UNITRODE bq2007 handbook
Contents
1. Audio output Audio alarm output Timer mode select TM is a three level input that controls the set tings for charge control functions See Table 5 Voltage termination select This input switches the voltage detect sensitivity See Table 5 Fast charge rate select The FAST input switches between Fast and Standard charge rates See Table 4 Discharge command The DCMD input controls the discharge before charge function A negative going pulse initiates a discharge action If DCMD is connected to Vss automatic discharge before charge is enabled See Figure 3 Temperature cut off threshold input Minimum allowable battery temperature sensor voltage If the potential between TS and SNS is less than the voltage at the TCO input then any fast charging or top off charging is terminated Sense resistor input SNS controls the switching of MOD output based on an external sense resistor This provides the lower reference potential for the BAT pin and the TS pin Battery voltage input Battery voltage sense input referenced to SNS for the battery pack being charged This resis tor divider network is connected between the positive and the negative terminals of the battery See Figure 1 bq2007 TS Temperature sense input Input referenced to SNS for battery tem perature monitoring negative temperature coefficient NTC thermistor DIS Discharge control DIS is a push pull output that controls an external transistor2. input selects the bargraph or BCD digit dis play mode See Table 3 MSEL Display driver mode select Soft programmed input selects LED or LCD driver configuration at initialization When MSEL is pulled up to Vcc outputs SEGA G are LED interface levels when MSEL is pulled down to Vss outputs SEGA G are LCD levels DSEL DSEL Display mode select 1 2 Soft programmed inputs control the LED1 2 charger status display modes at initialization See Table 2 MULT Fixed cell pack select Soft programmed input is pulled up to Vcc when charging multi cell packs and is pulled down to Vss for charging packs with a fixed number of cells QDSEL _ State of charge display select The QDSEL input controls the SEGA G state of charge display modes See Table 3 LED LED2 Charger status outputs 1 2 Charger status output drivers for direct drive of LED displays Display modes are selected by the DSEL input See Table 2 INH Charge inhibit input When low the bq2007 suspends all charge ac tions drives all outputs to high impedance and assumes a low power operational state When transitioning from low to high a charge cycle is initiated See page 10 for details COM ALARM TM VSEL FAST DCMD TCO SNS BAT Common LCD LED output Common output for LCD LED display SEGa c Output is high impedance during initialization to allow reading of soft programmed inputs DSELi DSEL MSEL MULT and QDSEL
3. 0 Vcc V Veat Vsns Vremp _ Voltage potential on TS 0 Voc V Vrs Vsns Logic input high 2 0 V DCMD FAST VSEL INH Tri level input high Vcc 0 3 V TM Logic input low 0 8 V DCMD FAST VSEL INH h Tri level input low 0 3 V TM Von Logic output high Vcc 0 8 V T el are F VoL Logic output low a 0 8 Vv o cr g Voucom COM output Vcc 0 8 V_ Ioucom 40mA loucom COM source 40 mA Voucom Vcc 0 8V Icc Supply current 1 2 5 mA No output load Tou DIS LED1 2 SEGA G source 10 mA Vou Vcc 0 8V Ion MOD 5 mA Vou Vcc 0 8V Ton DIS LED1 2 SEGA G sink 10 mA Vor Vss 0 8V ToL MOD 5 mA Vor Vss 0 8V liz A 2 0 gt 20 uA TM A Input leakage 1 uA INH VSEL V Vss to Voc Input leakage 50 400 uA DCMD FAST V Vss to Vcc IL Logic input low current 70 uA TM V Vss to Vss 0 3V hH Logic input high current 70 uA TM V Vcc 0 3V to Voc 12 bq2007 Impedance Symbol Parameter Minimum Typical Maximum Unit Notes DC input impedance pins Ri TS BAT SNS TCO 50 i me SiR eed eee ei MSEL DSELi DSEL2 MULT RPROG ve PrOeY P P 150 200 KQ QDSEL resistor value 10 tol resistor erance Ri Float state external y 5 3 Mo TM resistor Timing Ta 0 to 70 C Vcc 10 Symbol Parameter Minimum Typical Maximum Unit Notes Deviation of fast
