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evaluates: max8845z/max8845y max8845z evaluation kit ________________________________________________________________ maxim integrated products 1 19-4405; rev 0; 12/08 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. general description the max8845z evaluation kit (ev kit) is a fully assem-bled and tested pcb for evaluating the max8845z/ max8845y 28v linear li+ battery chargers. the max8845z ev kit features an overvoltage-protect- ed ldo output (safeout) for low-voltage-rated usb or charger inputs in the system, and a battery pack detection circuit (detbat) that disables the ic when the battery pack is absent. the ic disables charging if the input sources exceed 7.5v to protect against unqualified or faulty ac adapters. the max8845z ev kit also features an adjustable fast-charge current set by an external resistor (r1) and an adjustable top-off cur- rent threshold set by an external resistor (r2). other features include an active-low control input ( en ) and an active-low input power source detection output( pok ). the ic also contains a booting assistant circuit that distinguishes input sources and battery connec-tion, and provides an output signal (max8845z = abo, max8845y = abo ) for system booting. to evaluate the max8845y version, order themax8845yetc+ along with the MAX8845ZEVKIT+ and see the evaluating the max8845y section. features ? cccv, thermally regulated linear single-cell li+battery charger ? no external mosfet, reverse-blocking diode, orcurrent-sense resistor ? programmable fast-charge currents (1a rms max) ? programmable top-off current threshold ? input overvoltage-protected 4.7v output(safeout) from dc ? proprietary die temperature regulation control(+115?) ? 4.25v to 28v input-voltage range with inputovervoltage protection above +7.5v ? low-dropout voltage (300mv at 500ma) ? input power-source detection output ( pok ), charge status output ( chg ), and charge-enable input ( en ) ? output for autobooting (max8845z = abo,max8845y = abo ) ? lead(pb)-free and rohs compliant component list ordering information designation qty description c1 1 1? ?0%, 35v x5r ceramiccapacitor (0603) taiyo yuden gmk107bj105ka c2 1 2.2? ?0%, 10v x5r ceramiccapacitor (0603) taiyo yuden lmk107bj225ka murata grm188r61a225ke34 c3 1 0.1? ?0%, 16v x7r ceramiccapacitor (0402) tdk c1005x7r1c683k designation qty description c4 1 1? ?0%, 10v x5r ceramiccapacitor (0402) murata grm155r61a105k c5 0 not installed, capacitor d1, d2 2 red ledspanasonic lnj208r8ara ju1?u4 4 2-pin headers, 0.1in centersullins pec36saan digi-key s1012e-36-nd r1 1 2.80k ?% resistor (0402) part type MAX8845ZEVKIT+ ev kit + denotes lead(pb)-free and rohs compliant. downloaded from: http:///
evaluates: max8845z/max8845y max8845z evaluation kit 2 _______________________________________________________________________________________ component list (continued) designation qty description r2 1 1.74k ?% resistor (0402) r3, r4 2 200 ?% resistors (0402) r5 1 4.7k ?% resistor (0402) r6, r7 0 not installed, resistors?cb short(0402) r8 1 200k ?% resistor (0402) designation qty description u1 1 28v linear li+ battery charger(12 thin qfn-ep*) maxim max8845zetc+ (top mark: abl) 1 pcb: max8845z evaluation kit+ * ep = exposed pad. component suppliers supplier phone website digi-key corp. 800-344-4539 www.digikey.com murata electronics north america, inc. 770-436-1300 www.murata-northamerica.com panasonic corp. 800-344-2112 www.panasonic.com sullins electronics corp. 760-744-0125 www.su llinselectronics.com taiyo yuden 800-348-2496 www.t-yuden.com tdk corp. 847-803-6100 www.component.tdk.com note: indicate that you are using the max8845z when contacting these component suppliers. quick start recommended equipment 4v to 28v adjustable power supply (ps1) capable of 1a one 5v power supply (ps2) capable of 100ma three digital multimeters (dmm1, dmm2, dmm3) one 10a ammeter one single-cell lithium-ion (li+) battery (not fully charged) procedure the max8845z ev kit is a fully assembled and testedsurface-mount board. follow the steps below and figure 1 to set up and verify the max8845z and board operation: 1) preset the power supply (ps1) to 5v. turn off the power supply. do not turn on the power supply until all connections are completed. 