VCR2N/4N/7N
Vishay Siliconix
JFET Voltage-Controlled Resistors
PRODUCT SUMMARY
Part Number
VCR2N
VCR4N
VCR7N
V
GS(off)
Max (V)
−7
−7
−5
V
(BR)GSS
Min (V)
−25
−25
−25
r
DS(on)
Max (W)
60
600
8000
FEATURES
D
Continuous Voltage-Controlled
Resistance
D
High Off-Isolation
D
High Input Impedance
BENEFITS
D
Gain Ranging Capability/Wide Range
Signal Attenuation
D
No Circuit Interaction
D
Simplified Drive
APPLICATIONS
D
Variable Gain Amplifiers
D
Voltage Controlled Oscillator
D
AGC
DESCRIPTION
The VCR2N/4N/7N JFET voltage controlled resistors have an
ac drain-source resistance that is controlled by a dc bias
voltage (V
GS
) applied to their high impedance gate terminal.
Minimum r
DS
occurs when V
GS
= 0 V. As V
GS
approaches the
pinch-off voltage, r
DS
rapidly increases. This series of junction
FETs is intended for applications where the drain-source
voltage is a low-level ac signal with no dc component.
Key to device performance is the predictable r
DS
change
versus V
GS
bias where:
r
DS
(@ V
GS
+
0)
r
DS
bias
[
1– V
GS(off)
V
GS
These n-channel devices feature r
DS(on)
ranging from 20 to
8000
W
. All packages are hermetically sealed and may be
processed per MIL-S-19500 (see Military Information).
TO-206AA
(TO-18)
TO-206AF
(TO-72)
S
S
C
1
1
4
2
D
Top View
3
G and Case
D
2
3
G
Top View
VCR7N
VCR2N, VCR4N
For applications information see AN105.
Document Number: 70293
S-41225—Rev. F, 28-Jun-04
www.vishay.com
1
VCR2N/4N/7N
Vishay Siliconix
ABSOLUTE MAXIMUM RATINGS
a
Gate-Source, Gate-Drain Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
−25
V
Gate Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 mA
Power Dissipation
b
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 mW
Operating Junction Temperature Range . . . . . . . . . . . . . . . . . . .
−55
to 175_C
Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
−65
to 200_C
Lead Temperature (
1
/
16
” from case for 10 sec.) . . . . . . . . . . . . . . . . . . . 300_C
Notes:
a. T
A
= 25_C unless otherwise noted.
b. Derate 2 mW/_C above 25_C.
SPECIFICATIONS (T
A
= 25_C UNLESS OTHERWISE NOTED)
Limits
VCR2N
VCR4N
VCR7N
Parameter
Static
Gate-Source Breakdown Voltage
Gate-Source Cutoff Voltage
Gate Reverse Current
Symbol
V
(BR)GSS
V
GS(off)
I
GSS
Test Conditions
I
G
=
−1
mA,
V
DS
= 0 V
V
DS
= 10 V, I
D
= 1
mA
V
GS
=
−15
V, V
DS
= 0 V
V
GS
= 0 V, I
D
= 10 mA
Typ
a
−55
Min
−25
−3.5
20
Max
Min
−25
Max
Min
−25
Max
Unit
−7
−5
60
−3.5
−7
−0.2
−2.5
−5
−0.1
V
nA
Drain-Source On-Resistance
Gate-Source Forward Voltage
r
DS(on)
V
GS(F)
V
GS
= 0 V, I
D
= 1 mA
V
GS
= 0 V, I
D
= 0.1 mA
V
DS
= 0 V, I
G
= 1 mA
0.7
200
600
4000
8000
W
V
Dynamic
Drain-Source On-Resistance
Drain-Gate Capacitance
Source-Gate Capacitance
r
ds(on)
C
dg
C
sg
V
GS
= 0 V, I
D
= 0 mA
f = 1 kHz
V
GD
=
−10
V, I
S
= 0 mA
f = 1 MHz
V
GS
=
−10
V, I
D
= 0 mA
f = 1 kHz
20
60
7.5
7.5
200
600
3
3
4000
8000
1.5
pF
1.5
W
Notes:
a. Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing.
NCB/NPA/NT
TYPICAL CHARACTERISTICS (T
A
= 25_C UNLESS OTHERWISE NOTED)
Output Characteristics (VCR2N)
30
V
GS(off)
=
−4
V
25
I
D
−
Drain Current (mA)
20
15
10
5
V
GS
= 0 V
0.8
−0.5
V
−1.0
V
−1.5
V
−2.0
V
−2.5
V
−3.0
V
0
0
0.2
0.4
0.6
0.8
1
V
DS
−
Drain-Source Voltage (V)
www.vishay.com
0
0
0.1
0.2
0.3
0.4
0.5
V
DS
−
Drain-Source Voltage (V)
Document Number: 70293
S-41225—Rev. F, 28-Jun-04
I
D
−
Drain Current (mA)
1.0
−1.5
V
−2.0
V
−2.5
V
0.6
−3.0
V
−4.0
V
−3.5
V
Output Characteristics (VCR4N)
V
GS
= 0 V
0.4
0.2
V
GS(off
)
=
−4.2
V
2
VCR2N/4N/7N
Vishay Siliconix
TYPICAL CHARACTERISTICS (T
A
= 25_C UNLESS OTHERWISE NOTED)
Output Characteristics (VCR7N)
200
V
GS(off)
=
−2.5
V
V
GS
= 0 V
120
−0.5
V
−1.0
V
80
−1.5
V
40
−2.0
V
0
0
0.2
0.4
0.6
0.8
1
V
DS
−
Drain-Source Voltage (V)
160
I
D
−
Drain Current (mA)
APPLICATIONS
A simple application of a FET VCR is shown in Figure 1, the
circuit for a voltage divider attenuator.
The output voltage is:
V
OUT
=
R
V
IN
r
DS
R +
r
DS
It is assumed that the output voltage is not so large as to push
the VCR out of the linear resistance region, and that the r
DS
is
not shunted by the load.
V
OUT
V
IN
The lowest value which V
OUT
can assume is:
V
OUT(min)
=
V
IN
r
DS(on)
R +
r
DS(on)
−
V
GS
VCR
+
Since r
DS
can be extremely large, the highest value is:
FIGURE 1.
Simple Attenuator Circuit
V
OUT(max)
= V
IN
Document Number: 70293
S-41225—Rev. F, 28-Jun-04
www.vishay.com
3
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Vishay
Disclaimer
All product specifications and data are subject to change without notice.
Vishay Intertechnology, Inc., its affiliates, agents, and employees, and all persons acting on its or their behalf
(collectively, “Vishay”), disclaim any and all liability for any errors, inaccuracies or incompleteness contained herein
or in any other disclosure relating to any product.
Vishay disclaims any and all liability arising out of the use or application of any product described herein or of any
information provided herein to the maximum extent permitted by law. The product specifications do not expand or
otherwise modify Vishay’s terms and conditions of purchase, including but not limited to the warranty expressed
therein, which apply to these products.
No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted by this
document or by any conduct of Vishay.
The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications unless
otherwise expressly indicated. Customers using or selling Vishay products not expressly indicated for use in such
applications do so entirely at their own risk and agree to fully indemnify Vishay for any damages arising or resulting
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Document Number: 91000
Revision: 18-Jul-08
www.vishay.com
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