Features • QField™ Touchscreen: – Up to 3.4 inches diagonal screen size supported • Technology: – Patented spread-spectrum charge-transfer (transverse mode) • Panel Materials: • • • • • • • • • – Plastic, glass, composites, painted surfaces (low particle density metallic paints possible) Adjacent Metal: – Compatible with grounded metal immediately next to sensing channels Panel Thickness: – 1 to 2 mm glass, 0.5 to 1.5 mm plastic Interface: – I2C-compatible slave mode, 100 kHz or 400 kHz Moisture Tolerance: – Best in class Power: – 1.8V to 5.5V (2.5V to 5.5V in high speed mode) Packages: – 32-pin 5 x 5 mm MLF RoHS compliant Signal Processing: – Self-calibration, auto drift compensation, noise filtering Applications: – Mobile electronics, terminals, appliances Patents: – QMatrix™ (patented Charge-transfer method) – QField (patented Charge-transfer method, patent-pending QField optimized for one-layer sensor element designs) QField™ 10-bit Touchscreen Sensor IC AT42QT4120 Summary 1. Pin-out and Pin Listing Descriptions 1.1 Device Pin-out N/C Y2B N/C SDA Vss Vdd N/C SCL Vdd RST Y0A Y1A Y2A N/C CHANGE Vss 1 2 32 31 30 29 28 27 26 25 24 23 3 4 5 22 21 20 6 7 8 AT42QT4120 19 18 17 9 10 11 12 13 14 15 16 Y1B Y0B A0 Vss Vdd Vdd Vdd N/C Note: This is a summary document. A complete document is available under NDA. For more information contact www.atmel.com/touchscreen. N/C X3 X2 X1 X0 SMP VREF Vss 9506AS–AT42–10/08 1.2 Pin Listing Description Table 1-1. Pin Listing Pin Name Type Comments If Unused, connect To... 1 N/C O Not connected Leave open 2 CHANGE OD State change notification Leave open 3 Vss P Supply ground – 4 Vdd P Power – 5 Vss P Supply ground – 6 Vdd P Power – 7 N/C O Not connected Leave open 8 N/C O Not connected Leave open 9 Vss P Supply ground – 10 VREF I Supply ground – 11 SMP O Sample output – 12 X0 O X matrix drive line Leave open 13 X1 O X matrix drive line Leave open 14 X2 O X matrix drive line Leave open 15 X3 O X matrix drive line Leave open 16 N/C O Not connected Leave open 17 N/C O Not connected Leave open 18 Vdd P Power – 19 Vdd P Power – 20 Vdd P Power – 21 Vss P Supply ground – 22 A0 I I C-compatible address select – 23 Y0B I/O Y line connection Leave open 24 Y1B I/O Y line connection Leave open 25 Y2B I/O Y line connection Leave open 26 N/C O Not connected Leave open 27 SDA OD Serial Interface Data – 28 SCL OD Serial Interface Clock – 29 RST I Reset low; has internal 30k - 60k pull-up Leave open or Vdd 30 Y0A O Y line connection Leave open 31 Y1A O Y line connection Leave open 32 Y2A O Y line connection Leave open I O OD 2 2 Input only Output only, push-pull Open drain output I/O X P Input and output Clock resonator Ground or power AT42QT4120 9506AS–AT42–10/08 AT42QT4120 1.3 Wiring Diagram Figure 1-1. Wiring Diagram VDD Vunreg follow regulator manufacturer's recommended values for input and output bypass capacitors; keep output capacitor close to pins 4 and 6. If not possible, add a 100nF capacitor next to those pins. VREG N/C VDD N/C N/C N/C QT4120 2 I C-COMPATIBLE SDA N/C N/C Rx3 SCL Rx2 Rx1 VDD Rx0 Ry0 Rc CHANGE CHANGE Cs0 Ry1 Cs1 Ry2 I2C-COMPATIBLE ADDRESS SELECT MATRIX X DRIVE Rp MATRIX Y SCAN IN Rp Cs2 NOTES: Rs2 Rs1 Rs0 1) The central pad on the underside of the chip is a Vss pin and should be connected to ground. Do not put any other tracks underneath the body of the chip. 2) It is important to place all Cs, Rs, Rx and Ry components physically near to the chip. Suggested regulator manufacturers: • Torex (XC6215 series) • Seiko (S817 series) • BCDSemi (AP2121 series) 3 9506AS–AT42–10/08 2. Overview The AT42QT4120 (QT4120) QField IC is a self-contained capacitive touchscreen controller that employs Atmel’s patented transverse charge-transfer (QT™) acquisition method. The controller senses changes in electrical charge forced across two electrode elements by a pulse edge (see Figure 2-1). Figure 2-1. Field Flow Between X and Y Elements overlying