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general description the max8844z evaluation kit (ev kit) is a fully assembledand tested pcb for evaluating the max8844z/ max8844y 28v linear li+ battery chargers. the max8844z ev kit operates from two power sources (usb or in) and automatically selects between the two. the ic disables charging if the input sources exceed 7.5v to protect against unqualified or faulty ac adapters. the max8844z ev kit features two input overvoltage- protected ldo outputs (safeout, safeusb) 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 max8844z ev kit also features an adjustable fast-charge current set by an external resistor (r1) and an adjustable top- off current 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 (max8844z = abo, max8844y = abo ) for system booting. to evaluate the max8844y version, sample themax8844yetd+ along with the MAX8844ZEVKIT+ and see the evaluating the max8844y 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 ( m in) ? input overvoltage protected 4.7v output(safeout) from dc ? input overvoltage-protected 4.7v output(safeusb) from usb ? 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 (max8844z = abo,max8844y = abo ) ? lead(pb)-free and rohs compliant evaluates: max8844z/max8844y max8844z evaluation kit ________________________________________________________________ maxim integrated products 1 19-4381; rev 0; 11/08 component list for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. ordering information designation qt description c1, c6 2 1f 10%, 35v x5r ceramic capacitors (0603) taiyo yuden gmk107bj105ka c2 1 2.2f 10%, 10v x5r ceramic capacitor (0603) taiyo yuden lmk107bj225ka murata grm188r61a225ke34 c3 1 0.1f 10%, 16v x7r ceramic capacitor (0402) tdk c1005x7r1c683k designation qt description c4, c7 2 1f 10%, 10v x5r ceramic capacitors (0402) murata grm155r61a105k c5 0 not installed, capacitor d1, d2 2 red leds panasonic lnj208r8ara ju1Cju4 4 2-pin headers, 0.1in center sullins pec36saan digi-key s1012e-36-nd r1 1 2.8k 1% resistor (0402), lead free part type MAX8844ZEVKIT+ ev kit + denotes lead(pb)-free and rohs compliant. downloaded from: http:///
evaluates: max8844z/max8844y max8844z evaluation kit 2 _______________________________________________________________________________________ component list (continued) designation qt description r2 1 1.74k 1% resistor (0402), lead free r3, r4 2 200 5% resistors (0402), lead free r5 1 4.7k 5% resistor (0402), lead free r6, r7 0 not installed, resistorspcb short (0402) designation qt description r8 1 200k 5% resistor (0402), lead free u1 1 28v linear li+ battery charger (14 tdfn-ep*) maxim max8844zetd+ (top mark: aek) 1 pcb: max8844z 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 max8844z when contacting these component suppliers. quick start recommended equipment two 4v to 28v adjustable power supplies (ps1, ps2) capable of 1a each one 5v power supply (ps3) capable of 100ma four digital multimeters (dmm1?mm4) one 10a ammeter one single-cell lithium-ion (li+) battery (not fully charged) procedure the max8844z ev kit is a fully assembled and testedsurface-mount board. follow the steps below and figure 1 to set up and verify the max8844z and board operation. caution: do not turn on the power sup- plies until all connections are completed. 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) preset the power supply (ps3) to 5v. turn off the power supply. do not turn on the power supply until all connections are completed. 4) verify that a shunt is installed on ju1 ( en ) to set the ev kit in disable mode. 5) verify that a shunt is installed on ju2 (detbat). 6) verify that ju3 and ju4 are open and shunts are not installed. 7) 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. 8) connect the positive lead of the power supply (ps2) to the ev kit pad labeled usb. connect the nega-tive lead of the power supply to the ev kit pad labeled gnd. 9) connect the positive lead of the power supply (ps3) to the ev kit pad labeled vi/o. connect the negativelead of the power supply to the ev kit pad labeled gnd. 10) 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 downloaded from: http:///
