RT9526A 1 ds9526a-01 april 2011 www.richtek.com pin configurations (top view) linear single cell li-ion battery charger with input over voltage protection general description the RT9526A is a fully integrated low cost single cell li- ion battery charger ideal for portable applications. the RT9526A is capable of being powered up from ac adapter and usb (universal serial bus) port inputs. the RT9526A enters sleep mode when supplies are removed. the RT9526A optimizes the charging task by using a control algorithm including preconditioning mode, fast charge mode, and constant voltage mode. the charging task will remain in constant voltage mode to hold the battery in a full charge condition. the charge current can be programmed with an external resistor. the internal thermal feedback circuitry regulates the die temperature to optimize the charge rate under all ambient temperatures. the RT9526A features 28v maximum rating voltage for vin. the other features are under voltage protection and over voltage protection for the ac adapter supply. the RT9526A is available in wdfn-8l 2x3 package to achieve best solution for pcb space and total bom cost saving considerations. features z z z z z 28v maximum rating for ac adapter z z z z z internal integrated power fets z z z z z ac adapter power good status indicator z z z z z programmed charging current z z z z z charge status indicator z z z z z programmed end of charge current z z z z z under voltage protection z z z z z over voltage protection z z z z z thermal feedback optimizing charge rate z z z z z rohs compliant and halogen free applications z cellular phones z digital cameras z pdas and smart phones z portable instruments ordering information note : richtek products are : ` rohs compliant and compatible with the current require- ments of ipc/jedec j-std-020. ` suitable for use in snpb or pb-free soldering processes. wdfn-8l 2x3 vin enb pgb batt iset imin gnd chg_sb gnd 9 7 6 5 1 2 3 4 8 marking information 05 : product code w : date code RT9526A package type qw : wdfn-8l 2x3 (w-type) lead plating system g : green (halogen free and pb free) 05w
RT9526A 2 ds9526a-01 april 2011 www.richtek.com function block diagram function pin description pin no. pin name pin function 1 vin supply voltage input. vin can withstand up to 28v input. 2 pgb power good indicator. this pin connects to vin with 10sl n-mosfet as power good condition. 3 chg_sb charge status indicator output (open drain). indicate low when battery is charging; indicate high when battery charging finished or any fault happened. 4 enb charge enable (active low). connect this pin with 200k pull low resistor. 5, 9 (exposed pad) gnd ground. the exposed pad must be soldered to a large pcb and connected to gnd for maximum power dissipation. 6 imin eoc current setting pin. 7 iset charge current set point. 8 batt battery charge current output. typical application circuit imin chg_sb batt enb RT9526A c in vin adapter or usb gnd c out r iset v batt pgb iset r imin r1 v batt r2 cc/cv/tr multi loop controller logic 200k batt chg_sb gnd pgb enb iset vin imin current set block sleep mode ovp uvlo base eoc set block switch well v ref i bias
RT9526A 3 ds9526a-01 april 2011 www.richtek.com absolute maximum ratings (note 1) z supply voltage, vin ------------------------------------------------------------------------------------------------------ ? 0.3v to 28v z chg_sb, pgb pins ------------------------------------------------------------------------------------------------------ ? 0.3v to 7v z others ------------------------------------------------------------------------------------------------------------------------ ? 0.3v to 6v z power dissipation, p d @ t a = 25 c wdfn-8l 2x3 -------------------------------------------------------------------------------------------------------------- 0.833w z package thermal resistance (note 2) wdfn-8l 2x3, ja --------------------------------------------------------------------------------------------------------- 120 c/w wdfn-8l 2x3, jc --------------------------------------------------------------------------------------------------------- 8.2 c/w z lead temperature (soldering, 10 sec.) ------------------------------------------------------------------------------- 260 c z junction temperature ----------------------------------------------------------------------------------------------------- 150 c z storage temperature range -------------------------------------------------------------------------------------------- ? 