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AIC1781A battery charge controller analog integrations corporation 4f, 9 industry e. 9th rd, science - based industrial park, hsinchu, taiwan ds - 178 1ap - 01 011604 tel: 886 - 3 - 5772500 fax: 886 - 3 - 5772510 www.analog.com.tw 1 n features l fast charge control of nimh/nicd batteries, even with a fluctuating charging current. l fast charge termination by: d d t / t , - d v , 0 v d , safety timer, maximum temperature, maximum vol t age. l lin early adjustable d d t / t detection slope and safety timer. l adjustable peak voltage timer for 0 v d . l battery voltage protection range s e lectable. l selectable battery temperature protection mode. l protection against battery volta ge and battery te m perature faults. l selectable led display mode for battery status. l five pulsed trickle charge modes. l discharge - before - charge function available for eliminating memory effect. l quick and easy testing for production. l 16 - pin dip or so packages. n applications battery fast chargers for: l mobile phones. l notebook and laptop personal computers. l portable power tools and toys. l portable communication equipments. l portable video & stereo equipments. 0 10 20 30 40 50 60 1.15 1.25 1.35 1.45 1.55 100 80 60 40 20 temperature ( c ) temperature cell voltage cell voltage (v) charge time (min.) charge current = 600 ma cell capacity = 550 ma nimh battery fig. 1 battery charging cha racteristics resulting from an AIC1781A - controlled charger with a flu c tuating charging current n description the AIC1781A fast charge controller ic is designed for intelligent charging of nimh or nicd batteries without the risk of overcharge. - d v detection ( - 0.25%), 0 v d detection (peak voltage timer) and d d t / t detection are the primary methods e m ployed by the AIC1781A to terminate fast charge. the fast charge can also be cut off by maximum battery volta ge and maximum battery temperature dete c tion along with the safety timer to prevent charging under fault conditions of the charging system or the battery i t self. both d d t / t and - d v detection methods have been proved power ful in terminating fast charging for nimh and nicd batteries. the AIC1781A utilizes the combination of these two methods to achieve reliable decision of ending fast charge and prevent misacting caused by using - d v detection alone under ce rtain conditions. fig. 1 shows an example of charging curve of a battery charged by a fluctuating current from a nimh battery charger, which uses the AIC1781A controller ic to achieve optimal charging. this technique, in cooperating with the 0 v d dete c tion (peak voltage timer), is particularly suitable for nimh batteries, whose voltage drop is hardly signif i cant yet temperature rises rapidly. the d d t / t or - d v detection circuitry may be disabled indepen d entl y for di f ferent applications, such as system - integrated chargers, chargers with varying charge current, or battery packs lack of temperature sensing thermi s tor. the safety timer period, mode of battery temper a ture protection, battery voltage protection ra nge, pulsed trickle charge duty, and led display mode are all adjustable or selectable.
