Datasheet
11
LDC1612
,
LDC1614
www.ti.com
SNOSCY9A –DECEMBER 2014–REVISED MARCH 2018
Product Folder Links: LDC1612 LDC1614
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Feature Description (continued)
At the end of each conversion in single channel mode, or after converting all selected channels when in multi-
channel mode, the LDC1612/LDC1614 can be configured to assert the INTB pin to indicate completion of the
conversion.
Refer to Multi-Channel and Single Channel Operation for details on the LDC1612/LDC1614 channel functionality
and configuration.
7.3.2 Adjustable Conversion Time
The LDC1612/LDC1614 conversion provides a tradeoff between measurement resolution and conversion
interval. Longer conversion intervals have higher measurement resolution. The conversion interval can be
configured from 3.2 µs to >26.2 ms with 16 bits of resolution. Note that it is possible to configure the conversion
interval to be shorter than the time required to read back the DATAx registers. The LDC1612/LDC1614 supports
per-channel adjustment of the conversion interval by setting the RCOUNTx register.
Refer to Sensor Conversion Time for details on the LDC1612/LDC1614 configuration and details on the setting
conversion interval.
7.3.3 Sensor Startup and Glitch Configuration
For minimum noise, the sensor measurement should be performed after the sensor amplitude has stabilized. The
LDC1612/LDC1614 provides an adjustable sensor startup timing per channel. The timing can be varied from 1.2
µs to >26.2 ms by setting the SETTLECOUNTx register. Sensors with lower resonant frequencies or higher Qs
may require additional time to stabilize.
Refer to Settling Time for details on the LDC1612/LDC1614 configuration and details on the setting conversion
interval.
The LDC1612/LDC1614 can be configured with a faster sensor activation, or to use a lower current sensor
activation. Refer to Sensor Activation for details on this capability.
The LDC1612/LDC1614 provides an internal filter to attenuate interference from external noise sources. Refer to
Input Deglitch Filter for information on configuration on the deglitch filter.
7.3.4 Reference Clock
Optimum LDC1612/LDC1614 performance requires a clean reference clock. This reference frequency is
equivalent to the reference voltage of an Analog-to-Digital converter. The LDC1612/LDC1614 provide an internal
reference oscillator with a typical frequency of 43 MHz. This internal oscillator has good stability, with a typical
temperature coefficient of -13 ppm/°C. For applications requiring higher resolution or improved performance
across temperature, an external reference frequency can be applied to the CLKIN input.
The LDC1612/LDC1614 provide digital dividers for the ƒ
CLK
and the sensor inputs to adjust the effective
frequency measured by the LDC core. For most systems, the maximum permitted reference frequency provides
the best performance. The dividers provide flexibility in system design so that the full range of sensor frequencies
can be supported with a wide range of ƒ
CLK
. Each channel has a dedicated divider configuration.
Refer to Reference Clock for details on clocking requirements, configuration, and divider setup.
7.3.5 Sensor Current Drive Control
The lossy characteristic of the sensors used for inductive sensing require injection of energy to maintain a
constant sensor amplitude. The LDC1612/LDC1614 provides this energy by driving an AC current matching the
sensor resonant frequency across the LC sensor. To achieve optimum performance, it is necessary to set the
current drive so that the sensor amplitude is within the range of 1.2 V
P
to 1.8 V
P
. Each channel current drive is
set independently between 16 µA and 1.6 mA by setting the corresponding IDRIVEx register field. The
LDC1612/LDC1614 can also automatically determine the appropriate sensor current drive, and even dynamically
adjust the sensor current by use of the RP_OVERRIDE_EN function.
Refer to Sensor Current Drive Configuration for detailed information on configuration of the sensor drive.