6

FN6096.1

Detailed Description

The ISL43L840 analog switches offer precise switching

capability from a single 1.6V to 3.6V supply with low on-

resistance (0.5

The device is especially well-suited to portable battery

powered equipment thanks to the low operating supply

voltage (1.6V), low power consumption (0.2

µW), and low

leakage currents (60nA max). High frequency applications

also benefit from the wide bandwidth, and the very high off

isolation and crosstalk rejection.

Supply Sequencing And Overvoltage Protection

With any CMOS device, proper power supply sequencing is

required to protect the device from excessive input currents

which might permanently damage the IC. All I/O pins contain

ESD protection diodes from the pin to V+ and to GND (see

Figure 8). To prevent forward biasing these diodes, V+ must

be applied before any input signals, and the input signal

voltages must remain between V+ and GND. If these

conditions cannot be guaranteed, then one of the following

two protection methods should be employed.

Logic inputs can easily be protected by adding a 1k

Ω

resistor in series with the input (see Figure 8). The resistor

limits the input current below the threshold that produces

permanent damage, and the sub-microamp input current

produces an insignificant voltage drop during normal

operation.

This method is not applicable for the signal path inputs.

Adding a series resistor to the switch input defeats the

diodes can be added in series with the supply pins to provide

overvoltage protection for all pins (see Figure 8). These

additional diodes limit the analog signal from 1V below V+ to

1V above GND. The low leakage current performance is

unaffected by this approach, but the switch signal range is

FIGURE 4. OFF ISOLATION TEST CIRCUIT

FIGURE 6. CROSSTALK TEST CIRCUIT

FIGURE 7. CAPACITANCE TEST CIRCUIT

ANALYZER

SIGNAL

GENERATOR

0V or V+

NO or NC

COM

ADDX

GND

V+

C

0V or V+

NO or NC

COM

ADDX

GND

100mA

V+

C

0V or V+

ANALYZER

SIGNAL

GENERATOR

GND

ADDX

50

Ω

N.C.

V+

C

GND

NO or NC

COM

ADDX

IMPEDANCE

ANALYZER

0V or V+

V+

C

ISL43L840