panel X eleme nt Y elem ent The touchscreen is critical to the design and is specially patterned to improve linearity, limit hand shadow and keep the number of connection lines to a minimum. The device includes all signal processing functions necessary to provide stable sensing under a wide variety of changing conditions. Only a few external parts are required for operation. The entire circuit can be built within a few square centimeters of single-sided PCB area. CEM-1 and FR1 punched, single-sided materials can be used for the lowest possible cost. The PCB’s rear can be mounted flush on the back of a glass or plastic panel using a conventional adhesive, such as 3M VHB two-sided adhesive acrylic film. The device uses an I2C-compatible interface to allow channel data to be extracted and to permit touchscreen parameter setup. The command structure is designed to minimize the amount of data traffic while maximizing the amount of information conveyed. In addition to normal operating and setup functions the device can also report back actual signal strengths. 4 AT42QT4120 9506AS–AT42–10/08 AT42QT4120 3. Revision History Revision No. History Revision AS – October 2008 Initial release for chip revision 7.0 5 9506AS–AT42–10/08 Headquarters International Atmel Corporation 2325 Orchard Parkway San Jose, CA 95131 USA Tel: 1(408) 441-0311 Fax: 1(408) 487-2600 Atmel Asia Unit 01-05 & 16, 19/F BEA Tower, Millennium City 5 418 Kwun Tong Road Kwun Tong Kowloon Hong Kong Tel: (852) 2245-6100 Fax: (852) 2722-1369 Atmel Europe Le Krebs 8, Rue Jean-Pierre Timbaud BP 309 78054 Saint-Quentin-enYvelines Cedex France Tel: (33) 1-30-60-70-00 Fax: (33) 1-30-60-71-11 Atmel Japan 9F, Tonetsu Shinkawa Bldg. 1-24-8 Shinkawa Chuo-ku, Tokyo 104-0033 Japan Tel: (81) 3-3523-3551 Fax: (81) 3-3523-7581 Technical Support [email protected] Sales Contact www.atmel.com/contacts Touch Technology Division 1 Mitchell Point Ensign Way Hamble Southampton Hampshire SO31 4RF United Kingdom Tel: (44) 23-8056-5600 Fax: (44) 23-8045-3939 Product Contact Web Site www.atmel.com Literature Requests www.atmel.com/literature Disclaimer: The information in this document is provided in connection with Atmel products. No license, express or implied, by estoppel or otherwise, to any intellectual property right is granted by this document or in connection with the sale of Atmel products. EXCEPT AS SET FORTH IN ATMEL’S TERMS AND CONDITIONS OF SALE LOCATED ON ATMEL’S WEB SITE, ATMEL ASSUMES NO LIABILITY WHATSOEVER AND DISCLAIMS ANY EXPRESS, IMPLIED OR STATUTORY WARRANTY RELATING TO ITS PRODUCTS INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. IN NO EVENT SHALL ATMEL BE LIABLE FOR ANY DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE, SPECIAL OR INCIDENTAL DAMAGES (INCLUDING, WITHOUT LIMITATION, DAMAGES FOR LOSS OF PROFITS, BUSINESS INTERRUPTION, OR LOSS OF INFORMATION) ARISING OUT OF THE USE OR INABILITY TO USE THIS DOCUMENT, EVEN IF ATMEL HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. Atmel makes no representations or warranties with respect to the accuracy or completeness of the contents of this document and reserves the right to make changes to specifications and product descriptions at any time without notice. Atmel does not make any commitment to update the information contained herein. Unless specifically provided otherwise, Atmel products are not suitable for, and shall not be used in, automotive applications. Atmel’s products are not intended, authorized, or warranted for use as components in applications intended to support or sustain life. © 2008 Atmel Corporation. All rights reserved. Atmel®, Atmel logo and combinations thereof, and others are registered trademarks, Adjacent Key Suppression ™, AKS ™, QT™, QField ™, QMatrix™, QTouch ™and others are trademarks of Atmel Corporation or its subsidiaries. Other terms and product names may be registered trademarks or trademarks of others. 9506AS–AT42–10/08