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RT9502 1 ds9502-02 april 2011 www.richtek.com features z z z z z automatic input supplies selection z z z z z 18v maximum rating for ac adapter z z z z z integrated selectable 100ma and 500ma usb charge current z z z z z internal integrated p-mosfets z z z z z ac adapter power good status indicator z z z z z charge status indicator z z z z z under voltage protection z z z z z over voltage protection z z z z z automatic recharge feature z z z z z battery temperature monitoring z z z z z small 10-lead wdfn package z z z z z thermal feedback optimizing charge rate z z z z z rohs compliant and 100% lead (pb)-free pin configurations applications z digital cameras z cellular phones z personal digital assistants (pdas) z mp3 players z hand held pcs ordering information general description the RT9502 is a fully integrated low cost single-cell li- ion battery charger ic ideal for portable applications. the RT9502 is capable of being powered up from ac adapter and usb (universal serial bus) port inputs. the RT9502 can automatically detect and select the ac adapter and the usb port as the power source for the charger. the RT9502 enters sleep mode when both supplies are removed. the RT9502 optimizes the charging task by using a control algorithm including precondition mode, fast charge mode and constant voltage mode. the charging task is terminated as the charge current drops below the preset threshold. the usb charge current can be selected from preset ratings of 100ma and 500ma, while the ac adapter charge current can be programmed up to 1a with an external resister. the internal thermal feedback circuitry regulates the die temperature to optimize the charge rate for all ambient temperatures. the RT9502 features 18v and 7v maximum rating voltages for ac adapter and usb port inputs respectively. the other features are under voltage protection, over voltage protection for ac adapter supply and battery temperature monitoring. (top view) wdfn-10l 3x3 linear single cell li-ion battery charger ic with dual input supply 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. marking information for marking information, contact our sales representative directly or through a richtek distributor located in your area. acin usb gnd batt ts iseta isetu 9 8 7 9 1 2 3 4 5 10 gnd chg_s pgood en 11 RT9502 package type qw : wdfn-10l 3x3 (w-type) lead plating system p : pb free g : green (halogen free and pb free)
RT9502 2 ds9502-02 april 2011 www.richtek.com typical application circuit functional pin description pin no. pin name pin function 1 acin ac adaptor charge input supply. 2 usb usb charge input supply. 3 chg_s charge status indicator output (open drain). 4 pgood power good indicator output (open drain). 5 gnd ground. 6 iseta wall adaptor supply charge current set point. 7 isetu usb supply charge current set input (active low). 8 en charge enable input (active low). 9 ts temperature sense input. 10 batt battery charge current output. 11 (exposed pad) gnd the exposed pad must be soldered to a large pcb and connected to gnd for maximum power dissipation. RT9502 1uf ac adapter acin usb gnd batt ts iseta isetu usb 1uf + h : 500ma l : 100ma r set battery pack 1 2 3 4 5, exposed pad(11) 6 7 8 9 10 chg_s pgood en to system to system chip shutdown chip enable 0.1uf to 10uf pre-charge phase fast charge phase constant voltage phase & standby phase re-charge phase programmed charge current 4.1v recharge threshold 2.8v precharge threshold 1/10 programmed charge current charge complete battery voltage charging current
RT9502 3 ds9502-02 april 2011 www.richtek.com function block diagram charge input selection acin/usb acin usb iseta batt acin p-mosfet sense mosfet usb p-mosfet sense mosfet thermal sense v ref 2.5v 0.25v 0.5v 115 c gnd precharge loop controller + - 0.25v logic temperature sense temperature fault + - charge disable 0.9v 1ua ts termination comparator vcc/usb chg_s pgood en isetu 1ua 7.5k 1.5k v ref thermal sense v fb drv ovp + - 2.5v ovp comparator
RT9502 4 ds9502-02 april 2011 www.richtek.com table no yes yes yes no no yes yes no yes yes yes temp fault/chg_s high impedance v ts > 2.5v or v ts < 0.5v? v batt ~ 4.2v, i batt < 0.1 i chg ? v acin < v batt and v usb < v batt ? v acin > 6.5v or (v acin < 4.4v and v usb < 4.4v) ? v en > 1.4v ? disable mode p-mosfet off i batt =0 ovp/uvp mode p-mosfet off i batt =0 sleep mode p-mosfet off i batt =0 recharge i batt = 0.1 charge current /chg_s pull down standby pfet off v batt = 4.2v, i batt = 0 1ms delay i batt = charge current /chg_s pull down v batt > 4.1 v? v batt > 2.8v? acin/usb power up start-up precharge phase fast charge phase standby/fault recharge phase no RT9502 flow chart disable uvp / ovp sleep start-up no no
