MAX4648EUT-T Просмотр технического описания (PDF) - Maxim Integrated
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MAX4648EUT-T Datasheet PDF : 9 Pages
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25Ω SPST Analog Switches in SOT23-6
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, NC, or COM. If power-supply
sequencing is not possible, add two small signal
diodes (D1, D2) in series with supply pins (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 300MHz, 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. This effect is
more pronounced with higher source and load imped-
ances. Above 5MHz, circuit board layout becomes criti-
cal. The graphs shown in the Typical Operating
Characteristics were taken using a 50Ω source and
load connected with BNC connectors.
V+
D2
V+
MAX4647
MAX4648
NO
Vg
COM
V-
D1
V-
Figure 1. Overvoltage Protection Using External Blocking
Diodes
+3V
LOGIC
INPUT 0
50%
tr < 20ns
tf < 20ns
SWITCH 0
OUTPUT
VO 0.9V0
tON
tOFF
0.9V0
LOGIC INPUT WAVEFORMS INVERTED FOR SWITCHES
THAT HAVE THE OPPOSITE LOGIC SENSE.
Figure 2. Switching-Time Test Circuit
MAX4647
MAX4648
V+
SWITCH
INPUT
VCOM
COM
IN
V+
NO
OR NC
SWITCH
OUTPUT
VO
RL
300Ω
CL
35pF
LOGIC
INPUT
GND
V-
0
V-
REPEAT TEST FOR EACH SWITCH. FOR LOAD
CONDITIONS, SEE Electrical Characteristics.
CL INCLUDES FIXTURE AND STRAY CAPACITANCE.
( ) VO = VCOM
RL
RL + RON
6 _______________________________________________________________________________________
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