2) preset the power supply (ps2) to 5v. turn off the power supply. do not turn on the power supply until all connections are completed. 3) verify that a shunt is installed on ju1 ( en ) to set the ev kit in disable mode. 4) verify that a shunt is installed on ju2 (detbat). 5) verify that ju3 and ju4 are open and shunts are not installed. 6) connect the positive lead of the power supply (ps1) to the ev kit pad labeled in. connect the negativelead of the power supply to the ev kit pad labeled gnd. 7) connect the positive lead of the power supply (ps2) to the ev kit pad labeled vi/o. connect the negativelead of the power supply to the ev kit pad labeled gnd. 8) observe correct li+ cell polarity. connect the sin- gle-cell li+ battery and 10a ammeter, as shown infigure 1. the positive lead of the ammeter must connect to batt+ and the negative lead to the pos- itive terminal of the li+ battery. 9) connect a digital multimeter (dmm1) across the li+ battery. connect the positive lead of dmm1 to thepositive terminal of the li+ battery. connect the negative lead of dmm1 to the negative terminal of the li+ battery and note the battery voltage. if v batt < 2.5v, the charger starts in precharge mode. if v batt 2.5v, the charger starts up in fast- charge mode. downloaded from: http:///
evaluates: max8845z/max8845y max8845z evaluation kit _______________________________________________________________________________________ 3 10) connect a digital multimeter (dmm2) from abo (max8845z only) to gnd. 11) connect a digital multimeter (dmm3) from safeout to gnd. 12) turn on ps1 and then turn on ps2. 13) remove the shunt on ju1 to set the ev kit in enable mode. 14) verify that d2 is emitting light, indicating that pok is low and input power is valid. 15) verify that the voltage read by dmm3 is approxi- mately 4.7v. 16) if the charger is in fast-charge mode, verify that the ammeter reads approximately 500ma. if the charg-er is in precharge mode, verify that the ammeter reads approximately 50ma. 17) verify that d1 is emitting light, indicating that chg is low and the battery charger is on.note: if the battery is fully charged, d1 will not emit light. 18) verify that the voltage read by dmm2 is approxi- mately the same voltage read by dmm1. 19) when the battery is fully charged, dmm1 reads 4.2v. 20) remove the shunt on ju2 and verify that d1 and d2 are not emitting light. 21) install a shunt on ju2. 22) turn off the input power supply (ps1). 23) verify that d2 is not emitting light and the voltage read by dmm2 is 0v. 24) install a shunt on ju4. 25) verify that the voltage read at dmm2 is approxi- mately the same voltage read by dmm1. 26) turn on ps1 and increase to 8v. 27) verify that d1 and d2 are not emitting light and the voltage read by dmm3 is 0v. when evaluation of the max8845z ev kit is completed,use the following steps to power down the ev kit: 1) install a shunt on ju1. 2) turn off both power supplies. 3) remove the battery. 4) disconnect all test leads from the ev kit. detailed description of hardware the max8845z/max8845y chargers use voltage, cur-rent, and thermal-control loops to charge a single li+ cell and protect the battery. when a li+ battery with a cell voltage below 2.5v is inserted, the max8845z/ max8845y chargers enter a prequalification stage where it precharges that cell with 10% of the user-pro- grammed fast-charge current. the chg indicator is dri- ven low to indicate entry into the prequalification state.when the battery voltage exceeds 2.5v, the ic soft- starts as it enters the fast-charge stage. the fast- charge current level is programmed through a resistor from seti to gnd. as the battery voltage approaches 4.2v, the battery current is reduced. if the battery cur- rent drops to less than the top-off current threshold set by r min , the ic