---6----3---.--8---5----k---Ω---------------
163.85 + 220 + RX
x
0.64
CREF
100 kΩ
+
VR
VR
220Ω
(b)
VX
=
----------------------------R----X------------------------------
163.85kΩ + 220Ω + RX
x0.64
(c) “Ramp Up Voltage” = “Ramp Down Voltage”
.
..
-----V----X-------
(RICI)
x
T
I
=
(---R--V--I--CX-----I-)- T D E
VX
RX
To Analog Buffer
Where:
RI = Integrating Resistor, TI = Integrate Time
CI = Integrating Capacitor, TDE = Deintegrate Time
(d)
RX
=
163.85
(TDE)
TI
Independent of RI, CI or Internal Voltage Reference
DS21474B-page 8
© 2002 Microchip Technology Inc.
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