+Denotes lead-free and RoHS-compliant.

Transcription

1 9-0; Rev 0; /07 MAX7 Evaluation Kit General Description The MAX7 evaluation kit (EV kit) is an assembled and tested printed-circuit board (PCB) that evaluates the MAX7 IC. The MAX7 is a -tap, 0kΩ nonvolatile, linear-taper digital potentiometer. Windows 000/XP/Vista-compatible software is available to provide a convenient user interface for exercising the MAX7 features. The MAX7 EV kit provides three options to control the MAX7 wiper position using logic-input signals. The MAX7 logic-input signals can be controlled by an on-board USB interface circuit, PCB interfacing pads, or switches on the EV kit circuit for stand-alone operation. The EV kit can operate from a.v source generated from the USB interface circuit or from a.7v to.v external DC power supply. The EV kit can also evaluate the MAX7 (00kΩ) after IC replacement (U). DESIGNATION QTY DESCRIPTION Features.7V to.v Single-Supply Operation Power-On Recall of Wiper Position from Nonvolatile Memory On-Board USB Interface Circuit USB Powered USB-PC Connection (Cable Included) Stand-Alone Operation Using On-Board Switches PCB Pads for User-Supplied Microcontroller Interface Signals PCB Pads for Potentiometer Signals (L, W, H) Proven USB-Compatible PCB Layout Evaluates the MAX7/MAX7 in 8-Pin SOT Package Windows 000/XP/Vista (-Bit)-Compatible Software Fully Assembled and Tested PART MAX7EVKIT+ +Denotes lead-free and RoHS-compliant. Ordering Information TYPE EV Kit Component List DESIGNATION QTY DESCRIPTION C, C C0, C7, C C 0.µF ±0%, V X7R ceramic capacitors (00) Murata GRM88R7C0K TDK C08X7RC0K C8, C9 pf ±%, 0V C0G ceramic capacitors (00) Murata GRM88CH0J TDK C08C0GH0J C, C, C 0µF ±0%,.V XR ceramic capacitors (080) Murata GRMBR0J0M TDK C0XR0J0M C0 00pF ±0%, 0V X7R ceramic capacitor (00) Murata GRM88R7HK TDK C08X7RHK C, C 0pF ±%, 0V C0G ceramic capacitors (00) Murata GRM88CH00J TDK C08C0GH00J D FB 0 Green LED (00) Panasonic LNJG8TRA Not installed, ferrite-bead inductor short (PC trace) (00) C, C, C7 µf ±0%, 0V XR ceramic capacitors (00) Murata GRM88RA0K TDK C08XRA0K Windows is a registered trademark of Microsoft Corp. H 0 Not installed, dual-row 0-pin ( x ) header J 0 Not installed, dual-row 0-pin ( x ) header short JU -pin header JU, JU, JU -way, -pin headers Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at , or visit Maxim s website at

2 DESIGNATION QTY DESCRIPTION JU, JU -pin headers P USB type-b right-angle male receptacle R 0Ω ±% resistor (00) R 0Ω ±% resistor (00) R 0kΩ ±% resistor (00) R.kΩ ±% resistor (00) R.kΩ ±% resistor (00) R, R7 7Ω ±% resistors (00) R8 0 Not installed, resistor (00) R9, R0 00kΩ ±% resistors (00) R kω ±% resistor (00) SW, SW Single-pole/double-throw (SPDT) slide switches SW Momentary pushbutton switch U U Maxim -tap, 0kΩ nonvolatile, linear-taper digital potentiometer MAX7EKA+T (8-pin SOT) Maxim microcontroller Maxim MAXQ000-RAX+ (8-pin QFN-EP, 0mm x 0mm) Component List (continued) DESIGNATION QTY DESCRIPTION U U U U U7, U8 U9 Y 9C type -wire EEPROM (8-pin SO), -bit architecture Atmel AT9CA-0SU-.7 UART-to-USB converter (TQFP-L, 7mm x 7mm) FTDI FTBL Maxim.V regulator MAX8EXK+T (-pin SC70) Maxim.V regulator MAX8EXK+T (-pin SC70) Maxim low-voltage logic-level translators MAX7EEKA+T (8-pin SOT) Maxim CMOS switch debouncer MAX8EUS+T (-pin SOT) MHz crystal Citizen HCM9-.000MABJ-UT Y MHz crystal Citizen HCM9-.000MABJ-UT Shunts USB high-speed A-to-B cable, ft PCB: MAX7 Evaluation Kit+ Component Suppliers MAX7 EV Kit Software Files SUPPLIER PHONE WEBSITE Murata Mfg. Co., Ltd Panasonic Corp TDK Corp Note: Indicate that you are using the MAX7 when contacting these component suppliers. FILE INSTALL.EXE MAX7.EXE USB_Driver_Help.PDF FTDXX.INF UNINST.INI DESCRIPTION Installs the EV kit files on the computer Application program USB driver installation help file USB driver file Uninstalls the EV kit software