4. V40 and V20 correspond to a battery charge state indication of 90 70 50 and 30 respectively In bargraph format the same discharge thresholds correspond to a battery charge state indication of 90 60 40 and 30 respectively Differences in the battery charge state indications are due to the finer granularity of the BCD versus the bargraph format During discharge and when MULT is pulled up to Vcc the state of charge monitor BCD format displays the discharge condition letter d whereas the bargraph for mat has no indication The charge status display is blanked during the charge pending state and when the battery pack is removed Charge Status Display Modes The bq2007 charge status monitor can be displayed in two modes summarized in Table 3 The display modes are a seven segment monotonic bargraph or a seven segment BCD single digit format When QDSEL is pulled down to Vss pins SEGA G drive the decoded seven segments of a single BCD digit display and when QDSEL is pulled up to Vcc pins SEGa c drive the seven seg ments of a bargraph display In the bargraph display mode outputs SEGa_c allow op tions for a three segment to seven segment bargraph dis play The three segment charge status display uses out puts SEGp SEGp and SEGr for 30 60 and 90 charge indications respectively The four segment charge status display uses outputs SEGA SEGc SEGp and SEGgE for 20 40 60 and 80 indications resp
5. by the divider ra tio equation R1 N yet R2 2 Note The resistor divider network impedance should be above 200KQ to protect the bq2007 When battery temperature is monitored for maximum and minimum allowable limits the bq2007 requires that the thermistor used for temperature measurement have a negative temperature coefficient See Figure 2 Temperature and Voltage Prequalifications For charging to be initiated the battery temperature must fall within predetermined acceptable limits The voltage on the TS pin Vrs is compared to an internal low temperature fault threshold Vurr of 0 5 Vcc and the high temperature cutoff voltage Vrco on the TCO pin For charg ing to be initiated Vrs must be less than Virr and greater than Vrco Since Vrs decreases as temperature increases the TCO threshold should be selected to be lower than 0 5 Voc for proper operation If the battery temperature is outside these limits the bq2007 holds the charge pending state with a pulse trickle current until the temperature is within limits Temperature prequalification and termination is disabled if Vrs is greater than 0 8 Vcc See Figure 2 The bq2007 provides undervoltage battery protection by trickle current conditioning of a battery that is below the low voltage threshold Vepv The battery voltage VcELL is compared to the low voltage threshold Vepv and charge will be inhibited if VcELL lt Vepv The condi tion trickle current a
6. i 1 Inches Millimeters E gt Dimension Min Max Min Max E E 4 B e E A 0 095 0 105 2 41 2 67 E ET E Y a Al 0 004 0 012 0 10 0 30 a B 0 013 0 020 0 33 0 51 E El Co C 0 008 0 013 0 20 0 33 A 1 D 0 600 0 615 15 24 15 62 E E 0 290 0 305 7 37 7 75 a e 0 045 0 055 1 14 1 40 H 0 395 0 415 10 03 10 54 A z L 0 020 0 040 0 51 1 02 y 4 Q 004 LT So 77 14 Data Sheet Revision History bq2007 Change No Page No Description Nature of Change Was Vsnsut 0 01 Voc 1 11 VsnsLo Rating is 0 04 Vee Note Change 1 Sept 1996 B changes from Dec 1995 Ordering Information bq2007 Fast Charge IC bq2007 _ L Temperature Package Option S 24 pin SOIC Device Contact factory for availability 15 blank Commercial 20 to 70 C N Industrial 40 to 85 C PN 24 pin narrow plastic DIP IMPORTANT NOTICE Texas Instruments and its subsidiaries Tl reserve the right to make changes to their products or to discontinue any product or service without notice and advise customers to obtain the latest version of relevant information to verify before placing orders that information being relied on is current and complete All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement including those pertaining to w
7. to discharge the battery before charging Vss Ground Vcc Vcc supply input MOD Current switching control output Push pull output that controls the charging current to the battery MOD switches high to enable current flow and low to inhibit current flow Functional Description Figure 1 illustrates charge control and display status during a bq2007 charge cycle Table 1 summarizes the bq2007 operational features The charge action states and control outputs are given for possible input conditions Charge Action Control The bg2007 charge action is controlled by input pins DCMD VSEL FAST and TM When charge action is initiated the bq2007 enters the charge pending state checks for acceptable battery voltage and temperature and performs any required discharge before charge operations DCMD controls the discharge before charge function and VSEL FAST and TM select the charger configuration See Tables 4 and 5 During charging the bq2007 continuously tests for charge termination conditions negative delta voltage peak voltage detection maximum time out battery over voltage and high temperature cutoff When the charge state is terminated a trickle charge continues to compensate for self discharge and maintain the fully charged condition Charge Status Indication Table 2 summarizes the bq2007 charge status display indications The charge status indicators include the DIS output which can be used to indicate the discharg
