ZHCSKH7 November 2019 LDC1001
PRODUCTION DATA.
- 1 特性
- 2 應用
- 3 說明
- 4 修訂歷史記錄
- 5 Pin Configuration and Functions
- 6 Specifications
-
7 Detailed Description
- 7.1 Overview
- 7.2 Functional Block Diagram
- 7.3 Feature Description
- 7.4 Device Functional Modes
- 7.5 Programming
- 7.6
Register Maps
- 7.6.1
Register Description
- 7.6.1.1 Revision ID (Address = 0x00)
- 7.6.1.2 RP_MAX (Address = 0x01)
- 7.6.1.3 RP_MIN (Address = 0x02)
- 7.6.1.4 Watchdog Timer Frequency (Address = 0x03)
- 7.6.1.5 LDC Configuration (Address = 0x04)
- 7.6.1.6 Clock Configuration (Address = 0x05)
- 7.6.1.7 Comparator Threshold High LSB (Address = 0x06)
- 7.6.1.8 Comparator Threshold High MSB (Address = 0x07)
- 7.6.1.9 Comparator Threshold Low LSB (Address = 0x08)
- 7.6.1.10 Comparator Threshold Low MSB (Address = 0x09)
- 7.6.1.11 INTB Pin Configuration (Address = 0x0A)
- 7.6.1.12 Power Configuration (Address = 0x0B)
- 7.6.1.13 Status (Address = 0x20)
- 7.6.1.14 Proximity Data LSB (Address = 0x21)
- 7.6.1.15 Proximity Data MSB (Address = 0x22)
- 7.6.1.16 Frequency Counter LSB (Address = 0x23)
- 7.6.1.17 Frequency Counter Mid-Byte (Address = 0x24)
- 7.6.1.18 Frequency Counter MSB (Address = 0x25)
- 7.6.1
Register Description
- 8 Application and Implementation
- 9 Power Supply Recommendations
- 10Layout
- 11器件和文檔支持
- 12機械、封裝和可訂購信息
7.3.3 Measuring Inductance With LDC1001
LDC1001 measures the sensor’s frequency of oscillation using a frequency counter. The frequency counter timing is set by an external clock applied on TBCLK pin. The sensor frequency can be calculated from the frequency counter register value (see registers 0x23 through 0x25) in Equation 3:
where
- ƒSENSOR is the measured sensor frequency
- ƒEXT is the frequency of the external clock.
- FCOUNT is the value obtained from the Frequency Counter Data registers (address 0x23,0x24,0x25).
- RESPONSE_TIME is the programmed response time (set in the LDC configuration register, address 0x04).
Use Equation 4 to determine the sensor inductance:
where
- C is the parallel sensor capacitance
- ƒSENSOR is the sensor frequency calculated in Equation 3
Example: If ƒEXT = 6MHz, RESPONSE_TIME = 6144, C = 100 pF and measured Fcount = 3000 (dec) (address 0x23 through 0x25)
ƒsensor=(1/3) × (6000000/3000) × (6144)= 4.096 MHz
Using the ƒsensor = 4.096 MHz example for Equation 4, the sensor inductance L = 15.098 µH.
NOTE
The accuracy of a measurement largely depends upon the frequency of the external time-base clock (TBCLK). A higher frequency will provide better measurement accuracy. The maximum supported frequency is 8 MHz.