enters top-off mode and the chg indi- cator goes high impedance, signaling that the batteryis fully charged. overvoltage-protected output (safeout) safeout is a linear regulator that provides an outputvoltage of 4.7v and can be used to supply low-voltage- rated charging systems. the safeout linear regulator turns on when v in 4.25v regardless of en and is dis- abled when v in is greater than the overvoltage thresh- old (7.5v typ). battery pack detection input (detbat) detbat is a battery pack id resistor detector thatenables the battery charger if pulled low through a resistor that is < 51k . by installing a header on ju2, detbat is pulled to ground through r5 (4.7k ). if detbat is left unconnected, or the pulldown resistor is 51k or greater, the battery charger is disabled. if detbat is not used, connect detbat to gnd for nor-mal operation. pok output the open-drain pok output asserts low when 2.35v v in 7v, (v in - v batt ) 40mv (typ v in rising), and detbet is pulled low through a resistor that is < 51k . pok is high impedance during shutdown. when inter- facing with a microprocessor logic input, a pullup resis-tor to the microprocessor? i/o voltage may be required. autobooting assistant the max8845z/max8845y contain an autobooting assistant circuit that generates an enable signal for sys- tem booting (max8845z = abo, max8845y = abo ). for the max8845z, the booting assistant functions as aninternal or gate (refer to the max8845z/max8845y ic data sheet). the first input is dependent on the input supply voltage v in and detbat, while the second input downloaded from: http:///
evaluates: max8845z/max8845y max8845z evaluation kit 4 _______________________________________________________________________________________ max8845z evaluation kit+ ju2 + - - -+ seti min detbat abi safeout gnd in chg vi/o en pok batt- batt+ (abo) abo power supply (ps2) +5v + dmm1 dmm2 - + dmm3 ju3 d2 d1 shunt installed = battery present. shunt not installed = battery absent. shunt installed = ic disabled. shunt not installed = ic enabled. d2 is on when power supply is valid. ju4 ju1 shunt installed = abi connected to vi/o. shunt not installed = abi unconnected. ( ) = max8845y only. shunt installed = abo - max8845y only.shunt not installed = abo - max8845z only. d1 is on when battery charging. 10a ammeter li+ - power supply (ps1) +5v + figure 1. test procedure setup for max8845z ev kit jumper default settings function ju1 installed ju1 connects en (active-low enable input) to vi/o (system supply). install a shunt on ju1 to disable the ic. en has an internal pulldown resistor to gnd. remove the shunt from ju1 to enable the ic. ju2 installed ju2 connects detbat (battery pack id resistor detection input) to gnd through r5. install a shunton ju2 to simulate battery present. remove the shunt on ju2 to simulate battery absent. ju3 not installed remove the shunt on ju3 to evaluate the max8845z with an active-high autobooting logic output(abo). install a shunt on ju3 to connect abo to the vi/o supply through r8 in order to achieve a logic-high output on the drain of the internal open-drain mosfet (max8845y only). ju4 not installed ju4 connects abi (autobooting input) to vi/o (system supply). install a shunt on ju4 to connect abito vi/o. remove the shunt on ju4 to leave abi unconnected and when abi is driven by an external source. table 1. jumper settings (ju1?u4) downloaded from: http:///
evaluates: max8845z/max8845y max8845z evaluation kit _______________________________________________________________________________________ 5 is an external signal applied to abi. the first input ( pok ) is driven high once detbat is pulled low through aresistor < 51k , 2.35v v in 7v, and (v in - v batt ) 40mv (typ v in rising). the second input signal (abi) is driven by an externalsource (see table 2). abi enables an autoboot signal when a battery is connected at batt and is indepen- dent of pok . if pok is pulled low, the booting assistant always drives abo high (max8845z), regardless of abi.abi is pulled to gnd through an internal 200k