AIC1781A 2 di s charge - before - charge function is included to get rid of memory e f fect of nicd batteries without the risk of overdi s charging. test mode is provided for charger man u fa ctures to dramatically reduce pr o duction test time. n typical application circuit peak 1 vbt 2 dis 3 vts 4 vcc 5 adj 6 sel3 7 tmr 8 mode 9 sel2 10 sel1 11 gnd 12 led1 13 led2 14 icon 15 dsw 16 u2 aic1781 a r 8 30 0k r 9 91 k r10 100k + c9 4.7 m f c7 0.1 m f c10 47nf r15 680 r3 270 r2 20/5w sw1 pb sw r12 100k r16 680 r17 680 r14 200k c8 0. 1 m f + c11 100 m f rx r11 100k ry c6 0.1 m f r13 470k q2 mmbt2222a r 6 50k led2 green led3 red led1 yellow q1 mps2222a + c4 220 m f c5 0 .1 m f + c12 1 m f + c13 10 m f r5 120/0.5w r1 1k bat1 ** b attery r7 thermistor vin 11~15v l1 220 m h c2 1 m f c1 47 0p r s 0.3/1w 1 2 3 gnd 4 fb 5 vcc dc de cf 6 is 7 boost 8 u1 aic1563 + c3 220 m f r4 390k d3 in4148 d1 in4148 d2 in 5819 d4 1n5819 vin vout gnd u3 78l05 ** 3~5 nimh/nicd cells. note: charge current=0.3/rs ampere safety timer: 80min battery charge circuit for fluctuating charging current application
AIC1781A 3 n ordering information 16 14 15 10 12 11 13 top view pin configuration 9 1 3 2 5 7 6 4 8 peak vbt dis vts vcc adj sel3 sel1 sel2 mode led1 gnd tmr dsw icon led2 packing type tr: tape & reel tb: tube package type n : plastic dip s: s mall outline c: commercial p: lead free commercial (available for ps only) example: aic1781cstr in so - 16 package & tape & reel packing type (cn is not available in tr packing type) aic1781pstr in so - 16 lead free package & tape & reel packing type aic178 1axx xx n absolute maximum ratings supply voltage ............................................???? . ....................................... 5.5v dc voltage applied on any pin ......................????? . ..................................... 5.5v sink current of icon pin, led1 and led2 pi n .......................???.................. 20ma operating temperature range .....................................????? . ............. 0 c~ 70 c storage temperature range .............................................???? . ..... - 65 c~ 150 c n test circu it peak dsw vbt icon dis led2 vts led1 vcc gnd adj sel1 sel3 sel2 tmr mode v2 (3v) v1 (0.95v) v cc v cc (5v) v cc green orange red 560 aic1781 a r2 - + - + yellow voltage source voltage source v cc v cc v cc v cc 100k r1 560 560 r3 r4 560 r5
AIC1781A 4 n electrical characteristics (t a =25 c , v cc =5v, unless otherwise spec i fied.) parameter test cond i tions symbol min. typ. max. unit supply voltage v cc 4.5 5.0 5.5 v supply current i cc 1.1 ma ba ttery low during initial timer 0.11 0.16 0.21 after initial timer (sel3>3v) 0.63 0.69 0.75 (sel3<2v) 1.1 1.2 1.30 battery high (sel3>3v) 2.6 2.7 2.80 voltage protection limit (sel3<2v) v bt 1.9 2.0 2.10 v temperature h igh 1.35 1.45 1.55 temperature sense limit temperature low v ts 3.5 3.6 3.70 v output impedance of dis pin z dis 50 100 w led1, led2, icon p ins output impe d ance on off 1 25 50 w m w source current c a pability sel3 pin dsw pin i sel3 i dsw 5.5 90 m a mode, peak, sel1, sel2 pins 300 k w input impeda nce vbt, vts, adj pins 1 m w recommended external resistor of tmr pin r tmr 2 100 1000 k w - d v detection level w.r.t.* peak value - 0.25 % * w.r.t.: with respect to
AIC1781A 5 n typical performance characteristics (t a =25 c , r2=100k w , v cc =5v, refer to test circuit) 4.4 4.6 4.8 5.0 5.2 5.4 0.84 0.90 0.96 1.02 1.08 supply current (ma) v cc (v) fig. 2 supply current vs. supply voltage safety timer (min) v cc (v) fig. 3 safety timer vs. supply voltage 4.4 4.6 4.8 5.0 5.2 5.4 5.6 78.0 78.5 79.0 79.5 80.0 80.5 81.0 81.5 v cc (v) frequency (hz) fig. 4 led flashing frequency vs. supply voltage 4.4 4.6 4.8 5.0 5.2 5.4 5.6 3.6 3.8 4.0 4.2 4.4 supply current (ma) temperature ( c) fig.5 supply current vs. temperature 0 20 40 60 80 0.80 0.85 0.90 0.95 1.00 1.05 temperature ( c) safety timer (min) fig. 6 safety timer vs. temperature 0 20 40 60 80 75 76 77 78 79 80 81 82 frequency (hz) temperature ( c) fig. 7 led flashing frequency vs. temperature - 20 0 20 40 60 80 3.4 3.6 3.8 4.0 4.2 4.4 4.6 4.8 5.0