3 Quick Start Recommended Equipment Before beginning, the following equipment is needed: Maxim MAX7 EV kit (USB cable included) User-supplied Windows 000/XP/Vista-compatible PC with a spare USB port One ohmmeter Note: In the following sections, software-related items are identified by bolding. Text in bold refers to items directly from the EV kit software. Text in bold and underlined refers to items from the Windows operating system. Procedure The EV kit is fully assembled and tested. Follow the steps below to verify board operation. Caution: Do not turn on the power supply until all connections are completed. ) Visit to download the latest version of the EV kit software, 7Rxx.ZIP. Save the EV kit software to a temporary folder and uncompress the ZIP file. ) Install the EV kit software on the computer by running the INSTALL.EXE program inside the temporary folder. The program files are copied and icons are created in the Windows Start Programs menu. ) Verify that a shunt is installed on pins - of jumper JU. This configures the MAX7 IC s to.v from the USB interface circuit. ) Verify that a shunt is installed on pins - of jumpers JU, JU, and JU. This configures the logic-input pins to receive signals from the USB interface circuit. ) Verify that no shunt is installed on jumpers JU and JU, the L PCB pad is not connected to, and the H PCB pad is not connected to the W PCB pad. ) Connect the ohmmeter across the W and L PCB pads. 7) Connect the USB cable from the PC to the MAX7 EV kit. A Building Driver Database window pops up in addition to a New Hardware Found message when installing the USB driver for the first time. If a window similar to the one described above does not appear after 0s, remove the USB cable from the board and reconnect it. Administrator privileges are required to install the USB device driver on Windows 000/XP/Vista. 8) Follow the directions of the Add New Hardware Wizard to install the USB device driver. Choose the Search for the best driver for your device option. Specify the location of the device driver to be C:\Program Files\MAX7 (default installation directory) using the Browse button. During device driver installation, Windows may show a warning message indicating that the device driver Maxim uses does not contain a digital signature. This is not an error condition and it is safe to proceed with installation. Refer to the USB_Driver_Help.PDF document for additional information. 9) Start the MAX7 EV kit software by opening its icon in the Start Programs menu. 0) The software automatically searches for the MAX7. After successful connection, the EV kit software main window appears in the upper-left corner of the window. Select the Up/Down buttons to change the wiper position, or enter the desired wiper position into the Wiper Input combo box (see Figure ). See the Detailed Description of Software section for more information on the software features. Figure. MAX7 Evaluation Kit Software Main Window

