ISL43140IVZ-T データシートの表示（PDF） - Renesas Electronics

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ISL43140IVZ-T

Low-Voltage, Single and Dual Supply, High Performance, Quad SPST, Analog Switches

Renesas Electronics 

ISL43140, ISL43141, ISL43142

Detailed Description

The ISL43140–ISL43142 quad analog switches offer precise

switching capability from a bipolar 2V to 6V or a single 2V to

12V supply with low on-resistance (50) and high speed

switching (tON = 40ns, tOFF = 15ns). The devices are

especially well suited to portable battery powered equipment

thanks to the low operating supply voltage (2V), low power

consumption (1W), low leakage currents (1nA max), and the

tiny QFN packaging. 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 V- (see Figure

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

be applied before any input signals, and input signal voltages

must remain between V+ and V-. 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 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.

Adding a series resistor to the switch input defeats the purpose

of using a low RON switch, so two small signal 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 V-. The

low leakage current performance is unaffected by this

approach, but the switch resistance may increase, especially

at low supply voltages.

OPTIONAL

PROTECTION

RESISTOR

INX

VNO or NC

OPTIONAL PROTECTION

DIODE

V+

VCOM

V-

OPTIONAL PROTECTION

DIODE

FIGURE 8. OVERVOLTAGE PROTECTION

Power-Supply Considerations

The ISL4314X construction is typical of most CMOS analog

switches, in that they have three supply pins: V+, V-, and GND.

V+ and V- drive the internal CMOS switches and set their

analog voltage limits, so there are no connections between the

analog signal path and GND. Unlike switches with a 13V

maximum supply voltage, the ISL4314X 15V maximum supply

voltage provides plenty of room for the 10% tolerance of 12V

supplies (6V or 12V single supply), as well as room for

overshoot and noise spikes.

This family of switches performs equally well when operated

with bipolar or single voltage supplies. The addition of the GND

pin allows for asymmetrical bipolar supplies (e.g. +5V and -

3V). The minimum recommended supply voltage is 2V or 2V.

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 power the internal logic (thus setting the digital

switching point) and level shifters. The level shifters convert

the logic levels to switched V+ and V- signals to drive the

analog switch gate terminals, so switch parameters - especially

RON - are strongly influenced by V-.

Logic-Level Thresholds

V+ and GND power the internal logic stages, so V- has no

affect on logic thresholds. This switch family is TTL compatible

(0.8V and 2.4V) over a V+ supply range of 2.5V to 10V (see

Figure 17). At 12V the VIH level is about 2.7V, so for best

results use a logic family the provides a VOH greater than 3V.

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 5systems, signal response is reasonably flat even past

100MHz (see Figure 18). Figure 18 also illustrates that 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, while Crosstalk indicates

the amount of feedthrough from one switch to another. Figure

19 details the high Off Isolation and Crosstalk rejection

provided by this family. At 10MHz, off isolation is about 50dB in

5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

FN6032 Rev 2.00

Aug 24, 2015

Page 10 of 17

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