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semiconductor technical data lithium battery protection circuit for one cell smart battery packs d suffix plastic package case 751 (so8) 8 1 18 7 6 5 2 3 4 (top view) cell voltage test ground charge pump output pin connections order this document by mc33348/d discharge gate drive output v cc charge gate drive output charge gate drive common/discharge current limit 1 motorola analog ic device data

the mc33348 is a monolithic lithium battery protection circuit that is designed to enhance the useful operating life of a one cell rechargeable battery pack. cell protection features consist of internally trimmed charge and discharge voltage limits, discharge current limit detection with a delayed shutdown, and a virtually zero current sleepmode state when the cell is discharged. an additional feature includes an onchip charge pump for reduced mosfet losses while charging or discharging a low cell voltage battery pack. this protection circuit requires a minimum number of external components and is targeted for inclusion within the battery pack. this mc33348 is available in standard soic 8 lead surface mount package. ? internally trimmed charge and discharge voltage limits ? discharge current limit detection with delayed shutdown ? virtually zero current sleepmode state when cells are discharged ? charge pump for reduced losses with a low cell voltage battery pack ? dedicated for one cell applications ? minimum components for inclusion within the battery pack ? available in a low profile surface mount package ordering information shown on following page. typical one cell smart battery pack this device contains 1170 active transistors. v cc charge pump output 8 charge gate drive output discharge gate drive output 4 6 5 charge gate drive common/ discharge current limit 7 1 3 2 ground test mc33348 cell voltage this document contains information on a new product. specifications and information herein are subject to change without notice. ? motorola, inc. 1997 rev 1
mc33348 2 motorola analog ic device data ordering information device charge overvoltage threshold (v) charge overvoltage hysteresis (mv) discharge undervoltage threshold (v) discharge current limit threshold (mv) operating temperature range package mc33348d1 420 300 225 400 t25 85 c so 8 mc33348d2 4 . 20 300 2 . 25 200 t25 85 c so 8 mc33348d3 425 300 228 400 t a = 25 to +85 c so 8 mc33348d4 4 . 25 300 2 . 28 200 t a = 25 to + 85 c so 8 mc33348d5 435 230 400 mc33348d6 4 . 35 2 . 30 200 note: additional threshold limit options can be made available. consult factory for information. maximum ratings ratings symbol value unit input voltage (measured with respect to ground, pin 3) v ir v cell voltage (pin 1) 7.5 test (pin 2) 7.5 discharge gate drive output (pin 4) 18 charge gate drive common/discharge current limit (pin 5) 11 charge gate drive output (pin 6) 11 v cc (pin 7) 7.5 charge pump output (pin 8) 10 thermal resistance, junctiontoair r q ja c/w d suffix, so8 plastic package, case 751 178 operating junction temperature (note 1) t j 40 to +150 c storage temperature t stg 55 to +150 c notes: 1. tested ambient temperature range for the mc33348: t low = 25 ct high = +85 c 2. esd data available upon request.
