PicoCap Capacitance Measurement

PCAP04 PICOCAP

Capacitance-to-Digital Converter

The PCap04 is a capacitance-to-digital converter (CDC) with integragrated digital signal processor (DSP) for on-chip data post processing. The front end is based on the ScioSense PICOCAP principle.

This conversion principle offers outstanding flexibility with respect to power consumption, resolution and speed.The PCap04 covers a wide capacitance input range from a few femtofarads up to several hundred nanofarads. It is easy to configure the PCap04 for different capacitance measurement tasks, i.e. single as well as differential sensors in both, grounded or floating connection. The on-chip DSP allows for implementation of sensor algorithms like linearization and temperature compensation, with data output in a digital (SPI or IIC) or analog (PDM/PWM) way.

precision-measurement-pcap04-block-diagram

PicoCap: Capacitance Measurement

PCAP04 DIE CAPABILITY

For customers that are unable to use the QFN24 packaged Pcap04 or require die for their own packaging, ScioSense now offers die in wafer form. Customers requiring less than a wafer for smaller projects or first article builds, PMT (Precision Measurement Technologies) in Clearwater, Florida has wafer packs in 100 and 250 quantities available for quick turnaround. Whether you need just a few hundred or a few thousand, PMT, a ScioSense Technology Center, ships worldwide and can help with your project.

BENEFITS

  • High Flexibility: Easy adaption to various applications – ultra low power, high resolution or high speed – just by configuration
  • High resolution or high speed
  • On-chip DSP for sensor algorithms, signal post-processing including linearization and temperature compensation
  • On-chip and external temperature measurement capability

FEATURES

  • UP to 6 capacitors in grounded mode
  • Up to 3 capacitors in floating mode
  • Internal reference 1 to 31pF
  • Integrated guarding operational amplifier
  • Up to 8aF at 2.5Hz and 10pF base capacitance
  • UP to 50kHz sample rate
  • 32-bit DSP
  • 3k ROM code, 1k NVRAM/li>
  • 96 x 32 RAM
  • SPI / IIC interface
  • PDM / PWM outputs, GPIO
  • Supply voltage 3.0V to 3.6V (integrated 1.8V regulator)
  • QFN24 or dice (1.588 x 1.46 mm2

