MAX312 Maxim, MAX312 Datasheet - Page 7

• Manufacturer Part Number: MAX312
• Description: Maxim's MAX312/MAX313/MAX314 analog switches feature low on-resistance (10Ω max) and 1
• Manufacturer: Maxim

The MAX312/MAX313/MAX314, having very low R
and very low R
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.
In 50Ω 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 50Ω source and load connected with BNC connec-
Figure 2. Switching-Time Test Circuit
__________Applications Information
OUTPUT
SWITCH
LOGIC
INPUT
+3V
0V
0V
Off Isolation at High Frequencies
ON
10 Ω Ω , Quad, SPST, CMOS Analog Switches
LOGIC INPUT WAVEFORMS INVERTED FOR SWITCHES
THAT HAVE THE OPPOSITE LOGIC SENSE.
_______________________________________________________________________________________
variation with signal amplitude, are
t
V
ON
50%
O
0.9V
Low-Distortion Audio
0
t
OFF
t r < 20ns
t f < 20ns
0.9V
0
ON
SWITCH
INPUT
LOGIC
INPUT
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.
Figure 1. Overvoltage Protection Using External Blocking
Diodes
V
COM1
V g
REPEAT TEST FOR EACH SWITCH. FOR LOAD
CONDITIONS, SEE Electrical Characteristics.
C
V
O
L
INCLUDES FIXTURE AND STRAY CAPACITANCE.
= V
COM1
IN1
+5V
GND
COM
VL
0V
NO_
(
R
L
R
+ R
L
ON
)
OR NC1
+15V
-15V
V+
V-
NO1
V+
V-
V+
V-
R
300Ω
L
MAX312
MAX313
MAX314
SWITCH
OUTPUT
C
35pF
L
COM_
V
O
7