mc33348 3 motorola analog ic device data electrical characteristics (v cc = 4.0 v, t a = 25 c, for min/max values t a is the operating junction temperature range that applies (note 1), unless otherwise noted.) characteristic symbol min typ max unit voltage sensing cell charging cutoff (pin 1 to pin 3) overvoltage threshold, v cell increasing, t a = 25 c v th(ov) v 1 suffix 4.158 4.20 4.242 2 suffix 4.158 4.20 4.242 3 suffix 4.208 4.25 4.293 4 suffix 4.208 4.25 4.293 5 suffix 4.306 4.35 4.394 6 suffix 4.306 4.35 4.394 overvoltage hysteresis v cell decreasing v h mv 1 suffix 300 2 suffix 300 3 suffix 300 4 suffix 300 5 suffix 300 6 suffix 300 cell discharging cutoff (pin 1 to pin 3, t a = 25 c) undervoltage threshold, v cell decreasing v th(uv) v 1 suffix 2.205 2.25 2.295 2 suffix 2.205 2.25 2.295 3 suffix 2.234 2.28 2.326 4 suffix 2.234 2.28 2.326 5 suffix 2.254 2.30 2.346 6 suffix 2.254 2.30 2.346 input bias current during cell voltage sample (pin 1) i ib 28 m a cell voltage sampling rate t (smpl) 1.0 s current sensing discharge current limit (pin 3 to pin 5, t a = 25 c) threshold voltage v th(dschg) mv 1 suffix 360 400 440 2 suffix 180 200 220 3 suffix 360 400 440 4 suffix 180 200 220 5 suffix 360 400 440 6 suffix 180 200 220 delay i dly(dschg) 1.0 2.3 4.0 ms charge pump output voltage (pin 8, r l 10 10 , t a = 25 c) v o 8.0 10.2 12 v total device average cell current (t a = 25 c, battery pack unloaded and without current limit fault) i cc operating (v cc = 4.0 v) 17 20 m a sleepmode (v cc = 2.0 v) 2.0 na minimum operating cell voltage for logic and gate drivers v cc 1.5 v note: 1. tested ambient temperature range for the mc33348: t low = 25 ct high = +85 c
mc33348 4 motorola analog ic device data battery pack sleepmode range 10 4 10 3 10 0 0 1.0 2.0 3.0 5.0 10 2 10 1 10 6.0 4.0 12 5.0 1.0 0 2.0 3.0 8.0 4.0 0.4 0.8 0.4 0 0.8 0 16 8.0 8.0 4.0 10 2 10 6.0 12 1.0 0.8 0.6 0.2 0 0.4 8.0 4.0 10 12 100 40 20 20 40 0 60 80 9.0 8.0 11 100 40 20 20 40 0 60 80 100 40 20 20 40 0 60 80 10 1 1 2 3 16 1.2 1.2 typical threshold change typical threshold change maximum threshold charge limits v cc = 4.0 v v cc = 4.15 v v cc = 3.25 v v cc = 2.35 v c o = 10 nf t a = 25 c c o = 10 nf pin 2 = gnd r l 10 10 w t a = 25 c c o = 10 nf r l 10 10 w v cc = 4.15 v in regulation v cc = 2.35 v out of regulation battery pack operating range 1 battery pack unloaded without discharge current limit fault. 2 battery pack loaded without discharge current limit fault. 3 battery pack loaded or unloaded with discharge current limit fault. figure 1. charge and discharge threshold voltage change versus temperature figure 2. discharge current limit threshold voltage change versus temperature figure 3. gate drive output voltage versus load current figure 4. gate drive output voltage versus supply voltage figure 5. charge pump output voltage versus temperature figure 6. supply current versus supply voltage t a , ambient temperature ( c) t a , ambient temperature ( c) v o , gate drive output voltage (v) i l , output load current ( m a) v cc , supply voltage (v) i cc , supply current ( a) m v cc , supply voltage (v) t a , ambient temperature ( c) v o , gate drive output voltage (v) v o , charge pump output voltage (v) d v th(dschg) , current limit threshold d v th(ov & uv) , threshold voltage change (%) voltage change (%) t a = 25 c
mc33348 5 motorola analog ic device data protection circuit operating mode table outputs mosfet switches function input conditions cell status circuit operation battery pack status charge q1 discharge q2 charge pump cell charging/discharging storage or nominal operation: no current or voltage faults both charge mosfet q1 and discharge mosfet q2 are on. the battery pack is available for charging or discharging. on on active cell charging fault/reset charge voltage limit fault: v pin 1 v th(ov) for 1.0 s charge mosfet q1 is latched off and the cell is disconnected from the charging source. an internal current source pullup is applied to divider resistors r1 and r2 creating a hysteresis voltage of v h . the battery pack is