www.siliconstandard.com 1 of 10 SS6821 single-cell lithium-ion battery protection ic features reduction in board size with miniature sot-23-5 package and few external components. ultra-low quiescent current of 7ma (v cc =3.5v). ultra-low power-down current of 0.6 m a (v cc =2.2v). precision over-charge protection voltage 4.3 5 v 5 0mv for the SS6821a 4.30v 50mv for the SS6821b 4. 25 v 5 0mv for the SS6821c 4. 20 v 5 0mv for the SS6821d built-in delay-time circuits for over -charge, over- discharge, and over-current protection. load detection function during overcharge mode. two detection levels for over-current protection. applications protection ic for single-cell lithium-ion batter y packs. description the SS6821 battery protection ic is designed to protect a lithium - i on batter y from damage or reduced lifetime due to over - charge, over-discharge, and/or over-current in single-cell lithium - ion battery powered systems, such as cellular phones. the ultra - small package and few external components make the SS6821 ideal for integration into the limited space of of a battery pack. the accurate 50mv over - charging detection voltage ensures safe and full-utilization charging. four different specification values for over - charge protection voltage are provided for various protection requirements. the very low standby current drains little current from the cell while in storage. typical application circuit batt - batt+ 100k 5 4 3 2 1 r2 r3 fuse c1 0. 1 m f r1 100 10 m m2 ssm9926 m1 ssm9926 battery o c cs od gnd vcc SS6821 protection circuit for single-cell lithium-ion battery 12/6/2004 rev.2.02
www.siliconstandard.com 2 of 10 SS6821 ordering information pin configuration example: SS6821-acvtr 4.35v version, in sot-23-5 package shipped in tape and reel sot-2 3- 5 top view vcc od gnd cs oc 321 45 packing: tr: tape and reel package type v: sot-23-5 overcharge protection: a: 4.35v b: 4.30v c: 4.25v d: 4.20v absolute maximum ratings supply voltage ....................................???????.................................................... 18v dc voltage applied on other pins ...............? ?????? ???.............................. 18v charger volta ge ..............? ????????.?? ??????................................ 14v operating temperature range .....................................? ????? . ............. - 40 c~ 85 c storage temperature range .........................? ?????? ..................... - 65 c~1 25 c test circuit 100k i cc v oc r3 10m v od v cc v cs r2 5 4 3 2 1 c1 0.1 m f r1 100 oc cs od gnd vcc SS6821 SS6821-xcxxx 12/6/2004 rev.2.02
www.siliconstandard.com 3 of 10 SS6821 electrical characteristics (ta=25c, unless otherwise specified.) parameter test conditions symbol min. typ. max. unit supply current v cc = 3.5 v i cc 7 11 m a power-down current v cc = 2.2 v, i pd 0. 6 1.0 m a SS6821a 4.30 4.35 4.40 SS6821b 4.25 4.30 4.35 SS6821c 4.20 4.25 4.30 over-charge protection voltage SS6821d v ocp 4.1 5 4.20 4.2 5 v over - charge hysteresis voltage v hys 230 300 370 mv over - discharge protection voltage v odp 2. 25 2. 4 2. 55 v over - discharge release voltage v odr 2.85 3.0 3.15 v over - current protection voltage v cc =3.5v v oip 180 200 220 mv over - charge delay time v cc =v ocp - 0.1 ? v ocp + 0.1v t oc 100 150 200 ms over - dis charge delay time v cc = 2.6v ? 2.2v t od 6 12 18 ms over - current delay time (1) v cc =3.5v, 1v>v cs >0.2v t oi1 6 12 18 m s over - current delay time (2) v cc =3.5v, v cs >1v t oi2 50 ms od pin output ? h ? voltage v dh v cc - 0. 2 v cc - 0.02 v od pin output ? l ? voltage v dl 0.01 0.1 v load de tection threshold voltage v cc =v ocp ? 50mv v ld 0.3 0.4 v charge detection threshold voltage v cc =2. 4 v v ch - 0.45 - 0.3 v 12/6/2004 rev.2.02
www.siliconstandard.com 4 of 10 SS6821 typical performance characteristics 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 6.4 6.8 7.2 7.6 8.0 t a=25 c supply current vs. supply voltage supply voltage (v) supply current ( m a) -40 -20 0 20 40 60 80 5 6 7 8 9 10 vcc=3.5v supply current vs. temperature supply current ( m a) t emperature ( c) -40 -20 0 20 40 60 80 0.54 0.57 0.60 0.63 0.66 vcc=2. 2 v power-down current vs. temperature power-down current ( m a) temperature ( c) -40 -20 0 20 40 60 80 4.24 4.26 4.28 4.30 4.32 4.34 4.36 SS6821b overcharge protection voltage vs. temperature overcharge protection voltage (v) temperature ( c) t emperature ( c) -40 -20 0 20 40 60 80 2. 38 2. 39 2. 40 2. 41 2. 42 overdischarge protection voltage vs. t emperature overdischarge protection voltage (v) temperature ( c) -40 -20 0 20 40 60 80 198 199 200 201 202 vcc=3.5v overcurrent protection voltage vs. temperature overcurrent protection voltage (mv) 12/6/2004 rev.2.02