resistor. if abi is supplied from an outside exposed pin, an rcfilter (r1/c3 in figure 2) is required for esd protection and noise filtering. if abi is supplied by a system? inter- nal gpio, or logic, the rc filter is not required. for the max8845y, the output abo is only dependent on the state of abi (table 2). charger enable input the max8845z ev kit contains an active-low logic input( en ) used to enable the ic. drive en low, leave ju1 unconnected, or connect en to gnd to enable the charge-control circuitry. drive en high to disable the charge-control circuitry. en has an internal 200k pull- down resistor. fast-charge current setting the maximum charging current is programmed by anexternal resistor connected from seti to gnd (r1 in figure 2). use the following equation to determine the fast-charge current (i fast_charge ): where i fast_charge is in amperes and r seti is in ohms. r seti must always be 1.40k or higher due to the continuous charging current limit of 1a. the voltageat seti can be used to monitor the fast-charge current level. the output current from seti is 1016? per ampere of charging current. the output voltage at setiis proportional to the charging current: the voltage at seti is nominally 1.4v at the selected fast-charge current, and falls with charging current as the cell becomes fully charged or as the thermal- regulation circuitry activates. top-off current threshold setting the top-off current threshold is programmed by anexternal resistor connected from min to gnd (r2 in figure 2). use the following equation to determine the top-off current (i min ): where i min is in amperes and r min is in ohms. thermal regulation the thermal-regulation loop limits the max8845z/max8845y die temperature to +115? by reducing the charge current, as necessary. this feature not only pro- tects the ic from overheating, but also allows a higher charge current without risking damage to the ic. evaluating the max8845y to evaluate the max8845y version, order themax8845yetc+ along with the MAX8845ZEVKIT+. remove u1 and replace with the max8845yetc+ (top mark: abm) and install a shunt on ju3. the max8845y features an active-low autobooting logic output ( abo ) and requires an external power supply (vi/o on themax8845z ev kit) to achieve logic-high. to evaluate the max8845y and board operation, see figures 1 and 3 and follow the procedure on the next page. the max8845y procedure is similar to the max8845z procedure with a few minor differences. i v r min min = 140 v ir seti charge seti = 1016 i v r fast charge seti _ = 1400 abi batt pok charger state abo (max8845z) abo (max8845y) low present high impedance shutdown low high impedance high present high impedance shutdown high low low not present low fast char g e/top off high high impedance low present low fast char g e/top off high high impedance high present low fast char g e/top off high low table 2. autobooting output states note: present indicates that v batt 2v and not present indicates that battery is not connected. downloaded from: http:///
evaluates: max8845z/max8845y max8845z evaluation kit 6 _______________________________________________________________________________________ max8845y procedure follow the steps below and figure 1 to set up and verifythe max8845y and board operation: 1) preset the power supply (ps1) to 5v. turn off the power supply. do not turn on the power supply until all connections are completed. 2) preset the power supply (ps2) to 5v. turn off the power supply. do not turn on the power supply until all connections are completed. 3) verify that a shunt is installed on ju1 ( en ) to set the ev kit in disable mode. 4) verify that a shunt is installed on ju2 (detbat). 5) verify that a shunt is installed on ju3. verify that a shunt is installed on ju4. 