7

FN6130.0

March 15, 2005

Detailed Description

The ISL43L110 and ISL43L111 are bidirectional, single

pole/single throw (SPST) analog switches. They offer

precise switching capability from a single +1.1V to 4.5V

supply with ultra low on-resistance and high speed

operation. With a single supply of 4.3V the typical on-

resistance is only 0.21

Ω, with a typical turn-on and turn-off

well suited for portable battery powered equipment due to its

low operating supply voltage (1.1V), low power consumption

(1.8

µW max), low leakage currents (200nA max), and the tiny

SC70 packaging.

The ISL43L110 is a normally open (NO) SPST analog

switch. The ISL43L111 is a normally closed (NC) SPST

analog switch.

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 6). 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 precautions

must be implemented to prohibit the current and voltage at

the logic pin and signal pins from exceeding the maximum

ratings of the switch. The following two methods can be used

to provided additional protection to limit the current in the

event that the voltage at a signal pin or logic pin goes below

ground or above the V+ rail.

Logic inputs can be protected by adding a 1k

Ω resistor in

series with the input (see Figure 6). The resistor limits the

input current below the threshold that produces permanent

FIGURE 3. OFF ISOLATION TEST CIRCUIT

FIGURE 5. CAPACITANCE TEST CIRCUIT

ANALYZER

SIGNAL

GENERATOR

V+

C

0V or V+

NO or NC

COM

IN

GND

V+

C

0V or V+

NO or NC

COM

IN

GND

100mA

V+

C

GND

NO or NC

COM

IN

IMPEDANCE

ANALYZER

0V or V+

ISL43L110, ISL43L111