Datasheet

SCL SDA
LMP91000
SDA
SCL
I
2
C EEPROM
SDA
SCL
A0
MENB
MENB
LMP91000
µC
SCL
SDA
GPIO 1 GPIO 2
GPIO 3
GPIO N
SDA
SCL
MENB
LMP91000
SDA
SCL
MENB
LMP91000
SDA
SCL
MENB
LMP91000
SDA
SCL
MENB
LMP91000
SNAS506H –JANUARY 2011–REVISED MARCH 2013 www.ti.com
Figure 32. More than one LMP91000 on I
2
C bus
SMART GAS SENSOR ANALOG FRONT END
The LMP91000 together with an external EEPROM represents the core of a SMART GAS SENSOR AFE. In the
EEPROM it is possible to store the information related to the GAS sensor type, calibration and LMP91000's
configuration (content of registers 10h, 11h, 12h). At startup the microcontroller reads the EEPROM's content
and configures the LMP91000. A typical smart gas sensor AFE is shown in Figure 33. The connection of MENB
to the hardware address pin A0 of the EEPROM allows the microcontroller to select the LMP91000 and its
corresponding EEPROM when more than one smart gas sensor AFE is present on the I
2
C bus. Note: only
EEPROM I
2
C addresses with A0=0 should be used in this configuration.
Figure 33. SMART GAS SENSOR AFE
SMART GAS SENSOR AFES ON I
2
C BUS
The connection of Smart gas sensor AFEs on the I
2
C bus is the natural extension of the previous concepts. Also
in this case the microcontroller starts communication asserting 1 out of N MENB signals where N is the total
number of smart gas sensor AFE connected to the I
2
C bus. Only one of the devices (either LMP91000 or its
corresponding EEPROM) in the smart gas sensor AFE enabled will acknowledge the I
2
C commands. When the
communication with this particular module ends, the microcontroller de-asserts the corresponding MENB and
repeats the procedure for other modules. Figure 34 shows the typical connection when several smart gas sensor
AFEs are connected to the I
2
C bus.
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