Datasheet

OEM electrical isolation
If the EC OEM
™
Class Embedded Conductivity Circuit is going to be used in
consumer, industrial, or scientific /medical applications electrical isolation is strongly
recommended. Electrically isolating the device will insure that the readings are accurate,
the EC probe does not interfere with other sensors and that outside electrical noise does
not affect the device.
The goal of electrically isolating the EC OEM
™
circuit is to insure that the device no longer
shares a common ground with the master CPU, other sensors and other devices that are
can be traced back to a common ground. It is important to keep in mind that simply
isolating the power and ground is not enough. Both data lines (SDA, SCL) and the INT
pin must also be isolated.
This technology works by using tiny transformers to induce the voltage across an air gap.
PCB layout requires special attention for EMI/EMC and RF Control, having proper ground
planes and keeping the capacitors as close to the chip as possible are crucial for proper
performance. The two data channels have a 4.7kΩ pull up resistor on both the isolated
and non-isolated lines (R1, R2, R3, and R4) The output voltage is set using a voltage
divider (R5, R6, and R,7) this produces a voltage of 3.9V regardless of your input voltage.
C4
10uF
C1
0.1uf
VDDP
ADM3260
OUTPUT
ISO-VCC
ISO-VCC
ISO-VCC
ISO-VCC
ISO-VCC
R5 R7
R4
R3
1.5K
R6
1.5K
C3
C2
C6
C5
10uF
10uF
0.1uF
0.1uF
1.5K
4.7K
4.7K
VDDISO
VISO
VSEL
NCNC
SCL1
SDA1
SCL2
SDA2
VIN
GNDP
GNDISO
GNDISO
GNDISO
GNDISO
GNDP
GNDP
GNDP
PDIS
VCC
VCC
VCC
VCC
VCC
VCC
RX/SCL
TX/SDA
NC
GND
ISO-GND
ISO-GND
GND
R2 R14.7K 4.7K
R5
1M
INPUT
VCC
RX/SCL
TX/SDA
EN
GND
Non-isolated
N-FET
VCC = 3.0v − 5.5v
Isolated
D
G
S
GND
VCC
R8
1M
(GENERAL PURPOSE TRANSISTOR)
GND
Isolated ground is different from non-isolated ground, these two lines should not
be connected together.