evaluates: max8844z/max8844y max8844z evaluation kit _______________________________________________________________________________________ 3 connect to batt+ and the negative lead to the pos-itive terminal of the li+ battery. 11) connect a digital multimeter (dmm1) across the li+ battery. connect the positive terminal of dmm1 tothe positive terminal of the li+ battery. connect the negative terminal 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. 12) connect a digital multimeter (dmm2) from abo (max8844z only) to gnd. 13) connect a digital multimeter (dmm3) from safeout to gnd. 14) connect a digital multimeter (dmm4) from safeusb to gnd. 15) turn on ps1 and then turn on ps3. 16) remove the shunt on ju1 to set the ev kit in enable mode. 17) verify that d2 is emitting light, indicating that pok is low. 18) verify that the voltage read by dmm3 is approxi- mately 4.7v. 19) if the charger is in fast-charge mode, verify that the ammeter reads approximately 440ma. if the charg-er is in precharge mode, verify that the ammeter reads approximately 48ma. 20) 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. 21) verify that the voltage read by dmm2 is approxi- mately the same voltage read by dmm1. 22) when the battery is fully charged, dmm1 reads 4.2v. 23) remove the shunt on ju2 and verify that d1 and d2 are not emitting light. 24) install a shunt on ju2. 25) turn off the input power supply (ps1). 26) verify that d2 is not emitting light and the voltage read by dmm2 is 0v. 27) install a shunt on ju4. 28) verify that the voltage read at dmm2 is approxi- mately the same voltage read by dmm1. 29) increase ps1 to 8v. 30) verify that d1 and d2 are not emitting light and the voltage read by dmm3 is 0v. 31) install a shunt on ju1. 32) turn off ps1 and then turn on ps2. 33) remove the shunt on ju1 to set the ev kit in enable mode. 34) verify that d2 is emitting light, indicating pok is low. 35) verify that the voltage read by dmm4 is approxi- mately 4.7v. 36) if the charger is in fast-charge mode, verify that the ammeter reads approximately 380ma. if the charg-er is in precharge mode, verify that the ammeter reads 48ma. 37) 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. 38) increase ps2 to 8v. 39) verify that d1 and d2 are not emitting light and the voltage on dmm4 is 0v. when evaluation of the max8844z ev kit is completed,use the following steps to power down the ev kit: 1) install a shunt on ju1. 2) turn off all power supplies. 3) remove the battery. 4) disconnect all test leads from the ev kit. detailed description of hardware the max8844z/max8844y 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 max8844z/ max8844y 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- downloaded from: http:///
evaluates: max8844z/max8844y max8844z evaluation kit 4 _______________________________________________________________________________________ max8844z evaluation kit+ ju4 -+ - - + pok usb vi/o gnd in safeout (abo) abo abi min seti detbat chg en batt+ batt- safeusb power supply (ps2) +5v - power supply (ps3) +5v - + dmm2 + dmm1 dmm4 - + dmm3 ju1 d1 d2 shunt installed = abi connected to vi/o. shunt not installed = abi unconnected. d2 emits light when valid power supply is connected. shunt installed = ic enabled.shunt not installed = ic disabled. ju3 ju2 shunt installed = abo, max8844y only. shunt not installed = abo, max8844z only. ( ) = max8844y only. shunt installed = battery present.shunt not installed = battery absent. d1 emits light when batterycharger is on. 10a ammeter li+ + - power supply (ps1) +5v + figure 1. test procedure setup for max8844z ev kit jumper default settings function ju1 installed ju1 connects en (active-low enable input) to vi/o (system supply). install a sh unt on ju1 to disable the ic. en has an internal pulldown resistor to gnd. leave ju1 open to enable t he ic. ju2 installed ju2 connects detbat (battery pack id resistor detection input) to gnd through r5 . install a shunt on ju2 to simulate battery present. leave ju2 open to simulate batter y absent. ju3 not installed leave ju3 open when evaluating the max8844z with an active-high autobooti ng 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 (max8844y only). ju4 not installed ju4 connects abi (autobooting input) to vi/o (system supply). install a shunt on ju4 to connect abi to vi/o. leave ju4 open to leave abi unconnected and when abi is dr iven by an external source. table 1. jumper settings (ju1?u4) downloaded from: http:///
rated charging systems. the safeout linear regulatorturns 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). overvoltage protected output (safeusb) safeusb is a linear regulator that provides an outputvoltage of 4.7v and can be used to supply low-voltage- rated usb systems. the safeusb linear regulator turns on when v usb 4.25v regardless of en and is disabled when v usb is greater than the overvoltage threshold (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 shunt on ju2, detbat is pulled to ground through r5 (4.7k ). if detbat is left unconnected, or the pulldown resistor is51k or greater, the battery charger is disabled. pok output the open-drain pok output asserts low when 2.35v (v in or v usb ) 7v, [(v in or v usb ) - v batt ] 40mv (typ v in or v usb rising), and detbet is pulled