available for discharging. discharge current limit protection is disabled. on to off on active charge voltage limit reset: v pin 1 < (v th(ov) v h ) for 1.0 s charge mosfet q1 will turn on when the voltage across the cell falls sufficiently to overcome hysteresis voltage v h . this can be accomplished by applying a load to the battery pack. discharge current limit protection is enabled. off to on on active cell discharging fault/reset discharge current limit fault: v pin 5 (v pin 3 + v th(dschg) ) for 3.0 ms and v pin 1 < (v th(ov) v h ) for 1.0 ms discharge mosfet q2 is latched off and the cell is disconnected from the load. q2 will remain in the off state as long as v pin 5 exceeds v pin 3 by v th(dschg) . the battery pack is available for charging. on on to off active discharge current limit reset: v pin 5 v pin 3 < v th(dschg) the sense enable circuit will reset and turn on discharge mosfet q2 when v pin 3 no longer exceeds v pin 5 by v th(dschg) . this can be accomplished by either disconnecting the load from the battery pack, or by connecting the battery pack to the charger. on off to on active discharge voltage limit fault: v pin 1 v th(uv) for three consecutive 1.0 s samples discharge mosfet q2 is latched off, the cells are disconnected from the load, and the protection circuit enters a low current sleepmode state. the battery pack is available for charging. on on to off disabled discharge voltage limit reset: v pin 3 > (v pin 5 + 0.6 v) the sense enable circuit will reset and turn on discharge mosfet q2 when v pin 3 exceeds v pin 5 by 0.6 v. this can be accomplished by connecting the battery pack to the charger. on off to on active faulty cell discharge voltage limit fault: v pin 1 1.5 v this condition can happen if the cell is defective (<1.5 v). the protection circuit logic will not function and the battery pack cannot be charged. disabled disabled disabled
mc33348 6 motorola analog ic device data cell voltage sample switch over/under cell voltage detector & reference over/under data latch & control logic charge/discharge gate drivers charge pump oscillator ck ck en charge pump output 8 charge gate drive output discharge gate drive output 4 6 5 charge gate drive common/ discharge current limit 7 v cc 1 3 ground r1 r2 r3 1.0 m mc33348 c o 0.01 discharge overcurrent detector 2 test discharge switch q2 charge switch q1 cell voltage 10 5.1 k sense enable 2.0 k figure 7. one cell smart battery pack cell c i 0.1 components c i is mandatory. refer to the battery pack application text. pin function description pin symbol description 1 cell voltage this input is connected to the positive terminal of the cell for voltage monitoring. internally, the cell voltage sample switch applies this voltage to a resistor divider where it is compared by the cell voltage detector to an internal reference. 2 test this pin is normally not connected and is used in testing the protection ic. an active low at this input resets the internal logic and turns on both mosfet switches. upon release, the logic becomes active and the cell voltage is sampled within 1.0 ms. 3 ground this is the protection ic ground and all voltage ratings are with respect to this pin. 4 discharge gate drive output this output connects to the gate of discharge switch q2 allowing it to enable or disable battery pack discharging. 5 charge gate drive common/discharge current limit this is a multifunction pin that is used to monitor cell discharge current and to provide a gate turnoff path for charge switch q1. a discharge current limit fault is set when the battery pack load causes the combined voltage drop of charge switch q1 and discharge switch q2 to exceed the discharge current limit threshold voltage, v th(dschg) , with respect to pin 3. 6 charge gate drive output this output connects to the gate of charge switch q1 allowing it to enable or disable battery pack charging. 7 v cc this pin is the positive supply voltage for the protection ic. 8 charge pump output this is the charge pump output. a reservoir capacitor is connected from this pin to ground.
