Texas Instruments LMP90100 User manual

User’s Guide
August 2012
LMP90100 EVB User’s Guide
August 2012 LMP90100EVB User’s Guide 1
User’s Guide for the LMP90100 Evaluation Board with Sensor
AFE Software
Table of Contents
1.0. INTRODUCTION ........................................................................................................2
2.0. EQUIPMENT...............................................................................................................2
2.1. CONNECTION DIAGRAM..........................................................................................2
2.2. BOARD ASSEMBLY....................................................................................................4
3.0. EXAMPLE #1: QUICK START – DC READING ........................................................5
4.0. EXAMPLE #2: SHORTED INPUT AND CALIBRATION TEST...............................10
5.0. EXAMPLE #3 - 3-WIRE RTD APPLICATION..........................................................15
6.0. EXAMPLE #4: THERMOCOUPLE AND LM94022 APPLICATION........................21
7.0. POWERING THE LMP90100EB...............................................................................31
8.0. EVALUATING THE LMP90100 WITHOUT THE SPIO-4 BOARD. ........................31
9.0. INSTALLING THE LMP90100 SENSOR AFE SOFTWARE.....................................32
10.0. SCHEMATIC...........................................................................................................36
11.0. LAYOUT..................................................................................................................37
12.0. BOM.........................................................................................................................39

2 LMP90100 EVB User’s Guide August 2012
1.0. Introduction
The LMP90100 Design Kit (consisting of the LMP90100 Evaluation Board, the SPIO-4 Digital
Controller Board, the Sensor AFE software, and this user’s guide) is designed to ease evaluation and
design-in of National Semiconductor’s LMP90100 24-bit Fully Programmable Low Power Σ∆ ADC with
True Continuous Background Calibration.
Data capturing and static evaluations are simplified by connecting the SPIO-4 Digital Controller Board
(SPIO-4 board) to a PC via USB and running the Sensor AFE software. The data capture board will
generate the SPI signals to communicate to and capture data from the LMP90100. The user will also have
the option to evaluate the LMP90100 without using the SPIO-4 board or the Sensor AFE software.
The LMP90100 will digitize the analog input, and the software will display these results in time domain
and histogram. The software also allows customers to write to and read from registers, to calibrate the
device or the system’s gain, offset, and scale settings, and most importantly, to configure and learn about
the LMP90100.
This document describes the connection between the boards and PC, provides a quick start for a DC,
shorted input, 3-wire RTD, and thermocouple/temperature sensor applications. This document also
describes how to evaluate the LMP90100 with and without the SPIO-4 board and provides the schematic,
board layouts, and BOM.
2.0. Equipment
1. LMP90100 evaluation board (NSID: LMP90100EB)
2. SPIO-4 digital controller board (NSID: SPIO-4)
3. PC with Sensor AFE software
4. Power supplies (optional) to source VA, VIO, VREFP, or VIN.
5. Multimeter (optional)
6. 3-wire RTD (optional)
7. Thermocouple (optional)
2.1. Connection Diagram
Figure 1 shows the connection between the LMP90100 Evaluation Board (LMP90100EB), SPIO-4
board, and a personal computer with the LMP90100 Sensor AFE software. LMP90100 can be
powered using external power supplies or from the SPIO-4 board.

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Figure 1 – Connection Diagram

4 LMP90100 EVB User’s Guide August 2012
2.2. BoardAssembly
The schematic of the evaluation board can be seen in section 10.
Figure 2 – LMP90100 Evaluation Board Assembly

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3.0. Example #1: Quick Start – DC Reading
The following procedures show a quick method to assemble the LMP90100EB and perform a quick DC
voltage reading.
A. LMP90100 EB Jumper Connections
1. The jumpers for this example application can be seen in Figure 3 and Table 1. Jumpers not
shown can be left unpopulated.
2. The SPIO-4 board is properly setup out of the box (no assembly required).
3. The schematic for the LMP90100EB can be seen section 10.
Figure 3 – Jumper Settings (Default) for the DC Test
Jumpers
Pin
Purpose
JP1: VA_EXT
P1-P2
Source VA externally