8. O0 O BQ2007 0 0 mae UNITRODE Features Fast charging and conditioning of NiCd and NiMH batteries Precise charging independent of battery pack number of cells Discharge before charge on demand Pulse trickle charge conditioning Battery undervoltage and overvoltage protection gt Built in 10 step voltage based charge status monitoring Charge status display options include seven segment monotonic bargraph and fully decoded BCD digit Display interface options for direct drive of LCD or LED segments Charger state status indicators for pending discharge charge completion and fault Audible alarm for charge completion and fault conditions gt Charge control flexibility Fast or Standard speed charging Top off mode for NiMH Charge rates from to 2C 30 minutes to 8 hours gt Charge termination by Negative delta voltage AV Peak voltage detect PVD Maximum voltage Maximum time Maximum temperature gt High efficiency switch mode de sign Ideal for small heat sensitive enclosures gt 24 pin 300 mil SOIC or DIP bq2007 Fast Charge IC General Description The bq2007 is a highly integrated monolithic CMOS IC designed to pro vide intelligent battery charging and charge status monitoring for stand alone charge systems The bq2007 provides a wide variety of charge status display formats The bq2007 internal charge status moni tor suppor
9. SEL2 display select 2 SEGp Display output segment D DSEL display select 1 bq2007 The acceptable battery temperature range is set by an internal low temperature threshold and an external high temperature cutoff threshold The absolute tem perature is monitored as a voltage on the TS pin with the external thermistor network shown in Figure 2 The bq2007 provides for undervoltage battery protection from high current charging if the battery voltage is less than the normal end of discharge value In the case of a deeply discharged battery the bq2007 enters the charge pending state and attempts trickle current condi tioning of the battery until the voltage increases Should the battery voltage fail to increase above the discharge value during the undervoltage time out period a fault condition is indicated Discharge before charge may be selected to automatically discharge the battery pack on battery insertion or with a push button switch Discharge before charge on demand provides conditioning services that are useful to correct or prevent the NiCd voltage depression or memory effect and also provide a zero capacity reference for accurate capacity monitoring After prequalification and any required discharge before charge operations charge action begins until one of the full charge termination conditions is detected The bq2007 terminates charging by any of the following methods m Negative delta voltage AV m Peak volt
10. age detect PVD a Maximum absolute temperature a Maximum battery voltage a Maximum charge time out The bq2007 may be programmed for negative delta voltage AV or peak voltage detect PVD charge termination algorithms The VSEL input pin selects AV or PVD termination to match the charge rate and battery characteristics To provide maximum safety for battery and system charging terminates based on maximum temperature cutoff TCO maximum cutoff voltage MCV and maximum time out MTO The TCO threshold is the maximum battery temperature limit for charging TCO terminates charge action when the temperature sense input voltage on the TS pin drops below the TCO pin voltage threshold MCV provides battery overvoltage protection by detecting when the battery cell voltage VcELL Vear Vsns exceeds the VMCV value and ter minates fast charge standard charge or top off charge The maximum time out MTO termination occurs when the charger safety timer has completed during the active charge state The bq2007 indicates charge state status with an audio alarm output option and two dedicated output pins with pro grammable display options The DSEL1 2 inputs can select one of the three display modes for the LED1 2 outputs Charger status is indicated for m Charge pending m Charge in progress m Charge complete a Fault condition Pin Descriptions SEGa c Display output segments A G State of charge monitoring outputs QDSEL
