Справочник Пользователя для Texas Instruments LDC1000EVM - Evaluation Module for Inductance to Digital Converter with Sample PCB Coil LDC1000EVM LDC1000EVM
Модели
LDC1000EVM
Interfacing Different Sensor Coils
Getting a custom sensor to operate with LDC1000
1. Break off EVM coil along perforation
2. Connect custom sensor coil and capacitor (C) to J2 on the EVM (Fig. 2)
Steps to pick C:
a. Calculate / measure inductance of the coil (L)
b. Calculate / measure resistance of the coil (R
b. Calculate / measure resistance of the coil (R
S
)
c. Pick C value to satisfy
both conditions below:
Resonance frequency between
5 kHz to 5 MHz:
5 kHz to 5 MHz:
Resonance impedance (R
P
) between
798 Ω to 3.93 MΩ:
Note: If L is not large enough, add discrete inductor in series with sensor
3. Plug EVM into host and ensure GUI indicates EVM connection
4. GUI settings
Update
Sensor Capacitor value on GUI configuration page to
the chosen value of C
Program
Sensor Frequency register: value should be 20% below
sensor’s resonant frequency
Program
LDC Configuration register:
Amplitude: 4V
Response time: 6144 cycles
Response time: 6144 cycles
Determine
Rp_MAX and Rp_MIN register values:
Set Rp_MIN to minimum value = 0.798 kΩ
Set Rp_MAX to maximum value = 3926.991 kΩ
START data capture. Check “Proximity Data” value.
Set Rp_MAX to maximum value = 3926.991 kΩ
START data capture. Check “Proximity Data” value.
2
LDC1000EVM Quick Start Guide
Texas Instruments 2013
Note: If “Proximity Data” equals 0, add a discrete inductor in series to the sensor coil
to get into the operating range of the LDC
J2 connector block
4a
4d
4b
4c
Fig.2 Custom coil connection
Note: On the streaming screen (Fig. 1), make sure to STOP data capture when making
changes to register settings and START data capture to apply the changes
f
RES
=
2*pi*√LC
1
R
P
=
R
S
*
1
C
L