E240 Atmel, E240 Datasheet
E240
Specifications of E240
Available stocks
Related parts for E240
E240 Summary of contents
Page 1
... E240 User Manual ™ 13 ...
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). ...
Page 3
... 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 help eliminate trapped air. Take care to flex the board only slightly to prevent the delicate SMT parts on the board from cracking and failing ...
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 ...
Page 5
... 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
... LEDs — The board has one ‘Power’ LED which remains on as long as the board is powered, plus one 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 Figure 1 — Board Layout Battery Connector Connector (CN1) Table 1 — Connector (CN1) Pinout Pin Description Pin 1 SYNC 5 2 OUT ‘D’ OUT ‘C’ 4 OUT ‘B’ Electrodes (on user side) ...
Page 8
SCHEMATIC 6 Figure 2 — Schematic Diagram 7 ...
Page 9
PCB LAYERS 8 Figure 3 — Silk Layer Figure 4 — Top Layer (user side) ...
Page 10
... 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 10 Jumpers 1, 2 and 3 set the mode to Fast (40msec response) or Slow (110msec response), Spread Spectrum, and external sync. Table 2 — Jumpers Fast, Slow, Spread Spectrum Modes Description JMP 1 Fast ...
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 ...
Page 13
... As pin 9 ramps up, the sample burst frequency increases. The effect of Spread Spectrum operation is twofold: - Peak EMC emissions are reduced 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. The 2V SPREAD sawtooth causes the oscillator to sweep about ± ...
Page 14
... Supply voltage is too low 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 ...
Page 15
Development Team: Luben Hristov, Peter Dennis, Matthew Trend Corporate Headquarters North America 1 Mitchell Point 651 Holiday Drive Bldg 300 Ensign Way, Hamble Pittsburgh, ...