11. arranty patent infringement and limitation of liability Tl warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with Tl s standard warranty Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty Specific testing of all parameters of each device is not necessarily performed except those mandated by government requirements CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH PERSONAL INJURY OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE CRITICAL APPLICATIONS TI SEMICONDUCTOR PRODUCTS ARE NOT DESIGNED AUTHORIZED OR WARRANTED TO BE SUITABLE FOR USE IN LIFE SUPPORT DEVICES OR SYSTEMS OR OTHER CRITICAL APPLICATIONS INCLUSION OF TI PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE FULLY AT THE CUSTOMER S RISK In order to minimize risks associated with the customer s applications adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards Tl assumes no liability for applications assistance or customer product design TI does not warrant or represent that any license either express or implied is granted under any patent right copyright mask work right or other intellectual property right of TI covering or relating to any combination machine or process in which such semiconductor products or services might be or are
12. battery voltage directly indicates 20 charge increments while the 10 charge increments use a timer that is a function of the charge safety timer When MULT is pulled down to Vss and when VBAT exceeds Vao during charging the 20 charge indication is activated and the timer begins counting for a period equal to to of the charge safety time out period When the timer count is completed the 30 charge indication is activated Should Var exceed V40 prior to the timer count completion the charge status monitor activates the 30 and 40 indications This technique Table 1 bq2007 Operational Summary Charge Action State Conditions MOD Output DIS Output Battery absent Vcc applied and VceLL Vucv Trickle charge per Table 4 Low ee Vcc applied or VcELL drops Charge initiation from Vinewto lt Viney Low Discharge before DCMD high to low transition or to Vss on charge AE Low High charge initiation and Vepv lt VcELL lt Vucv A Charge initiation occurred and Vremp gt VLTF or y Charge pending View lt Veco or Venid Ven Trickle charge per Table 4 Low s Low if Vsns gt 250mV Fast charging Charge pending complete and FAST Vcc high if Vans lt 200mV Low 3 Low if Vsns gt 250mV Standard charging Charge pending complete and FAST Vss high if Vans lt 200mV Low AV termination or Vremp lt Vtco or PVD 0 to Charge complete 3mV cell or maximum time out or VcELL gt Vucv
13. charge At Voc 10 Ta 0 to 60 C drev safety time out eS A ue see Table 3 MOD output regulation Typical regulation range tREG frequency j 7 300 kHz Vcc 5 0V F Ratio of fast charge time out tPEND Charge pending time out 25 ses Table 4 Fcom Common LED backplane tre 73 Hz LCD segment frame rate quency FaLarm Alarm frequency output 3500 kHz High tone Pulse width for DCMD and onas tpw INH pulse command 1 us Signal valid time If VcELL gt Vacv for tucv during Valid period for VcELL gt charge or top off then a transition tmcv 0 5 1 sec Vucv is recognized as a battery replacement Note Typical is at Ta 25 C Vcc 5 0V 13 bq2007 24 Pin DIP Narrow PN Pop 24 Pin PN 0 300 DIP 3 E Inches Millimeters s P D Dimension Min Max Min Max gq P A 0 160 0 180 4 06 4 57 T pR Al 0 015 0 040 0 38 1 02 1 B 0 015 0 022 0 38 0 56 Bl 0 045 0 055 1 14 1 40 mE C 0 008 0 013 0 20 0 33 E L At A a B1 D 1 240 1 280 31 50 32 51 1 E A aa M a E 0 300 0 325 7 62 8 26 nA rm El 0 250 0 300 6 35 7 62 Les o s B ne _ aG 0 300 0 370 7 62 9 40 0 090 0 110 2 29 2 79 0 115 0 150 2 92 3 81 0 070 0 090 1 78 2 29 Nit OQi o S 24 Pin S 0 300 SOIC 24 Pin S 0 300 SOIC 1 co Tiar un L l
14. charge status i e charging and completion DSEL pulled up to Vcc and DSELa pulled down to Vss mode is for implementation of a single tri color LED such that discharge charging and completion each have a unique color DSELi pulled down to Vss and DSELa2 pulled up to Vcc allows for fault status information to be displayed Audio Output Alarm The bq2007 audio alarm output generates an audio tone to indicate a charge completion or fault condition The audio alarm output is a symmetrical duty cycle AC sig nal that is compatible with standard piezoelectric alarm elements A valid battery insertion is indicated by a sin gle high tone beep of second typical duration The charge completion and fault conditions are indicated by a 9 5 to 15 second high tone sequence of 44 second typi cal duration at a 2 second typical repetition rate bq2007 Charge Status Monitoring The bq2007 charge status monitor may display the bat tery voltage or charge safety timer as a percentage of the full charged condition These options are selected with the MULT soft programmed input pin When MULT is pulled down to Vss the battery charge status is displayed as a percentage of the battery voltage and the single cell battery voltage at the BAT pin is compared with internal charge voltage reference thresholds When Vear is greater than the internal thresholds of V20 V40 Veo or Vso the respective 20 40 60 or 80 display outputs are activated The
