7

supply voltage provides plenty of room for the 10% tolerance

of 3.6V supplies, as well as room for overshoot and noise

spikes.

The minimum recommended supply voltage is 3.6V but the

part will operate with a supply below 1.5V. It is important to

note that the input signal range, switching times, and on-

resistance degrade at lower supply voltages. Refer to the

electrical specification tables and Typical Performance

curves for details.

V+ and GND also power the internal logic and level shiftier.

The level shiftier converts the input logic levels to switched

V+ and GND signals to drive the analog switch gate

terminals.

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 3.6V (see Figure 13). At 3.6V

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 50

Ω systems, signal response is reasonably flat even past

100MHz (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 1MHz, Off

Isolation is about 45dB in 50

Ω 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.

FIGURE 7. ON RESISTANCE vs SUPPLY VOLTAGE vs

SWITCH VOLTAGE

FIGURE 8. ON RESISTANCE vs SWITCH VOLTAGE

01

23

4

0.2

0.3

0.4

0.5

0.6

0.7

V+ = 2.7V

V+ = 1.8V

V+ = 1.5V

V+ = 3.6V

V+ = 3V

00.5

11.5

22.5

3

V+ = 2.7V

0.15

0.2

0.25

0.3

0.35

0.4

25°C

85°C

-40°C

ISL84715, ISL84716