View EMC5042_7776474.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 1/20 standalone linear li-ion charger (two-cell) with thermal regulation general description the EMC5042 is a complete linear charger for two-cell lithium-ion batteries. with small tdfn-10 package and few external components, EMC5042 is well suited for portable applications. no external sense resistor and blocking diode are required. charging current can be programmed externally with a single resistor. the built-in thermal regulation facilitates charging with maximum power without risk of overheating. the EMC5042 always preconditions the battery with 1/10 of the programmed charge current at the beginning of a charge cycle, after it verifies that the battery can be fast-charged. the EMC5042 automatically terminates the charge cycle when the charge current drops to 1/10th the programmed value after the final float voltage is reached. the EMC5042 features 13.5v maximum rating voltage for ac adapter, and it provides the charge current up to 1.2a. other features include battery temperature monitoring, reverse current protection, shutdown mode, charging current monitor, under voltage lockout, automatic recharge and status indicator. features g programmable charge current up to 1.2a g no mosfet, sense resistor or blocking diode required g complete linear charger in tdfn-10 for two-cell li-ion batteries g thermal regulation maximizes charge rate without risk of overheating g thermistor input for temperature qualified charging g preset 8.4v charge voltage with 1% accuracy g automatic recharge g charge status indicator g c/10 charge termination g 5.8v trickle charge threshold g battery reverse leakage current less than 1ua applications g wireless handsets g hand-held instruments g portable information appliances
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 2/20 typical application circuit in 1uf gnd v in = 9v~13.5v r set batt ts 1k 1k 1uf 7.4v li-ion battery pack iseta chg_sb pgoodb enb EMC5042 1uf 1 complete charger cycle
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 3/20 connection diagrams top view order information EMC5042-84ff10nrr 84 output voltage ff10 tdfn-10 package nrr rohs & halogen free package rating: -40 to 85c package in tape & reel order, marking & packing information package product id. marking packing tdfn-10 (3x3 mm) EMC5042-84ff10nrr pin1 dot emp EMC5042 tracking code 1 2 4 3 5 10 9 7 8 6 tape & reel 5kpcs
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 4/20 pin functions name tdfn-10 function in 1 positive input supply voltage. provides power to the charger, v in can range from 9v to 13.5v and should be bypassed with at least a 1 f capacitor. when in pin drops to within 30mv above the batt pin voltage, the EMC5042 enters shutdown mode, dropping i batt to less than 1 a. nc 2 not connected. chg_sb 3 open-drain charge status output. an internal n-channel mosfet connects chg_sb pin to ground when the battery is charging. after the charge cycle is completed, the internal n-channel mosfet is replaced by a weak pull-down of approximately 25 a, indicating an ?v in present? condition. when the EMC5042 detects an under voltage lock out condition, chg_sb is forced high impedance. pgoodb 4 open-drain battery power good output. an internal n-channel mosfet connects pgoodb pin to ground when v in is reached to 8.4v. pgoodb is forced low during normal operation. gnd 5 ground. iseta 6 charge current program, charge current monitor and shutdown pin. the charge current is programmed by connecting a 1% resistor, r set , to ground. when charging in constant-current mode, this pin serv os to 1.5v. in all modes, the voltage on this pin can be used to measure the charge current using the following formula: i batt = (v set / r set ) * 500 the iseta pin can also be used to shutdo wn the charger. disconnecting the program resistor from ground allows a 1 a current to pull the iseta pin high. when it reaches the 2.15v shutdown threshold voltage, the char ger enters shutdown mode. this pin is also clamped to approximately 2.5v. reconnecting r set to ground will return the charger to normal operation. the iseta pin must not be directly shorted to ground at any condition. nc 7 not connected. enb 8 charge enable input (active low). this pin is weakly pulled low internally. ts 9 ts pin is the input for an external ntc thermistor. when the ts pin voltage is out of the window, determined by the v tmin and v tmax , the EMC5042 stops charging and indicates a fault condition. batt 10 charge current output and battery voltage feedback. this pin provides charge current to the batt ery and regulates the final float voltage to 8.4v. an internal precision resistor divider from this pin sets the float voltage which is disconnected in shutdown mode.