15. d the SNS pin is connected to Vss bq2007 Absolute Maximum Ratings Symbol Parameter Minimum Maximum Unit Notes Vcc Vcc relative to Vss 0 3 7 0 V DC voltage applied on any pin ex Vr cluding Vcc relative to Vss 0 3 7 0 V TOPR Operating ambient temperature 20 70 C Commercial TsTG Storage temperature 40 85 C TsoLDER Soldering temperature 260 26 Note Permanent device damage may occur if Absolute Maximum Ratings are exceeded Functional opera tion should be limited to the Recommended DC Operating Conditions detailed in this data sheet Expo sure to conditions beyond the operational limits for extended periods of time may affect device reliability DC Thresholds TA TOPR Vcc 5V 10 Symbol Parameter Rating Tolerance Unit Notes High threshold at SNS re i VsNSHI sulting in MOD Low 0 05 Veo ea mV Low threshold at SNS result VsNSLO ing in MOD High 0 04 Voc 10 mV Viir TS pin low temperature 0 5 Vcc 30 mV SNS 0V threshold TS pin high temperature e VuTF threshold Virco 30 mV SNS 0V End of discharge voltage 262 x V Pe z MULT is pulled up to Voc oba ENOC TaN MV PNS EOV Veny End of discharge voltage MULT is pulled down to Vss 0 4 Voo o ay SNS oe BAT pin maximum cell mm PY E Vucv voltage threshold Oe Veg 290 mV SNS 0V 20 state of charge voltage im a Fast or standard cha
16. e state the audio ALARM output which indicates charge completion and fault conditions and the dedicated status outputs LED and LED 1 Charge Dis Fast Charging Top Off 1 Pulse Trickle Pending charge Optional Pulse Trickle Optional DIS l l H 260us k Note Switching MOD Configuration A M 2080us gt gt 260us le 260 Note or External EROH MOD Regulation 2080us gt l le 260us Mode 1 LED gt Status Output A Mode 1 LED Status Output 2 Ln Mode 2 LED2 Status Output So Ll Mode 2 LED Status Output n es Mode 3 LED gt Status Output ees Mode 3 LEDy Status Output W W l l i i Battery discharged to Vgpy or battery within l l temperature voltage limits Discharge before charge not qualified by temperature e Low voltage fault Battery voltage less than VEpy for under voltage time out I l Charge initiated Battery outside temperature voltage limits Note See Table 4 for pulse trickle period TD200701 eps Figure 1 Example Charging Action Events Outputs LED 2 have three display modes that are selected at initialization by the input pins DSEL 1 and DSEL2 The DSEL 1 and DSELa input pins when pulled down to Vss are intended for implementation of a simple two LED system LED2 indicates the precharge status i e charge pending and discharge and LED indi cates the
17. e battery voltage divider range is between 0 4 Vcc Vepv and 0 8 Vcc Table 3 bq2007 Charge Status Display Summary 20 charge n m o o Mode Display Indication SEGA SEGsg SEGc SEGp SEGe SEGF 30 charge 40 charge QDSEL H 60 charge 80 charge 90 charge Charge complete 0 charge digit 0 10 charge digit 1 20 charge digit 2 30 charge digit 3 40 charge digit 4 50 charge digit 5 QDSEL L 60 charge digit 6 70 charge digit 7 80 charge digit 8 90 charge digit 9 Charge complete letter F Fault condition letter E oe O A Aja la aja aja Discharge letter d RIO O p Rr A O lO Ri aa IR aa aja a aja O Rh O O p Ra aja Ra Je jr O Ra aja a an o o Ria Opa a O ja Rh lO a RO a Raja a ah o o o Ria ajo a O p n O OoJo RlOo a Ra ja ojo ojo CR Ria fe Je ia Ra ia Ojo JO Rara a ojo lolo Bee Je le RO a Ra ja a RO Oo rRrjo lojo o lojo Note 1 on 0 off L pulled down to Vss H pulled up to Vcc bq2007 Vcc BAT bq2007 BAT Voltage Connection Voc TS bq2007 Thermistor Connection NTC negative temperature coefficient thermistor FG200701 eps Figure 2 Voltage and Temperature Limit Measurement Vucv The bq2007 charges fixed cell battery packs of N cells The battery voltage divider is set