AIC1781A 6 n typical performance characteristics (co ntinued) temperature ( c) v bt (v) fig. 8 vbt (high) limit vs. temperature (sel3>3v) 0 20 40 60 80 2.60 2.64 2.68 2.72 2.76 2.80 temperature ( c) v bt (v) fig. 9 vbt (high) limit vs. temperature (sel3<2v) 0 20 40 60 80 1.92 2.04 2.16 2.28 0 20 40 60 80 0.12 0.14 0.16 0.18 0.20 temperature ( c) v bt (v) fig.10 vbt (low) limit vs. temperature (during initial timer) 0 20 40 60 80 21 24 27 30 33 temperature ( c) output impedance (o) fig.11 output impedance vs. temperature (led1, led2, icon pins) 0 20 40 60 80 3.2 3.4 3.6 3.8 4.0 temperature ( c) v bt (v) fig.12 vts (low temp) limit vs. temperature 0 20 40 60 80 1.35 1.40 1.45 1.50 1.55 temperature ( c) v ts ( v ) fig.13 v ts (high temp) limit vs. temperature
AIC1781A 7 temperature ( c) v bt (v) fig. 14 v bt (low) limit vs. temperature (sel3>3v, after initial timer) 0 20 40 60 80 0. 64 0.68 0. 72 0. 76 0. 80 0.8 4 temperature ( c) v bt ( v ) fig.15 vbt (low) limit vs. temperature (sel3<2v, after initial timer) 0 20 40 60 80 1.0 1.1 1.2 1.3 1.4 1.5 n block diagram charge control state machine sel1 sel2 adj sel3 icon led1 led2 vts vbt dsw dis discharge control unit battery voltage protection 13-bit a/d battery temp. protection display control unit tmr oscillator vcc gnd bandgap reference & voltage regulator peak mode mode selection peak voltage timer control battery voltage & temperature portection setting led?s display & trickle pulse duty setting d t/ d t detection setting charge control unit
AIC1781A 8 n pin descriptions pin 1: peak - tri - level input, determining the period of peak voltage timer. (see 0 d v cut - off section in application informations.) pin 2: vbt - divided battery voltage input to sense the battery voltage. pin 3: dis - p ush - pull output, used to control an external transistor to discharge the battery. dis is active high when the AIC1781A enters discharge mode. pin 4: vts - the battery cell temperature is represented as a voltage input to the AIC1781A at this pin. the accept able voltage range of vts pin is 0.29v cc to 0.72v cc . the battery temperature is regarded as too high if the voltage of vts pin is lower than 0.29v cc , and is otherwise regarded as too low if the voltage of vts pin is higher than 0.72v cc . pin 5: vcc - power s upply input at 5v 10%. pin 6: adj - for adjusting the slope of d t/ d t. acceptable voltage range for this pin is approximately 0.28v to 3.8v. if voltage higher than vcc - 0.3v, the function of d t/ d t detection is disabled. pin 7: sel3 - determine the acceptable voltage range of vbt pin and mode of temperature protection function. pin 8: tmr - determine the period of safety timer with an external resistor connected to gnd. pin 9: mode - determine the mode of oper a tion for the AIC1781A. pin 10: sel2 - tri - level inp uts, that jointly co n trol the led display mode and the duty of trickle charge after the completion of fast charge. pin 11: sel1 - the same as pin 10. pin 12: gnd - power ground. pin 13: led1 & pin 14: led2 - open - drained outputs used to i n dicate the batt ery charging status. two modes of display are available, depending on the se t ting of sel1 and sel2 pins. pin 15: icon - open - drained output, used to control the charging current to the ba t tery. pin 16: dsw - controlling the function of di s charge - before - cha rge. (see di s charge - before - charge subsection in application info r mations).