65 c to 150 c recommended operating conditions (note 3) z junction temperature range -------------------------------------------------------------------------------------------- ? 40 c to 125 c z ambient temperature range -------------------------------------------------------------------------------------------- ? 40 c to 85 c electrical characteristics parameter symbol test conditions min typ max unit vin por rising threshold voltage v por_h 3.4 3.8 4.2 v vin por falling threshold voltage v por_l 3.1 3.5 3.9 v vin ? v batt vos rising v os_h -- 90 150 mv vin ? v batt vos falling v os_l 10 50 -- mv vin standby current v batt = 4.5v -- 400 600 a batt sleep leakage current i sleep -- 1 5 a battery regulation voltage v re g 4.158 4.2 4.242 v vin power fet on-resistance r ds(o n) i batt = 0.5a -- 0.6 -- iset set voltage (fast charge phase) v iset -- 1.22 -- v charge current accuracy r iset = 24.3k 450 500 550 ma batt pre-charge threshold v chg_pre 2.45 2.55 2.65 v batt pre-charge threshold hysteresis v chg_pre 40 100 150 mv pre-charge current i chg_pre 12 16.7 21.3 % logic-high v ih 1.5 -- -- v enb input threshold voltage logic-low v il v in = 4.2v to 24v -- -- 0.4 v thermal regulation t reg -- 115 -- c vin over voltage protection threshold v ovp 6.7 7 7.5 v vin ovp hysteresis v ovp -- 0.1 -- v pgb pull down voltage 5ma -- 200 -- mv chg_sb pull down voltage 5ma -- 200 -- mv (v in = 4.5v, t a = 25 c unless otherwise specified) to be continued
RT9526A 4 ds9526a-01 april 2011 www.richtek.com note 1. stresses listed as the above ? absolute maximum ratings ? may cause permanent damage to the device. these are for stress ratings. functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. note 2. ja is measured in natural convection at t a = 25 c on a low-effective thermal conductivity test board of jedec 51-3 thermal measurement standard. the measurement case position of jc is on the exposed pad of the packages. note 3. the device is not guaranteed to function outside its operating conditions. parameter symbol test conditions min typ max unit eoc current setting i imin r imin = 243k -- 45 -- ma eoc rising threshold r iref = 24.3k 337.5 375 412.5 ma
RT9526A 5 ds9526a-01 april 2011 www.richtek.com typical operating characteristics batt sleep leakage current vs. battery voltage 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 1 1.5 2 2.5 3 3.5 4 4.5 battery voltage (v) batt sleep leakage current (a) 1 vout regulation voltage vs. input voltage 4.1580 4.1748 4.1916 4.2084 4.2252 4.2420 4.5 5 5.5 6 6.5 7 input voltage (v) vout regulation voltage (v) 1 pre-charge current vs. input voltage 75 79 83 87 91 95 44.555.566.57 input voltage (v) pre-charge current (ma ) v batt = 3.8v, r iset = 24.3k charge current vs. input voltage 450 460 470 480 490 500 510 520 530 540 550 4 4.5 5 5.5 6 6.5 7 input voltage (v) charge current (ma ) v batt = 3.8v, r iset = 24.3k iset voltage v s. input voltage 1.20 1.21 1.22 1.23 1.24 1.25 4 4.5 5 5.5 6 6.5 7 input voltage (v) iset voltage (v) v batt = 3.8v, r iset = 24.3k ovp time (500 s/div) v batt (2v/div) v in = 0v to 12v, v batt = 3.8v, r iset = 24.3k v in (10v/div) v chg_sb (2v/div) i chg (500ma/div) enb : low
RT9526A 6 ds9526a-01 april 2011 www.richtek.com power on time (500 s/div) v batt (2v/div) v batt = 3.8v, r iset = 24.3k v in (5v/div) v chg_sb (2v/div) i chg (500ma/div) enb : low shutdown time (5ms/div) v batt (2v/div) v batt = 3.8v, r iset = 24.3k v in (5v/div) v chg_sb (2v/div) i chg (500ma/div) enb : low
RT9526A 7 ds9526a-01 april 2011 www.richtek.com application information the RT9526A is a fully integrated low cost single cell li- ion battery charger operable in constant current (cc) mode or constant voltage (cv) mode. the cc mode current is set with the external resistor, r iset , and the cv mode voltage is fixed at 4.2v. if the battery voltage is below a typical 2.55v pre-charge threshold, the RT9526A charges the battery with a trickle current until the battery voltage rises above the pre-charge threshold. the RT9526A is capable of being powered up from ac adapter and usb (universal serial bus) port inputs. vin over voltage protection the input voltage is monitored by the internal comparator. the ovp threshold is set at 7v (typ.). when the input voltage exceeds the threshold, the controller outputs a logic signal to turn off the power p-mosfet to prevent high input voltage from damaging the electronics in the handheld system. nevertheless, an ac input voltage over 28v will still damage the RT9526A. when