RT9502 5 ds9502-02 april 2011 www.richtek.com absolute maximum ratings (note 1) z acin input voltage -------------------------------------------------------------------------------------------------------- ? 0.3v to 18v z usb input voltage --------------------------------------------------------------------------------------------------------- ? 0.3v to 7v z en input voltage ----------------------------------------------------------------------------------------------------------- ? 0.3v to 6v z output current ------------------------------------------------------------------------------------------------------------- 1.2a z power dissipation, p d @ t a = 25 c wdfn-10l 3x3 ------------------------------------------------------------------------------------------------------------- 0.926w z package thermal resistance (note 2) wdfn-10l 3x3, ja ------------------------------------------------------------------------------------------------------- 108 c/w wdfn-10l 3x3, jc ------------------------------------------------------------------------------------------------------- 8.2 c/w z lead temperature (soldering, 10 sec.) ------------------------------------------------------------------------------- 260 c z junction te mperature ---------------------------------------------------------------------------------------------------- 150 c z storage temperature range -------------------------------------------------------------------------------------------- ? 65 c to 150 c z esd susceptibility (note 3) hbm (human body mode) ---------------------------------------------------------------------------------------------- 2kv mm (ma chine mode) ------------------------------------------------------------------------------------------------------ 200v electrical characteristics (acin = usb = 5v, t a = 27 c, unless otherwise specification) to be continued parameter symbol test conditions min typ max units supply input acin/usb uvp rising threshold voltage v uv_high -- 4.4 4.5 v acin/usb uvp hysteresis v uv_low 50 80 120 mv acin/usb standby current i stby v batt = 4.5v -- 300 500 ua acin/usb shutdown current i shd n v en = high -- 50 100 ua acin/usb uvp current i uvp v acin = 4v, v usb = 4v, v batt = 3v -- 150 250 ua batt sleep leakage current i sl eep v acin = 4v, v usb = 4v v batt = 4.5v -- 2 5 ua voltage regulation batt regulation voltage v reg i batt = 60ma 4.158 4.2 4.242 v regulation voltage accuracy ? 1 -- +1 % acin mosfet r ds(on)_aci n i batt = 500ma -- 600 -- m usb mosfet r ds(on)_usb i batt = 500ma -- 1200 -- m current regulation iseta set voltage (fast charge phase) v iseta v batt = 3.5v 2.42 2.5 2.55 v full charge setting range i chg_acin 100 -- 1200 ma recommended operating conditions (note 4) z acin, usb input voltage range --------------------------------------------------------------------------------------- 4.5v to 6v z junction temperature range -------------------------------------------------------------------------------------------- ? 40 c to 125 c z ambient temperature range -------------------------------------------------------------------------------------------- ? 40 c to 85 c
RT9502 6 ds9502-02 april 2011 www.richtek.com parameter symbol test conditions min typ max units acin charge current accuracy i chg_acin v batt = 3.8v; r iset = 1.5k -- 500 -- ma precharge batt pre-charge rising threshold v prech 2.6 2.8 3 v batt pre-charge threshold hysteresis v prech 50 100 200 mv pre-charge current i pc hg v batt = 2v 8 10 12 % recharge threshold batt re-charge falling threshold hysteresis v rech_l v reg ? v batt 60 100 150 mv charge termination detection iseta charge termination set voltage v term v batt = 4.2v 200 250 275 mv termination current ratio (default) i term v batt = 4.2v -- 10 -- % logic input/output chg_s pull down voltage v chg_s tbd; i chg_s = 5ma -- 65 -- mv pgood pull down voltage v pgood tbd; i pgood = 5ma -- 220 -- mv logic-high voltage v ih 1.5 -- -- v en threshold logic-low voltage v il -- -- 0.4 v en pin input current i en v en = 2v -- -- 2 ua high voltage v isetu_high 1.5 -- v isetu threshold low voltage v isetu_low -- -- 0.4 v isetu pin input current i isetu v isetu =2v -- -- 2 ua usb charge current & timing i chg(usb100) v usb = 5v; v batt = 3.5v, i setu = 0v -- -- 100 usb charge current i chg(usb500) v usb = 5v; v batt = 3.5v, i setu = 5v 400 450 500 ma battery temperature sense ts pin source current i ts v ts = 1.5v 96 102 108 ua low voltage v ts_low falling 0.485 0.5 0.515 v ts pin threshold high voltage v ts_high rising 2.45 2.5 2.55 v protection thermal regulation -- 125 -- c ovp set internal default -- 6.5 -- v
RT9502 7 ds9502-02 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 the natural convection at t a = 25 c on a high effective thermal conductivity test board (4 layers, 1s) of jedec 51-7 thermal measurement standard. the case point of jc is on the expose pad for the package. note 3. devices are esd sensitive. handling precaution is recommended. note 4. the device is not guaranteed to function outside its operating conditions.