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 5/20 functional block diagram body switch acin bat bs bs bs in batt + - 1.2v regulation controller + - + - temperature controller 1.5v 0.15v + - 5.8v bat + - + - 0.15v 2.15v logic controller iseta uvlo/ovp ts + - + - 2.5v 0.5v + - bat 8.1v hot cold gnd disable pgoodb chg_sb enb fig.1 functional block diagram of EMC5042
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 6/20 state diagram trickle charge mode 1/10th full current chg_bs: strong pull-down charge mode full current chg_sb: strong pull-down standby mode no charge current chg_sb: weak pull-down batt < 5.8v batt > 5.8v batt > 5.8v iseta < 0.15v 5.8v < batt < 8.1v shutdown mode chg_sb: hi-z in uvlo weak pull-down otherwise iseta floated, iseta > 2.15v or uvlo/ovp condition batt < 5.8v iseta reconnected or uvlo/ovp condition stops power on battery thermal fault no charge current chg_sb: weak pull-down no fault thermal fault fig.2 EMC5042 charge flow chart
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 7/20 absolute maximum ratings (notes 1, 2) v in , v batt , v chgsb , v proodb , v en -0.3v to 15v v iseta , v ts -0.3v to 3.6v power dissipation (note 5) storage temperature range -65c to 150c junction temperature (t j ) 150c lead temperature (soldering, 10 sec.) 260c operating ratings (note 1, 2) supply voltage 9v to 13.5v operating temperature range -40c to 85c thermal resistance ( ja , note 3)) 110c/w thermal resistance ( jc , note 4)) 8.5c/w electrical characteristics t a = 25c, v in = 10v; unless otherwise specified. symbol parameter conditions min typ max units v in input operating voltage range 9 10 13.5 v charge mode, r set = 30k (note 6) 300 ua standby mode (charge terminated) 250 ua i cc input supply current shutdown mode (r set not connected, v in < v batt or v in < v uv ) 190 ua v float regulated output (float) voltage 0c Q t a Q 85c 8.316 8.4 8.484 v r set = 1.5k, current mode 500 ma r set = 0.75k, current mode 1000 ma standby mode, v batt = 8.4v -1 0 1 ua shutdown mode -1 0 1 ua i batt batt pin current sleep mode, v in = 0v -1 0 1 ua v batt < v trickle , r set = 1.5k 60 ma i trickle trickle charge current v batt < v trickle , r set = 0.75k 120 ma v trickle trickle charge threshold voltage r set = 1.5k, v batt rising 5.8 v v trhys trickle charge hysteresis voltage r set = 1.5k 250 mv iseta pin rising 2.15 v v msd manual shutdown threshold voltage iseta pin falling 2.05 v v in from high to low 30 mv v asd v in -v batt lockout threshold voltage v in from low to high 60 mv r set = 1.5k 0.1 ma/ma i term c/10 termination current threshold r set = 0.75k 0.1 ma/ma v set iseta pin voltage r set = 1.5k, current mode 1.5 v i chg_sb chg_sb pin weak pull-down current v chg_sb = 5.0v 25 ua v chg_sb chg_sb pin output low voltage i chg_sb = 5ma 0.35 v v poogdb pgoodb pin output low voltage i pgoodb = 5ma 0.35 v
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 8/20 v rechrg recharge battery threshold voltage v float - v batt-rechrg 300 mv t ilm junction temperature in constant temperature mode (thermal regulation) 120 r on power fet ?on? resistance i batt = 500ma 375 m t recharge recharge comparator filter time v batt high to low 150 us t term termination comparator filter time i batt falling below i chg /10 1 ms i set iseta pin pull-up current 1 ua i ts ts pin source current v ts = 1.5v 96 102 108 ua v ts-cold ts pin cold threshold voltage v ts rising 2.5 v v cold-hys ts pin cold hysteresis voltage 100 mv v ts-hot ts pin hot threshold voltage v ts falling 0.5 v v hot-hys ts pin hot hysteresis voltage 100 mv enable threshold 0.55 v v run shutdown threshold 2.8 v note 1: absolute maximum ratings indicate limits beyond which damage may occur. electrical specifications do not apply when operating the device outside of its rated operating conditions. note 2: all voltages are with respect to the potential at the ground pin. note 3: ja is measured in the natural convection at ta=25 on a high effective thermal conductivity test board (2 layers, 2s0p). note 4: jc represents the resistance to the heat flows the chip to package top case. note 5: maximum power dissipation for the device is ca lculated using the following equations: ja a t - ) regulation (thermal ilm t d p = where t ilm is the thermal regulation temperature, t a is the ambient temperature, and ja is the junction-to-ambient thermal resistance. e.g. for the tdfn-10 package ja = 110c/w, t ilm = 120c and using t a = 25c, the maximum power dissipation is found to be 0.86w. the de-rating factor (-1/ ja ) = -9.09mw/c, thus below 25c the power dissipation figure can be increased by 9.09mw per degree, and similarity decreased by this factor for temperatures above 25c. note 6: supply current includes iseta pin current but does not include any current delivered to the battery through the batt pin.