the input over voltage condition is removed, the controller will enable the output again by running through soft-start. charger enable input enb is an active-low logic input to enable the charger. drive the enb pin low or leave it floating to enable the charger. this pin has a 200k internal pull down resistor. so when left floating, the input is equivalent to logic-low. drive this pin high to disable the charger. battery charge profile the RT9526A charges a li-ion battery under constant current (cc) mode or constant voltage (cv) mode. the constant current of iset is set via the external resistor, r iset , and the constant voltage is fixed at 4.2v. if the battery voltage is below a typical 2.55v pre-charge threshold, the RT9526A charges the battery with a trickle current until the battery voltage rises above the pre-charge threshold. when the battery voltage reaches 4.2v, the charger enters cv mode and regulates the battery voltage at 4.2v to fully charge the battery without the risk of over charge. cv cc trickle 4.2v i chg_fast 2.8v 16.7 % i chg_fast chg_sb chg indication i imin charge current 75 % i chg_fast time charge voltage figure 1. typical charge profile a. battery pre-charge current during a charge cycle, if the battery voltage is below the pre-charge threshold, the RT9526A applies a pre-charge mode to the battery. this feature revives deeply discharged cells and protects battery life. the internally determined pre-charge rate of the RT9526A is 16.7% of the constant charge current. b. battery fast-charge current (cc mode) the RT9526A offers iset pin to determine the fast-charge current via an external resistor, r iset , connected between iset and gnd. the fast-charge current can be calculated by the following equation : iset chg_fast iset iset v i = k x (ma) r k set = 9959; v set = 1.22 (typ.) figure 2 battery charge current vs. r iset 0 200 400 600 800 1000 1200 1400 10 19 28 37 46 55 r iset (k ) battery charge current (ma) 1
RT9526A 8 ds9526a-01 april 2011 www.richtek.com c. battery voltage regulation (cv mode) the battery voltage regulation feedback is through the batt pin. the RT9526A monitors the battery voltage between the batt and gnd pins. when battery voltage is close to battery regulation voltage threshold, the voltage regulation phase begins and the charging current begins to taper down. when battery voltage is over battery regulation voltage threshold and charge mode stops, the RT9526A still monitors the battery voltage. charge current is resumed when the battery voltage falls under battery regulation voltage threshold. sleep mode the RT9526A enters sleep mode if both ac and usb are removed from the input. this feature prevents draining the battery during the absence of input supply. power good this open-drain output pin is used to indicate the input voltage status. the pgb output asserts low when 1. v in > v por 2. v in ? ? ? ? ? v batt > v os 3. v in < v ovp it can be used to drive an led or communicate to the host processor. note that on indicates the open-drain transistor is turned on and led is bright. chg_sb indication the chg_sb pin is an open-drain output capable to at least 10ma current when the charger starts to charge and turns off when the eoc current is reached. the chg_sb signal is interfaced either with a micro processor gpio or an led for indication. end-of-charge current (eoc) connect a resistor between the imin pin and gnd to set the eoc current. the eoc current level, i imin , is programmable via the external resistor, r imin (k ), as shown in the following equation : imin imin 10935 i = r (ma) upon reaching the end-of-charge (eoc) current, the charger indicates charge completion via the chg_sb pin, but the charger continues to output 4.2v voltage. figure 1 shows the typical charge profile and the eoc/reset event. the chg_sb signal asserts low when the trickle charge starts and changes to high at eoc. after eoc is reached, the charge current has to rise above 75% of i chg_fast before the chg_sb signal is allowed to turn on again. a current surge after eoc may occur due to a load connected to the battery. temperature regulation and thermal protection in order to maximize charge rate, the RT9526A features a junction temperature regulation loop. if the power dissipation of the ic results in junction temperature greater than the thermal regulation threshold (115 c), the RT9526A will cut back on the charge current and disconnect the battery in order to maintain thermal regulation at around 115 c. this