18. ectively The seven segment charge status monitor uses all segments The BCD display mode drives pins SEGA G with the decoded seven segment single digit information The display indicates in 10 increments from a BCD zero count at charge initiation to a BCD nine count indicat ing 90 charge capacity Charge completion is indicated by the letter F a fault condition by the letter E and the discharge condition by the letter d See Table 3 Table 2 bq2007 Charge Status Display Summary Mode Charge Action State LED LED2 DIS ALARM Battery absent 0 0 0 0 Charge pending temp limit low voltage 0 Flashing 0 0 Da i Discharge in progress 0 1 1 0 Mode 1 Charging Flashing 0 0 0 Charge complete 1 0 0 High tone Fault low voltage time out 0 0 0 High tone Battery absent 0 0 0 0 DSEL H Discharge in progress pending 1 1 1 0 DSEL2 L Charging 1 0 0 0 Mode 2 Charge complete 0 1 0 High tone Fault low voltage time out 0 0 0 High tone Battery absent 0 0 0 0 Charge pending temp limit low voltage 0 Flashing 0 0 a i Discharge in progress 0 Flashing 1 0 Mode 3 Charging Flashing 0 0 0 Charge complete 1 0 0 High tone Fault low voltage time out 0 1 0 High tone Note 1 on 0 off L pulled down to Vss H pulled up to Vcc Display Driver Modes The bq2007 is designed to interface with LCD or LED type displays The LED signal lev
19. els are driven when the MSEL soft programmed input is pulled to Vcc at ini tialization The output pin COM is the common anode connection for LED SEGA c The LCD interface mode is enabled when the MSEL soft programmed input pin is pulled to Vss at initializa tion An internal oscillator generates all the timing sig nals required for the LCD interface The output pin COM is the common connection for static direct driving of the LCD display backplane and is driven with an AC signal at the frame period When enabled each of the SEGa c pins is driven with the correct phase AC signal to activate the LCD segment In bargraph or BCD mode output pins SEGa c interface to LED or LCD segments bq2007 Battery Voltage and Temperature Measurement The battery voltage and temperature are monitored within set minimum and maximum limits When MULT is pulled up to Vcc battery voltage is sensed at the BAT pin by a resistive voltage divider that divides the terminal voltage between 0 262 Vcc Vepv and 0 8 Vcc Vucv The bq2007 charges multi cell battery packs from a mini mum of N cells to a maximum of 1 5 N cells The battery voltage divider is set to the minimum cell battery pack N by the BAT pin voltage divider ratio equation R qN ja R2 1 33 When MULT is pulled down to Vss tighter charge voltage limits and voltage based charge status display are selected This is recommended for charging packs with a fixed number of cells where th
20. i 3 VSEL Vcc charge complete and Vremp gt VLTF Top off pending e Vrcoor Ven Neo Trickle charge per Table 4 Low VSEL Vcc and charge complete and Acti ctivated per Vong for Top off charging time out not exceeded and Vremp gt Vico and 73ms of every 585ms low VcELL lt Vucv Trickle charging Charge complete and top off disabled ms Trickle charge per Table 4 Low top off complete or pending Fault Charge pending state and charge pending Trickle charge per Table 4 Low time out tPEND complete Definitions VcELL Vear Vsns Vucv 0 8 Vec Vepv 0 262 x Vcc or 0 4 x Vcc Vremp VTS VsNs Vutr 0 5 Vac bq2007 is used for all the odd percentage charge indications to assure a monotonic charge status display When MULT is pulled up to Vcc the bq2007 charge status monitor directly displays 4 of the charge safety timer as a percentage of full charge This method is rec ommended over the voltage based method when charg ing fixed cell packs where the battery terminal voltages can vary greatly between packs This method offers an accurate charge status indication when the battery is fully discharged When using the timer based method discharge before charge is recommended During discharge with MULT pulled down to Vss the charge status monitor indicates the percentage of the bat tery voltage by comparing Vegar to the internal discharge voltage reference thresholds In BCD format the dis charge thresholds Vso Veo
21. nd fault time out are a percentage of the fast charge rate and maximum time out MTO Initiating Charge Action and Discharge Before Charge A charge action is initiated under control of 1 battery insertion or 2 power applied Battery insertion is detected when the voltage at the BAT pin falls from above Vmcv to below Vyucv Power applied is detected by the rising edge of Vcc when a battery is inserted Discharge before charge see Figure 3 is initiated auto matically on application of power or battery insertion when DCMD is connected to Vss Discharge on demand is initiated by a negative going pulse on the DCMD pin DCMD DCMD bq2007 bq2007 Always Discharge Discharge on Command Figure 3 Discharge Before Charge Table 4 bq2007 Charge Action Control Summary bq2007 FAST TM Time out MOD Hold off Trickle Trickle Input Input Period Duty period Rep Rate Rep Rate State State min Cycle sec AV 9 PVD Vss Float 640 cz 25 2400 219Hz 109Hz Vss Vss 320 9 25 1200 109Hz 55Hz Vss Voc 160 9 25 600 55Hz 27Hz Vec Float 160 9 100 600 219Hz 109Hz Vcc Vss 80 C 100 300 109Hz 55Hz Voc Voc 40 2C 100 150 55Hz 27Hz regardless of charging activity The DCMD pin is inter nally pulled up to Vcc therefore not connecting this pin results in disabling the discharge before charge func tion When the discharge begins the DIS output goes high t