mc33348 7 motorola analog ic device data introduction the insatiable demand for smaller lightweight portable electronic equipment has dramatically increased the requirements of battery performance. batteries are expected to have higher energy densities, superior cycle life, be safe in operation and environmentally friendly. to address these high expectations, battery manufacturers have invested heavily in developing rechargeable lithiumbased cells. today's most attractive chemistries include lithiumpolymer, lithiumion, and lithiummetal. each of these chemistries require electronic protection in order to constrain cell operation to within the manufacturers limits. rechargeable lithiumbased cells require precise charge and discharge termination limits for both voltage and current in order to maximize cell capacity, cycle life, and to protect the end user from a catastrophic event. the termination limits are not as well defined as with older nonlithium chemistries. these limits are dependent upon a manufacturer's particular lithium chemistry, construction technique, and intended application. battery pack assemblers may also choose to enhance cell capacity at the expense of cycle life. in order to address these requirements, six versions of the mc33348 protection circuit were developed. these devices feature charge overvoltage protection, discharge current limit protection with delayed shutdown, low operating current, a virtually zero current sleepmode state, and requires few external components to implement a complete one cell smart battery pack. operating description the mc33348 is specifically designed to be placed in the battery pack where it is continuously powered from a single lithium cell. in order to maintain cell operation within specified limits, the protection circuit senses both cell voltage and discharge current, and correspondingly controls the state of two nchannel mosfet switches. these switches, q1 and q2, are placed in series with the negative terminal of the cell and the negative terminal of the battery pack. this configuration allows the protection circuit to interrupt the appropriate charge or discharge path fet in the event that either a voltage threshold or the discharge current limit for the cell has been exceeded. 84 65 1 3 mc33348 cell charge mosfet q1 discharge mosfet q2 7 figure 8. one cell smart battery pack a functional description of the protection circuit blocks follows. refer to the detailed block diagram shown in figure 7. voltage sensing voltage sensing is accomplished by the use of the cell voltage sample switch in conjunction with the over/under voltage detector and reference block. the sample switch applies the cell voltage to the top resistor of an internal divider string. the voltage at each of the tap points is sequentially polled and compared to an internal reference. if a limit has been exceeded, the result is stored in the over/under data latch and control logic block. the cell voltage sample switch is gated on for a 1.0 ms period at a one second repetition rate. this low duty cycle sampling technique reduces the average load current that the divider presents across the cell, thus extending the useful battery pack capacity. the cell voltage limits are tested in the following sequence: figure 9. cell sensing sequence polling sequence time (ms) tested limit 1 0.5 overvoltage 2 0.5 undervoltage by incorporating this polling technique with a single comparator and voltage divider, a significant reduction of circuitry and trim elements is achieved. this results in a smaller die size, lower cost, and reduced operating current. figure 10. cell voltage limit sampling from cell voltage sample switch over/under cell voltage detector & reference discharge voltage threshold charge voltage threshold cell voltage return cell voltage + cell voltage r1 r2 r3 to cell negative terminal the cell charge and discharge voltage limits are controlled by the values selected for the internal resistor divider string and the comparator input threshold. as the battery pack reaches full charge, the cell voltage detector will sense an overvoltage fault condition when the cell exceeds the designed overvoltage limit. the fault information is stored in a data latch and charge mosfet q1 is turned off, disconnecting the battery pack from the charging source. an internal current source pullup is then applied to lower tap of the divider, creating a hysteresis voltage. as a result of an overvoltage fault, the battery pack is available for discharging only. the overvoltage fault is reset by applying a load to the battery pack. as the voltage across the cell falls below the hysteresis level, charge mosfet q1 will turn on and the current source pullup will turn off. the battery pack will now be available for charging or discharging.