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 9/20 typical performance characteristics unless otherwise specified, v in = 10v, t a = 25c v set vs. temperature (v batt > 5.8v) v set vs. temperature (v batt < 5.8v) vset v.s. temperat ure 1.485 1.487 1.489 1.491 1.493 1.495 1.497 1.499 1.501 1.503 1.505 1.507 1.509 1.511 1.513 1.515 -40 -15 10 35 60 85 temperature ( ) vset (v) vset v s. t emperat ure 0.145 0.146 0.147 0.148 0.149 0.150 0.151 0.152 0.153 0.154 0.155 -40 -15 10 35 60 85 temperature ( ) vset (v) charge current vs. battery voltage (v in =10v) charge current vs. v in (v batt =8.0v) 0 100 200 300 400 500 600 700 800 900 1000 5.4 6 6.6 7.2 7.8 8.4 v batt (v) i batt ( ma ) rset=15k rset=3k rset=1.5k rset=1k rset=0.75k ? ??? ??? ??? ??? ?? ?? ?? ??? ?? ???? ? ? ?? ?? ?? ?? ?? ?? ?? ?? ?? ???? ? ? ? ????e?t ????e?t ????e?t ????e?t ????e?t regulated output voltage vs. supply voltage regulated output voltage vs. temperature 8.3 8.31 8.32 8.33 8.34 8.35 8.36 8.37 8.38 8.39 8.4 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5 v in (v) v flo at (v) rset=15k ? 8.32 8.328 8.336 8.344 8.352 8.36 8.368 8.376 8.384 -40 -25 -10 5 20 35 50 65 80 95 110 125 temperat ure ( ) v flo a t (v) rset=15k ?
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 10/20 typical performance characteristics (continued) unless otherwise specified, v in = 10v, t a = 25c recharge voltage threshold vs. temperature trickle charge threshold vs. temperature 8.04 8.05 8.06 8.07 8.08 8.09 8.1 -40 -15 10 35 60 85 temperature ( ) v rechrg (v ) rset=15k ? 5.6 5.65 5.7 5.75 5.8 5.85 5.9 5.95 6 -40 -15 10 35 60 85 temperature ( ) v tric kle (v ) rset=15k ? trickle charge current vs. supply voltage 0 20 40 60 80 100 120 140 160 180 9 9.5 10 10.5 11 11.5 12 12.5 13 13.5 v in (v) i trickle (m a) rset=15k rset=3k rset=1.5k rset=1k rset=0.5k
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 11/20 operation the EMC5042 is a two-cell lithium-ion battery charger using a constant-current/constant-voltage algorithm. it can deliver up to 1.2a of charge current (using a good thermal pcb layout) with a final float voltage accuracy of 1%. the EMC5042 includes an in ternal p-channel power mosfet and thermal regulation circuitry. no blocking diode or external current sense resistor is re quired; thus, the basic charger circuit requires only two external components. normal charge cycle a charge cycle begins when the voltage at the in pin rises above the uvlo threshold level and a 1% program resistor is connected from the iseta pin to ground or when a battery is connected to the charger output. if the batt pin is less than 5.8v, the charger enters tric kle charge mode. in this mode, the EMC5042 supplies approximately 1/10 the programmed charge current to bring the battery voltage up to a safe level for full current charging. when the batt pin voltage rises above 5.8v, the charger enters constant-current mode, where the programmed charge current is supplied to th e battery. when the batt pin approaches the final float voltage (8.4v), the EMC5042 enters constant- volt age mode and the charge curr ent begins to decrease. when the charge current drops to 1/10 of th e programmed value, the charge cycle ends. programming charge current the charge current is programmed using a single resistor from the iseta pin to ground. the battery charge current is 500 times the current out of the iseta pin. vset is 1.5v when charging in constant-current mode. the program resistor and the charge current ar e calculated using the following equations: set set chg chg set set r 500v i , i 500v r = = the charge current out of the batt pin can be determi ned at any time by monitoring the iseta pin voltage using the following equation: 500 r v i set set batt = charge termination a charge cycle is terminated when the charge current falls to 1/10th the programmed value after the final float voltage is reached. this condition is detected by using an internal, filtered comparator to monitor the iseta pin. when the iseta pin voltage falls below 150mv for longer than t term (typically 1ms), charging is