22. o activate an external transistor that connects a load to the battery The bq2007 terminates discharge before charge by detecting when the battery cell voltage is less than or equal to the end of discharge voltage VEpv Charge State Actions Once the required discharge is completed and temperature and voltage prequalifications are met the charge state is initiated The charge state is configured by the VSEL FAST and TM input pins The FAST input selects between Fast and Standard charge rates The Standard charge rate is Y of the Fast charge rate which is accomplished by dis abling the regulator for a period of 286us of every 1144us 25 duty cycle In addition to throttling back the charge current time out and hold off safety time are increased ac cordingly See Table 4 The VSEL input selects the voltage termination method The termination mode sets the top off state and trickle charge current rates The TM input selects the Fast charge rate the Standard rate and the corresponding charge times Once charging begins at the Fast or Stan dard rate it continues until terminated by any of the fol lowing conditions m Negative delta voltage AV m Peak voltage detect PVD a Maximum temperature cutoff TCO m Maximum time out MTO a Maximum cutoff voltage MCV Voltage Termination Hold off To prevent early termination due to an initial false peak battery voltage the AV and PVD terminations are disabled during a sho
23. rge state V20 threshold at the BAT pin Zaa Voc 220 mV MULT pulled to Vsg 40 state of charge voltage wy V Fast or standard charge state Vao threshold at the BAT pin a a my MULT pulled to Vss 60 state of charge voltage 195 4 Fast or standard charge state Veo threshold at the BAT pin 2 Vcc AN my MULT pulled to Vsg 80 state of charge voltage Pe Fast or standard charge state Veo threshold at the BAT pin hn Veo 290 my MULT pulled to Vsg 20 state of charge voltage 158 3 Vi Discharge before charge state Vao threshold at the BAT pin 7520 VCC 30 my MULT pulled to Vgg DIS 1 40 state of charge voltage 1637 4 Vi Discharge before charge state Vao threshold at the BAT pin 820 YCC Fao my MULT pulled to Vss DIS 1 60 state of charge voltage 157 Vi e Discharge before charge state Veo threshold at the BAT pin ce oe 590 mV MULT pulled to Vgg DIS 1 80 state of charge voltage Y e V P Discharge before charge state Veo threshold at the BAT pin 720 VCC 80 RY MULT pulled to Vgs DIS 1 11 bq2007 Recommended DC Operating Conditions Ta 0 to 70 c Symbol Parameter inimum Typical Maximum Unit Notes Vcc Supply voltage 4 5 5 0 5 5 V 10 VBAT Voltage on BAT pin 0 Voc V Vrs Voltage on TS pin 0 Vec V Thermistor input Vrco Temperature cutoff on TCO 0 0 5 Voc V_ Note 2 VCELL Battery voltage potential
24. riod specified in Table 4 This results in a trickle rate of for PVD and 9 when AV is enabled 10 DC Source Switch bq2007 MOD Battery L Under Charge Figure 4 Constant Current Switching Regulation Charge Inhibit Fast charge top off and pulse trickle may be inhibited by using the INH input pin When low the bq2007 sus pends all charge activity drives all outputs to high impedance and assumes a low power operational state When INH returns high a fast charge cycle is qualified and begins as soon as conditions allow Charge Current Control The bq2007 controls charge current through the MOD output pin In a frequency modulated buck regulator configuration the control loop senses the voltage at the SNS pin and regulates to maintain it between 0 04 Vcc and 0 05 Vcc The nominal regulated current is Irec 0 225V Rsns See Figure 4 MOD pin is switched high or low depending on the voltage input to the SNS pin If the voltage at the SNS pin is less than VsnsLo 0 04 Vcc nominal the MOD output is switched high to gate charge current through the inductor to the battery When the SNS voltage is greater than VsnsuI 0 05 Vcc nominal the MOD out put is switched low shutting off charge current from the supply The MOD pin can be used to gate an external charging current source When an external current source is used no sense resistor is required an
