qt300 Quantum Research Group, qt300 Datasheet

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qt300

Manufacturer Part Number
qt300
Description
Capacitance To Digital Converter
Manufacturer
Quantum Research Group
Datasheet

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Part Number:
qt300-ISG
Manufacturer:
ATMEL
Quantity:
3 822
LQ
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 single 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.
The device operates on demand, and can be synchronized to allow several QT300’s to operate near each other without
cross-interference.
LQ
Capacitance to Digital Converter (CDC) IC
Direct-to-digital conversion, 16 bits
Log response: Wide dynamic range
Outputs raw data to a host device
Single 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
-40
0
0
C to +70
0
C to +85
T
A
0
Copyright © 2002 QRG Ltd
C
0
C
AVAILABLE OPTIONS
C
APACITANCE TO
QT300-IS
SOIC
-
DRDY
SNS1
SCK
Vss
8-PIN DIP
QT300-D
-
D
1
2
3
4
APPLICATIONS
IGITAL
Fluid level sensors
Prox sensors
Moisture detection
Position sensing
Transducer driver
Material sensors
QT300 R1.02/0204
8
7
6
5
C
QT300
ONVERTER
Vdd
SDO
REQ / 1W
SNS2

Related parts for qt300

qt300 Summary of contents

Page 1

... 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 single wire UART type interface ...

Page 2

... UART. The SPI interface allows multiple devices to be connected on one SPI bus, while the1W UART requires that the controller have one dedicated pin for each QT300. There are two types of SPI mode, master and slave. LQ Function ...

Page 3

... When finished, the DRDY line is pulled low by the QT300 to indicate it is ready to send data. (Figure 2-1). The transfer is done as two bytes, with the highest byte transferred first. In master mode, /DRDY goes high between bytes for the period determined by Setup parameter MLS ...

Page 4

... QT300 pulls /DRDY low when ready to send data back. 4) Host detects /DRDY is low. 5) Host clocks out the high byte of data from the QT300. 6) Host waits for ≥12µs. 7) Host clocks out the low byte of data from the QT300. 8) QT300 releases /DRDY to float high. ...

Page 5

... The host device triggers the QT300 to acquire by means of a pulse sent to the QT300 over the wire. The Baud rate is established by the width of this pulse; the pulse width establishes the bit rate of the UART transmission to follow ...

Page 6

... Baud rate. The QT300 measure this pulse and uses its length to set the Baud bit (shift out) rate. 30µs (or more) of logic-low must follow this pulse. The host must then float the 1W line to allow the QT300 to start the signal acquisition. 5 Circuit Guidelines 5 ...

Page 7

... QTM300CA instruction guide. The parameters which can be altered are shown in Table 7-4. The internal eeprom has a life expectancy of 100,000 erase/write cycles and the minimum voltage for a write cycle is 2.2 Volts. A serial interface specification for the device can be obtained by contacting Quantum. 7 QT300 R1.02/0204 ...

Page 8

... Min Typ Max 2 5.5 60 1,500 0.3 Vdd 0.6 Vdd 0.4 Vdd-0.6 16 1,000 +125 Units Notes 4.7nF to 200nF µs Units Notes V µA Dependent on duty cycle V Vdd = 2.5 to 5.0V V Vdd = 2 bits fF Figs 7-4, 7-5 pF Combined for both SNS pins QT300 R1.02/0204 O C ...

Page 9

... DRDY {from QT300} SCK {from host} SDO {from QT300} DRDY {from QT300} SCK {from QT300} SDO {from QT300} Table 7-1 Slave SPI Timing Symbol Parameter T Clock Duration SKD T SCK High Duration SKH T SCK Low Duration SKL SCK High To SDO Ready T SOSH Setup Time ...

Page 10

... Idle High 0 - 255 255 148 10 Tmls 8bits LSB Tstop Notes - 210 - - - 2 - 400 Depends on Cs and 850 - 8 bits data, LSB first Calculation / Notes - Tscd = (30 + (SCD x 8))/1.2 Tmls = (10 + (MLS x 4))/1.2 Units µs µs µ µs µs µs Unit - µs µs QT300 R1.02/0204 ...

Page 11

... Cx Load, pF Figure 7-5 Typical Burst Length versus Cx & Cs; VDD= 5.0 Volts Cs 43nF 74nF 124nF 200nF Load, pF Figure 7-7 Typical resolution vs Cx & Cs; Vdd = 3.0 Volts QT300 R1.02/0204 22nF 10nF 4.7nF ...

Page 12

... Temperature, C Figure 7-8 Typical Signal Deviation vs. Temperature Vdd = 5.0 Volts 10pF 5~200nF PPS Film 0 - Temperature, °C Figure 7-9 Typical Signal Vs. Cs & Temp Vdd = 5.0 Volts 10pF, PPS film capacitors 12 200nF PPS 100nF PPS 4.7nF PPS QT300 R1.02/0204 ...

Page 13

... L2 L Inches Min Max 0.24 0.28 0.3 0.325 0.355 0.4 0.3 - 0.027 0.037 0.014 0.022 0.045 0.07 0.008 0.012 0.1 - 0.015 - 0.115 0.15 - 0.21 0.43 H φ h Inches Min Max 0.205 0.213 0.3 0.33 0.203 0.212 0.05 0.012 0.02 0.004 0.013 0.07 0.08 0.007 0.01 0.02 0.035 QT300 R1.02/0204 A x Notes Typical BSC e E Notes BSC ...

Page 14

Tel: +44 (0)23 8056 5600 Fax: +44 (0)23 8045 3939 The specifications set out in this document are subject to change without notice. All products sold and services supplied by QRG are subject to our Terms and Conditions of ...

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