LMP91000SDE National Semiconductor, LMP91000SDE Datasheet - Page 20

• Manufacturer Part Number: LMP91000SDE
• Description: AFE, SENSOR, 14LLP
• Manufacturer: National Semiconductor

Specifications of LMP91000SDE

• Brief Features: Programmable Cell Bias Voltage, Low Bias Voltage Drift, I2C Compatible Digital Interface
• Supply Voltage Range: 2.7V To 5.25V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: LLP
• Ic Function: Programmable Analogue Front End (AFE)
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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SMART GAS SENSOR ANALOG FRONT END
The LMP91000 together with an external EEPROM repre-
sents 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 microcon-
troller reads the EEPROM's content and configures the
LMP91000. A typical smart gas sensor AFE is shown in
ure
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
only EEPROM I
this configuration.
POWER CONSUMPTION
The LMP91000 is intended for use in portable devices, so the
power consumption is as low as possible in order to guarantee
a long battery life. The total power consumption for the
8. The connection of MENB to the hardware address pin
FIGURE 8. SMART GAS SENSOR AFE
2
C addresses with A0=0 should be used in
FIGURE 9. SMART GAS SENSOR AFEs on I
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2
C bus. Note:
Fig-
20
SMART GAS SENSOR AFES ON I
The connection of Smart gas sensor AFEs on the I
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
(either LMP91000 or its corresponding EEPROM) in the
smart gas sensor AFE enabled will acknowledge the I
mands. When the communication with this particular module
ends, the microcontroller de-asserts the corresponding
MENB and repeats the procedure for other modules.
Figure 9
sensor AFEs are connected to the I
LMP91000 is below 10µA @ 3.3v average over time, (this
excludes any current drawn from any pin). A typical usage of
the LMP91000 is in a portable gas detector and its power
consumption is summarized in the
nario
table. This has the following assumptions:
shows the typical connection when several smart gas
2
C bus
2
C bus. Only one of the devices
Power Consumption Sce-
2
2
C bus.
C BUS
2
C bus is
2
C com-
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