AIC1781A 9 n application informations l the AIC1781A operation power - on and battery pre - qualif y ing when power is first applied to the AIC1781A, all i n ternal digital circuit blocks of the a ic1781a are r e set by the internal power - on - reset circuitry and output leds (depending on the setting of sel1 and sel2 pins) flash 3 times to indicate the initi a tion of power - on. the internal control unit then e x amines the battery condition through the vbt and vts pins. the acceptable limits of vbt pin is determined by the input voltage of sel3 pin and the acceptable temperature sense voltage window for vts pin is 0.29 v cc to 0.72 v cc . if the voltage of vbt pin fails to fall within the predetermined acceptab le limits, the AIC1781A enters a charge - suspending mode, in which all the internal circuitry remains in reset state. if the voltage of vts pin is outside the 0.29 v cc to 0.72 v cc window, action of AIC1781A is determined by the i n put voltage of sel3 pin. di scharge - before - charge the AIC1781A provides the function of discharge - before - charge to precondition nicd batteries which suffer from memory effect. this function can only be activated after the pre - qualification of battery voltage and temperature, yet befo re the charge completion is registered for the fast cha r ge cycle. to trigger this function, dsw pin has to be biased to gnd for over 0.18 second. after discharge b e gins, led1 and led2 pins are both off, icon pin is on, and dis pin goes high to activate an exte r nal circuit to discharge the battery until the voltage of vbt pin falls below 0.9v (or 0.69v, depending on the input voltage of sel3 pin) or dsw pin is biased to gnd for over 0.18 second again. fast charge will automatically start after discharge is finished. the application circuit is included in typical application circuit. fast charge after the battery passes fault checks and required discharging of the battery is completed, fast charging begins while initial timer and safety timer of the AIC1781A start counting. functions of - d v detection, peak voltage timer, t t/ d d detection, and maximum battery voltage are, however, di s abled temporarily until the initial timer period in the initial stage of a charge cycle elapses. the initial time r period is equal to 1/80 of safety timer. since the low limit of acceptable vbt voltage is only about 0.16v during the initial timer period, even deeply discharged batteries can easily qua l ify to be fast charged subsequently. in the course of fast charge, the AIC1781A co n stantly monitors the voltages at vbt and vts pins. the fast charge process is switched to trickle charge when any one of the following situations is encountered, which are explained b e low: l negative delta voltage ( - d v) l peak voltage timer ( 0 v d ) l delta temperature/ delta time ( d t/ d t) l maximum charge time l maximum battery voltage l maximum battery temperature - d v cutoff the AIC1781A makes a voltage sampling at vbt pin every 4 seconds when safety timer period is set equal to 80 minu tes. if a negative delta voltage of 0.25% compared to its peak value is detected at vbt pin, the fast charge cycle is term i nated. 0 d v cutoff if the battery voltage stays at its peak value or d e creases very slowly for the duration determined
AIC1781A 10 by the peak vo ltage timer, which is in turn determined by peak pin voltage, the fast charge action is term i nated. d t/ d t cutoff the t t/ d d detection of the AIC1781A is performed by sensing the decrease of vts pin voltage in a specific timer interval dicta ted by the safety timer. the fast charging terminates when the decrease of vts pin voltage in 56 seconds exceeds the predetermined value set by adj pin input. this time interval of 56 seconds is based on the a s sumption that voltage of vts pin is sampled on ce for every 8 seconds, which is also determined by safety timer. functioning of - d v detection and peak