RT9502 8 ds9502-02 april 2011 www.richtek.com typical operating characteristics v batt = 3.7v usb power off time (200us/div) i charge (0.5a/div) v usb (5v/div) v batt (2v/div) chg_s (5v/div) v batt = 3.7v usb power on time (250us/div) i charge (0.5a/div) v usb (5v/div) v batt (2v/div) chg_s (5v/div) v batt = 3.7v acin power on time (250us/div) i charge (0.5a/div) v acin (5v/div) v batt (2v/div) chg_s (5v/div) v batt = 3.7v acin power off time (500us/div) i charge (0.5a/div) v acin (5v/div) v batt (2v/div) chg_s (5v/div) acin = 0v to 10v, v batt = 3.7v acin ovp time (1ms/div) i charge (0.5a/div) v acin (10v/div) v batt (5v/div) chg_s (5v/div) acin ovp time (1ms/div) i charge (1a/div) v acin (5v/div) v batt (5v/div) acin = 5v to 8v to 5v, v batt = 3.7v chg_s (5v/div)
RT9502 9 ds9502-02 april 2011 www.richtek.com acin power off input voltage transition time (500us/div) i charge (1a/div) v acin (5v/div) v usb (5v/div) v batt = 3.7v chg_s (5v/div) input voltage transition time (500us/div) i charge (1a/div) v acin (5v/div) v usb (5v/div) acin power on v batt = 3.7v chg_s (5v/div)
RT9502 10 ds9502-02 april 2011 www.richtek.com application information automatically power source selection the RT9502 is a battery charger ic which is designed for li-ion battery with 4.2v rated voltage. the RT9502 can be adopted for two input power source, acin or usb input. it will automatically select the input source and operate in different mode as below. acin mode : when the acin input voltage (acin) is higher than the uvp voltage level (4.4v), the RT9502 will enter acin mode. in the acin mode, acin p-mosfet is turned on and usb p-mosfet is turned off. usb mode : when acin input voltage is lower than uvp voltage level and usb input voltage is higher than uvp voltage level (4.4v), the RT9502 will operate in the usb mode. in the usb mode, acin p-mosfet is turned off and usb p-mosfet is turned on. sleep mode : the RT9502 will enter sleep mode when both acin and usb input voltage are removed. this feature provides low leakage current from the battery during the absence of input supply. figure 1. input power source operation mode. acin over voltage protection the acin input voltage is monitored by an internal ovp comparator. the comparator has an accurate reference of 2.5v from the band-gap reference. the ovp threshold is set by the internal resistive. the protection threshold is set to 6.5v. when the input voltage exceeds the threshold, the comparator outputs a logic signal to turn off the power p-mosfet to prevent the high input voltage from damaging the electronics in the handheld system. when the input over oltage condition is removed (acin < 6v), the comparator re-enables the output by running through the soft-start. battery temperature monitoring the RT9502 continuously monitors battery temperature by measuring the voltage between the ts and gnd pins. the RT9502 has an internal current source to provide the bias for the most common 10k negative-temperature coefficient thermal resistor (ntc) (see figure 2). the RT9502 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_low thresholds is detected, the device will immediately stop the charge. the RT9502 stops charge and keep monitoring the battery temperature when the temperature sense input voltage is back to the threshold between vts_high and vts_low, the charger will be resumed. charge is resumed when the temperature returns to the normal range. however the user may modify thresholds by the negative-temperature coefficient thermal resistor or adding two external resistors. (see figure 3.) the capacitor should be placed close to ts(pin 9) and connected to the ground plane. the capacitance value (0.1uf to 10uf) should be selected according to the quality of pcb layout. it is recommended to use 10uf if the layout is poor if prevent noise. ts ts ntc ts ts v = i r turn off when v 2.5v or v 0.5v ? figure 2. temperature sensing configuration + 0.1uf to 10uf battery a ts temperature sense i ts v batt ntc acin mode usb mode v acin < uvp v usb > uvp sleep mode v acin < uvp v usb < uvp v acin > uvp
RT9502 11 ds9502-02 april 2011 www.richtek.com figure 3. temperature sensing circuit t2 t1 ntc ts ts t1 t2 ntc ts ts r(r + r) v = i r + r + r turn off when v 2.5v or v 0.5v ? + r t2 battery a ts temperature sense i ts v batt ntc r t1 0.1uf to 10uf set charge_ac set seta v i = k r fast-charge current setting case 1 : acin mode the RT9502 offers iseta pin to determine the acin charge rate from 100ma to 1.2a. the charge current can be calculated as following equation. the parameter k set = 300 ; v set = 2.5v. r seta is the resistor connected between the iseta and gnd. figure 4. acin mode charge current setting case 2 : usb mode when charging from a usb port, the isetu pin can be used to determine the charge current of 100ma or 