Datasheet

12 LMP90100 EVB User’s Guide August 2012
2. Step 2: Configure Inputs – click on the “INPUT MUX” block to set “VINP = 000: VIN2”
and “VINN = 000: VIN2”. Since VINP = VINN, a reading of approximately 0V should
be read.
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”. On the left hand side of the GUI, change the VREF1 (left hand side of the GUI)
value to 4.1V.
5. Step 5: Set Gain – since VIN ≈ 0V, the maximum gain that can be set is 128x. Click on the
“FGA” block, “PGA” block, or the “Gain” slider to select the gain.
6. Step 6: Set Buffer – click on the “ B U F F” block to include or exclude the buffer from the
signal path.
7. Step 7: Set Calibration - the purpose of this example is to show how the LMP90100 removes
the offset error using background calibration. Initially, disable the calibration by selecting
“000: No Calibration” under the “No Calibration” block.
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 without Calibration
1. Click on the “Measurement” tab and set the “Scan Mode” as follows:
Figure 10 - Scan Mode Settings
2. Under the “Output Format” field, select Display “Output Voltage (V)”
3. Under the “Stop Condition” field, select Run “500” samples.
4. Click on the “Run” button to view the output voltage results. A reading in the hundreds of
uV should be plotted similar to Figure 11.