LMP90100MHE National Semiconductor, LMP90100MHE Datasheet - Page 28

• Manufacturer Part Number: LMP90100MHE
• Description: AFE, SENSOR, 28TSSOP
• Manufacturer: National Semiconductor

Specifications of LMP90100MHE

• Brief Features: 24bit Low Power Sigma Delta ADC, Automatic Channel Sequencer
• Supply Voltage Range: 2.7V To 5.5V
• Operating Temperature Range: -40°C To +105°C
• Digital Ic Case Style: TSSOP
• No. Of Pins: 28
• Base: RoHS Compliant
• Ic Function: Multi-Channel, Low Power 24-bit Sensor AFE
• Rohs Compliant: Yes

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4.
5.
6.
16.3 CHANNELS SCAN MODE
There are four scan modes. These scan modes are selected
using the CH_SCAN: CH_SCAN_SEL bit. The first scanned
channel is FIRST_CH, and the last scanned channel is
LAST_CH; they are both located in the CH_SCAN register.
The CH_SCAN register is double buffered. That is, user in-
puts are stored in a slave buffer until the start of the next
conversion during which time they are transfered to the mas-
ter buffer. Once the slave buffer is written, subsequent up-
dates are disregarded until a transfer to the master buffer
happens. Hence, it may be appropriate to check the
CH_SCAN_NRDY bit before programming the CH_SCAN
register.
ScanMode0: Single-Channel Continuous Conversion
LMP90100 continuously converts the selected FIRST_CH.
Do not operate in this scan mode if gain
LMP90100 is running in background calibration modes Bg-
LMP90100 starts a fresh conversion.
LMP90100 computes the system gain calibration
coefficient once, stores this coefficient in the
CHx_SCAL_GAIN registers, and continuously calibrates
the system using this coefficient.
LMP90100 exits the “System Calibration Gain Coefficient
Determination” mode.
≥
16 and the
28
calMode1 or BgcalMode2. If this is the case, then it is more
suitable to operate the device in ScanMode2 instead.
ScanMode1: Multiple-Channels Single Scan
LMP90100 converts one or more channels starting from
FIRST_CH to LAST_CH, and then enters the stand-by state.
ScanMode2: Multiple-Channels Continuous Scan
LMP90100 continuously converts one or more channels start-
ing from FIRST_CH to LAST_CH, and then it repeats this
process.
ScanMode3: Multiple-Channels Continuous Scan with
Burnout Currents
This mode is the same as ScanMode2 except that the burnout
current is provided in a serially scanned fashion (injected in a
channel after it has undergone a conversion). Thus it avoids
burnout current injection from interfering with the conversion
result for the channel.
The sensor diagnostic burnout currents are available for all
four scan modes. The burnout current is further gated by the
BURNOUT_EN bit for each channel. ScanMode3 is the only
mode that scans multiple channels while injecting burnout
currents without interfering with the signal. This is described
in details in
Section 16.4.2 Burnout
Currents.