MAX4555 Maxim, MAX4555 Datasheet - Page 21

• Manufacturer Part Number: MAX4555
• Description: The MAX4554/MAX4555/MAX4556 are CMOS analog ICs configured as force-sense switches for Kelvin sensing in automated test equipment (ATE)
• Manufacturer: Maxim

Figure 6 shows how to switch a single voltage or cur-
rent source between two loads using the MAX4554 or
MAX4556. By interchanging loads and sources, the cir-
cuits can be reversed so that they switch two sources
to a single load. The two loads are electrically connect-
ed together at one point, but may be physically sepa-
rated. This means that one force wire does not need to
be switched, but the corresponding sense wires do.
The MAX4554 has independent 3PST, NO switches dri-
ven out of phase by an external CMOS inverter, so that
one switch is on while the other is off. If both switches
were turned on at the same time, both loads would be
connected, and the resulting voltage at either load
Figure 6. Using the MAX4554/MAX4556 to Switch 4-Wire Force-Sense Circuits from One Source to Two Loads
VOLTAGE/CURRENT SOURCE
VOLTAGE/CURRENT SOURCE
______________________________________________________________________________________
FEEDBACK
FEEDBACK
IN
IN
0
1
0
1
V
V
LOGIC
LOGIC
LOAD
LOAD
1
2
FORCE
FORCE
SENSE
SENSE
FORCE
FORCE
1
2
SENSE
SENSE
IN
IN
SCOM
GCOM
FCOM
COM1
COM2
COM3
IN1
IN1
IN2
IN3
IN2
V+
V+
would be close to (but not exactly equal to) the desired
value; this would not cause any damage to the device.
Figure 7 shows how to switch a single guarded voltage
or current source between two loads using the
MAX4554 or MAX4556. By interchanging loads and
sources, the circuits can be reversed to switch two
sources to a single load. If the loads have a common
connection, the switch to that node can be eliminated.
Note that these circuits use sense (high-resistance)
switches to switch the common wire. This is permissible
only if the load currents are very low. If the currents are
high, the common connection should not be switched
unless another force switch is substituted.
Force-Sense Switches
CMOS INVERTER
MAX4554
MAX4556
V-
V-
Switching 3-Wire Guarded Circuits
VL
VL
NOF1
NOF2
NOS1
NOS2
NOG2
NOG1
EN
GND
NC1
NC2
NO2
NC3
NO3
GND
NO1
LOAD2
LOAD2
LOAD1
LOAD1
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