EV-121 AAT4298EVAL: Six-Channel Push/Pull I/O Expander with Serial Control Introduction The AAT4298 EVAL board demonstrates the AAT4298 SmartSwitch™ with a microprocessor I/O expander application. This application shows how a microcontroller can free up five I/O ports by connecting one I/O port to the AAT4298's EN/SET pin. The AAT4298 operates from 1.8V to 5.5V, making it ideal for 2.5V, 3.3V, or 5V systems, as well as systems powered by lithium-ion/polymer batteries. The AAT4298 is controlled by an S2Cwire™ (Simple Serial Control™) interface with easy control and efficiency. Each switch features a typical turn-on and turn-off time of 280µs. The AAT4298 comes with an optional Fast Auto-Discharge feature which utilizes an internal ~2Ω resistor switch that, upon turning off, quickly discharges the output voltage. This document describes the evaluation board and its accompanying user interface; in addition, a brief “Getting Started” section is included to help the user begin operating the evaluation board. A schematic of the complete circuit and the actual board layout are also included in the documentation. For additional information, please consult the AAT4298 product datasheet. Schematic DC+ R13 R12 1K 1K 02 4 1 3 5 02 4 1 3 5 02 4 1 3 5 02 4 1 3 5 02 4 1 3 5 R8 330 C8 1µF R11 R10 R9 1K 1K 1K U2 1 2 3 4 SW5 SW4 VDD GP5 GP4 GP3 VSS GP0 GP1 GP2 8 7 6 5 LED1 RED R7 100K PIC12F675 SW3 SW2 SW1 3 2 1 J2 U1 1 N/C 2 GND 3 OUT5 4 OUT4 5 OUT3 6 N/C DC- N/C EN/SET OUT1 OUT2 VIN OUT6 DC+ 12 11 10 9 8 7 3 C7 1µF AAT4298 TP R6 330 D6 TP R5 330 C6 0.1µF D5 TP R4 330 C5 0.1µF D4 TP R3 330 C4 0.1µF D3 TP R2 330 C3 0.1µF 2 1 JP1 D2 J1 TP R1 330 C2 0.1µF D1 C1 0.1µF Figure 1: Evaluation Board Schematic. EV-121.2005.10.1.0 1 EV-121 AAT4298EVAL: Six-Channel Push/Pull I/O Expander with Serial Control Getting Started An external power supply is needed to connect the positive terminal to the DC+ and the negative terminal to the DC-. The power supply voltage level can be set anywhere between 1.8V and 5.5V. After applying power to the board, ensure the jumper J1 is in the ON position. The red LED1 should illuminate, indicating that power has been connected to the board. There is an additional jumper labeled J2, which provides access to EN/SET. Ensure that it is in the left position for normal operation. There are five buttons on the board, labeled SW1 to SW5. After a button or combination of buttons is triggered, the corresponding LED for OUT1 to OUT6 will toggle ON or OFF, indicating that the selected state has been submitted through the EN/SET line from the microcontroller to the AAT4298. The detailed operations are described in Table 1. Holding the SW5 button for 1.5 seconds will activate the state into auto-cycling through the settings detailed in the "AAT4298 Output Settings" table in the product datasheet. The microcontroller will submit a burst of edges, pause, and submit another burst of edges and so on. It will start by submitting 64 edges, and then decrement by one edge per cycle until the final cycle, which will submit 1 edge. All LEDs should blink five times before the sequence of auto-cycling. By pushing and releasing the SW5 button once, all states are reset and all LEDs should turn off. The AAT4298 outputs can be probed via the test points near the output capacitors (C1 to C6). User Interface Functionality Button(s) Pushed1 Description SW1 [Push/Release once] Toggles output channel 1 on/off. SW2 [Push/Release once] Toggles output channel 2 on/off. SW3 [Push/Release once] Toggles output channel 3 on/off. SW4 [Push/Release once] Toggles output channel 4 on/off. SW1 + SW2 [Push/Release together] Toggles output channel 5 on/off. SW3 + SW4 [Push/Release together] Toggles output channel 6 on/off. [Push/Release once] Reset; all outputs turn off. SW5 [Hold for ~1.5 seconds] Auto-cycling; all outputs blink (on/off) five times and device begins binary increment mode. Table 1: User Interface Functionality. 1. The '+' sign indicates that these buttons are all pressed and released together. 2 EV-121.2005.10.1.0 EV-121 AAT4298EVAL: Six-Channel Push/Pull I/O Expander with Serial Control Printed Circuit Board Figure 2: AAT4298 Evaluation Board Top Layer (not to scale). Figure 3: AAT4298 Evaluation Board Bottom Layer (not to scale). EV-121.2005.10.1.0 3 EV-121 AAT4298EVAL: Six-Channel Push/Pull I/O Expander with Serial Control AAT4298 EVAL Component Listing Component Part Number U1 AAT4298ITP U2 PIC12F675 SW1 - SW5 R1 - R6, R8 R7 R9 - R13 JP1 C1 - C6 (optional) C7 C8 J1, J2 LED1 OUT1 - OUT6 Description PTS645TL50 Chip Resistor Chip Resistor Chip Resistor Chip Resistor GRM188R71C104KA01D GRM188R61A105KA61B GRM21BR71C105KA01B PRPN401PAEN CMD15-21SRC/TR8 CMD15-21UGC/TR8 Six-Channel Push/Pull I/O Expander; TSOPJW-12 Package 8-Bit CMOS, FLASH-based µC; 8-Pin PDIP Package Switch Tact, SPST, 5mm 330Ω, 5%, 1/4W; 0603 100KΩ, 5%, 1/4W; 0603 1KΩ, 5%, 1/4W; 0603 0Ω, 5%; 0805 0.1µF, 16V, 10%; 0603 1µF, 10V, X5R, 10%; 0603 1µF, 16V, X7R, 10%; 0805 Connecting Header, 2mm Zip Red LED; 1206 Green LED; 1206 Manufacturer AnalogicTech Microchip ITT Industries Vishay Vishay Vishay Vishay MuRata MuRata MuRata Sullins Electronics Chicago Miniature Lamp Chicago Miniature Lamp Table 2: Component Listing. 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Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. Advanced Analogic Technologies, Inc. 830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737-4600 Fax (408) 737-4611 4 EV-121.2005.10.1.0