25. rt hold off period at the start of charge During the hold off period when fast charge is selected FAST 1 the bq2007 will top off charge to prevent excessive overcharging of a fully charged battery Once past the initial charge hold off time the termination is enabled TCO and MCV terminations are not affected by the hold off time AV or PVD Termination Table 5 summarizes the two modes for full charge voltage termination detection When VseL Vss negative delta voltage detection occurs when the voltage seen on the BAT pin falls 12mV typical below the maximum sampled value VseL Vcc selects peak voltage detect termination and the top off charge state PVD termination occurs when the BAT pin voltage falls 6mV per cell below the maximum sampled value When charging a battery pack with a fixed number of cells the AV and PVD termination thresholds are 6mV and 0 to 3mV per cell respectively The valid battery voltage range on Vegar for AV or PVD termination is from 0 262 Voc to 0 8 Vac Table 5 VSEL Configuration Detection Pulse Trickle VSEL Method Top Off Rate Vss AV Disabled Cho Vec PVD Enabled a bq2007 Maximum Temperature Maximum Voltage and Maximum Time Safety Terminations The bq2007 also terminates charge action for maximum temperature cutoff TCO maximum cutoff voltage MCV and maximum time out MTO Temperature is monitored as a voltage on the TS pin Vrs which i
26. s compared to an internal high temperature cutoff threshold of Vrco The TCO reference level provides the maximum limit for battery temperature during charging MCV termination occurs when VceLL gt Vmcv The maximum time out MTO termination is when the charger safety timer countdown has completed during the active charge state If the MTO MCV or TCO limit is exceeded during Fast charge Standard charge or top off states charge action is terminated Top Off and Pulse Trickle Charging The bq2007 provides a post detection timed charge capability called top off to accommodate battery chemis tries that may have a tendency to terminate charge prior to achieving full capacity When VsEL Vcc the top off state is selected charging continues after Fast charge termination for a period equal to the time out value In top off mode the Fast charge control cycle is modified so that MOD is activated for a pulse output of 73ms of every 585ms This results in a rate that of the Fast charge rate Top off charge is terminated by maxi mum temperature cutoff TCO maximum cutoff voltage MCV or maximum time out termination Pulse trickle is used to compensate for self discharge while the battery is idle and to condition a depleted low voltage battery to a valid voltage prior to high current charging The battery is pulse trickle charged when Fast Standard or top off charge is not active The MOD output is active for a period of 286us of a pe
27. ts up to a seven segment bargraph or a single BCD digit dis play The bargraph display indicates up to seven monotonic steps whereas the BCD digit counts in ten steps of 10 increments The bq2007 output drivers can direct drive either an LCD or LED display Charge action begins either by appli cation of the charging supply or by replacement of the battery pack For safety charging is inhibited until battery temperature and voltage are within configured limits Pin Connections SEGC MSEL 1 SEGD DSEL1 SEGBO 2 SEGE DSEL2 SEGA Q 3 SEGF MULT LED 4 SEGG QDSEL LED2O 5 MOD INHO 6 Vcc COM 7 VSS ALARM O 8 DIS TM TS VSEL BAT FAST SNS DCMD TCO 24 Pin Narrow DIP or SOIC PN200701 eps 9 96 B Pin Names SEGc Display output segment C MSEL driver mode select SEGB Display output segment B SEGA Display output segment A LED Charge status output LED Charge status output 2 INH Charge inhibit input COM Common LED LCD output ALARM Audio alarm output TM Timer mode select VSEL Voltage termination select FAST Fast charge rate select DCMD Discharge command TCO Temperature cutoff SNS Sense resistor input BAT Battery voltage TS Temperature sense DIS Discharge control Vss System ground Vec 5 0V 10 power MOD Modulation control SEGc Display output segment G QDSEL charge status display select SEGp Display output segment F MULT multi cell pack select SEGg Display output segment E D
28. used Tl s publication of information regarding any third party s products or services does not constitute Tl s approval warranty or endorsement thereof Copyright 1999 Texas Instruments Incorporated
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UNITRODE bq2007 handbook