voltage timer ( 0 v d ) can be disabled if the mode pin is biased to gnd. functioning of t t/ d d detection can be disabled i f the voltage of adj pin is higher than v cc - 0.3v. maximum safety timer cutoff the maximum fast charge period is determined by the safety timer, which is set by a resistor co n nected from tmr pin to gnd. safety timer, - d v sampling rate, and t t/ d d sampling rate will be longer if the resistor value is larger. when the value of the resistor is 100k w , the safety timer p e riod equals 80 minutes. this can be verified by b i asing mode pin to v cc and the measured fr e quency on dsw pin should be aroun d 32.8 khz. after the safety timer period is finished, the fast charge action is term i nated. maximum voltage and temperature cu t off the AIC1781A guards against the maximum limits for battery voltage and temperature during fas t charging. if either of these limits is exceeded, fast charge action is term i nated. trickle charge there are five different selectable duty cycles for trickle charge after the fast charge to prevent the loss of charge due to battery self - discharging. the duty cycle is controlled by the setting of sel1 and sel2 pins. the functions and charging states control mentioned above are illustrated in the fun c tion flow chart of AIC1781A (fig. 16 ) l design guide selecting peak voltage timer (0 d v) the voltage of peak pin along with safety timer de termines the period of peak voltage timer. it can be selected according to the follo w ing table: table 1 peak pin peak voltage timer v cc 1.5% of safety timer floa t ing 3.7% of safety timer gnd 6% of safety timer battery voltage mea s urement the AIC1781A measures the battery voltage through vbt pin, which is connected to battery positive terminal through a resistor - divider ne t work, as shown in fig. 17 . the input voltage of sel3 pin determines the acceptable limit of divided battery voltage. v bat ra rb c5 4.7 m f 2 r5 100k c6 0.1 m f aic1781 a vbt + fig. 17 battery voltage divider for sel3 > (v cc /2) + 0.4v, the suggested divider resistance of ra and rb for the corresponding number of ba t tery cells are as below:
AIC1781A 11 table 2 battery cells ra/rb ra (k w ) rb (k w ) 2~4 2 240 120 3~6 3.3 300 91 4~8 4.9 300 62 5~10 6.4 300 47 6~12 7.8 310 39 8~16 10.8 390 36 for sel3 < (v cc /2) - 0.4v, the suggested divider resistance of ra and rb for the corresponding number of battery cells are as below: table 3 battery cells ra/rb ra(k w ) rb (k w ) 2 1 240 240 3 2 240 120 4 3 240 80 5 4 300 75 6 5 300 60 8 7 360 51 10 9 360 40 12 11 390 36 16 15 410 27 battery temperature measurement the AIC1781A employs a negative temperature c o efficient (ntc) thermistor to measure the battery?s temperature. the the rmistor is inherently nonlinear with respect to temperature. to reduce the effect of nonlinearity, a resistor - divider network in para l lel with the thermistor is recommended. a typical application circuit is shown in fig. 18 . v bat 4 rx c7 0.1 m f v cc ry 5 vcc gnd 12 thermistor vts aic1781 a fi g. 18 battery temperature sense circuit with a negative temperature coefficient (ntc) thermistor
AIC1781A 12 power on led flash 3 times if vbt in normal range if vntc<0.72 vcc if vntc>0.29vcc if discharge enabled led's display abnormal, icon on, safety timer reset if sel3>vcc-0.3v or vcc/2-0.4v>sel3 >1.4v if discharge finished led's display fast charge, icon off safety timer counts if initial timer finished if peak timer period has finished if 0.25% decline of vbt is detected if d t/ d t has reached if safety timer period has finished led's display battery fulll, fast charge finished, trickle charge starts d t/ d t detector, - d v detector, peak timer are all disabled led's display, abnormal, icon on, safety timer reset if sel3>vcc-0.3v or vcc/2-0.4v>sel3 >1.4v battery replacement battery replacement no no yes yes no yes yes yes no no yes no yes no no yes yes yes yes yes no no no yes yes no no no d t/ d t disabled fig. 16 function flow chart of AIC1781A
