1 of 10 features ? demonstrates the capabilities of the ds2740 high-precision coulomb counting ic including: ? real-time current measurements ? high-precision current accumulation ? identification ? programmable i/o operation ? interfaces to the usb port of a pc running windows ? xp or older operating system index evaluation kit contents equipment needed introduction setup and installation board connections software installation selecting the com port program menus program tabs meters tab data log tab memory tab pack information tab evaluation kit contents 1 pc. tssop evaluation board 1 pc. ds9123 serial port adapter 1 pc. rj-11 phone cable equipment needed 1) a pc running windows xp or older operating system with an available usb port. 2) cables with mini-grabbe r style clips or the ability to solder direct ly to connection pads. 3) a lithium-ion (li+) battery or 3-cell nimh stack and a power supply and/or load circuit. ordering information part type DS2740EVKIT+ ev kit + denotes lead(pb)-free and rohs compliant. introduction the ds2740 evaluation kit (ev kit) makes perf ormance evaluation, software development, and prototyping with the ds2740 high-precision coulomb c ounting ic easy. the evaluation board interfaces to a pc running windows xp or older through a ds 9123o usb adapter and rj-11 cable connection. the ds2740 ev kit evaluation software gives the user complete control of a ll functions of the ds2740. separate control tabs allow the user access to all me mory locations, all status registers, and real-time updates of all monitored parameters. the software al so incorporates a data-l ogging feature to monitor a battery over time. the evaluation board circuit is designed to provide the ds2740 with accurate parameter measurements and protect the ds2740 from esd damage. *kit demonstration boards will vary as they are improved upon over time. for information on the demonstration board circuits visit our website at www.maxim-ic.com . pd122402* DS2740EVKIT+ tssop DS2740EVKIT high-precision coulomb counter ic evaluation kit 19-4843; rev 1; 10/09 www.maxim-ic.com windows xp is a registered trademark of microsoft corp. downloaded from: http:///
DS2740EVKIT 2 of 10 setup and installation board connections connections to the demonstration boar d are best made either by soldering directly to the pads or by using cables with mini-grabber clips. communication to th e board can be accomplished by connecting the rj- 11 jack to the ds9123o usb adapter with the 2 conductor cable provided. then the dq and pac- terminals on the rj-11 jack can be wired directly to the dq and pac- pads on the demonstration board. figure 1 shows the recommended circuit for the ds2740 ev kit boar d. the li+ cell or nimh cell stack is connected between the bat+ and bat- pads. if a li+ cell is used a protection circuit must be included between the battery and the demo board. the user system load circuit/charger is connected from bat+ to pac-. the evaluation software can be run with or wit hout a load or charger as long as a cell is connected between the bat+ and bat- terminals provid ing a minimum of 2.7v to power the ds2740. figure 1. pd122402 cell, load, and charger connections software installation to install the ds2740 ev kit soft ware, exit all programs currentl y running and download the latest ds2740 ev kit software from our website at www.maxim-ic.com. unzi p the compressed file and run setup.exe to begin the installati on process. follow the prompts to complete the installation. the ds2740 ev kit software can be uninstalled in the add/remove programs tool in the control panel . after the installation is comp lete, open the ds2740k folder and run ds2740k.exe or select ds2740k from the program menu. a splash screen containing information about the evaluation kit appears as the program is being loaded. all relevant data sheets and appl ication notes on the ds2740 and ds2740 ev kit can be found on our website at www.maxim-ic.com. selecting the com port battery + - load circuit/ charger ds2740 e v kit board b+ dq b- pio p- li-ion protection circuit dq p- rj-11 jack downloaded from: http:///
DS2740EVKIT 3 of 10 the first time the software runs, the port settings window appears. in this window, select the com port to which the ds9123o is attached and the desired communication rate, then hit ok. the ds2740 ev kit software saves this com port selection and automatically uses the selection each time the program starts. to change the com port later, click the preferences option on the menu bar, select edit preferences , and then select the appropriate port. to attempt to automati cally locate the ds9123o, click the poll ports button. warning: automatically po lling for the ds9123o can disrupt ot her devices conne cted to your computer?s com ports. program menus several pull-down menu options have been provided to simplify use of the ds2740 ev kit software for the user. their functions are in dividually detailed below. registers menu the registers menu gives immediate access to the status and special feature registers in the ds2740. selecting one of the registers will open an individua l control window giving the us er a description of each register bit and the ability to read or write it. see th e status register window ex ample in the next section. the individual control window can al so be displayed by left clicking on any label referring to any of the bits of the status or special feature registers . status register the present states of all register bits are di splayed immediately upon ope ning the register window. read/write locations contain a selection field to allow the user to determine their state. resolution menu the resolution menu allows the user to select which version of the ds2740 is being used. this selection will affect the value of the units used to calculate th e current. the software cannot detect which version of the ds2740 is being used, so if the wr ong version is selected, the current r eading will be off by a factor of 4. downloaded from: http:///
