Fo rc e -S e n s e S w it c h e s
FORCE-SENSE AMPLIFIER
TWINAX CABLE
+FORCE
V+
V-
VL
V+
+SENSE
CURRENT SENSE
V
+DRIVEN GUARD
NC1
NC2
NC3
NO1
NO2
NO3
MAX4556
V+
V-
VL
V-
COM1
COM2
COM3
V+
MAX4556
NC1
NO1
GND
COM1
COM2
IN1 IN2 IN3
INA
NC2
NO2
GUARD AMPLIFIER
LEAKAGE
CURRENT
V-
V+
V-
NC3
NO3
VOLTAGE SOURCE
V+
COM3
IN1
LOAD 2
LOAD 1
LEAKAGE
CURRENT
V+
V-
VL
IN2
GUARD AMPLIFIER
GND
MAX4556
IN IN3
NC1
NC2
NC3
NO1
NO2
NO3
GND
COM1
COM2
COM3
V-
V+
V
-DRIVEN GUARD
-SENSE
-FORCE
CURRENT SENSE
IN1 IN2 IN3
LOGIC
V-
TWINAX CABLE
INA
IN A,B LOAD
FORCE-SENSE
AMPLIFIER
0
1
1
2
TWINAX CABLE
+FORCE
V+
V-
VL
V+
+SENSE
CURRENT SENSE
V
+DRIVEN GUARD
NC1
NC2
NC3
NO1
NO2
NO3
5
MAX4554
V-
COMF
COMS
COMG
V+
V-
VL
V+
EN
GND
MAX4554
NOG1
IN1
IN2
GUARD AMPLIFIER
COMG
COMF
INB
NOG2
NOF1
V-
LEAKAGE
CURRENT
V+
VOLTAGE SOURCE
V+
NOF2
LOAD 2
LOAD 1
LEAKAGE
CURRENT
V-
COMS
IN1
NOS1
NOS2
V+
V-
VL
GUARD AMPLIFIER
MAX4554
EN
NOG1
NOS1
NOF1
NOG2
NOS2
NOF2
COMG
COMS
COMF
V-
GND
IN2
V+
IN
V
LOGIC
IN A,B LOAD
-DRIVEN GUARD
-SENSE
-FORCE
TWINAX CABLE
EN
GND
0
1
2
1
CURRENT SENSE
CMOS INVERTER
LOGIC
V-
IN1
IN2
IN A,B LOAD
INB
FORCE-SENSE
AMPLIFIER
0
1
2
1
Figure 9. Switching 8-Wire Guarded Force-Sense Measurements from One Precision Source-Monitor to Two Loads
24 ______________________________________________________________________________________
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
