ISL54051 Datasheet, PDF (8/12 Pages) Intersil Corporation – Ultra Low ON-Resistance, Low Voltage, Single Supply, Single SPST Analog Switches

ISL54051, ISL54052
This family of switches cannot be operated with bipolar
supplies because the input switching point becomes
negative in this configuration.
Logic-Level Thresholds
This switch family is 1.8V CMOS compatible (0.5V and
1.4V) over a supply range of 2V to 5V (see Figure 13). At
5V the V_IH level is about 1.2V. This is still below the 1.8V
CMOS guaranteed high output minimum level of 1.4V,
but noise margin is reduced.
The digital input stages draw supply current whenever
the digital input voltage is not at one of the supply rails.
Driving the digital input signals from GND to V+ with a
fast transition time minimizes power dissipation.
High-Frequency Performance
In 50Ω systems, the ISL54051 and the ISL54052 have a
-3dB bandwidth of 190MHz (see Figure 14). The
frequency response is very consistent over a wide V+
range, and for varying analog signal levels.
An OFF switch acts like a capacitor and passes higher
frequencies with less attenuation, resulting in signal
feedthrough from a switch’s input to its output. Off
isolation is the resistance to this feedthrough. Figure 15
details the high off isolation rejection provided by this
family. At 100kHz, off isolation is about 80dB in 50Ω
systems, decreasing approximately 20dB per decade as
frequency increases. Higher load impedances decrease
off isolation and crosstalk rejection due to the voltage
divider action of the switch OFF impedance and the load
impedance.
Leakage Considerations
Reverse ESD protection diodes are internally connected
between each analog-signal pin and both V+ and GND.
One of these diodes conducts if any analog signal
exceeds V+ or GND.
Virtually all the analog leakage current comes from the
ESD diodes to V+ or GND. Although the ESD diodes on a
given signal pin are identical and therefore fairly well
balanced, they are reverse biased differently. Each is
biased by either V+ or GND and the analog signal. This
means their leakages will vary as the signal varies. The
difference in the two diode leakages to the V+ and GND
pins constitutes the analog-signal-path leakage current.
All analog leakage current flows between each pin and
one of the supply terminals, not to the other switch
terminal. This is why both sides of a given switch can
show leakage currents of the same or opposite polarity.
There is no connection between the analog signal paths
and V+ or GND.
Typical Performance Curves T_A = +25°C, Unless Otherwise Specified
2.5
1.0
I_COM = 100mA
V+ = 1.8V
0.9
2.0
0.8
1.5
V+ = 2.7V
1.0
V+ = 4.5V
V+ = 3V
V+ = 5V
0.5
0
0
1
2
3
4
5
V_COM (V)
FIGURE 7. ON-RESISTANCE vs SUPPLY VOLTAGE vs
SWITCH VOLTAGE
0.7
+85°C
0.6
+25°C
0.5
0.4
-40°C
0.3
V+ = 5V
I_COM = 100mA
0.2
0
1
2
3
4
5
V_COM (V)
FIGURE 8. ON-RESISTANCE vs SWITCH VOLTAGE
8
FN6459.3
October 19, 2009