4 Detailed Description of Hardware The MAX7 EV kit demonstrates the MAX7, a - tap, 0kΩ nonvolatile, linear-taper digital potentiometer IC s features. The EV kit uses a MAX7 IC in an 8-pin SOT package on a proven two-layer PCB design. The MAX7 EV kit provides two options to power the MAX7 IC. It can operate from the.v supply generated from the USB interface circuit, or from a user-supplied.7v to.v external DC power supply. The USB interface circuit features MAX7 low-voltage logiclevel translators (U7 and U8) for.7v to.v operation. Nonvolatile Memory Programming Nonvolatile (NV) Memory in Stand- Alone Operation In stand-alone operation, the MAX7 wiper position is stored in nonvolatile memory whenever the SPDT slide switch SW (CS) is moved from EN to DIS (rising edge) and the pushbutton switch SW (INC) is not depressed (high). The wiper returns to this stored position upon power-up. Software Operation In software operation, the MAX7 wiper position is stored in nonvolatile memory when the Store button is pressed. The MAX7 wiper returns to this position upon power-up. After powering up the EV kit, before changing the wiper position from the nonvolatile memory position, press the Reset button to reinitialize the wiper to a known position (midscale). Reset does not overwrite the MAX7 nonvolatile memory; press the Factory Default button to reset the NV memory to the factory-preset position (midscale). See the Detailed Description of Software section for more information. Jumper and Switch Functions Using an External DC Power Supply The MAX7 EV kit can be powered by an external.7v to.v DC power supply. To connect the EV kit to an external power supply, disconnect the USB cable and install a shunt on pins - of jumper JU. Turn off the power supply and connect the power-supply ground terminal to the EV kit pad and the powersupply positive terminal to the VIN pad. Table lists the various options for powering the MAX7 EV kit. Table. JU Jumper Functions () SHUNT POSITION V DD PIN CONNECTED TO EV KIT POWERED FROM -*.V USB interface circuit Open No connect Do not use (EV kit will not be powered) - VIN External power supply *Default position. Interface Control Signals The MAX7 EV kit circuit features three logic-input signals to control the MAX7 wiper position. The chip-select (CS), up/down (U/D), and increment (INC) interface signals are controlled by the on-board USB interface circuit or the PCB pads, along with user-supplied external control signals, or stand-alone operation using switches on the EV kit. Jumpers JU, JU, and JU select the interface-signal-control sources for the MAX7 IC. Table lists the various options for configuring logic-input signal controls. Table. JU, JU, JU Jumper Functions (CS, U/D, INC) SHUNT POSITION INTERFACE CONTROL SIGNALS CONNECTED TO INTERFACE SIGNALS CONTROLLED BY - PCB pads User-supplied external signals (EV kit software not updated) -* USB interface circuit USB interface circuit and EV kit software - Switches Open No connect Do not use this configuration *Default position. S tand - al one op er ati on, sw i tches S W, S W, S W ( E V ki t softw ar e not up d ated ) : SW controls the CS signal SW controls the U/D signal SW controls the INC signal

5 The stand-alone-operation switches can be used to store the MAX7 wiper position into nonvolatile memory. To store the MAX7 wiper position into nonvolatile memory, set the wiper to the desired position and slide the SPDT switch SW (CS) from EN to DIS (rising edge), while pushbutton switch SW (INC) is not depressed (high). The wiper returns to this stored position upon power-up. Voltage-Divider with Ground Reference The MAX7 EV kit provides an option to configure the MAX7 as a voltage-divider referenced to ground (). To configure the EV kit as a voltage-divider referenced to ground, connect the L PCB pad to using jumper JU, connect the voltage source to the H PCB pad, and the application input signal to the W PCB pad. Jumper JU connects or disconnects the L signal from. Table lists the JU jumper options. Table. JU Jumper Functions (L Signal and ) SHUNT POSITION Not installed* Installed *Default position. L PIN CONNECTED TO L PCB pad EV KIT FUNCTIONS Potentiometer or variable resistor Variable Resistor or Potentiometer The MAX7 EV kit configures the MAX7 as a potentiometer by default. The EV kit provides an option to reconfigure the MAX7 as a variable resistor by connecting the MAX7 IC s H and W pins. To reconfigure the MAX7 as a variable resistor, install a shunt on jumper JU. Table lists the JU jumper options. Table. JU Jumper Functions (H and W pins) SHUNT POSITION H AND W PINS Voltage-divider with ground reference EV KIT FUNCTIONS Not installed* Not connected Potentiometer Installed Connected Variable resistor *Default position. Stand-Alone Operation Switches (SW, SW, SW) The MAX7 EV kit features three switches to control the MAX7 interface signals for stand-alone operation. SPDT slide switches SW and SW control the CS and U/D signals, respectively, and pushbutton switch SW controls the INC signal. The CS, U/D, and INC signals interact to control the wiper position of the MAX7. Table lists the functions of switches SW, SW, and SW for stand-alone operation. Refer to the Truth Table in the MAX7 IC data sheet for specific switch sequence. Table. Stand-Alone Operation for SW, SW, SW Switch Functions (CS, U/D, INC Signals) SWITCH SW SW SW LOGIC- INPUT PINS CS U/D INC = High-to-low transition. LOGIC-INPUT PINS FUNCTION High = U disabled Low = U enabled High = Increment up Low = Decrement down Increment if: CS = low, U/D = high, and INC = Decrement if: CS = low, U/D = low, and INC = Note: For stand-alone operation: ) To power the EV kit, connect an external power supply to V IN and and install a shunt on pins - of jumper JU (see Table ). ) To utilize the switches, install a shunt across pins - of jumpers JU, JU, and JU (see Table ). Evaluating the MAX7 The MAX7 is similar to the MAX7, but has an end-to-end resistance of 00kΩ. To evaluate the MAX7, order a free sample of the MAX7 and replace IC U. The software is compatible with the MAX7 IC.