6 LMP90100 EVB User’s Guide August 2012
JP2: VIO_EXT
P1-P2
Source VIO externally
JP6
P1-P2
Connect VA supply to the LMP90100
JP7
P1-P2
Connect VIO supply to the LMP90100
JP10: VIN_JMP
P5-P6
Connect a DC input to VIN2
JP10: VIN_JMP
P7-P8
Connect a DC input to VIN3
JP13: VREF_JMP1
P3-P4
VREFP1 = 4.1V from U4 (LM4140)
JP13: VREF_JMP1
P9-P10
VREFN1 = ground
JP14: VREF_JMP2
P1-P2
Connect VREFP1 source to the LMP90100
JP14: VREF_JMP2
P3-P4
Connect VREFN1 source to the LMP90100
Table 1 - Jumpers for DC Measurement
B. Installing/Opening the Software - follow section 9.0 to install and open the LMP90100 Sensor
AFE software.
C. Connecting and Powering the Boards – these steps have to be done in this order.
1. Connect a 5.0V power supply to J1 (VA_EXT) and GND (J2). Don’t turn on the power
supply yet.
2. Connect a 5.0V power supply to J3 (VIO_EXT) and GND (J2). Don’t turn on the power
supply yet.
3. Turn on the power supply that is sourcing VA (J1), and then turn on the power supply that is
sourcing VIO (J3).
4. Connect the LMP90100EB’s JP12 to SPIO-4 Board’s J6 (pins 1-16). See Figure 4.
Figure 4 – LMP90100EB-to-SPIO-4 Board Connection
5. Connect SPIO-4 board to a PC via USB.
6. Use a multimeter to measure LMP90100EB’s JP6, JP7; they should all be approximately 5V.
If they are not, check your power supplies and jumpers. Measure JP14.P2; it should be
approximately 4.1V. If it’s not, check your jumpers and U4.
D. Configuring the LMP90100 Using the Sensor AFE Software

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Follow the step-by-step instructions under the “HelpBar” mini-tab (left hand side of the GUI) to
configure the LMP90100 for this example. These step-by-step instructions are discussed in
details below, and the recommended configuration should look similar to the figure below.
Figure 5 - Recommended LMP90100 Configuration for a DC Reading
1. Step 1: Select a Sensor - select “DC” “DC” since the input source is not a sensor.
2. Step 2: Configure Inputs – click on the “INPUT MUX” block to set “VINP = 000: VIN2”
and “VINN = 001: VIN3”. Since VIN0 = (3/4) VREF1 and VIN1 = (1/4) VREF1, the
measurement across this channel will be (1/2) VREF1.
3. Step 3: Source IB1/IB2? – this step can be ignored because neither IB1 nor IB2 is connected
to the inputs.
4. Step 4: Select Reference – click on the “VREF MUX” block to choose “VREF_SEL = 0:
VREF1”. Make sure the VREF1 value on the upper left hand side of the GUI is 4.1V
(default).
5. Step 5: Set Gain – since VIN = (1/2) VREF1, the maximum gain that can be set is 2 (with
buffer disabled). If the buffer is enabled, then the output might rail and enable the
“OFLO_FLAGS” flag. In this case, set the gain to 1. Click on the “FGA” block, “PGA”
block, or the “Gain” slider to select the gain.

8 LMP90100 EVB User’s Guide August 2012
6. Step 6: Set Buffer – click on the “BUFF” block to include or exclude the buffer from the
signal path.
7. Step 7: Set Calibration - click on the “No Calibration” block to enable or disable calibration.
Refer to the LMP90100 datasheet to more information on the LMP90100’s background
calibration types and modes.
8. Step 8: Int/Ext CLK? – click on the “CLK MUX” block and make sure the internal clock is
selected.
9. Step 9: Performance - click on the “Performance” mini-tab. This tab displays the Estimated
Device Performance base on the block diagram that you’ve configured, as well as the
Measured System Performance if you’ve connected a board and ran the LMP90100.
E. Capturing Data
1. Click on the “Measurement” tab and set the “Scan Mode” as follows:
Figure 6 - Scan Mode Settings
2. Under the “Output Format” field, select Display as “Output Voltage (V)”
3. Under the “Stop Condition” field, select Run as “1000” samples.
4. Click on the “Run” button to view the output voltage results. A reading of approximately
½(VREF1) should be plotted as seen in Figure 7.

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Figure 7 - Results for Example #1 - DC Reading

10 LMP90100 EVB User’s Guide August 2012
4.0. Example #2: Shorted Input and Calibration Test
This example demonstrates LMP90100’s ability to calibrate for offset error.
A. LMP90100 EB Jumper Connections
1. Connect the LMP90100EB jumpers like the jumpers shown in the figure and table below.
Jumpers not mentioned can be left unconnected.
2. The SPIO-4 board is properly setup out of the box (no assembly required).
3. The schematic for the LMP90100EB can be seen in section 10.
Figure 8 – LMP90100EB Jumper Settings for the Shorted input and Calibration Test
Jumpers
Pin
Purpose
JP1: VA_EXT
P2-P3
Source VA with the 5.0V from the SPIO-4 board.
JP2: VIO_EXT
P2-P3
Source VIO with the 5.0V from the SPIO-4 board.
JP4
P2-P3
Get 5.0V from the SPIO-4 board
JP6
P1-P2
Connect VA supply to the LMP90100
JP7
P1-P2
Connect VIO supply to the LMP90100
JP9
P1-P2
Force the odd pins of JP10 to be midscale (VREF1/2)
JP10: VIN_JMP
P5-P6
Connect a DC (midscale) voltage to VIN2
JP13: VREF_JMP1
P3-P4
VREFP1 = 4.1V from U4 (LM4140)
JP13: VREF_JMP1
P9-P10
VREFN1 = ground