www.siliconstandard.com 1 of 9 SS4036G 1/09/2006 rev.3.01 two-cell li-ion and li-polymer charge management ic pb-free, rohs compliant. description the SS4036G is a charging control ic designed for battery packs with two cells in series. when multiple cells in a battery pack are connected in series, the weakest cell determines the overall pack capacity. the SS4036G monitors the voltage of each cell toensure that no cell is overcharged. the pulse width modulation (pwm) output can be used as either a linear or switching charge-control circuit. the small 8-pin tssop package is ideal for compact battery packs used for portable applications. the SS4036G continuously monitors each cell voltage, cell current and the battery temperature. any unspecified condition will stop the charging to to protect the battery cells. an external negative- temperature-coefficient thermistor is used as a sensor to monitor the battery pack temperature. to be safe, charging is suspended if the voltage of the temperature sense input pin is higher than min temp threshold (vtmin) or lower than max temp threshold (vtmax). when the battery temperature is within the safe zone, the SS4036G charges the battery in three phases: pre-charging, constant-current, or constant- voltage. if the battery voltage is less than 3.1v, the SS4036G pre-charges the battery with a low current. after the pre-charging, the SS4036G applies a constant current to the battery. the value of this constant current is determined by the value of the current sense resistor. when the battery voltage is above the threshold, the SS4036G begins constant-voltage charging until the battery is fully charged. the battery is fully charged when the current drops down to the termination threshold. features optional external thermistor monitors the pack temperature conditioning charge for reviving deeply discharged cells timer function available to limit the charging time charge management for two-cell li-ion or li-polymer battery packs individual cell monitoring - avoids over-charging tssop-8 small industry-standard package product summary
www.siliconstandard.com 2 of 9 ss 40 36g 1/09/2006 rev.3.01 pin description pin configuration v dd 1 8 gnd temp 2 SS4036G 7 v2 cctl 3 6 v1 led 4 5 isense pin name pin no i/o description vdd 1 p operating v oltage input temp 2 a temperature sense voltage input cctl 3 o charging control (pwm) output led 4 o status indication isense 5 a current sense voltage input v1 6 a cell 1 voltage (low side) v2 7 a cell 2 v oltage (high sid e) gnd 8 g g round absolute maximum ratings dc voltage ???? - 0.3v to +7.0v storage temper ature??? ?. - 55c to +125c i /o vol tag e? ?. (gnd-0.3v) to (v dd +0.3v) operating temperature???. -40c to +85c * stresses beyond those listed as ?absolute maximum ratings? may cause permanent damage to the device. these are stres s ratings only, and fun ctional operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied or intended. exposure to the absolute maximum rating condition for an extended period may affect devi ce reliability . electrical characteristics v dd = 4.5v ? 5.5v, gnd = 0v, t a = 25c, f osc = 4mhz, unless otherwise specified. parameter symbol min. typ. max unit condition operating voltage v dd 4.5 5.0 5.5 v operating current i op - 1.5 2 ma no load, adc off standby current i sb - - 1 ua no load, adc off, wdt off, lvr off output high voltage v oh vdd-0.7 - - v all i/o, i oh = -10ma output low voltage v ol - - gnd+0.6 v all i/o, i ol =20ma analog in put a in gnd vdd v temp, isense, v1, v2
www.siliconstandard.com 3 of 9 ss 40 36g 1/09/2006 rev.3.01 electrical characteristics (continued) v dd = 5v, gnd = 0v, t a = 25c, f osc = 4mh z, r sens =100m ? , u nless otherwise specified. parameter symbol min. typ. max unit description voltage control precharge thres hold v low - 3.10 - v cc/cv threshold v cv - 4.15 - v switch to cv mode above this value max cell voltage v max - 4.25 - v maximum cell voltage bad battery t hresho ld v bad - 0.5 - v difference between v1 and v2 temperature sensing low temp thres hold vt low - 3.0 3 - v upper limit of temperature-sense voltage high temp thres hold vt high - 1.5 3 - v l ower limit of temperature-sense voltage resume threshold vt rsm - 1.84 - v thresh old for resuming charging current control precharge current i pre - 20/rsense - ma see note 1 below. charge current ichg - 100/rsense - ma see note 1 below. taper current i taper - 20/rsense - ma see note 1 below. fully charged if the taper current is below this value time control max charge time t chg 340 min maximum charging time allowed note 1: the SS4036G monitors charging current by sensing, at the input pin isense (5), the voltage drop across a sense resistor, rsense - see the explanation on page 7.