AIC1781A 13 the calculation for rx and ry in the circuit is as fo l lowing. 0.29 v cc = ) r (ry// rx ry//r th th + x v cc r th = the resistance of thermistor at upper limit of temperature pr o tection. 0.72 v cc = ) r (ry// rx ry//r tl tl + x v cc r tl = the resistance of thermistor at lower limit of temperature prote c tion. substitution and rearranging the equations yield rx= 2.061 - r r r r tl th tl th ry = 5 . 3 r r r 6 . 3 r tl th tl th - if temperature characteristic of the thermistor is like that of semitec 103at - 2, the resistance of rx and ry is tabulated for different tl and th as b e low. (note: tl is lower temperature limit and th is u p per te m perature limit.) table 4 values of rx and ry at tl = 0 c th ( c ) rx(k w ) ry (k w ) 50 10.1 551.1 51 9.7 300.7 52 9.4 204.8 53 9.0 153.9 54 8.7 122.8 55 8.4 101.8 56 8.1 86.5 57 7.8 75.0 58 7.5 66.0 59 7.2 58.7 60 7.0 52.8 61 6.8 47.8 62 6.5 43.6 63 6.3 39.9 64 6.1 36.8 65 5.9 34.0 66 5.7 31.6 67 5.5 29.5 68 5.3 27.5 69 5.2 25.8 70 5.0 24.3 table 5 values of rx and ry at tl = - 10 c th ( c ) rx (k w ) ry (k w ) 45 11.4 95.6 46 11.0 85.0 47 10.6 76.2 48 10.2 68.9 49 9.8 62.8 50 9.5 57.5 51 9.1 52.9 52 8.8 48.8 53 8.5 45.3 54 8.2 42.1 55 7.9 39.4 56 7.6 36.8 57 7.4 34.6 58 7.1 32.5 59 6.9 30.7 60 6.7 29.0 61 6.4 27.4 62 6.2 26.0 63 6.0 24.6 64 5.8 23.4 65 5.6 22.2 setting the adj pin voltage the slope of d t/ d t detection is determined by adj pin voltage of the AIC1781A. the calculation of adj pin vo ltage is shown in the fo l lowing procedure followed by an example.
AIC1781A 14 procedure (a) first, determine the temperature protection limits th and tl. then, substitute th & tl into the fo l lowing equation: tl th 0.43v tl th 0.29v 0.72v t v cc cc cc base ts - = - - = d d (b) determine the safety timer to o btain the value of d t base . .) (min timer safety .) (min 80 56(sec.) = (sec.) t base d (c) determine the expected slope of d d t / t at which temperature rises y c in x seconds and fast charge is subs e quently cut off. d d t t y x = (d) calculate the value of v adj base base ts adj t t t t v 30 v d d d d d = example (a) let th=50 c , tl=0 c , v cc =5v. we have d d v t 0.43 5 50 0 0.043v/ c ts base = - = which means that v ts decreases 43mv as te m perature rises 1 c . (b) if safety timer is equal to 80 minutes, d t base is then 56 seconds. (c) if fast charge should be termina ted when te m perature rises 1 c in 60 seconds, then 0.0166 60 1 = t t/ = d d (d) v adj =30 x 0.043x 0.0166 x 56 = 1 .2 (v) if the temperature range is from 0 c to 50 c , the voltage of v adj under different setting conditions should be set as tab u lated below. tab le 6 adj pin voltage (tl=0 c, th=50 c ) d d t / t s.t. 0.75 ( c /min.) 1.0 ( c /min.) 1.25 ( c /min.) 40 min. (2c) 0.45 0.60 0.75 80 min. (1c) 0.90 1.20 1.50 120 min. (0.67c) 1.35 1.80 2.25 160 min. (0.5c) 1.80 2.40 3.01 200 min. (0.4c) 2.25 3.01 3.76 240 min. (0.33c) 2.70 3.61 4.51 a similar table for temperature range from 0 c to 60 c is as below. table 7 adj pin voltage (tl=0 c , th=60 c ) d d t / t s.t. 0.75 ( c /min.) 1.0 ( c /min.) 1.25 ( c /min.) 40 min. (2c) 0.37 0.50 0.6 2 80 min. (1c) 0.75 1.00 1.25 120 min. (0.67c) 1.12 1.50 1.88 160 min. (0.5c) 1.50 2.00 2.50 200 min. (0.4c) 1.88 2.50 3.13 240 min. (0.33c) 2.25 3.01 3.76 vbt range and temper a ture protection the acceptable voltage range of vbt pin and mode of temp erature protection function is dete r mined by the voltage of sel3 pin, shown as the following: (a) sel3 > v cc - 0.3v acceptable vbt range: before initial timer: 0.16v~2.7v after initial timer: 0.69v~2.7v temperature protection mode: entering charge - susp ending mode when te m perature is either too low or too high, same as a b normal battery vol t age. latch for charge - suspending function is provided for high temper a ture protection, but not for low temperature prote c tion.