terminated. the charge current is latched off and the EMC5042 enters standby mode, where the input supply current drops to 150ua. (note: c/10 termination is disabled in trickle charging and thermal limiting modes). the EMC5042 draws no current from the battery in standby mode. this feature reduces the charge and discharge cycles on the battery, further prolonging the battery life. any external source (v set ) that holds the iseta pin above 150mv will prevent the EMC5042 from terminating a charge cycle. however, if the iseta pin is controlled by external source, current sourcing from the batt pin can be infinity (until the internal power mosfet is burned out or the batt pin voltage is close to its final float voltage), and the formula for charge current is not valid anymore. when charging, transient loads on the batt pin can cause the iseta pin to fall below 150mv for short periods of time before the dc charge current has dropped to 1/10th the programmed value. the 1ms filter time (t term ) on the termination comparator ensures that transient loads of this nature do not result in premature charge cycle termination. once the average charge current drop s below 1/10th the programmed value, the EMC5042 terminates the charge cycle and ceases to provide any current through the batt pin. this is the standby mode, and all loads on the batt pin must be supplied by th e battery. in the standby mode, any signal below the manual shutdown threshold voltage (typically 2.15v) on the iseta pin is transparent to EMC5042.
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 12/20 the EMC5042 constantly monitors the batt pin voltage in standby mode. if this voltage drops below the 8.1v recharge threshold (v rechrg ), another charge cycle begins and current is once again supplied to the battery. to manually restart a charge cycle when in standby mo de, the input voltage must be removed and reapplied, or the charger must be shut down and restarted using the iseta pin. charge status indicator (chg_sb) the charge status output has three different states: strong pull-down (~10ma), weak pull-down (~25ua) and high impedance. the strong pull-down state indicates that the EMC5042 is in a charge cycle. once the charge cycle has terminated, the pin state is determined by under-voltage lockout conditions. a weak pull-down indicates that v in meets the uvlo conditions and the EMC5042 is ready to charge. high impedance indicates that the EMC5042 is in under-voltage lockout mode: either v in is less than 60mv of the batt pin voltage or insufficient voltage is applied to the in pin. a microp rocessor can be used to distinguish between these three states. this method is discussed in the applications information section. thermal limiting an internal thermal feedback loop reduces the programmed charge current if the die temperature attempts to rise above a preset value of approximately 125c. this feature protects the EMC5042 from excessive temperature and allows the user to push the limits of the power handling capability of a given circuit board without risk of damaging the EMC5042. the charge current can be set according to typical (not worst-case) ambient temperature with the assurance that the charger will automatically reduce the current in worst-case conditions. tdfn-10 package power considerations are discussed further in the applications information section. under-voltage lockout (uvlo) an internal under-voltage lockout circuit monitors th e input voltage and keeps the charger in shutdown mode until v in rises above the under-voltage lockout threshold. th e uvlo circuit has a built-in hysteresis of 150mv. furthermore, to protect against reverse current in th e power mosfet, the uvlo ci rcuit keeps the charger in shutdown mode if v in falls to within 30mv of the battery voltage. if the uvlo comparator is tripped, the charger will not come out of shutdown mode until v in rises 60mv above the battery voltage. manual shutdown at any point in the charge cycle, the EMC5042 can be put into shutdown mode by removing r set thus floating the iseta pin. this reduces the battery drain