DS2740EVKIT 4 of 10 1-wire speed menu the 1-wire ? speed menu allows the user to select with which 1-wire speed the device is set. the speed is determined by the state of the pin 1 (ovd pin). if pin 1 has a value of 1, the devi ce communicates with 1- wire overdrive timing. if pin 1 has a value of 0, the device communicates with regular 1-wire timing. preferences menu the preferences menu allows the user to change com port settings at any time. edit preferences opens the select preferences window. see selecting the com port above. help menu selecting the about topic from the help menu will open a window containing information about this program and dallas semiconductor. program tabs all functions of the program are divided under four ta bs in the main program window. left click on the appropriate tab to move to the de sired function page. located under the meters tab is all information on real-time updates measured by the ds2740: current, accumulated charge, and the state of the smod, rnaop and pio bits of the status and special feature registers . the data log tab allows the user to store all real-time information to a file. the memory tab displays the contents of every register and memory location inside the ds2740 and allo ws the user to alter the data. the pack information tab gives the user the ability to choose with which device on the 1-wire bus to communicate and set the value of the sense resistor. 1-wire is a registered trademark of maxim integrated products, inc. downloaded from: http:///
DS2740EVKIT 5 of 10 meters tab the meters screen displays the latest real-time measuremen ts of current and accumulated charge with both analog meter readouts and digita l values. the sense resistor valu e used to calculate the current reading is shown in the current section. left click on it or go to the sense resist or sub-tab under pack info to change this value. the values of the smod, rn aop, and pio bits of the status and special feature registers are also displayed. the user also has the abilit y to toggle the value of these bits by left clic king on the associated button. set accumulated current register the user can bring up the set accumulated current register window by left clicking the set acr button. this window allows the user to enter values for the accumulated current register and rated battery capacity in mah. clicking the ok button will write the new acr value to the ds2740?s accumulated current register . the rated battery capacity is used to determine full-scale range on the accumulated charge meter and is only a software value; it is not stored on the device. downloaded from: http:///
DS2740EVKIT 6 of 10 data log tab real-time graphs the data log tab allows the user to see the ds2740?s para meter measurements graphed over time. there are separate sub-tabs for current and accumulat ed current. each graph disp lays the last 500 data points collected by the ds2740 ev kit software. the sa mpling interval can be adjusted using the menu located at the bottom of the window. th e interval can be set from as slow as every 15 minutes to as fast as communication and the pc will allow. the clear graphs button will clear all da ta from both graphs, but does not reset the log to file function. log data to file downloaded from: http:///
DS2740EVKIT 7 of 10 the log to file sub-tab contains control information for stori ng all log data to an ascii file. the default filename is c:\ds2740k_datalog.tx t, but can be modified in the filename text field. the log data button toggles data logging off and on. data will be stored at the same interv al selected for updating the graphs in the tab-delimited format of: ?time current acr? for easy import into a spreadsheet. the 50 most recent samples are displa yed in the window for observation. warning: the log data function overwrites previous file information. to prevent the loss of data previously stored in the file, change the filename before clicking the log data button. memory tab the memory tab gives the user access to al l 6 user registers inside th e ds2740. most values can be modified by clicking in that addr ess? text box and typing a new value in hexadecimal format. the current register and some bits in the status and special feature registers are read-only so they can not be modified by the user. the write button will write all of the data lo cations displayed to the corresponding location inside the ds2740. the read button will update the text boxes with data from the ds2740. downloaded from: http:///
DS2740EVKIT 8 of 10 pack information tab device select the device select sub-tab allows the user to choose with which device on the 1-wire bus to communicate. clicking on the find net addresses button will begin a search net address operation on the 1-wire bus. all 1-wire devices found on the bus and communicating at the selected 1- wire speed will be listed in the net addresses field. to communicate to any device on the bus, click on its address inside the net addresses field to select it. the program will now use this device for all operations (communicating using the match net address command) until a different ds2740 is chosen. sense resistor downloaded from: http:///
DS2740EVKIT 9 of 10 the sense resistor sub-tab allows the user to more accurately measure the current by entering the exact value of the sense resistor that is use d. enter the value of the resistor in m ? s in the sense resistor value field. this value will be used in software to calc ulate the current flowing th rough the sense resistor. find sense resistor the find sense resistor button opens the find sense resistor window. the user can then determine the resistance by forcing a known current and measur ing the voltage drop with the ds2740. the program uses this value to convert the voltage difference fro m the sns and vss pins into mamps. if this value does not match the value of the external resistor, current measurements will be inaccurate. if the value is 0 the program automatically defa ults to a resistor of 20m ? s. this is a software value only, it is not stored on the ds2740. ds2740 ev kit schematic downloaded from: http:///
DS2740EVKIT 10 of 10 revision history revision number revision date description pages changed 0 4/03 initial release. ? 1 10/09 changed the part number from ds2740k to DS2740EVKIT. all downloaded from: http:///
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