I
NTEGRATED
C
IRCUITS
D
IVISION
CPC7512
14 www.ixysic.com R01
4. Design Example
The CPC7512 can be used to provide a multiplexer function in ultrasonic transducer applications allowing the
expense and the PCB real estate consumption of a transducer drive circuitry to be spread across multiple
transducers. The steps to implement this concept are shown in the minimal two channel example below.
To maximize isolation between the drive circuit and non-driven transducer receiver circuits, the Sx
C
terminal must be
connected to ground.
4.1 Startup State Following Power Up
To facilitate a stable and safe power up transition or recovery from a supply voltage droop, all of the switches in the
CPC7512 are preconditioned to the All-Off state upon power up. As can be seen in the figure below, all of the
switches are open.
Figure 6: Power Up Default State
4.2 Initial Configuration State
Following power up, the switches should be placed in the high impedance shunt isolation state. To provide maximum
shunt isolation, switches SW1
C
and SW2
C
must be terminated to ground and the switches enabled (Closed). This
state minimizes signal transfer through the open A and B switches.
Figure 7: Switches A and B Open With Shunt Isolation Enabled
S1
B
S1
C
S1
COM
S1
A
S2
B
S2
C
S2
COM
S2
A
SW1
A
SW1
B
SW1
C
SW2
A
SW2
B
SW2
C
X
1
X
2
To Receiver Circuit 1
To Receiver Circuit 2
S1
B
S1
C
S1
COM
S1
A
S2
B
S2
C
S2
COM
S2
A
SW1
A
SW1
B
SW1
C
SW2
A
SW2
B
SW2
C
X
1
X
2
To Receiver Circuit 1
To Receiver Circuit 2
