Related Manuals for Quantum E240
Summary of Contents for Quantum E240
- Page 1 E240 User Manual T h e N e w V i s i o n o f T o u c h ™ Downloaded from Elcodis.com electronic components distributor...
- Page 2 User Manual OVERVIEW The E240 is designed to let you evaluate and develop with the QT240 4 key QTouch™ IC. It includes four independent touch sensitive electrodes with corresponding LEDs to indicate touch. Connections are provided for external interfacing. The E240 is powered from an external 7V to 12V DC source (such as a common 9V battery).
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Page 3: Board Mounting
Place the plastic panel face down on a table; tape down the edges of the panel to the table so it cannot move. Remove the peel-back paper from the E240 PCB and adhere the E240 to the back of the panel. Flex the E240 slightly while pressing down lightly on it to help eliminate trapped air. - Page 4 Connect the 9V battery while making sure your fingers are clear of the touch areas to allow proper no-signal calibration. The E240 is now ready to use! Touch the keys to see the LEDs light up. A continuous touch of 10 seconds will cause the key to recalibrate. Releasing the key after such an event and waiting a few seconds will cause the key to recalibrate yet again, and the key will function normally thereafter.
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Page 5: Theory Of Operation
THEORY OF OPERATION The E240 scans the keys using bursts of charge-transfer pulses. Immediately after power up, the signals from these bursts are used to calibrate the baseline reference values of the keys. This makes the device highly adaptive to mechanical differences (i.e. varying panel thicknesses). The QT240 chip also performs drift compensation on a continuous basis, so that the signals are constantly being adjusted at a slow rate to accommodate drift. -
Page 6: Board Details
LED per key to indicate touch. Connector CN1 — The main interface connector is located at one end of the E240 board. The pinout of this connector is shown in Table 1 (next page). The pin functions are as follows: [1] SYNC —... -
Page 7: Board Layout
BOARD LAYOUT Figure 1 — Board Layout Battery Connector Electrodes (on user side) Connector (CN1) Table 1 — Connector (CN1) Pinout Description Description SYNC OUT ‘A’ OUT ‘D’ /RESET OUT ‘C’ GND (Ground, 0V) OUT ‘B’ +POWER (+7 .. +12V) Downloaded from Elcodis.com electronic components distributor... - Page 8 SCHEMATIC Figure 2 — Schematic Diagram Downloaded from Elcodis.com electronic components distributor...
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Page 9: Pcb Layers
PCB LAYERS Figure 3 — Silk Layer Figure 4 — Top Layer (user side) Downloaded from Elcodis.com electronic components distributor... -
Page 10: Board Options
Figure 5 — Jumper Positions Showing Default Configuration The E240 as shipped is factory configured to operate in fast mode with spread spectrum enabled, and with a 10-second recalibration delay. The user can re-configure the jumpers to change these settings using zero-ohm 0603 SMD resistors or bits of fine wire. -
Page 11: Option Jumpers
OPTION JUMPERS Jumpers 1, 2 and 3 set the mode to Fast (40msec response) or Slow (110msec response), Spread Spectrum, and external sync. Table 2 — Jumpers 1, 2, 3: Fast, Slow, Spread Spectrum Modes Factory Description JMP 1 JMP 2 JMP 3 Default Fast Mode &... - Page 12 SENSITIVITY The sensitivity of the keys has been tailored to match the supplied plastic panel. To make a key more sensitive, increase the value of its corresponding Cs capacitor (see chart below). To make it less sensitive, decrease it’s Cs value. Only use 5% or 10% X7R ceramic capacitors; most other types will be unstable and give erratic results.
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Page 13: Spread Spectrum
Spectrum operation is twofold: - Peak EMC emissions are reduced by up to 10dB, and, - The E240’s susceptibility to external interference is reduced by a similar amount. These benefits are highly significant in all applications. The burst and spread modulation waveforms are as shown: The burst frequency centers at ~100KHz. - Page 14 Cables or board too close to a strong noise source (ie, a power line or switcher) Increase the distance from the noise source Place a grounded shield between the noise source and the E240 E240 is not mechanically stable Prevent board from moving around Downloaded from Elcodis.com...
- Page 15 Development Team: Luben Hristov, Peter Dennis, Matthew Trend w w w . q p r o x . c o m Corporate Headquarters North America 1 Mitchell Point 651 Holiday Drive Bldg. 5 / 300 Ensign Way, Hamble Pittsburgh, PA 15220 Southampton SO31 4RF United Kingdom 412-391-7367...