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5
PRODUCT SPECIFICATION
RC4200
Voltage Multiplier/Divider
Figure 3. Voltage Multiplier/Divider
Extended Range
The input and output voltage ranges can be extended to
include 0 and negative voltage signals by adding bias
currents. The R
S
C
S
filter circuits are eliminated when the
input and biasing resistors are selected to limit the respective
currents to 50
m
A min. and 250
m
A max.
Extended Range Multiplier
Figure 4. Extended Range Multiplier
65-4200-04
RC4200
V
Z
R
1
–V
S
I
3
3
6
4
5
8
7
1
2
I
2
I
1
I
4
V
X
V
Y
R
2
R
4
R
O
V
O
V
X
V
Y
R
1
R
2
=V
O
V
Z
R
O
R
4
Solving for V
0
V
V
R
R
4
V
Z
R
1
R
2
-------------------------------------
=
For a multiplier circuit V
Z
V
R
cons
t
tan
=
=
Therefore: V
0
V
X
V
Y
K where K
R
R
V
R
R
1
R
2
---------------------
=
=
For a divider circuit V
Y
V
R
cons
t
tan
=
=
Therefore: V
0
V
V
Z
------- K where K
V
R
R
4
R
1
R
2
---------------------
=
=
65-4200-05
RC4200
V
X
(Input)
V
Y
(Input)
+V
REF
R
A
R
B
R
O
R
C
–V
S
–V
S
+V
S
R
D
R
1
R
2
R
C4
R
CX
I
3
V
O
(Output)
3
6
4
5
8
7
1
2
I
2
I
1
I
4
Resistors R
a
and R
b
extend the range of the V
X
and V
Y
inputs by picking values such that:
Resistor R
C
supplies bias current for I
3
which allows the
output to go negative.
Resistors R
CX
and R
CY
permit equation (6) to balance, ie.:
Cross-Product Cancellation
Cross-products are a result of ths
V
X
V
R
and V
Y
V
R
terms.
To the extend that R
1
R
b
= R
CX
R
D
, and R
2
R
a
= R
CY
R
d
cross-product cancellation will occur.
Arithmetic Offset Cancellation
The offset caused by the V
REF
2
term will cancel to the
extent that R
a
R
b
=
R
0
R
d
, and the result is:
Resistor Values
Inputs:
I
1
min.
(
)
V
min.
(
R
1
)
-----------------------
V
R
a
-------------
+
50
m
A,
=
=
and I
1
(max.)
V
(max.)
R
1
-----------------------
V
R
a
-------------
+
250
m
A,
=
=
also I
2
(min.)
V
(min.)
R
2
----------------------
V
R
b
-------------
+
50
m
A,
=
=
and I
2
(max.)
V
(max.)
R
2
-----------------------
V
R
b
-------------
+
250
m
A.
=
=
R1
VRa
+
è
÷
è
R2
VRb
+
÷
R0
VRC
RCX
RCY
+
+
+
è
÷
è
VRD
÷
=
R1R2
VR1Rb
VR2Ra
RaRb
+
+
+
VR0Rd
RcxRd
RCYRd
RcRd
+
+
+
V
V
X
R
1
R
2
---------------
V
V
R
0
R
d
-------------------- or V
0
V
X
V
Y
K
=
=
where K =
R
R
V
REF
R
1
R
2
---------------------------
V
X
min.
(
)
V
X
V
X
(max.)
£
£
D
V
X
V
X
(max.) –
=
V
X
(min.)
V
Y
min.
(
)
V
Y
V
Y
(max.)
£
£
D
V
Y
V
Y
(max.) =
=
V
Y
(min.)
V
REF
Constant (+7V to +18V)
=
K
V
V
X
V
Y
--------------- Design Requirements
)
=