500ma. a low-level signal of isetu pin sets the charge current at 100ma and a high level signal sets the charge current at 500ma. pre- charge current setting during a charge cycle if the battery voltage is below the vprech threshold, the RT9502 applies a pre-charge mode to the battery. this feature revives deeply discharged cells and protects battery life. the RT9502 internal determines the pre-charge rate as 10% of the fast-charge current. battery voltage regulation the RT9502 monitors the battery voltage through the batt pin. once the battery voltage level closes to the vreg threshold, the RT9502 voltage enters constant phase and the charging current begins to taper down. when battery voltage is over the vreg threshold, the RT9502 will stop charge and keep to monitor the battery voltage. however, when the battery voltage decreases 100mv below the v reg , it will be recharged to keep the battery voltage. charge status outputs the open-drain chg_s and pgood outputs indicate various charger operations as shown in the following table. these status pins can be used to drive leds or communicate to the host processor. note that on indicates the open-drain transistor is turned on and led is bright. charge state chg_s pgood charge on on acin charge done off on charge on off usb charge done off off 0 200 400 600 800 1000 1200 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5 r seta (k) charge current (ma) r seta (k )
RT9502 12 ds9502-02 april 2011 www.richtek.com temperature regulation and thermal protection in order to maximize the charge rate, the RT9502 features a junction temperature regulation loop. if the power dissipation of the ic results in a junction temperature greater than the thermal regulation threshold (125 c), the RT9502 throttles back on the charge current in order to maintain a junction temperature around the thermal regulation threshold (125 c). the RT9502 monitors the junction temperature, t j , of the die and disconnects the battery from the input if t j exceeds 125 c. this operation continues until junction temperature falls below thermal regulation threshold (125 c) by the hysteresis level. this feature prevents the chip from damage. selecting the input and output capacitors in most applications, the most important is the high- frequency decoupling capacitor on the input of the RT9502. a 1uf ceramic capacitor, placed in close proximity to input pin and gnd pin is recommended. in some applications depending on the power supply characteristics and cable length, it may be necessary to add an additional 10uf ceramic capacitor to the input. the RT9502 requires a small output capacitor for loop stability. a 1uf ceramic capacitor placed between the batt pin and gnd is typically sufficient. layout consideration the RT9502 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 RT9502. ` input capacitor should be placed close to ic and connected to ground plane. the trace of input in the pcb should be placed far away the sensitive devices or shielded by the ground. ` the gnd should be connected to a strong ground plane for heat sinking and noise protection. ` the connection of r seta should be isolated from other noisy traces. the short wire is recommended to prevent emi and noise coupling. figure 5 9 8 7 9 1 2 3 4 5 10 gnd c3 c4 c2 c1 acin usb gnd chg_s pgood batt ts iseta isetu en r seta battery gnd the capacitor should be placed close to ic pin and connected to ground plane. the gnd should be connected to a strong ground plane for heat sinking and noise protection. the connection of r seta should be isolated from other noisy traces. the short wire is recommended to prevent emi and noise coupling. the ts's capacitor should be placed close to ts(pin 9) and connected to ground plane. the capacitance (0.1uf to 10uf) base on pcb layout. when pcb has poor layout the 10uf is recommended to prevent noise. ` output capacitor should be placed close to ic and connected to ground plane to reduce noise coupling. ` the ts's capacitor should be placed close to ts (pin 9) and connected to ground plane. the capacitance (0.1uf to 10uf) base on pcb layout. when pcb has poor layout, the 10uf is recommended to prevent noise.
RT9502 13 ds9502-02 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 inf ringement of the applications should be guaranteed by users when integrating richtek products into any application. no legal responsibility for any said applications i s assumed by richtek. outline dimension 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 0.180 0.300 0.007 0.012 d 2.950 3.050 0.116 0.120 d2 2.300 2.650 0.091 0.104 e 2.950 3.050 0.116 0.120 e2 1.500 1.750 0.059 0.069 e 0.500 0.020 l 0.350 0.450 0.014 0.018 w-type 10l dfn 3x3 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

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