low through a resistor that is < 51k . pok is high impedance dur- ing shutdown. when interfacing with a microprocessorlogic input, a pullup resistor to the microprocessor? i/o voltage may be required. if detbat is not used, con- nect detbat to gnd for normal operation. autobooting assistant the max8844z/max8844y contain an autobootingassistant circuit that generates an enable signal for sys- tem booting (max8844z = abo, max8844y = abo ). the booting assistant functions as an internal or gate(refer to the max8844z/max8844y ic data sheet). the first input is dependent on the input supply voltage (v in or v usb ) and detbat, while the second input is an external signal applied to abi. the first input ( pok ) is driven high once detbat is pulled low through a resis-tor < 51k , 2.35v (v in or v usb ) 7v, and [(v in or v usb ) - v batt ] 40mv (typ v in or v usb 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 (max8844z) or abo low (max8844y), regardless of abi. abi is pulled to gndthrough an internal 200k resistor. if abi is supplied from an outside exposed pin, an rc filter (r1/c2 infigure 2) is required for esd protection and noise filter- ing. if abi is supplied by a system? internal gpio, or logic, the rc filter is not required. charger enable input the max8844z 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 1.25k or higher due to the continuous charging current limit of 1a rms . the voltage at seti can be used to monitor the fast-chargecurrent level. the output current from seti is 1120? per ampere of charging current. the output voltage at seti is 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. v ir seti charge seti = 1120 i v r fast charge seti _ = 1250 evaluates: max8844z/max8844y max8844z evaluation kit _______________________________________________________________________________________ 5 abi batt pok charger state abo (max8844z) abo (max8844y) 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 low low 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: max8844z/max8844y 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. dc and usb power supplies the ic operates from well-regulated dc sources andautomatically selects between both input power-supply connections (see table 3). if both sources are present at the same time, highest priority is given to the in source. the in source is selected to ensure the short- est charging time for the system since it is able to deliv- er the highest current. the usb fast-charge current is fixed at 380ma. the full charging input-voltage range for in and usb is 4.25v to 7.5v. the device can withstand up to 28v on both inputs (in and usb) without damage to the ic. if v in or v usb is > 7.5v, the internal overvoltage- protection circuitry disables charging until the inputfalls below 7.5v. the power supplies must provide at least 4.25v at the desired peak charging current and stay below 7v when unloaded. thermal regulation the thermal-regulation loop limits the max8844z/max8844y 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 max8844y to evaluate the max8844y version, order themax8844yetd+ along with the MAX8844ZEVKIT+. remove u1 and replace with the max8844yetd+ (topmark: aen) and install a shunt on ju3. the max8844y features an active-low autobooting logic output ( abo ) and requires an external power supply (vi/o on themax8844z ev kit) to achieve logic-high. to evaluate the max8844y and board operation, see figures 1 and 3 and follow the same steps as listed in the quick start/procedures section, but with the follow- ing procedure: 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) preset the power supply (ps3) to 5v. turn off the power supply. do not turn on the power supply until all connections are completed. 4) verify that a shunt is installed on ju1 ( en ) to set the ev kit in disable mode. 5) verify that a shunt is installed on ju2 (detbat). 6) verify that a shunt is installed on ju3. verify that ju4 is open and a shunt is not installed. 7) 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. 8) connect the positive lead of the power supply (ps2) to the ev kit pad labeled usb. connect the nega-tive lead of the power supply to the ev kit pad labeled gnd. 9) connect the positive lead of the power supply (ps3) to the ev kit pad labeled vi/o. connect the nega-tive lead of the power supply to the ev kit pad labeled gnd. i v r min min = 125 max8844z evaluation kit 6 _______________________________________________________________________________________ in usb charger state 4.25v v in 7v 4.25v v usb 7v enabled (selects in power supply) 4.25v v in 7v not present enabled (selects in power supply) not present 4.25v v usb 7v enabled (selects usb power supply) v in 7.5v 4.25v v usb 7v disabled 4.25v v in 7v v usb 7.5v enabled table 3. input power-supply selection downloaded from: http:///
