Datasheet

I2C INTERFACE
AND
CONTROL
REGISTERS
RE
VREF
VDD
AGND
CE
WE
VOUT
C1
SCL
TEMP
SENSOR
VREF
DIVIDER
C2
SDA
R
Load
VARIABLE
BIAS
MENB
DGND
A1
+
-
TIA
+
-
R
TIA
VE-
VE+
NC
LMP91000
2-wire Sensor
such as Oxygen
LMP91000
www.ti.com SNAS506H –JANUARY 2011–REVISED MARCH 2013
Figure 31. 2-Lead Galvanic Cell In Potentiostat Configuration
APPLICATION INFORMATION
CONNECTION OF MORE THAN ONE LMP91000 TO THE I
2
C BUS
The LMP91000 comes out with a unique and fixed I
2
C slave address. It is still possible to connect more than one
LMP91000 to an I
2
C bus and select each device using the MENB pin. The MENB simply enables/disables the
I
2
C communication of the LMP91000. When the MENB is at logic level low all the I
2
C communication is enabled,
it is disabled when MENB is at high logic level.
In a system based on a μcontroller and more than one LMP91000 connected to the I
2
C bus, the I
2
C lines (SDA
and SCL) are shared, while the MENB of each LMP91000 is connected to a dedicate GPIO port of the
μcontroller.
The μcontroller starts communication asserting one out of N MENB signals where N is the total number of
LMP91000s connected to the I
2
C bus. Only the enabled device will acknowledge the I
2
C commands. After
finishing communicating with this particular LMP91000, the microcontroller de-asserts the corresponding MENB
and repeats the procedure for other LMP91000s. Figure 32 shows the typical connection when more than one
LMP91000 is connected to the I
2
C bus.
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