www.siliconstandard.com 4 of 9 ss 40 36g 1/09/2006 rev.3.01 functional description pbv ppv pmv i tc pev plv pcv i cv i cc trickle charge cc charge cv charge finished capacity figure 1. typical charge profile a well-known li-ion charge algorithm is used by the the SS4036G to control the charging. figure 1 shows shows the typical charge profile. figure 2 is the control flow chart. during the process of charging, the SS4036G continuously monitors each cell voltage, current and the battery temperature. any unqualified condition will stop the charging to protect the battery cells.
www.siliconstandard.com 5 of 9 ss 40 36g 1/09/2006 rev.3.01 figure 2. control flow chart yes yes power on reset start timer measure v1, v2, i, t temperature ok? vcell, vpack ok? no time out? vpack > vlow ? vpack > vcv? i < itaper ? i regulate pre-charge i regulate constant current v regulate constant voltage set charge-full end of charge yes no yes no no no
www.siliconstandard.com 6 of 9 ss 40 36g 1/09/2006 rev.3.01 voltage, current and temperature sensing 10k w cell2 cell1 r a 6.8k w 103at thermister r13 51k w 51k w r14 51k w 100m w vdd r b 20k w 3k w led vdd 1 gnd 8 temp 2 v2 7 cctl 3 v1 6 led 4 isense 5 SS4036G figure 3. cell voltage, current sense and temperature sensor figure 3 shows the cell voltage sense, current sense sense and temperature detecting circuit. the pack pack voltage is divided by 2 (by using two equal resistors, r13 and r14). this guarantees that the the voltage on the v2 input pin (7) will not exceed vdd. the SS4036G monitors the charge current by measuring at the isense input pin (5) the voltage drop across a sense resistor, connected between vss (battery negative) and gnd (charger ground). the value of this resistor should be between 50mw and 150mw . to detect the temperature, a negative-temperature- coefficient thermistor is used as a sensor. a 103at sensor. a 103at and a voltage divider (resistor r a and r b ) are recommended. the resistor values for r a and r b are calculated using the following equations: where, v dd is 5v rc is the cold temperature resistance rh is the hot temperature resistance ra, rb are in kw . example : for thermistor 103at, the hot temperature temperature is 55c and the cold temperature is 5c, then r a = 6.8kw , r b = 20kw . the temperature detection can be disabled by connecting the temp pin (2) to v dd . 1.615 x rc x rh rc - rh ra = 5 x rc x rh 2rc - 7 rh rb =
www.siliconstandard.com 7 of 9 ss 40 36g 1/09/2006 rev.3.01 charging control 1k w 3.3k w 10k w npn1 1 cap v+ vb+ vdd vdd 1 gnd 8 temp 2 v2 7 cctl 3 v1 6 led 4 isense 5 u? SS4036G figure 4 shows the linear charger circuit using the mosfet which is working in the active region. this SS4036G. the output of pin cctl (3) is a pulse- p-channel mosfet must be chosen carefully to width-modulated (pwm) signal. this signal is handle the required power dissipation. translated to a dc voltage to control the p-channel charging status indication the led (4) output pin can sink at most 20ma to light up the led. table 1 summarizes the operation of this led pin. led pin output condition high n ormal charging low fully charged 4 hz square signal bad battery, charging continued hi-z temper ature fault, charging suspended figure 4. charging control table 1. charging status p-channel mosfet
www.siliconstandard.com 8 of 9 ss 40 36g 1/09/2006 rev.3.01 physical dimensions (units: inches) tssop-8 f d h g e c b a c 1 min. nom. max. a 6.2 - 6.6 b 4.2 - 4.6 c 0.1 - 0.3 c1 2.8 - 3.3 d- -1 . 1 e - 0.65 - f 0.05 - 0.10 g-0 . 5 0- h0 . 1 2 - 0 . 2 2 dimension in mm symbol
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