mc33348 8 motorola analog ic device data as the load eventually depletes the battery pack charge, the cell voltage detector will sense an undervoltage fault condition when the cell falls below the designed undervoltage limit. after three consecutive faults are detected, discharge mosfet q2 is turned off, disconnecting the battery pack from the load. the protection circuit will now enter a low current sleepmode state. refer to figure 6. as a result of the undervoltage fault, the battery pack is available for charging only. the typical cutoff thresholds and hysteresis voltage are shown in figure 11. figure 11. cutoff and hysteresis limits device suffix charging cutoff (v) hysteresis (mv) disharging cutoff (v) 1, 2 4.20 300 2.25 3, 4 4.25 300 2.28 5, 6 4.35 300 2.30 the undervoltage logic is designed to automatically reset if less than three consecutive faults appear. this helps to prevent a premature disconnection of the load during high current pulses when the battery pack charge is close to being depleted. the undervoltage fault is reset by applying charge current to the battery pack. when the voltage on pin 3 exceeds pin 5 by 0.6 v, discharge mosfet q2 will turn on. the battery pack will now be available for charging or discharging. 84 6 5 3 mc33348 c dly r dly figure 12. additional discharge current limit delay the discharge current limit shutdown delay time is typically 3.0 ms. this time can be extended with the addition of components r dly and c dly . with an r dly of 5.1 k and c dly of 10 m f, the current limit shutdown time is extended to 40 ms. the additional discharge current limit delay circuitry must not be used if the anticipated opencircuit charger voltage will exceed 6.0 v. when the charger causes the battery pack input to exceed 6.0 v, additional current will flow out of pin 5, creating a voltage drop across resistor r dly . this voltage drop causes the source of mosfet q1 to fall below it's gate, allowing it to unexpectedly turn back on. current sensing discharge current limit protection is internally provided by the mc33348. as the battery pack discharges, pins 5 and 3 sense the voltage drop across mosfets q1 and q2. a discharge current limit fault is detected if the voltage at pin 5 is greater than pin 3 by 400 mv for 1, 3 and 5 suffix devices, or 200 mv for 2, 4 and 6 suffix devices. the fault information is stored in a data latch and discharge mosfet q2 is turned off, disconnecting the battery pack from the load. as a result of the discharge current fault, the battery pack is available for charging only. the discharge current limit is given by: i lim(dschg) v th(dschg) r lim(dschg) v th(dschg) r ds(on)q1 r ds(on)q2 the discharge current fault is reset by either disconnecting the load from the battery pack, or by connecting the battery pack to the charger. when the voltage on pin 5 no longer exceeds pin 3 by approximately v th(dschg) , the sense enable circuit will turn on discharge mosfet q2. c 10 r 5.1 k mc33348 cell 7 1 3 figure 13. power supply decoupling in order to guarantee proper discharge current limit operation when the battery pack output is shorted, power must be made available to the mc33348. this can be accomplished by decoupling the v cc input with the r/c component values shown above. the capacitor value must be increased to 100 m f if the discharge current limit shutdown delay time is extended to 40 ms as shown in figure 12. a small signal schottky diode can be used in place of r for enhanced short circuit operation. the diode cathode is connected to pin 7 and c, and the anode is connected to the positive terminal of the cell. the schottky diode solution may be a better choice in applications that have a charger with a relatively high open circuit voltage. these components can be deleted if operation of the discharge current limit is not required when the battery pack output is shorted.
mc33348 9 motorola analog ic device data as previously stated in the voltage sensing operating description, charge mosfet q1 is held off during an overvoltage fault condition. when this condition is present, the discharge current limit protection function is internally disabled. this is required, since the voltage across q1, in the off state, would exceed the current sense threshold. this would cause q2 to turn off as well, preventing both charging and discharging of the cell. discharge current limit protection is enabled whenever an overvoltage fault is not present. the discharge current protection circuit contains a built in response delay of 3.0 ms. this helps to prevent fault activation when the battery pack is subjected to pulsed currents during discharging. an additional current sense delay can be added as shown in figure 12. if the battery pack is subjected to extremely high discharge current pulses or is shorted, the v cc pin must be decoupled from the cell. this is required so that the protection circuit will have sufficient operating voltage during the load transient, to ensure turn off of discharge mosfet q2. figure 13 shows the placement of decoupling components. charge pump and mosfet switches the mc33348 contains an on chip charge pump to ensure that the mosfet switches are fully enhanced for