MAX4517

__________Applications Information

Power-Supply Considerations

The MAX4516/MAX4517 operate with power-supply

voltages from ±1V to ±6V, but are tested and guaran-

teed only with ±5V supplies. Similarly, they will operate

with a single +2V to +12V supply, but logic-level inputs

can shift with higher voltages. The pin-compatible

MAX4514/MAX4515 are recommended for use with a

single supply.

The MAX4516/MAX4517 construction is typical of most

CMOS analog switches, except that they have only two

supply pins: V+ and V-. V+ and V- drive the internal

CMOS switches and set their analog voltage limits.

Reverse ESD-protection diodes are internally connected

between each analog-signal pin and both V+ and V-.

One of these diodes conducts if any analog signal

exceeds V+ or V-.

Virtually all the analog leakage current comes from the

ESD diodes to V+ or V-. 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 V- 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 V-

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 ter-

minal. 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 V-.

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

translators. The logic-level translators convert the logic

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

signal gates.

Logic-Level Thresholds

The logic-level thresholds are CMOS-compatible but

not TTL-compatible. Since these parts have no

ground pin, the logic-level threshold is referenced to

V+. The threshold limits are V+ = -1.5V and V+ = -3.5V

for V+ levels between +6V and +3V. When V+ = +2V,

the logic threshold is approximately 0.6V.

Do not connect the MAX4516/MAX4517’s V+ to +3V

and then connect the logic-level pins to logic-level

signals that operate from a +5V supply. TTL levels

can exceed +3V and violate the absolute maximum

ratings, damaging the part and/or external circuits.

High-Frequency Performance

In 50

Ω systems, signal response is reasonably flat up

to 250MHz (see

Typical Operating Characteristics).

Above 20MHz, the on response has several minor

peaks that are highly layout dependent. The problem is

not in turning the switch on; it’s in turning it off. The off-

state switch acts like a capacitor and passes higher fre-

quencies with less attenuation. At 10MHz, off isolation is

about -48dB in 50

Ω systems, decreasing (approximate-

ly 20dB per decade) as frequency increases. Higher cir-

cuit impedances also cause off isolation to decrease.

Off isolation is about 3dB above that of a bare IC sock-

et, and is due entirely to capacitive coupling.

Dual-Supply, Low-On-Resistance,

SPST, CMOS Analog Switches

_______________________________________________________________________________________

5

______________________________________________________________Pin Description

SOT23-5

DIP/SO

SOT23-5

DIP/SO

Analog Switch (normally closed)

—

—

3

2

4

5

—

Negative Supply-Voltage Input (analog and digital)

1

7

Analog Switch (normally open)

8

2

8

3

Digital Control Input

—

6

Positive Supply-Voltage Input (analog and digital)

4

4

No Connect (not internally connected)

5

2, 3, 5

Analog Switch Common Terminal

1

—

1

7

—

6

4

2, 3, 5

1

NC

V-

NO

IN

V+

N.C.

COM

Note: NO, NC, and COM pins are identical and interchangeable. Any may be considered as an input or an output; signals pass

equally well in both directions.

NAME

FUNCTION

MAX4516

MAX4517

PIN