MAX335
__________Applications Information
8 x 1 Multiplexer
To use the MAX335 as an 8 x 1 multiplexer, tie all
drains together (COM0 to COM7); the mux inputs now
source each switch (NO0 to NO7). Input a single 0V to
+3V pulse at DIN. As this is clocked through the regis-
ter by SCLK, each switch will sequence on one at a
time.
4-2 Differential Multiplexer
To use the MAX335 as a 4-2 differential multiplexer, tie
COM0 through COM3 together and COM4 through
COM7 together. Differential inputs will be the source
inputs as follows: (NO0, NO4), (NO1, NO5), (NO2,
NO6), (NO3, NO7). Figure 7 shows the serial input con-
trol at DIN required to turn on two switches making a
differential multiplexer.
CS is held low for four clock pulses; the first pulse is
clocked into the fifth switch position as the second
pulse is clocked into the first switch position. CS is
pulled high to update switches; then CS is pulled low,
and SCLK advances pulses to S1 and S5 positions,
where CS is pulled high to update, etc.
SPDT Switches
Tie COM0 to NO1 so that NO0 and COM1 are now
inputs and COM0/NO1 is the common output. SP is
common output. Up to four SPDT switches can be
made from each MAX335. Multiples of four or more can
be made by daisy chaining devices. In Figure 8, DIN is
a pulse train. Again, CS is held low to clock in pulses
and CS is pulled high to update; CS is held low to shift
pulses, then pulled high to update, etc.
Reset Function
Pulsing V
L
below +0.8V initiates the power-up reset
function. The switches are set to the off position, and
the serial shift register is reset to all zeros.
Power-Supply Operation
The MAX335 operates with V = ±4.5V to ±20V and
V
L
= +5V. With V- tied to ground, the part operates with
V+ = +10V to +30V.
The V
L
supply sets TTL input compatibility at a 1.6V
switching threshold. As V
L
is raised, the switching
threshold is raised, so the part is no longer TTL com-
patible. The MAX335 also operates with a single power
supply: V
L
= V+ and V- = 0V. With V
L
tied to V+, the V
L
supply cannot be used as a reset function.
Serial Controlled, 8-Channel SPST Switch
10 ______________________________________________________________________________________
1 CLOCK
PULSE
DIN
Figure 8. Serial-Input Control for SPDT Switch
___________________Chip Topography
V-
DIN
GND
NO4
0.156"
(3.96mm)
0.099"
(2.51mm)
NO0
COM0
COM1
NO2
COM2
COM3NO3
COM4
COM5
NO5
COM6
NO6
COM7
NO7
DOUT
V+
SCLK
CS
VL
NO1
TRANSISTOR COUNT: 387
SUBSTRATE CONNECTED TO V+.
Figure 7. Differential Multiplexer Input Control
4 CLOCK
PULSES
DIN
SCLK
D4
SW4
DØ
SWØ
