V+ and GND power the internal logic and logic-level

translators, and set both the input and output logic lim-

its. The logic-level translators convert the logic levels

into switched V+ and V- signals to drive the gates of

the analog signals. This drive signal is the only connec-

tion between the logic supplies (and signals) and the

analog supplies. V+ and V- have ESD-protection

diodes to GND.

The logic-level thresholds are TTL/CMOS compatible

when V+ is +5V. As V+ rises, the threshold increases

slightly, so when V+ reaches +12V, the threshold is

about 3.1V; above the TTL-guaranteed high-level mini-

mum of 2.8V, but still compatible with CMOS outputs.

Bipolar Supplies

These devices operate with bipolar supplies between

±3.0V and ±8V. The V+ and V- supplies need not be

symmetrical, but their sum cannot exceed the absolute

maximum rating of +17V.

Single Supply

These devices operate from a single supply between

+3V and +16V when V- is connected to GND. All of the

bipolar precautions must be observed. At room temper-

ature, they actually “work” with a single supply at near

or below +1.7V, although as supply voltage decreases,

switch on-resistance and switching times become very

high.

Overvoltage Protection

Proper power-supply sequencing is recommended for

all CMOS devices. Do not exceed the absolute maxi-

mum ratings, because stresses beyond the listed rat-

ings can cause permanent damage to the devices.

Always sequence V+ on first, then V-, followed by the

logic inputs (NO) and by COM. If power-supply

sequencing is not possible, add two small signal diodes

(D1, D2) in series with the supply pins for overvoltage

protection (Figure 1).

Adding diodes reduces the analog signal range to one

diode drop below V+ and one diode drop above V-, but

does not affect the devices’ low switch resistance and

low leakage characteristics. Device operation is

unchanged, and the difference between V+ and V-

should not exceed 17V. These protection diodes are

not recommended when using a single supply if signal

levels must extend to ground.

High-Frequency Performance

In 50

Ω systems, signal response is reasonably flat up

to 50MHz (see

Typical Operating Characteristics).

Above 20MHz, the on response has several minor

peaks which are highly layout dependent. The problem

is not turning the switch on, but turning it off. The off-

state switch acts like a capacitor, and passes higher

frequencies with less attenuation. At 10MHz, off isola-

tion is about -45dB in 50

Ω systems, becoming worse

(approximately 20dB per decade) as frequency

increases. Higher circuit impedances also make off iso-

lation worse. Adjacent channel attenuation is about 3dB

above that of a bare IC socket, and is entirely due to

capacitive coupling.

Low-Voltage, CMOS Analog

Multiplexers/Switches

12

______________________________________________________________________________________

COM

NO

V-

V+

* INTERNAL PROTECTION DIODES

D2

D1

EXTERNAL BLOCKING DIODE

EXTERNAL BLOCKING DIODE

V-

V+

MAX4051/A

MAX4052/A

MAX4053/A

*

*

*

*

Figure 1. Overvoltage Protection Using External Blocking

Diodes