reduced power losses. an external reservoir capacitor normally connects from the charge pump output to ground, pins 8 and 3. the capacitor value is not critical and is usually within the range of 10 nf to 100 nf. the charge pump output is regulated at 10.2 v allowing the use of the more economical logic level mosfets. the main requirement in selecting a particular type of mosfet switch is to consider the desired onresistance at the lowest anticipated operating voltage of the battery pack. a table of small outline surface mount devices is given in figure 14. when using extremely low threshold mosfets, it may be desirable to disable the charge pump so that the maximum gate to source voltage is not exceeded. this can be accomplished by connecting pin 6 to pin 5, and will result in an additional cell drain current of approximately 8.0 m a. testing a test pin is provided in order to speed up device and battery pack testing. by grounding pin 2, the internal logic is held in a reset state and both mosfet switches are turned on. upon release, the logic becomes active and the cell voltage is polled within 1.0 ms. battery pack application the one cell smart battery pack application shown in figure 7 contains a capacitor labeled c i that connects directly across the battery pack terminals. this component prevents excessive currents from flowing into the mc33348 when the battery pack terminals are shorted or arced, and is mandatory . capacitor c i is a 100 nf 20% ceramic leaded or surface mount type. it must be placed directly across the battery pack plus and minus terminals with extremely short lead lengths ( 1/16 ). in applications where inordinately low leakage mosfets are used, the protection circuit may take a considerable amount of time to reset from an overcurrent fault after the load is removed. this situation can be remedied by providing a small leakage path for charging c i , thus allowing pin 5 to rapidly fall below the discharge current limit threshold. a 1.0 megohm resistor placed across the mosfet switches accomplishes this task with a minimum increase in cell discharge current when the battery pack is connected to a load. figure 14. small outline surface mount mosfet switches device onresistance ( w ) versus gate to source voltage (v) type 2.5 v 3.0 v 4.0 v 5.0 v 6.0 v 7.5 v 9.0 v mmft3055vl 0.120 w 0.115 w 0.108 w 0.100 w mmdf3n03hd 0.525 w 0.080 w 0.065 w 0.063 w 0.062 w 0.060 w mmdf4n01hd 0.047 w 0.042 w 0.037 w 0.035 w 0.034 w 0.033 w 0.033 w mmsf5n02hd 0.065 w 0.023 w 0.021 w 0.020 w 0.018 w 0.018 w mmdf6n02hd 0.043 w 0.035 w 0.029 w 0.028 w 0.026 w 0.025 w 0.023 w
mc33348 10 motorola analog ic device data d suffix plastic package case 75105 (so8) issue s outline dimensions seating plane 1 4 5 8 a 0.25 m cb ss 0.25 m b m h c x 45 l dim min max millimeters a 1.35 1.75 a1 0.10 0.25 b 0.35 0.49 c 0.18 0.25 d 4.80 5.00 e 1.27 bsc e 3.80 4.00 h 5.80 6.20 h 0 7 l 0.40 1.25 0.25 0.50 notes: 1. dimensioning and tolerancing per asme y14.5m, 1994. 2. dimensions are in millimeters. 3. dimension d and e do not include mold protrusion. 4. maximum mold protrusion 0.15 per side. 5. dimension b does not include mold protrusion. allowable dambar protrusion shall be 0.127 total in excess of the b dimension at maximum material condition. d e h a b e b a1 c a 0.10
mc33348 11 motorola analog ic device data motorola reserves the right to make changes without further notice to any products herein. motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does motorola assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. atypicalo parameters which may be provided in motorola data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. all operating parameters, including atypicalso must be validated for each customer application by customer's technical experts. motorola does not convey any license under its patent rights nor the rights of others. motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the motorola product could create a situation where personal injury or death may occur. should buyer purchase or use motorola products for any such unintended or unauthorized application, buyer shall indemnify and hold motorola and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that motorola was negligent regarding the design or manufacture of the part. motorola and are registered trademarks of motorola, inc. motorola, inc. is an equal opportunity/affirmative action employer.
mc33348 12 motorola analog ic device data mfax is a trademark of motorola, inc. how to reach us: usa / europe / locations not listed : motorola literature distribution; japan : nippon motorola ltd.: spd, strategic planning office, 4321, p.o. box 5405, denver, colorado 80217. 13036752140 or 18004412447 nishigotanda, shinagawaku, tokyo 141, japan. 81354878488 customer focus center: 18005216274 mfax ? : rmfax0@email.sps.mot.com touchtone 1 6022446609 asia / pacific : motorola semiconductors h.k. ltd.; 8b tai ping industrial park, motorola fax back system us & canada only 18007741848 51 ting kok road, tai po, n.t., hong kong. 85226629298 http://sps.motorola.com/mfax/ home page : http://motorola.com/sps/ mc33348/d ?

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