www.siliconstandard.com 5 of 10 SS6821 typical performance characteristics (continued) -40 -20 0 20 40 60 80 3.90 3.95 4.00 4.05 4.10 overcharge release voltage vs. temperature overcharge release voltage (v) te mperature ( c) SS6821b temperature ( c) -40 -20 0 20 40 60 80 2.90 2.95 3.00 3.05 3.10 overdischarge release voltage vs. temperature overdischarge release voltage (v) -40 -20 0 20 40 60 80 125 130 135 140 145 overcharge delay time vs. temperature overcharge delay time ( ms) temperature ( c) temperature ( c) -40 -20 0 20 40 60 80 8 9 10 11 12 overdischarge delay time vs. t emperature overdischarge delay time ( ms) temperature ( c) -40 -20 0 20 40 60 80 8 9 10 11 12 vcc=3.5v overcurrent delay time 1 vs. temperature overcurrent delay time 1 ( ms) 12/6/2004 rev.2.02
www.siliconstandard.com 6 of 10 SS6821 block diagram power-down control wake-up control -0.3v 3 4 1 2 5 vcc overdischarge delay circuit overcharge delay circuit overcurrent delay circuit enable enable load detected 0.3v 0.2v cs gnd oc od 1.2v 1v pin descriptions pin 1: oc - pmos open drain output for control of the charge control mosfet m2. in normal mode, this pmos turns on to pu ll the gate of the mosfet m2 high, and the mosfet m2 turns on. when over - charge o ccurs, this pmos turns off, no current flows through r3 and the mosfet m2 turns off. pin 2 : gnd - ground pin. this pin is to be connected to the negative terminal of the battery cell. pin 3 : od - output pin for control of the discharge control mosfet m1. when over - discharge occurs, this pin goes low to turn off the mosfet m1 and discharging is halted . pin 4 : cs - input pin for current sensing. using the sum of the drain - source voltages of the mosfet m1 a nd the mosfet m2 (voltage between cs and gnd), it senses the discharge current during normal mode and detects whether charg ing current is present during the power - down mode. it is also used to detect whether the load is connected during over - charge mode. p in 5: vcc - power supply pin. this pin is to be connected to the positive terminal of the battery cell. 12/6/2004 rev.2.02
www.siliconstandard.com 7 of 10 SS6821 application information operation over - charge protection when the voltage of the battery cell exceeds the overcharge protection voltage (v ocp ) for longer than the overcharge delay time (t oc ) period, charging is halted by turning off t he charge control mosfet m2. the overcharge delay time is fixed to 100ms by circuitry internal to the ic . the over - charge condition is released in one of two ways : 1. the voltage o f the battery cell becomes lower than the over - charge release voltage (v ocr or v ocp - v hys ) through self - discharge. 2. the voltage of the battery cell falls below the over - charge protection voltage (v ocp ) because a load has been connected. when the battery voltage is abov e v ocp , the over - charge condition is never released even if a load is connected to the pack. over - discharge p rotection when the voltage of the battery cell goes below the over - discharge protection voltage (v odp ) for longer than the over - discharge delay time (t od ) period, discharging is halted by turning off the discharge control mosfet m1. the over - discharge delay time defaults to 10ms. discharging is immediately resumed when the voltage of the battery cell becomes higher than over - discharge release voltage (v odr ) through charging. over - current p rotection in normal mode, the SS6821 continuously monitors the discharge current by sensing the voltage of the cs pin. if the voltage of the cs pin exceeds the over - current protection voltage (v oip ) for longer than the ove r- current delay time (t oi ) period, the over - current protection circuit operates and discharging is halted by turning off of the discharge control mosfet m1. the over - current condition returns to the normal mode when the load is released and the impedan ce between the batt+ and batt - terminals is 1 m w or higher. the SS6821 is provided with two over- current detecti on levels (0.2v and 1v) and two over - current delay time s (t oi1 and t oi2 ) corresponding to each over - current detection level. load d etec tion after o vercharge the load detection function after over - charge is implemented by detecting the cs pin voltage. once a load is connected to the battery pack after an over - charge, discharge current flows through the parasitic diode of mosfet m2 and there is a diode voltage drop between cs and gnd. a l oad is determined to be connected to the pack if the cs pin voltage is above the load detection threshold voltage (v ld ). power - d own after o ver - discharge when an over-discharge occurs, the SS6821 will go into power - down mode, turning off all the timing generation and detection circuitry to reduce the quiescent current to 0. 