Documentation & Downloads

Datasheet

Description

Development Support PCap04:
Evaluation System for PCap04

Version

V1.0

Size

4MB

Download

PCAP04EVAL- DS.pdf

Description

Datasheet PCap04:
General Data

Version

V1.0

Size

3.2MB

Download

PCAP04.pdf

Description

Datasheet PCap02, Vol. 1:
General Data and Front-End

Version

V1.6

Size

2.6MB

Download

DB_PCap02A_Vol1_en.pdf

Description

Datasheet PCap02, Vol. 2:
Digital Signal Processor

Version

V0.2

Size

1.6MB

Download

DB_PCap02A_Vol2_en.pdf

Description

Datasheet PCap02 Eval System:
Evaluation System for PCap02

Version

V0.0

Size

990KB

Download

DB_PCap02-EVA-Kit_en.pdf

Description

Datasheet PCap02 Eval System:
Evaluation Software for PICOCAP Devices

Version

V0.0

Size

2MB

Download

DB_PCap02plus_en.pdf

Description

Datasheet PicoCap Devices:
Assembler Software PICOCAP Devices

Version

V0.0

Size

750KB

Download

DB_PCap-Assembler_en.pdf

Description

Datasheet PCap02, Linearize:
Description of Linearization Firmware

Version

V0.2

Size

1.2MB

Download

DB_PCap02_Linearize_en.pdf

Description

Datasheet PCap01:
Single-chip solution with standard firmware

Version

V0.6

Size

5MB

Download

DB_PCap01Ax_0301_en.pdf

Description

Datasheet PCap01:
Single-chip solution for humidity measurement

Version

V0.3

Size

4MB

Download

DB_PCap01AK-0101xx_en.pdf

Description

Datasheet PCap01:
Description of PCap01 DSP and Assembler

Version

V0.2

Size

3MB

Download

DB_PCap01_DSP_e.pdf

Description

Datasheet PCap01:
General evaluation kit for PCap01

Version

V0.3

Size

2.6MB

Download

DB_PCap01-EVA-KIT_en.pdf

Description

Datasheet PCap01:
Description of humidity measurement demonstrator

Version

V0.1

Size

3MB

Download

DB_PCap01_HUM_DEMO_en.pdf

Description

Datasheet PCap01-Touch:
Very-Low-Power IC for Capacitive Touch Sensor Solutions

Version

V0.1

Size

1.3MB

Download

DB_PCap01_Touch_en.pdf

Software

Datasheet

Description

Development Support PCap04:
Evaluation System for PCap04

Version

V1.0

Size

4MB

Download

PCAP04EVAL- DS.pdf

Description

Datasheet PCap04:
General Data

Version

V1.0

Size

3.2MB

Download

PCAP04.pdf

Description

Datasheet PCap02, Vol. 1:
General Data and Front-End

Version

V1.6

Size

2.6MB

Download

DB_PCap02A_Vol1_en.pdf

Description

Datasheet PCap02, Vol. 2:
Digital Signal Processor

Version

V0.2

Size

1.6MB

Download

DB_PCap02A_Vol2_en.pdf

Description

Datasheet PCap02 Eval System:
Evaluation System for PCap02

Version

V0.0

Size

990KB

Download

DB_PCap02-EVA-Kit_en.pdf

Description

Datasheet PCap02 Eval System:
Evaluation Software for PICOCAP Devices

Version

V0.0

Size

2MB

Download

DB_PCap02plus_en.pdf

Description

Datasheet PicoCap Devices:
Assembler Software PICOCAP Devices

Version

V0.0

Size

750KB

Download

DB_PCap-Assembler_en.pdf

Description

Datasheet PCap02, Linearize:
Description of Linearization Firmware

Version

V0.2

Size

1.2MB

Download

DB_PCap02_Linearize_en.pdf

Description

Datasheet PCap01:
Single-chip solution with standard firmware

Version

V0.6

Size

5MB

Download

DB_PCap01Ax_0301_en.pdf

Description

Datasheet PCap01:
Single-chip solution for humidity measurement

Version

V0.3

Size

4MB

Download

DB_PCap01AK-0101xx_en.pdf

Description

Datasheet PCap01:
Description of PCap01 DSP and Assembler

Version

V0.2

Size

3MB

Download

DB_PCap01_DSP_e.pdf

Description

Datasheet PCap01:
General evaluation kit for PCap01

Version

V0.3

Size

2.6MB

Download

DB_PCap01-EVA-KIT_en.pdf

Description

Datasheet PCap01:
Description of humidity measurement demonstrator

Version

V0.1

Size

3MB

Download

DB_PCap01_HUM_DEMO_en.pdf

Description

Datasheet PCap01-Touch:
Very-Low-Power IC for Capacitive Touch Sensor Solutions

Version

V0.1

Size

1.3MB

Download

DB_PCap01_Touch_en.pdf

PicoCap Measurement Principle

he 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

Cycle Time

Ordering Numbers

Type
Part Number
Package
RoHS compl.
Shipping Package
PCap02:
PCap02A Dice Yes
PCap02AE QFN32 Yes
PCap02-EVA-KIT System Yes Box
PCap01:
PCap01A MNR 1613 Dice Yes
PCap01AD MNR 1793 QFN32 Yes
PCap01AK MNR 1795 QFN24 Yes
PCap01-EVA-KIT MNR 1912-01 System Yes Box
PCap01-HUM-EVA MNR 1796 System Yes Box
PCap01-HUM-DEMO MNR 1792 System Yes Box

Ordering Numbers

Type
Part Number
Package
RoHS compl.
Shipping Package
PCap02:
PCap02A Dice Yes
PCap02AE QFN32 Yes
PCap02-EVA-KIT System Yes Box
PCap01:
PCap01A MNR 1613 Dice Yes
PCap01AD MNR 1793 QFN32 Yes
PCap01AK MNR 1795 QFN24 Yes
PCap01-EVA-KIT MNR 1912-01 System Yes Box
PCap01-HUM-EVA MNR 1796 System Yes Box
PCap01-HUM-DEMO MNR 1792 System Yes Box