AIC1781A 15 (b) v cc - 1.4v> sel3 > v 2 cc + 0.4v acceptable vbt range: before initial timer: 0.16v~2.7v after initial timer: 0.69v~2.7v temperature protection mode: if temperature is too high, battery charging is r e garded as completed. if temperature is too low, function of d t/ d t detection i s disabled, just as thermistor is not exis t ing. (c) v 2 cc - 0.4v>sel3 >1.4v acceptable vbt range: before initial timer: 0.16v~2v after initial timer: 1.2v~2v temperature protection mode: entering charge - suspending mode when te m perature is either too low or too high, same as a b normal battery vol t age. latch for charge - suspending function is provided for high temper a ture protection, but not for low temperature prote c tion. (d) 0.3v> sel3 acceptable vbt range: before initial timer: 0.16v~2v af ter initial timer: 1.2v~2v temperature protection mode: if temperature is too high, battery charging is r e garded as completed. if temperature is too low, function of d t/ d t detection is disabled, just as thermistor is not existing. setting the period of sa f e ty timer the AIC1781A provides a method for linearly a d justing the period of safety timer with an external resistor connected from tmr pin to gnd. the r e lation between safety timer length and the external resistor (r tmr ) is shown in fig. 19 . the table f o l lowing shows the resistor values for some of the commonly chosen safety timer periods. also shown in the table are their corresponding oscillator frequencies. 0 100 200 300 400 500 0 200 400 600 800 r tmr (k w ) safety timer (min.) fig. 19 safety timer vs . r tmr table 8 r tmr (k w ) osc. freq.(khz ) safety timer (min.) 11 256 10 23 131 20 48 65.8 40 74 43.1 60 100 32.8 80 152 21.6 120 206 16.0 160 314 10.6 250 491 6.89 380 667 5.04 520 selecting mode of oper a tion the AIC1781A provides three modes of operation: normal, test, and ac mode de termined by the setting of mode pin according to table 9 . the AIC1781A will operate normally when the mode pin is left floating (a 0.1 m f capacitor is recommended to be tied to mode pin if the charge circuit works in a noisy environment). when the mode pin is biased to gnd, the function of - d v detection is disabled. when the mode pin is biased to vcc, the AIC1781A enters the test mode. the test mode can be used to significantly reduce production test time. for relevant informations please contact aic directl y.