operation continues until the junction temperature falls below thermal regulation threshold (115 c) by the hysteresis level. this feature prevents the maximum power dissipation from exceeding typical design conditions. selecting the input and output capacitors in most applications, a 1 f high frequency decoupling capacitor placed in close proximity to the input is sufficient. however, depending on the power supply characteristics and cable length, it may be necessary to add an additional 10 f ceramic capacitor to the input. for the RT9526A, a small output capacitor is required for loop stability. a 1 f ceramic capacitor placed between the batt pin and gnd is typically sufficient. thermal considerations for recommended operating condition specifications of the RT9526A, the maximum junction temperature is 125 c and t a is the ambient temperature. the junction to ambient thermal resistance, ja , is layout dependent. for wdfn- 8l 2x3 packages, the thermal resistance, ja , is 120 c/ w on a standard jedec 51-3 single-layer thermal test board. the maximum power dissipation at t a = 25 c can be calculated by the following formula :
RT9526A 9 ds9526a-01 april 2011 www.richtek.com figure 4. pcb layout guide layout consideration the RT9526A is a fully integrated low cost single-cell li- ion battery charger ideal for portable applications. careful pcb layout is necessary. for best performance, place all peripheral components as close to the ic as possible. a short connection is highly recommended. the following guidelines should be strictly followed when designing a pcb layout for the RT9526A. ` input capacitor should be placed close to the ic and connected to the ground plane. the trace of input on the pcb should be placed far away from the sensitive devices and shielded by the ground. ` the gnd and exposed pad should be connected to a strong ground plane for heat sinking and noise protection. ` the connection of r iset should be isolated from other noisy traces. ` output capacitor should be placed close to the ic and connected to the ground plane to reduce noise coupling. figure 3. derating curve for RT9526A package iset vin enb pgb batt gnd chg_sb 7 6 5 1 2 3 4 8 gnd 9 imin batt batt vin batt c out c in r1 r2 r iset r imin gnd c in should be placed near the ic to improve performance. the copper area connecting the resistors of iset and imin should be minimized and kept far away from noise sources. the gnd plane should be connected to a strong ground plane for heat sinking and noise protection. 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 0 25 50 75 100 125 ambient temperature (c) maximum power dissipation (w) 1 four-layer pcb p d(max) = (125 c ? 25 c) / (120 c/w) = 0.833w for wdfn-8l 2x3 package the maximum power dissipation depends on the operating ambient temperature for fixed t j(max) and thermal resistance, ja . for the RT9526A packages, the derating curves in figure 3 allow the designer to see the effect of rising ambient temperature on the maximum power dissipation.
RT9526A 10 ds9526a-01 april 2011 www.richtek.com richtek technology corporation headquarter 5f, no. 20, taiyuen street, chupei city hsinchu, taiwan, r.o.c. tel: (8863)5526789 fax: (8863)5526611 richtek technology corporation taipei office (marketing) 5f, no. 95, minchiuan road, hsintien city taipei county, taiwan, r.o.c. tel: (8862)86672399 fax: (8862)86672377 email: marketing@richtek.com information that is provided by richtek technology corporation is believed to be accurate and reliable. richtek reserves the ri ght to make any change in circuit design, specification or other related things if necessary without notice at any time. no third party intellectual property infringemen t of the applications should be guaranteed by users when integrating richtek products into any application. no legal responsibility for any said applications is assumed b y richtek. dimensions in millimeters dimensions in inches symbol min max min max a 0.700 0.800 0.028 0.031 a1 0.000 0.050 0.000 0.002 a3 0.175 0.250 0.007 0.010 b 0.200 0.300 0.008 0.012 d 1.900 2.100 0.075 0.083 d2 1.550 1.650 0.061 0.065 e 2.900 3.100 0.114 0.122 e2 1.650 1.750 0.065 0.069 e 0.500 0.020 l 0.350 0.450 0.014 0.018 w-type 8l dfn 2x3 package 1 1 2 2 note : the configuration of the pin #1 identifier is optional, but must be located within the zone indicated. det ail a pin #1 id and tie bar mark options d 1 e a3 a a1 d2 e2 l b e see detail a outline dimension
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