PicoCAP Overview

PICOCAP: Capacitance Measurement

PICOCAP: Capacitance Measurement

The Most Flexible Solution in Direct Capacitance-to-Digital Conversion

The patended PICOCAP measuring principle shows a versatile approach to capacitance measurement.

The input capacitance can range between 0fF up to hundreds of nF so there is practically no limit for the capacitor value. This provides high flexibility to the user and allows the same chip to be used in a broad range of sensors. PICOCAP also provides a powerful combination of performance and accuracy with the option for ultra-low current applications.


Advantages

  • 2 channels with typ. 50 ps rms resolution
  • 65 ps Bin size
  • Measurement range 3.5 ns to 1.8 µs
  • 15 ns pulse-pair resolution with 4-fold multihit capability
  • 4 events can be measured arbitrarily against each other
  • Windowing for precise stop enable

Applications

  • Humidity sensors
  • Pressure sensors
  • MEMS
  • Acceleration sensors
  • Inclination sensors
  • Freefall sensors
  • Position sensors
  • Touch sensors
  • Angle sensors
  • Level sensors
  • Microphones


    Block Diagram
    (click to enlarge)

    Package Outline
    (click to enlarge)


    DescriptionVersionSizeDownload
    Development Support PCap04:
    Evaluation System for PCap04
    V1.04MBPCAP04EVAL- DS.PDF
    Datasheet PCap04:
    General Data
    V1.03.2 KBPCAP04.PDF
    Datasheet PCap02, Vol. 1:
    General Data and Front-End
    V1.62.6MBDB_PCap02A_Vol1_en.pdf
    Datasheet PCap02, Vol. 2:
    Digital Signal Processor
    V0.21.6MBDB_PCap02A_Vol2_en.pdf
    Datasheet PCap02 Eval System:
    Evaluation System for PCap02
    V0.0990kBDB_PCap02-EVA-Kit_en.pdf
    Datasheet PCap02 Eval System:
    Evaluation Software for PICOCAP Devices
    V0.02MBDB_PCap02plus_en.pdf
    Datasheet PICOCAP DEVICES:
    Assembler Software PICOCAP Devices
    V0.0750kBDB_PCap-Assembler_en.pdf
    Datasheet PCap02, Linearize:
    Description of Linearization Firmware
    V0.21.2MBDB_PCap02_Linearize_en.pdf
    Datasheet PCap01:
    Single-chip solution with standard firmware
    V0.65MBDB_PCap01Ax_0301_en.pdf
    Datasheet PCap01:
    Single-chip solution for humidity measurement
    V0.34MBDB_PCap01AK-0101xx_en.pdf
    Datasheet PCap01:
    Description of PCap01 DSP and Assembler
    V0.23MBDB_PCap01_DSP_e.pdf
    Datasheet PCap01:
    General evaluation kit for PCap01
    V0.32.6MBDB_PCap01-EVA-KIT_en.pdf
    Datasheet PCap01:
    Description of humidity measurement demonstrator
    V0.13MBDB_PCap01_HUM_DEMO_en.pdf
    Datasheet PCap01-Touch:
    Very-Low-Power IC for Capacitive Touch Sensor Solutions
    V0.11.3MBDB_PCap01_Touch_en.pdf
    DescriptionVersionSizeDownload
    Screencasts PCap01:
    2:44 min. webcast introduction into PCap01 Evaluation Kit
    -7MBPCap01_Evaluation-Software_en.zip
    Screencasts PCap02plus:
    9:37 min. webcast introducing a Sensor Scaling + PDM / PWM output with PCap02
    -26MBPCap02plus-Scaling-PDM-PWM_en.zip
    DescriptionVersionSizeDownload
    Software PCap04:
    Evaluation software for PICOCAP Devices
    Full installer package incl. drivers
    1.2.7297MBPCap04-EVA-SW_W7.zip
    Software PCap04 (32-bit):
    Using our DLL combing with your own software.
    ZIP package incl. e.g. header file, example c-code
    1.0423kBPCap04-DLL-Library.zip
    Software PCap04 (64-bit):
    Using our DLL combing with your own software.
    ZIP package incl. e.g. header file, example c-code
    1.0378kBlinearize_r01.zip
    Software PCap02:
    Evaluation software for PICOCAP Devices
    Full installer package incl. drivers
    1.3.1168MBPCap02plus.zip
    Software PCap01:
    Evaluation software for PCap01-EVA-KIT and PCap01-HUM-EVA
    Full installer package incl. drivers
    0.80150MBPCap01-EVA-SW_W7_XP.zip
    Software PCap01:
    Assembler software for PCap01, installer package
    V20.4160MBPCap01_Assembler.zip
    Software PCap01:
    Standard firmware for PCap01A
    03.01.0225kPCap01_standard.hex
    Software PCap01:
    Firmware for humidity+temperature measurement
    01.01.0425kPCap01_humidity.hex
    Software PICOPROG V3 (V2.0):
    Driver Installer Stand-Alone
    R113.1MBPicoProg_v2_Driver_Installer_Stand-Alone.zip
    PICOSTRAIN Measurement Principle

    The PICOCAP measuring principle shows a new approach to capacitance measurement. For this purpose the sense capacitor and a reference capacitor are connected to a resistor, forming a low-pass filter. Sense and reference capacitor should be in the same range to minimize gain drift. Practically there is no limit for the capacitor value. Sensors from nearly 0 fF up to tens of nF can be measured. The PICOCAP devices also support differential sensors with inside linearization.

    The capacitors are charged to the supply voltage and then discharged through the resistor. The discharge time down to an arbitrary trigger level is measured with ultra-high precision using a TDC (Time-to-Digital Converter).

    This measuring process is repeated in time-multiplex with both Capacitors, using the same resistor and the same comparator. Calculating the ratio of the results will turn out the absolute values and temperature dependencies of the resistor and the comparator.

    The Compensated Mode offers the solution for highest resolution applications with low offset and extremely low gain drift. The capacitors are connected floating, not referenced to ground. They are switched alternately to the resistor by an integrated analog switch. Additional patented circuits and algorithms compensate for parasitic capacities. Parasitic capacities would have a negative effect on the gain drift over temperature. The compensation results in a very low gain drift over temperature down to 0.5 ppm / K. It is much better than the intrinsic gain drift of most sensors.

    General Circuit
    (click to enlarge)

    Cycle Time
    (click to enlarge)

    TypePart numberPackageRoHS compl.Shipping package
    PCap02:
    PCap02ADiceYes
    PCap02AEQFN32Yes
    PCap02-EVA-KITSystemYesBox
    PCap01:
    PCap01AMNR 1613DiceYes
    PCap01ADMNR 1793QFN32Yes
    PCap01AKMNR 1795QFN24Yes
    PCap01-EVA-KITMNR 1912-01SystemYesBox
    PCap01-HUM-EVAMNR 1796SystemYesBox
    PCap01-HUM-DEMOMNR 1792SystemYesBox

    ADDITIONAL INFORMATION