6 Detailed Description of Software The MAX7 EV kit software graphical user interface (GUI) is a Windows program that provides a convenient means to control the MAX7, as shown in Figure. Text in bold denotes user-selectable features in the MAX7 EV kit software. A mouse or the keyboard s TAB key is used to navigate various items on the main window. The bottom left-side status bar of the main window provides the USB interface circuit communication status. The bottom right-side status bar indicates the presence or absence of the MAX7 IC and operational status. Software Startup Upon starting the program, the MAX7 EV kit software automatically detects for the USB and interface circuit connection. The MAX7 EV kit enters normal operating mode when the USB connection is detected. The software Wiper Position and Wiper Input are initialized to midscale position at startup. Software initialization sets the volatile register of the MAX7 IC to midscale. The NV memory remains unchanged. If the USB connection is not detected, the software prompts the user to retry, exit the program, or enter the demo mode. Demo Mode The MAX7 EV kit software can enter the demo mode, when the USB connection is not detected, by pressing the Cancel button in the MAX7 Evaluation Kit Interface Circuit Popup Window (Figure ). The software can also enter the demo mode at any time using the Options Demo Mode pulldown menu item in the software main window. When in demo mode, all software communication to the EV kit circuit is disabled; however, most of the software GUI is functional. Demo mode allows the user to evaluate the software without hardware connectivity. To exit demo mode, select Options Demo Mode again from the pulldown menu. Note: When reentering normal operating mode from the demo mode, the MAX7 wiper position must be reset. Reset the wiper by pressing the Reset button. See the Nonvolatile Memory section for more details. Wiper Position Moving the Wiper Position track bar will update and display the MAX7 wiper position. Pressing the Store button stores the MAX7 wiper to the nonvolatile memory. Pressing the Reset button synchronizes the software and wiper position by returning the MAX7 wiper to the midscale position. The Wiper Input combo box accepts and displays a number between and for the wiper input. The Wiper Input also features a drop-down menu that stores the last four user entries. After pressing the Store button, the Wiper Stored edit box displays the MAX7 IC s stored wiper position, and is read only. Up and Down Pressing the Up button increments the wiper one tap position, while pressing the Down button decrements the wiper one tap position. These buttons also move the Wiper Position track bar to the respective position. Nonvolatile Memory The MAX7 wiper position is stored in nonvolatile memory when the Store button is pressed. The MAX7 wiper returns to this position upon power-up. To demonstrate the nonvolatile memory feature in software operation, press the Store button to store the wiper position to the nonvolatile memory. Power cycle the EV kit by removing the shunt from jumper JU and reinstalling the shunt after s or longer (to allow discharge of bypass capacitors). Do not restart the software. Use an ohmmeter to verify the resistance between the L and W PCB pads. Perform a Reset to synchronize the software and MAX7 IC wiper position. Pressing the Reset button does not overwrite the MAX7 nonvolatile memory. Factory Default Pressing the Factory Default button resets the wiper position in the MAX7 volatile and nonvolatile memory to the factory-default position. The factory-default wiper position in the volatile and nonvolatile memory is at midscale. Figure. MAX7 Evaluation Kit Interface Circuit Popup Window