6 m a (v cc =2.2v). at th e same time, the cs pin is pull ed high to vcc through a high resistance resistor. charge d etection after o ver - discharge when over - di scharge occurs, the discharge control mosfet m1 turns off and discharging is halted . however, charging is still permitted through the parasitic diode of m1. once the charger is connec ted to the battery pack, the SS6821 immediately turns on all the timing generation and detection circuitry. charging is determined to be in progress if the voltage between cs and gnd is below the charge detection threshold voltage (v ch ). . 12/6/2004 rev.2.02
www.siliconstandard.com 8 of 10 SS6821 design guide selection of e xternal c ontrol mosfets because the over - current protection voltage is pre - set, the threshold current for over - current detection is determined by the on - resistance of the discharge control mosfet m1. the required on - resistance of the external control mosfets can be determined by the equation: r on =v oip / (2 x i t ) (i t is the over - current threshold current). for example, if the over - current threshold current i t is designed to be 3 a, the on - resistance of the external control mosfets must be 33 m w . users should be aware that on - resistance of the mosfet changes with temperature variation due to heat dissipation. it changes with the voltage between gate and source as well. ( o n - resistance of a mosfet increases as the voltage between gate and s ource decreases). once the on - resistance of the external mosfet chan ges, the over - current threshold current will change accordingly. suppressing the r ipple and d isturbance from the c harger to suppress the ripple and disturbance from the charger, connecting r1, c1 to the vcc pin is recommended. protection at cs pin r2 is used for latc h - up protection when the charger is connected under an over - discharge condition , and over - stress protection for accidental reverse - connecti on of the charger. a l arger value of r2 reduces the charger leakage current in over - charge mode, but may possibly disable the charge detection func tion after over - discharge. a r esistance value of 100 k w is recommended. 12/6/2004 rev.2.02
www.siliconstandard.com 9 of 10 SS6821 timing diagrams l over - charge and o ver - discharge p rotection charger connected load connected load connected charger connected charger connected hi-z t od t oc t oc v cc v oc v od 0v v cc v cc v odr v odp v ocp v ocp - v hys hi-z l over - current p rotection (v cc =3.5v) v cc v cc 0.2v v od v batt- 0v 0v 1v v cc in formation furnished by silicon standard corporation is believe d to be accurate and reliable. however, silicon standard corporation makes no guarantee or warranty, express or implied, as to the reliability, accuracy, timeliness or completeness of such information and assumes no responsibility for its use, or for infri ngement of any patent or other intellectual property rights of third parties that may result from its use. silicon standard reserves the right to make changes as it deems necessary to any products described herein for any reason, including without limitat ion enhancement in reliability, functionality or design. no license is granted, whether expressly or by implication, in relation to the use of any products described herein or to the use of any information provided herein, under any patent or other intelle ctual property rights of silicon standard corporation or any third parties. www.siliconstandard.com 10 of 10 SS6821 physical dimensions sot-23-5 (unit: mm) symbol min max a 1.00 1.30 a1 ? 0.10 a2 0.70 0.90 b 0.35 0.50 c 0.10 0.25 d 2.70 3.10 e 1.40 1.80 e 1.90 (typ) h 2.60 3.00 l 0.37 ? e e d h a1 a a2 b l q 1 c q 1 1 9 sot-23-5 marking part no. marking SS6821acv bl0a SS6821bcv bl0b SS6821ccv bl0c SS6821dcv bl0d 12/6/2004 rev.2.02
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