AIC1781A 16 table 9 the operating mode of AIC1781A mode pin mode function vcc test safety timer period scaled down to 1/32....etc. floating normal normal operation gnd ac ?v d v detection di s abled the mode of led display and trickle charge the AIC1781A provides two led display modes and five - pulsed trickle charge modes. the tri - level inputs, sel1 and sel2 pins, as in the table 6 determine the modes of led display and trickle charge. table 10 mode of led display and trickle charge sel1 sel2 trickle charge duty le d display mode v cc v cc floating gnd n/a 1/32 1/64 type 1 type 1 type 1 floating v cc floating gnd 1/128 1/256 n/a type 1 type 1 type 2 gnd v cc floating gnd 1/32 1/64 1/128 type 2 type 2 type 2 display the battery charging status the AIC1781A provides tw o open - drained outputs, led1 and led2, to indicate the battery charging status. refer to the table of led display mode (table 10 ), depending on the setting of sel1 and sel2 pins, the outputs of led1 and led2 pins are shown in the following table: type 1 p ower on fast charging charge completed fault conditions led1 1hz on off off led2 off off on off type 2 power on fast charging charge completed fault conditions led1 1hz on off 4hz flashing led2 1hz 4hz flashing on off charging current control a s shown in the typical application circuit, the AIC1781A offers an open - drained output pin, icon pin, to control the charging current flow in fast charge state and switch on to inhibit the charging current flow in fault conditions. when fast charge is comp leted, the AIC1781A enters the trickle charge mode. in trickle charge mode, the icon pin output switches with predetermined duty cycle. refer to the table of trickle charge mode (table 6), the duty cycle is determined by the setting of sel1 and sel2 pins. the following table summarizes how icon pin corresponds to various charging states. power on fast charging charge completed fault conditions icon on off see pin 10 & 11 on test mode fig. 20 shows the timing diagram for externally controlled peak, adj, v bt, vts, sel1 and sel2 pin voltages of a recommended AIC1781A test scheme, utilizing test mode function. output waveforms of led1, led2 and icon of a properly functioning AIC1781A are also shown in the figure.
AIC1781A 17 n timing diagram floating floating safety timer test d t/ d t test floa ting gnd init. gnd gnd gnd floating vcc floating floating floating 4v ( - 0.15%) ( - 0.15%) ( - 2.5%) 4v on off 4v 2mv step/100ms 2mv step/100ms 1.993v ( - 0.35%) 2v 2v 1.95v on 1.9 7 v 2v 4v 2v 1.9v 1.997v 1.997v 1.5v vcc, sel3, mode=5v, (dsw freq.=820khz, 25 times of 32.8k) ( - 2.15%) 0v 1.85v 5v 5v 1.12v on on off 3.2khz on off on d t/ d t initial timer off off peak timer test - d v test off off on 2.14 9 0.4 8 0.12 4 0.28 0.12 2 0.02 10 0.32 5 0.32 0.7 0.32 0.2 3 0.24 0.1 0.5 7 0.12 6 5.92 6.02 6.04 3.78 3.38 3.14 2.64 1.94 1.62 0.74 0.54 1.5 1.18 0.86 0.26 0.14 0.14 1 icon vbt adj peak led2 led1 vts time (sec.) stage sel1 sel2 off on <2.1v 2v power on 3v 0v 0.1 0 2v 2v fig. 20 timing diagram of AIC1781A in test mode
AIC1781A 18 n physical dimensions (unit: mm) l 16 lead plastic so ( 300 mil) (cs ) (ps ) symbol min max a 2.35 2.65 a1 0.10 0.30 b 0.33 0.51 c 0.23 0.32 d 10.10 10.50 e 7.40 7.60 e 1.27(typ) h 10.00 10.65 h e e b c a a1 d l l 0.40 1.27 l 16 lead plastic dip ( cn ) symbol min max a1 0.381 ? a2 2.92 4.96 b 0.35 0.56 c 0.20 0.36 d 18.66 19.69 e 7.62 8.26 e1 6.09 7.12 e 2.54(typ) eb ? 10.92 b e l a2 a1 eb e c e1 d l 2.92 3.81 n ote: information provided by aic is believed to be accurate and reliable. however, we cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an aic product; nor for any infringement of patents or other rights of thi rd parties that may result from its use. we reserve the right to change the circuitry and specifications without notice. life support policy: aic does not authorize any aic product for use in life support devices and/or systems. life support devices or sy stems are devices or systems which, ( i ) are intended for surgical implant into the body or (ii) support or sustain life, and whose failure to perform, when properly used in accordance with instructions for use provided in the labeling, can be reasonably ex pected to result in a significant injury to the user.

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