MAX4607/MAX4608/MAX4609
2.5
Ω
, Dual, SPST,
CMOS Analog Switches
8
Maxim Integrated
Applications Information
Overvoltage Protection
Proper power-supply sequencing is recommended for
all CMOS devices. Do not exceed the absolute maxi-
mum ratings, because stresses beyond the listed rat-
ings can cause permanent damage to the devices.
Always sequence V+ on first, then V-, followed by the
logic inputs, NO, or COM. If power-supply sequencing
is not possible, add two small signal diodes (D1, D2) in
series with supply pins for overvoltage protection
(Figure 1). Adding diodes reduces the analog signal
range to one diode drop below V+ and one diode drop
above V-, but does not affect the devices’ low switch
resistance and low leakage characteristics. Device
operation is unchanged, and the difference between
V+ and V- should not exceed 44V. These protection
diodes are not recommended when using a single supply.
Off-Isolation at High Frequencies
With the N.C. pins connected to GND, the high-fre-
quency on-response of these parts extends from DC to
above 100MHz with a typical loss of -2dB. When the
switch is turned off, however, it behaves like a capaci-
tor, and off-isolation decreases with increasing frequen-
cy. (Above 300MHz, the switch actually passes more
signal turned off than turned on.) This effect is more
pronounced with higher source and load impedances.
Above 5MHz, circuit-board layout becomes critical, and
it becomes difficult to characterize the response of the
switch independent of the circuit. The graphs shown in
the
Typical Operating Characteristics
were taken using
a 50Ω source and load connected with BNC connectors
to a circuit board deemed “average;” that is, designed
with isolation in mind, but not using strip-line or other
special RF circuit techniques. For critical applications
above 5MHz, use the MAX440, MAX441, and MAX442,
which are fully characterized up to 160MHz.
INCLUDES FIXTURE AND STRAY CAPACITANCE.
THAT HAVE THE OPPOSITE LOGIC SENSE.
REPEAT TEST FOR EACH SWITCH. FOR LOAD
ELECTRICAL CHARACTERISTICS.
