Texas Instruments LMP91000EVM Evaluation Module LMP91000EVM/NOPB LMP91000EVM/NOPB Ficha De Dados
Códigos do produto
LMP91000EVM/NOPB
2
LMP91000EVM User’s Guide
SNAU121-April 2012
2.1. Gas Sensor Connection
Both 3-lead and 2-lead gas sensor need to be placed in the Gas Sensor Fooptrint
Figure 1: Gas sensor’s footprint
2.1.1. Not Biased Gas sensor
Even if the LMP91000 is provided with an internal switch to short the RE and WE pin that can be enabled
when the device is in Deep sleep mode, it is possible to add an external JFET which makes the same feature
when the gas sensor is left connected to the board and the LMP91000 is turned off.
when the device is in Deep sleep mode, it is possible to add an external JFET which makes the same feature
when the gas sensor is left connected to the board and the LMP91000 is turned off.
The JFET (Q1) should be a p-type FET. Recommended FETs are listed in the table below.
The gate resistance R12 can be populated with a 1kohm resistor.
The gate resistance R12 can be populated with a 1kohm resistor.
Table 2: Recommended p-FETs for short circuiting RE and WE when LMP91000 is OFF
DEVICE
IC
DESCRIPTION
MANUFACTURER
PACKAGE
Q1
PMBFJ177
P-channel Silicon Junction Field-
effect Transistor
NXP SEMICONDUCTOR
SOT23
SST177
VISHAY SILICONIX
MMBF177
Fairchild
2.2. Jumpers Configuration
2-WIRE is the jumper which shorts CE and RE pin when a 2-lead gas sensor is connected to the LMP91000.
2-WIRE
2-lead gas
sensor
2-WIRE
3-lead gas
sensor
Figure 2: 2-WIRE Jumper Settings
J_MENB configures the Module Enable of the LMP91000 either manual or controlled by external
microcontroller. In manual mode, the Module Enable of the LMP91000 is tied to GND. When the
LMP91000EVM is connected to the SPIO4 board pin 1-2 need to be shorted.
microcontroller. In manual mode, the Module Enable of the LMP91000 is tied to GND. When the
LMP91000EVM is connected to the SPIO4 board pin 1-2 need to be shorted.