MAX4604/MAX4605/MAX4606
5
Ω
, Quad, SPST, CMOS Analog Switches
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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
In 50Ω systems, the high-frequency on-response of
these parts extends from DC to above 100MHz with a
typical loss of -2dB. When the switch is turned off, how-
ever, it behaves like a capacitor, and off isolation
decreases with increasing frequency. (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 connec-
tors 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 appli-
cations 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.