6) connect the positive lead of the power supply (ps1) to the ev kit pad labeled in. connect the negativelead of the power supply to the ev kit pad labeled gnd. 7) connect the positive lead of the power supply (ps2) to the ev kit pad labeled vi/o. connect the negativelead of the power supply to the ev kit pad labeled gnd. 8) observe correct li+ cell polarity. connect a single- cell li+ battery and 10a ammeter, as shown infigure 1. the positive lead of the ammeter must connect to batt+ and the negative lead to the pos- itive terminal of the li+ battery. 9) connect a digital multimeter (dmm1) across the li+ battery. connect the positive lead of dmm1 to thepositive lead of the li+ battery. connect the nega- tive lead of dmm1 to the negative terminal of the li+ battery and note the battery voltage. if v batt < 2.5v, the charger starts in precharge mode. ifv batt 2.5v the charger starts up in fast-charge mode. 10) connect a digital multimeter (dmm2) from abo to gnd. 11) connect a digital multimeter (dmm3) from safeout to gnd. 12) turn on ps1 and then turn on ps2. 13) remove the shunt on ju1 to set the ev kit in enable mode. 14) verify that d2 is on indicating pok is low and input power is valid. 15) verify that the voltage read by dmm3 is approxi- mately 4.7v. 16) if the charger is in fast-charge mode, verify that the ammeter reads approximately 500ma. if the charg-er is in precharge mode, verify that the ammeter reads approximately 50ma. 17) verify that d1 is on indicating that chg is low and the battery charger is on.note: if the battery is fully charged, d1 will not turn on. 18) verify that the voltage read by dmm2 is 0v. 19) when the battery is fully charged, dmm1 reads 4.2v. 20) remove the shunt on ju2 and verify that d1 and d2 are not emitting light. 21) install a shunt on ju2. 22) turn off the input power supply (ps1). 23) verify that d2 is not emitting light and that the volt- age read by dmm2 is approximately 5v. 24) remove the shunt on ju4. 25) verify that the voltage read by dmm2 is approxi- mately 5v. 26) turn on ps1 and increase to 8v. 27) verify that d1 and d2 are not emitting light and that the voltage read by dmm3 is 0v. when evaluation of the max8845y is completed, usethe following steps to power down the ev kit: 1) ensure a shunt on ju1. 2) turn off both power supplies. 3) remove the battery. 4) disconnect all test leads from the ev kit. downloaded from: http:///
evaluates: max8845z/max8845y max8845z evaluation kit _______________________________________________________________________________________ 7 max8845z u1 ju4 vi/o vi/o vi/o ju1 12 safeout 2 detbat 9 min 8 batt 4 en r6 pcb short r12.80k r4200 r21.74k r54.7k c4 1 f c5open c22.2 f safeout detbat batt+ batt- vi/o pok seti abi chg (abo) abo 3 abi c3 0.1 f 11 in 7 abo 10 chg c1 1 f in gnd ju2 ju3 r8 200k vi/o r3 200 d1 d2 5 gnd ep en 6 pok 1 seti r7 pcb short ( ) - max8845y only. figure 2. max8845z ev kit schematic downloaded from: http:///
evaluates: max8845z/max8845y max8845z evaluation kit 8 _______________________________________________________________________________________ max8845y u1 ju4 vi/o vi/o vi/o ju1 12 safeout 2 detbat 9 min 8 batt 4 en r6 pcb short r12.80k r4200 r21.74k r54.7k c4 1 f c5open c22.2 f safeout detbat batt+ batt- vi/o pok seti abi chg (abo) abo 3 abi c3 0.1 f 11 in 7 abo 10 chg c1 1 f in gnd ju2 ju3 r8 200k vi/o r3 200 d1 d2 5 gnd ep en 6 pok 1 seti r7 pcb short ( ) - max8845y only. figure 3. max8845y ev kit schematic downloaded from: http:///
evaluates: max8845z/max8845y max8845z evaluation kit _______________________________________________________________________________________ 9 figure 4. max8845z ev kit component placement guide?omponent side downloaded from: http:///
evaluates: max8845z/max8845y max8845z evaluation kit 10 ______________________________________________________________________________________ figure 5. max8845z ev kit pcb layout?omponent side downloaded from: http:///
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, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 ____________________ 11 2008 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. evaluates: max8845z/max8845y max8845z evaluation kit figure 6. max8845z ev kit pcb layout?older side downloaded from: http:///

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