10) 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. 11) connect a digital multimeter (dmm1) across the li+ battery. connect the positive terminal of dmm1 to thepositive terminal of the li+ battery. connect the neg- ative terminal 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 in fast-charge mode. 12) connect a digital multimeter (dmm2) from abo (max8844y only) to gnd. 13) connect a digital multimeter (dmm3) from safeout to gnd. 14) connect a digital multimeter (dmm4) from safeusb to gnd. 15) turn on ps1 and then turn on ps3. 16) remove the shunt on ju1 to set the ev kit in enable mode. 17) verify that d2 is emitting light indicating pok is low. 18) verify that the voltage read by dmm3 is approxi- mately 4.7v. 19) if the charger is in fast-charge mode, verify that the ammeter reads approximately 440ma. if the charg-er is in precharge mode, verify that the ammeter reads 48ma. 20) verify that d1 is emitting light indicating that chg is low and the battery charger is on. note : if the bat- tery is fully charged, d1 will not emit light. 21) verify that the voltage read by dmm2 is 0v. 22) when the battery is fully charged, dmm1 reads 4.2v. 23) remove the shunt on ju2 and verify that d1 and d2 are not emitting light. 24) install a shunt on ju2. 25) turn off the input power supply (ps1). 26) verify that d2 is not emitting light and the voltage read by dmm2 is 5v. 27) install a shunt on ju4. 28) verify that the voltage read at dmm2 is approxi- mately 5v. 29) increase ps1 to 8v. 30) verify that d1 and d2 are not emitting light and the voltage read by dmm3 is 0v. 31) install a shunt on ju1. 32) turn off ps1 and then turn on ps2. 33) remove the shunt on ju1 to set the ev kit in enable mode. 34) verify that d2 is emitting light indicating pok is low. 35) verify that the voltage read by dmm4 is approxi- mately 4.7v. 36) if the charger is in fast-charge mode, verify that the ammeter reads approximately 380ma. if the charg-er is in precharge mode, verify that the ammeter reads 48ma. 37) verify that d1 is emitting light indicating that chg is low and the battery charger is on. note : if the bat- tery is fully charged d1 will not emit light. 38) increase ps2 to 8v. 39) verify that d1 and d2 are not emitting light and the voltage on dmm4 is 0v. when evaluation of the max8844z ev kit is completed,use the following steps to power down the ev kit: 1) install a shunt on ju1. 2) turn off all power supplies. 3) remove the battery. 4) disconnect all test leads from the ev kit. evaluates: max8844z/max8844y max8844z evaluation kit _______________________________________________________________________________________ 7 downloaded from: http:///
evaluates: max8844z/max8844y max8844z evaluation kit 8 _______________________________________________________________________________________ max8844z u1 ju4 vi/o vi/o vi/o ju1 14 safeout 8 detbat 6 min 12 batt 10 en r6 pcb short r12.8k r4200 r21.74k r54.7k c4 1 f c5open c22.2 f safeout detbat batt+ batt- vi/o pok seti abi chg (abo) abo 13 safeusb c7 1 f 4 abi c3 0.1 f safeusb 3 usb c6 1 f usb 1 in 5 abo 9 chg c1 1 f in gnd ju2 ju3 r8 200k vi/o r3 200 d1 d2 11 gnd ep en 2 pok 7 seti r7 pcb short ( ) - max8844y only. figure 2. max8844z ev kit schematic downloaded from: http:///
evaluates: max8844z/max8844y max8844z evaluation kit _______________________________________________________________________________________ 9 max8844y u1 ju4 vi/o vi/o vi/o ju1 14 safeout 8 detbat 6 min 12 batt 10 en r6 pcb short r12.8k r4200 r21.74k r54.7k c4 1 f c5open c22.2 f safeout detbat batt+ batt- vi/o pok seti abi chg (abo) abo 13 safeusb c7 1 f 4 abi c3 0.1 f safeusb 3 usb c6 1 f usb 1 in 5 abo 9 chg c1 1 f in gnd ju2 ju3 r8 200k vi/o r3 200 d1 d2 11 gnd ep en 2 pok 7 seti r7 pcb short ( ) - max8844y only. figure 3. max8844z ev kit schematic with max8844y installed downloaded from: http:///
evaluates: max8844z/max8844y max8844z evaluation kit 10 ______________________________________________________________________________________ figure 4. max8844z ev kit component placement guide?omponent side downloaded from: http:///
evaluates: max8844z/max8844y max8844z evaluation kit ______________________________________________________________________________________ 11 figure 5. max8844z 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. 12 __________________ maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2008 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. evaluates: max8844z/max8844y max8844z evaluation kit figure 6. max8844z ev kit pcb layout?older side downloaded from: http:///

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