current to about to 0ua and the supply current to less than 150ua. a new charge cycle can be initiated by reconnecting the program resistor. in manual shutdown, the chg_sb pin is in a weak pull- down state as long as v in is high enough to exceed the uvlo conditions. the chg_sb pin is in a high impeda nce state if the EMC5042 is in under-voltage lockout mode: either v in is within 60mv of the batt pin voltage or insufficient voltage is applied to the in pin. automatic recharge once the charge cycle is terminated, the EMC5042 contin uously monitors the voltage on the batt pin using a comparator with a 150us filter time (t recharge ). a charge cycle restarts when the battery voltage falls below 8.1v (which corresponds to approximately 80% to 90% battery capacity). this ensures that the battery is kept at or near a fully charged condition and eliminates the need for periodic charge cycle initiations. chg_sb output enters a strong pull-down state during recharge cycles.
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 13/20 application information stability considerations the constant-voltage mode feedback loop is stable without an output capacitor provided a battery is connected to the charger output. with no battery pres ent, an output capacitor is recommended to reduce ripple voltage. when using high value, low esr ceramic capacitors, it is recommended to add a 1 ? resistor in series with the capacitor. no series resistor is needed if tantalum capacitors are used. in constant-current mode, the iseta pin is in the feedback loop, not the battery. the constant-current mode stability is affected by the impedance at the iseta pin. with no additional capacitance on the iseta pin, the charger is stable with program resistor values as high as 100k. however, additional capacitance on this node reduces the maximum allowed program resistor. the pole frequency at the iseta pin should be kept above 100khz. therefore, if the iseta pin is loaded with a capacitance, c set , the following equation can be used to calculate the maximum resistance value for r set : set 5 set c 10 2 1 r average, rather than instantaneous, charge current may be of interest to the user. for example, if a switching power supply operating in low current mode is connect ed in parallel with the battery, the average current being pulled out of the batt pin is typically of more interest than the instantaneous current pulses. in such a case, a simple rc filter can be used on the iseta pin to measure the average battery current as shown in figure 3. a 10k ? resistor has been added between the iseta pin an d the filter capacitor to ensure stability. fig.3 isolating capacitive load on iseta pin and filtering power dissipation the conditions that cause the EMC5042 to reduce charge current through thermal feedback can be approximated by considering the power dissipated in the ic. nearly all of this power dissipation is generated by the internal mosfet, this is calculated to be approximately: p d = (v in ? v batt ) ? i batt where p d is the power dissipated, v in is the input supply voltage, v batt is the battery voltage and i batt is the charge current. the approximate ambi ent temperature at which the therma l feedback begins to protect the ic is: t a = 120 ? p d ? ja t a = 120 ? (v in ? v batt ) ? i batt ? ja example: an EMC5042 operating from a 9v supply is programmed to supply 500ma full-scale current to a discharged li-ion battery with a voltage of 7.4v. assuming ja is 110 /w, the ambient temperature at which the EMC5042 will begin to reduce the charge current is approximately: t a = 120 ? (9v ? 7.4v) ? (500ma) ?110 /w t a = 120 ? 0.8w ?110 /w = 120 ? 88
