6
FN6105.1
September 15, 2008
Detailed Description
The ISL84762 is a bidirectional, dual single pole/double
throw (SPDT) analog switch that offers precise switching
capability from a single 1.65V to 3.6V supply with low
ON-resistance (0.39) and high speed operation
(t
ON
=14ns, t
OFF
= 6ns). The device is especially well suited
for portable battery powered equipment due to its low
operating supply voltage (1.65V), low power consumption
(2.7µW max), low leakage currents (60nA max), and the tiny,
Thin DFN and MSOP packages. The ultra low ON-resistance
and r
ON
flatness provide very low insertion loss and distortion
to applications that require signal reproduction.
External V+ Series Resistor
For improved ESD and latch-up immunity, Intersil
recommends adding a 100 resistor in series with the V+
power supply pin of the ISL84762 IC (see Figure 8).
During an overvoltage transient event, such as occurs during
system level IEC 61000 ESD testing, substrate currents can
be generated in the IC that can trigger parasitic SCR
structures to turn ON, creating a low impedance path from
the V+ power supply to ground. This will result in a
significant amount of current flow in the IC, which can
potentially create a latch-up state or permanently damage
the IC. The external V+ resistor limits the current during this
over-stress situation and has been found to prevent latch-up
or destructive damage for many overvoltage transient
events.
Under normal operation, the sub-microamp I
DD
current of
the IC produces an insignificant voltage drop across the
100 series resistor resulting in no impact to switch
operation or performance.
FIGURE 4. OFF-ISOLATION TEST CIRCUIT FIGURE 5. r
ON
TEST CIRCUIT
FIGURE 6. CROSSTALK TEST CIRCUIT FIGURE 7. CAPACITANCE TEST CIRCUIT
Test Circuits and Waveforms (Continued)
ANALYZER
R
L
SIGNAL
GENERATOR
V+
C
0V OR V+
NO OR NC
COM
IN
GND
Signal direction through switch is reversed, worst case values
are recorded. Repeat test for all switches.
V+
C
0V OR V+
NO OR NC
COM
IN
GND
V
NX
V
1
r
ON
= V
1
/100mA
100mA
Repeat test for all switches.
0V OR V+
ANALYZER
V+
C
NO OR NC
SIGNAL
GENERATOR
R
L
GND
IN
1
COM
50
NC
COM
NC OR NO
Signal direction through switch is reversed, worst case values
are recorded. Repeat test for all switches.
V+
C
GND
NO OR NC
COM
IN
IMPEDANCE
ANALYZER
0V OR V+
Repeat test for all switches.
ISL84762