7 Keyboard Navigation Press the TAB key to select each GUI control. The selected control is indicated by a dotted outline. Using SHIFT+TAB moves the selection to the previously selected control. Buttons respond to the keyboard s SPACE bar. Some controls respond to the keyboard UP and DOWN arrow keys. Activate the program s menu bar by pressing the F0 key, and then press the letter of the desired menu item. Most menu items have one letter underlined, indicating their shortcut key. R kω SW,, VIN CS U/D INC IN U9 SW SW VCC MAX88 OUT U7_8 U7_ U8_8 C +.V JU JU R9 00kΩ JU R0 00kΩ C JU General Troubleshooting Problem: Software reports it cannot find the interface circuit. Is the interface circuit power LED lit? Is the USB cable connected? Has Windows plug-and-play detected the board? Bring up Control Panel-->System-->Device Manager and look at what device nodes are indicated for USB. If there is an unknown device node attached to the USB, delete it (this forces plug-and-play to try again). Are jumpers JU JU properly configured for USB operation? V DD CS U/D INC U MAX7 L W H 8 7 JU JU L W H Figure a. MAX7 EV Kit Schematic (Sheet of ) 7

8 C7 P VBUS SHIELD D- SHIELD D+ U_9 U_0 USB TYPE B C C U_ +.V +.V U AT9CA 8 VCC CS ORG SK 7 N.C. D D0 VL FB SHORT (PC TRACE) C THREE-STATE R.kΩ C 0μF R7 7Ω R 7Ω VCC 7 O VCC C C9 pf C8 pf MAX7E I VL O VCC 8 I VL VL U7 THREE-STATE R 0kΩ VCC 7 MAX7E I VL O VCC 8 I VL U8 O VCC C0 00pF R.kΩ Y MHz R 0Ω C +.V C C7 C8 C 0 AVCC VCC VCC VCCIO VOUT TXD TXD C U7_8 U7_ C U8_8 8 USBDM 7 USBDP RSTOUT RESET 7 XTIN 8 XTOUT EECS EESK EEDATA TEST A 9 C7 μf C μf U FTBL 9 IN 7 U RXD RXD RTS RTS CTS CTS DTR DTR DSR 0 DSR DCD 9 DCD 8 RI TXDEN TXLED RXLED PWRCTL PWREN SLEEP 0 H JTAG TCK H- H- TDO H- TMS H- H-7 TDI H-9 H- H-8 H- H-0 OUT SHDN MAX8 +.V +.V RI R 0Ω C 0μF RESET C μf C9 D +.V +.V J HEADER X RESET J- J- TDO J- J- TMS J- J- TDI J-7 J-8 TCK J-9 IN U SEG0/P. OUT SHDN MAX8 SEG9/P. SHORT J-0 +.V SEG8/P.0 SEG7/P0.7/INT C 0μF SEG/P0./INT SEG/P0./INT SEG/P0./INT0 DTR RI RTS DCD DSR U_ SEG/P0. U_ SEG/P0. IO 7 9 HFXIN SEG/P. SEG/P. SEG/P. HFXOUT 0 SEG/P. SEG/P.7 P./T0/WKOUT 8 SEG/P.0 P./T0B/WKOUT SEG7/P. P./T/OW_IN 8 SEG8/P. U P./TB/OW_OUT 9 SEG9/P. 0 MAXQ000 P./T/INT SEG0/P. P.0/TB/INT SEG/P. P.7/MISO SEG/P. P./SCLK 0 SEG/P.7 9 P./MOSI SEG/P.0 P./SS 8 SEG/P. P./TX/INT 7 SEG/P. P./RX/INT0 7 SEG7/P. KIN 8 KOUT U_9 SEG/P0. SEG0/P0.0 TCK VADJ TDI VLCD VLCD SEG8/P./INT SEG9/P./INT SEG0/P./INT SEG/P.7/INT7 SEG SEG/COM SEG/COM SEG/COM COM0 P.0/TCK/INT8 P./TDI/INT9 P./TMS P./TDO +.V VLCD RESET TMS TDO RESET TXD P7./RX0/INT RXD P7.0/TX0/INT +.V R8 OPEN C0 Y C MHz 0pF C 0pF CTS DSR Figure b. MAX7 EV Kit Schematic (Sheet of ) 8

9 Figure. MAX7 EV Kit Component Placement Guide Component Side 9

10 Figure. MAX7 EV Kit PCB Layout Component Side 0

11 Figure. MAX7 EV Kit PCB Layout Solder Side Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 0 San Gabriel Drive, Sunnyvale, CA Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. CARDENAS