FDC2114RGHT datasheet(45/60 Pages) TI1

45 / 60 page

Target Distance (mm) with 20.9 x 13.9 mm Sensor

0.005

0.01

0.015

0.02

0.025

0.03

0.035

D030

Target Distance (mm) with 20.9 x 13.9 mm Sensor

100

D032

4.08 ksps

610 sps

38 sps

Target Distance (mm) with 20.9 x 13.9 mm Sensor

D028

Target Distance (mm) with 20.9 x 13.9 mm Sensor

0.02

0.04

0.06

0.08

0.1

0.12

0.14

D029

FDC2212, FDC2214, FDC2112, FDC2114

www.ti.com

SNOSCZ5A – JUNE 2015 – REVISED JUNE 2015

10.2.4 Application Curves

Common test conditions (unless specified otherwise): Sensor capacitor: 1 layer, 20.9 x 13.9 mm, Bourns

CMH322522-180KL sensor inductor with L=18 µH and 33 pF 1% COG/NP0 Target: Grounded aluminum plate

(176 x 123 mm), Channel = Channel 0 (continuous mode) CLKIN = 40 MHz, CHx_FIN_SEL = b10,

CHx_FREF_DIVIDER = b00 0000 0001 CH0_RCOUNT = 0xFFFF, SETTLECOUNT_CH0 = 0x0100,

DRIVE_CURRENT_CH0 = 0x7800

Figure 59. FDC2212 / FDC2214: Capacitance vs. Target

Figure 60. FDC2112 / FDC2114: Capacitance vs. Target

Distance (0 to 20mm)

Distance (20 to 40mm)

Figure 61. FDC2212 / FDC2214: Capacitance vs. Target

Figure 62. Measurement precision in Distance vs. Target

Distance (40 to 60mm)

Distance (0 to 60mm)

10.2.5 Power-Cycled Applications

For applications which do not require high sample rates or maximum conversion resolution, the total active

conversion time of the FDC can be minimized to reduce power consumption. This can be done by either by using

sleep mode or shutdown mode during times in which conversions are not required (see Device Functional

Modes).

As an example, for an application which only needs 10 samples per second with a resolution of 16 bits can utilize

the low-power modes. The sensor requires SETTLECOUNT = 16 and IDRIVE of 01111b (0.146 mA). Given

FREF = 40 MHz and RCOUNT = 4096 will provide the resolution required. This corresponds to 4096 * 16 * 10 /

40 MHz

→ 16.4 ms of active conversion time per second. Start-up time and channel switch delay account for an

additional 0.34 ms. For the remainder of the time, the device can be in sleep mode: Therefore, the average

current is 19.4 ms * 3.6 mA active current + 980.6 ms of 35 µA of sleep current, which is approximately 104.6 µA

of average supply current. Sleep mode retains register settings and therefore requires less I2C writes to wake up

the FDC than shutdown mode.

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Product Folder Links: FDC2212 FDC2214 FDC2112 FDC2114

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