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ZHCSDM9A December 2014 – March 2018 LDC1612 , LDC1614

PRODUCTION DATA.

封裝選項

機(jī)械數(shù)據(jù) (封裝 | 引腳)

RGH|16
- MPQF182B

散熱焊盤機(jī)械數(shù)據(jù) (封裝 | 引腳)

RGH|16
- QFND440A

訂購信息

8.1.5.2 Automatic IDRIVE Setting with RP_OVERRIDE_EN

The LDC1612/LDC1614 can automatically determine the appropriate sensor current drive when entering Active Mode. For the majority of applications, it is recommended to program a fixed current drive for consistent measurement performance. The automatic sensor amplitude setting is useful for initial system prototyping if the sensor amplitude is unknown. When this function is enabled, the LDC attempts to find the IDRIVEx setting which results in a sensor amplitude between 1.2 V_P and 1.8V_P. For systems which have a large variation in target interaction, the LDC1612/LDC1614 may select a current drive setting which has poorer repeatability over the range of target interactions. In addition, measurement repeatability will be poorer with different sensor current drives. To enable the automatic sensor amplitude, set RP_OVERRIDE to b0.

The following sequence uses auto-calibration to configure sensor drive current for a sensor with an unknown R_P:

Set target at the maximum planned operating distance from the sensor.
Place the device into SLEEP mode by setting CONFIG.SLEEP_MODE_EN to b0.
Program the desired values of SETTLECOUNT and RCOUNT values for the channel.
Enable auto-calibration by setting RP_OVERRIDE_EN to b0.
Take the device out of SLEEP mode by setting CONFIG.SLEEP_MODE_EN to b1.
Allow the device to perform at least one measurement, with the target stable (fixed) at the maximum operating range.
Read the channel current drive value from the appropriate DRIVE_CURRENTx register (addresses 0x1e, 0x1f, 0x20, or 0x21), in the INIT_DRIVEx field (bits 10:6). Save this value.
During startup for normal operating mode, write the value saved from the INIT_DRIVEx bit field into the IDRIVEx bit field (bits 15:11).
During normal operating mode, the RP_OVERRIDE_EN should be set to b1 for a fixed current drive.

If the current drive results in the oscillation amplitude greater than 1.8 V, the internal ESD clamping circuit will become active. This may cause the sensor frequency to shift so that the output values no longer represent a valid system state. If the current drive is set at a lower value, the SNR performance of the system will decrease, and at near zero target range, oscillations may completely stop, and the output sample values will be all zeroes.

If there are significant differences in the sensor construction for different channels, then this process should be repeated for each channel.