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 14/20 t a = 32 the EMC5042 can be used above 55 ambient, but the charge current will be reduced from 500ma. the approximate current at a given ambien t temperature can be approximated by: ja batt in a o batt ) v (v t c 120 i ? ? = using the previous example with an ambient temperature of 70 , the charge current will be reduced to approximately: ma 284 i c/a 176 c 50 c/w 110 ) 4 . 7 (9 c 70 c 120 i batt o o o o o batt = = ? ? ? = moreover, when thermal feedback redu ces the charge current, the voltage at the iseta pin is also reduced proportionally as discussed in the operation section. it is important to remember that EMC5042 applications do not need to be designed for worst-case thermal conditions since the ic will automatically reduce power dissipation when the junction temp erature reaches approximately 120 . thermal considerations because of the small size of the tdfn-10 package, it is very important to use a good thermal pc board layout to maximize the available charge current. the thermal path for the heat generated by the ic is from the die to the copper lead frame, through the package leads, (especially the ground lead) to the pc board copper. the pc board copper is the heat sink. the footprint copper pa ds (thermal land) should be as wide as possible and expand out to larger copper areas to spread and dissip ate the heat to the surrounding ambient. feed-through vias to inner or backside copper layers are also useful in improving the overall thermal performance of the charger. other heat sources on the board, not relat ed to the charger, must also be considered when designing a pc board layout because they will affect overall temperature rise and the maximum charge current. increasing thermal regulation current reducing the voltage drop across the internal mosfet can significantly decrease the power dissipation in the ic. this has the effect of increasing the current delivered to the battery during thermal regulation. one method is by dissipating some of the power through an exte rnal component, such as a resistor or diode. example: an EMC5042 operating from a 10v wall adapter is programmed to supply 1a full-scale current to a discharged li-ion battery with a voltage of 7.4v. assuming ja is 50 o c/w, the approximate charge current at an ambient temperature of 25 is: 730ma c/w 50 .4v) 7 (10v c 25 c 120 i o o o batt = ? ? ? = by dropping voltage across a resistor in series with a 10v wall adapter (shown in figure 4), the on-chip power dissipation can be decreased, thus increasi ng the thermally regulated charge current
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 15/20 r set EMC5042 gnd iseta batt 7.4v li-ion battery pack in r cc 1uf v in fig.4 a circuit to maximize charge current ja batt cc batt in o o batt ) v r i (v c 25 c 120 i ? ? ? ? = solving for i batt using the quadratic formula. ] ) t c (120 4r ) v (v ) v [(v 2r 1 i ja a o cc 2 batt in batt in cc batt ? ? ? ? ? = (note: large values of r cc will result in no solution for i batt . this indicates that the EMC5042 will not generate enough heat to require thermal regulation.) using r cc = 0.5 ? , v in = 10v, v batt = 7.4v, t a = 25 and ja = 50 /w we can calculate the thermally regulated charge current to be: i batt = 880ma while this application delivers more energy to the ba ttery and reduces charge time in thermal mode, it may actually lengthen charge time in voltage mode if v in becomes low enough to put the EMC5042 into dropout. this technique works best when r cc values are minimized to keep compon ent size small and avoid dropout. remember to choose a resistor with adequate power handling capability. v in bypass capacitor many types of capacitors can be used for input bypassi ng, however, caution must be exercised when using multilayer ceramic capacitors. because of the self-resonant and high q characteristics of some types of ceramic capacitors, high voltage transients can be generated under some start-up conditions, such as connecting the charger input to a live power source. adding a 1.5 ? resistor in series with an x5r ceramic capacitor will minimize start-up voltage transients. charge current soft-start the EMC5042 includes a soft-start circuit to minimize the inrush current at the start of a charge cycle. when a charge cycle is initiated, the charge current ramps fr om zero to the full-scale current over a period of approximately 100us. this has the effect of minimizing the transient current load on the power supply during start-up.
