Datasheet
Yes
Set
BGCALCN = 10b to
operate the device in
BgcalMode2
No
Is the channel
JDLQ•16x?
Set CH_SCAN_SEL = 10b to
operate the device in
ScanMode2. Set FIRST_CH &
LAST_CH accordingly.
Set FGA_BGCAL = 0 (default)
Correct FGA
error?
Yes
No
Set
FGA_BGCAL = 1 to
correct for FGA error
using the last known
coefficients.
LMP90100
www.ti.com
SNAS510P –JANUARY 2011–REVISED MARCH 2013
The benefits of using type 2 calibration is a higher throughput, lower power consumption, and slightly better
noise. The exact savings would depend on the number of channels being scanned, and the ODR and gain of
each channel.
Using Background Calibration:
There are four modes of background calibration, which can be programmed using the BGCALCN bits. They are
as follows:
1. BgcalMode0: Background Calibration OFF
2. BgcalMode1: Offset Correction / Gain Estimation
3. BgcalMode2: Offset Correction / Gain Correction
– Follow Figure 45 to set other appropriate registers when using this mode.
4. BgcalMode3: Offset Estimation / Gain Estimation
Figure 45. BgcalMode2 Register Settings
If operating in BgcalMode2, four channels (with the same ODR) are being converted, and FGA_BGCAL = 0
(default), then the ODR is reduced by:
1. 0.19% of 1.6775 SPS
2. 0.39% of 3.355 SPS
3. 0.78% of 6.71 SPS
4. 1.54% of 13.42 SPS
5. 3.03% of 26.83125 SPS
6. 5.88% of 53.6625 SPS
7. 11.11% of 107.325 SPS
8. 20% of 214.65 SPS
System Calibration
The LMP90xxx provides some unique features to support easy system offset and system gain calibrations.
The System Calibration Offset Registers (CHx_SCAL_OFFSET) hold the System Calibration Offset Coefficients
in 24-bit, two's complement binary format. The System Calibration Gain Registers (CHx_SCAL_GAIN) hold the
System Calibration Gain Coefficient in 24-bit, 1.23, unsigned, fixed-point binary format. For each channel, the
System Calibration Offset coefficient is subtracted from the conversion result prior to the division by the System
Calibration Gain Coefficient.
Copyright © 2011–2013, Texas Instruments Incorporated Submit Documentation Feedback 29
Product Folder Links: LMP90100