Datasheet

Analog Signal Levels
These devices pass signals from V
CC
to as low as
V
CC
- 5.5V, including signals below ground with minimal
distortion and very little change in on-resistance (see the
Typical Operating Characteristics ). The switches are bidi-
rectional, so the NO_, NC_, and COM_ terminals can be
used as either inputs or outputs.
COM_ Protection with V
CC
= 0V
(MAX4744H/MAX4745H/MAX4746H)
This feature prevents any damage to the device due to
improper power-supply sequencing. The protection
applies if a signal is applied on COM_ when V
CC
is less
than 0.5V. The switch is not protected if V
CC
goes
above 0.5V due to parasitic capacitive coupling or any
leakage between COM_ and V
CC
. The signal at COM_
ranges between (V
CC
- 6.0V) to 6.0V under protection
conditions.
Click-and-Pop Suppression
The MAX4744/MAX4744H have a shunt resistor on all
their NO and NC terminals to automatically discharge
any capacitance when they are not connected to COM.
The shunt resistor reduces audible click-and-pop
sounds that occur when switching between audio
sources. Audible clicks and pops are caused when a
step DC voltage is switched into the speaker. The DC
step transients can be reduced by automatically dis-
charging the side that is not connected to the COM ter-
minal, reducing any residual DC voltage and reducing
clicks and pops.
MAX4744/MAX4744H/MAX4745/MAX4745H/MAX4746H
Low-Voltage, Dual SPDT, Audio Clickless
Switches with Negative Rail Capability
_______________________________________________________________________________________ 9
t
r
< 5ns
t
f
< 5ns
50%
0V
LOGIC
INPUT
R
L
COM_
GND
CB_
C
L
INCLUDES FIXTURE AND STRAY CAPACITANCE
V
OUT
= V
N_ (
R
L
)
R
L
+ R
ON
V
NC_
OR V
NO_
V
CC
t
OFF
0V
NO_
OR NC_
0.8 x V
0UT
0.2 x V
OUT
t
ON
V
OUT
SWITCH
OUTPUT
LOGIC
INPUT
IN DEPENDS ON SWITCH CONFIGURATION;
INPUT POLARITY DETERMINED BY SENSE OF SWITCH.
V
CC
C
L
V
CC
V
OUT
MAX4744/MAX4745/
MAX4744H/MAX4745H/
MAX4746H
Figure 2. Switching Time
50%
V
CC
0V
LOGIC
INPUT
V
OUT
0.9 x V
OUT
t
BBM
LOGIC
INPUT
R
L
GND
C
L
INCLUDES FIXTURE AND STRAY CAPACITANCE
NO_
CB_
NC_
V
OUT
V
CC
V
CC
C
L
COM_
MAX4744/MAX4745/
MAX4744H/MAX4745H/
MAX4746H
V
NC_
= V
NO_
Figure 3. Break-Before-Make Interval
Test Circuits/Timing Diagrams