__________Applications Information

Low-Distortion Audio

well suited for low-distortion audio applications. The

Typical Operating Characteristics show Total Harmonic

Distortion (THD) vs. Frequency graphs for several sig-

nal amplitudes and impedances. Higher source and

load impedances improve THD, but reduce off isolation.

Off Isolation at High Frequencies

In 50

Ω systems, the high-frequency on-response of

these parts extends from DC to above 100MHz with a

typical loss of -2dB. When the switch is turned off, how-

ever, it behaves like a capacitor, and off isolation

decreases with increasing frequency. (Above 300MHz,

the switch actually passes more signal turned off than

turned on.) This effect is more pronounced with higher

source and load impedances.

Above 5MHz, circuit board layout becomes critical, and

it becomes difficult to characterize the response of the

switch independent of the circuit. The graphs shown in

the

Typical Operating Characteristics were taken using

a 50

Ω source and load connected with BNC connec-

tors to a circuit board deemed “average”; that is,

designed with isolation in mind, but not using strip-line

or other special RF circuit techniques. For critical appli-

cations above 5MHz, use the MAX440, MAX441, and

MAX442, which are fully characterized up to 160MHz.

10

_______________________________________________________________________________________

7

V+

COM_

V-

NO_

Vg

V+

V-

tr < 20ns

tf < 20ns

50%

0V

LOGIC

INPUT

V-

-15V

300

Ω

NO1

OR NC1

GND

(

)

SWITCH

INPUT

IN1

+3V

0V

COM1

SWITCH

OUTPUT

SWITCH

OUTPUT

LOGIC

INPUT

LOGIC INPUT WAVEFORMS INVERTED FOR SWITCHES

THAT HAVE THE OPPOSITE LOGIC SENSE.

VL

V+

35pF

+5V

+15V

0V

REPEAT TEST FOR EACH SWITCH. FOR LOAD

CONDITIONS, SEE

Electrical Characteristics.

MAX312

MAX313

MAX314

Figure 1. Overvoltage Protection Using External Blocking

Diodes

Figure 2. Switching-Time Test Circuit