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 16/20 chg_sb status output pin the chg_sb pin can provide an indication that the input voltage is greater than the under-voltage lockout threshold level. a weak pull-down curr ent of approximately 25ua indicates th at sufficient voltage is applied to acin to begin charging. when a discharged battery is connected to the charger, the constant current portion of the charge cycle begins and the chg_sb pin pulls to ground. the chg_sb pin can sink up to 10ma to drive an led that indicates that a charge cycle is in progress. when the battery is nearing full charge, the charger enters the constant-voltage portion of the charge cycle and the charge current begins to drop. when the charge current drops belo w 1/10 of the programmed current, the charge cycle ends and the strong pull-down is replaced by the 25ua pull-down, indicating that the charge cycle has ended. if the input voltage is removed or drops below the under-voltage lockout threshold, the chg_sb pin becomes high impedance. figure 5 shows that by using two different value pull-up resistors, a microprocessor can detect all three states from this pin. fig.5 using a microprocessor to determine chg_sb state to detect when the EMC5042 is in charge mode, forc e the digital output pin (out) high and measure the voltage at the chg_sb pin. the internal n-channel mosfet will pull the pin voltage low even with the 2k pull-up resistor. once the charge cycle term inates, the n-channel mosfet is turned off and a 25ua current source is connected to the chg_sb pin. the in pin will then be pulled high by the 2k pull-up resistor. to determine if there is a weak pull-down current, the out pin should be forc ed to a high impedance state. the weak current source will pull the in pin low through the 800k resistor; if chg_sb is high impedance, the in pin will be pulled high, indicating that the part is in a uvlo state. reverse polarity input voltage protection in some applications, protection from reverse polarity volt age on in pin is desired. if the supply voltage is high enough, a series blocking diode can be used. in othe r cases, where the voltage drop must be kept low a p-channel mosfet can be used (as shown in figure 6). fig.6 low loss input revers e polarity protection
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 17/20 battery temperature monitoring the EMC5042 continuously monitors battery temperatur e by measuring the voltage between the ts and gnd pins. the EMC5042 has an internal current source to provide the bias for the most common 10k ? negative-temperature coefficient thermal resistor (ntc ) (see figure 7). the EMC5042 compares the voltage on the ts pin against the internal vts_high and vts_low thresholds to determine if charging is allowed. when the temperature outside the vts_high and vts_lo w thresholds is detected, the device will immediately stop the charge. the EMC5042 stops charge and keep monitoring the batter y temperature when the temperature sense input voltage is back to the thresh old between vts_high and vt s_low, the charger will be resumed. charge is resumed when the temperature return s to the normal range. however the user may modify the thresholds by the negative-temperature coefficient thermal resistor. the capacitor should be placed close to ts pin and connected to the ground plane. the ca pacitance value (0.1uf to 10uf) should be selected according to the quality of pcb layout. fig.7 the battery thermal detecting circuit
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 18/20 package outline drawing tdfn-10l (3x3 mm) min max a0.700.85 minmax a1 0.00 0.05 d2 2.20 2.70 a3 0.18 0.25 e2 1.40 1.75 b0.180.30 d2.953.05 e2.953.05 e l0.300.50 symbol dimension in mm 0.5 bsc dimension in mm exposed pad
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 19/20 revision history revision date description 0.1 2011.02.25 preliminary version 1.0 2011.08.03 skip ?preliminary? 1.1 2012.07.05 1. added v run operation in electrical characteristics. 2. updated the package outline drawing.
esmt/emp EMC5042 elite semiconductor memory technology inc./elite micropower inc. publication date : jul. 2012 revision : 1.1 20/20 important notice all rights reserved. no part of this document may be repr oduced or duplicated in any form or by any means without the prior permission of esmt. the contents contained in this docume nt are believed to be accurate at the time of publication. esmt assumes no responsibility for any error in this document, and reserves the right to change the products or specification in this document without notice. the information contained herein is pr esented only as a guide or examples for the application of our products. no responsibility is assumed by esmt for any infringement of patents, copyrights, or other intellect ual property rights of third parties which may result from its use. no license, either express , implied or otherwise, is granted un der any patents, copyrights or other intellectual property righ ts of esmt or others. any semiconductor devices may have in herently a certain rate of failure. to minimize risks associated with cu stomer's application, adequate design and operating safeguards against inju ry, damage, or loss from such failure, should be provided by the customer when making application designs. esmt's products are not authorized for use in critical applications such as, but not limited to, life support devices or system, where failure or abnormal operation may directly affect human lives or cause physical injury or property damage. if products described here are to be used for such kinds of application, purchaser must do its own quality assurance testing appropriate to such applications.

▲Up To Search▲

Price & Availability of EMC5042

	To Download EMC5042 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .