Quantum QTM300CA User Manual download pdf

LQ QT300

PRELIMINARY

ROX

™

CDC S

ENSOR

 Capacitance to Digital Converter (CDC) IC

 Direct-to-digital conversion, 16 bits

 Log response: Wide dynamic range

 Outputs raw data to a host device

 1-Wire UART interface

 Master or Slave mode SPI interface

 Programmable clock speed

 Turns objects into intrinsic touch sensors

 One external sample capacitor to control gain

 Multiple QT300’s possible on one SPI bus

The QT300 charge-transfer (“QT’”) IC is a self-contained Capacitance-to-

Digital-Converter (CDC) capable of detecting femotofarad level changes in

capacitance. While designed primarily for instrumentation applications, it can be used

also for touch control applications where signal processing is best handled by a host

MCU.

Primary applications include fluid level sensors, distance sensors, transducer

‘amplifiers’ for pressure and humidity sensing functions, material detectors, and other

uses requiring quantified capacitance data.

Unlike other Quantum products, the QT300 does not process its acquired data. Its only result is raw, unprocessed binary

data which can be transmitted to a host via either a bidirectional SPI interface or a simple polled 1-wire UART type interface.

This allows the designer to treat the device as a capacitance-to-digital-converter (CDC) for measurement applications. It is

ideal for situations where there are unique signal processing requirements.

The device requires only a single sampling capacitor to function. The value of this capacitor controls the gain of the sensor,

and it can be adjusted over 2½ decades of range from 1nF to 500nF. No external switches, opamps, or other components

are required.

Power consumption varies from 60µA to 1,500µA depending on the sample rate and Vdd.

The device operates on demand, and can be synchronized to allow several QT300’s to operate near each other without

cross-interference.

SDO

Vdd

REQ / 1W

SNS2Vss

SNS1

SCK

DRDY 1

QT300

-QT300-IS-40

C to +85

QT300-D-0

C to +70

8-PIN DIPSOICT

AVAILABLE OPTIONS

APPLICATIONS

 Fluid level sensors

 Prox sensors

 Moisture detection

 Position sensing

 Transducer driver

 Material sensors

1 2 3 4 5 6 ... 11 12

Summary of Contents

Page 1 - PRELIMINARY

LQ QT300PRELIMINARYQPROX™ CDC SENSOR IC Capacitance to Digital Converter (CDC) IC Direct-to-digital conversion, 16 bits Log response: Wide dynamic

Page 2 - 2 - Timing

LQ10QT300 R1.00 12/02Figure 7-4 Typical resolution vs Cx & Cs;Vdd = 3.0 VoltsCs0100200300400500011213448Cx LoadResolution Per Count (fF)9nF19

Page 3 - 3 - SPI Port

0.4310.9x0.21-5.33-S10.150.1153.812.92S-0.015-0.38rBSC-0.1BSC-2.54F0.0120.0080.3050.203L20.070.0451.781.14L10.0220.0140.5590.356L0.0370.0270.940.69QTy

Page 4 - 3.5 SPI Master Mode

Page 5 - Interface

Positive supplyVDD8Serial data outSDO7Request input/REQ6Sense 2 lineSNS25Negative supply (ground)VSS4Sense 1 lineSNS13Serial data clockSCK2Data Ready/

Page 6 - 6 Parameter Setups Cloning

The length of this burst is an importantparameter as it is directly related to the signalvalue. The burst duration also affects theresponse time of th

Page 7 - 7 Electrical specifications

SDO - Serial Data Output; Output-only. This is the dataoutput to the host during an SPI transfer. When not in use,this pin floats. This pin should be

Page 8

back to the host. During idle times this pin floats andtherefore must be connected to a pullup resistor. The DRDY line can be used as a Slave Select l

Page 9

4.3 Trigger pulse descriptionThe part wakes from low power mode when the first negativeedge is detected on the 1W pin (Figure 4-1, bottom). Thenegativ

Page 10 - Vdd = 5.0 Volts, Cx = 10pF

7 Electrical specifications7.1 ABSOLUTE MAXIMUM SPECIFICATIONSOperating temp...

Page 11 - Package type: 8-pin Wide SOIC

LQ8QT300 R1.00 12/02Figure 7-1 SPI Slave ModeSCK {from host}SDO{from QT300} D15DRDY {from QT300}D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0T

Page 12 - North America

LQ9QT300 R1.00 12/02Figure 7-3 1W (1-Wire) UART Mode1W UARTTwuTbrTs bTacqTs t a r tTstopTmls8bits MSB 8bits LSBµs8 x Tbr-LSBµs8 bits data, LSB firs

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Quantum QTM300CA User Manual

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Summary of Contents

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