View SM8135AB_4569880.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

sm8135a seiko npc corporation ? white led driver ic overview the sm8135a is a charge pump type white led driver. it can drive 1 to 4 backlight white led connected in parallel, making it ideal for portable devices with small lcd. the charge pump switches between 1 bypass mode, 1.5 and 2 boost mode in response to led drive current requirements. the boost switching occurs in response to the drive current of all the connected led and thus supports variations in led forward-bias volt- age drop (vf). besides, the detection of switching is repeated in approx. 1sec-cycle by mode reset action, the sm8135a can respond to temporary variation of supply voltage. these ingenuities on switching detection can prolong the battery life to the fullest extent. each led drive current is controlled by a 4-channel led drive current control circuit. the led drive current per channel is setup by external resistor. moreover, the pwm signal control of en pin can realize nonstep brightness control (10% to 100%). the ic on/off is controlled by en pin. features battery life extension by automatic charge pump switch between 1, 1.5 and 2 according to the detection of the led drive current controlling 1 to 4 lights of white led connected in parallel set up led drive current value by external resistor (120k ? : 20ma/ch) 1-wire input controlling on/off and brightness control by pwm signal controlling of en pin (10 to 100%) soft start circuit built-in thermal shut down circuit built-in input voltage range no-load current (i out = 0ma): 2.7 to 4.6v load current (i out = 80ma): 3.0 to 4.6v maximum output voltage: 4.9v (typ) maximum output current: 80ma (typ) quiescent current not-switching ( 1 mode): 0.3ma (typ) switching ( 1.5 mode): 1.5ma (typ) switching ( 2 mode): 1.5ma (typ) standby current: 0.01 a (typ) operating frequency: 1mhz (typ) led drive current accuracy between channel (rest = 120k ? ): ?5% (max) package: 16-pin qfn applications cellular phone pda portable games handy terminal digital still camera digital video camera lcd panel back light white led driving pinout (top view) package dimensions (unit: mm) ordering information device package SM8135AB 16-pin qfn iset en gnd vin gnd nc din3 din4 c2m pgnd c1p c1m din2 din1 vout c2p top view bottom view 3.0 0.08 3.0 0.08 0.22 0.05 0.3 0.1 c 0.3 1.8 1.8 0.05 m 0.5 3 = 1.5 0.05 s 0.02 s ab 0.5 b sa 0.2 s s 0.05 0.1 0.05 0.2 0.05 0.7 0.05 a b
sm8135a seiko npc corporation ? block diagram pin description number name i/o description 1 c2m charge pump boost capacitor connection 2m 2 pgnd charge pump ground 3 c1p charge pump boost capacitor connection 1p 4 c1m charge pump boost capacitor connection 1m 5 vin supply voltage input 6 gnd ground 7 en i enable/pwm dimming pulse input (high active) 8 iset i led drive current setting resistor connection 9 din4 o led drive current control output 4 ( connect to ground when not used) 10 din3 o led drive current control output 3 ( connect to ground when not used) 11 nc no connection (leave open circuit for normal operation) 12 gnd ground 13 din2 o led drive current control output 2 ( connect to ground when not used) 14 din1 o led drive current control output 1 ( connect to ground when not used) 15 vout o led drive voltage output 16 c2p charge pump boost capacitor connection 2p vin en control logic tsd current control & current detect mode control & output voltage control & protection c1p c1m c2p c2m vout din1 din2 din3 iset din4 gnd gnd charge pump nc (open at any time) 1/ 1.5/ 2 pgnd
sm8135a seiko npc corporation ? specifications absolute maximum ratings gnd = 0v note. the device may suffer breakdown if any one of these parameter ratings is exceeded. recommended operating conditions gnd = 0v parameter symbol rating unit vin voltage range v in ? 0.3 to 5.5 v input voltage range v en ?.3 to v in + 0.3 v output voltage range v din1 to 4 ?.3 to v in + 0.3 v v out 5.5 v vout output current i out 500 ma power dissipation p d 800 ( ta = 25 c) *1 *1. when mounted on a 4-layer pcb. mw junction temperature t jmax +125 c storage ambient temperature range t stg ? 55 to +125 c package power dissipation when mounted on 4-layer board parameter pin symbol conditions rating unit min typ max supply voltage range vin v in0 i out = 0ma 2.7 3.6 4.6 v v in i out = 80ma 3.3 3.6 4.6 v input voltage range en v es logic-level pin 0 ? v in v ambient temperature range ? ta ? 30 ? +85 c 0 200 400 600 800 1000 25 35 45 55 65 75 85 operating temperature [ c] power dissipation [mw]
sm8135a seiko npc corporation ? electrical characteristics v in = 3.6v, gnd = 0v, ta = 25 c unless otherwise noted. parameter pin symbol condition rating unit min typ max standby current vin i stb standby mode 0.01 1.00 a quiescent current vin i dd1 1.0 mode, i out = 0ma 0.3 1.0 ma i dd2 *1 *1. design guaranteed value 1.5 mode, i out = 0ma 1.5 4.5 ma i dd3 2.0 mode, i out = 0ma 1.5 4.5 ma output voltage vout v out 4.4 4.9 5.4 v maximum output current vout i out 1.5/ 2.0 mode 80 ma operating frequency c1m f osc 1.5/ 2.0 mode switching frequency 750 1000 1250 khz internal power-on reset time *1 en t por rest time from when power is applied 0.05 1.00 ms soft start time din1 to 4 t ss en startup i led rising edge 0.70 1.43 3.00 ms led drive pin leakage current din1 to 4 i leak1 to 4 standby mode, din pin = 4.9v 0.01 1.00 a led drive current din1 to 4 i led1 to 4 1.0 mode 18.0 20.0 22.0 ma led drive current matching din1 to 4 ? i led 1.0 mode, relative accuracy between channels at i led maximum setting ?.0 +5.0 % led drive pin voltage din1 to 4 v din1 to 4 1.0 mode 200 mv led drive current setting resistance *1 iset rset rset minimum value 60 k ? en hold time *1 en t ceh time from when en = low until shutdown 0.50 1.00 1.50 ms pwm input pulse frequency *1 en f pwm pwm dimming signal frequency 10 100 khz pwm input pulse duty *1 en d pwm pwm dimming signal duty range 10 100 % logic input voltage en v ih high-level input voltage range 1.4 v v il low-level input voltage range 0.3 v logic input current en i ih pull-down pin , en pin = 3.6v 5.0 10.0 a i il en pin = 0v ?.0 a
sm8135a seiko npc corporation ? functional description led drive current setting the sm8135a led drive current can be set using a combination of 2 methods: (1) current setting resistance connected to iset, and (2) pwm signal input control on the en pin. (1) setting led drive current using rset the led drive maximum current value per led (i led max ) is determined by the resistor (rset) connected to the iset pin. the relationship between rset and i led max is given by the following equation. i led max [ma] = 2400/rset [k ? ] (for example, i led max = 20ma when rset = 120k ? .) the rset resistance has a minimum rating of 60k ? . at this value of resistance, the i led max has a maximum rating of 40ma/led. however, note that the total led drive current for all leds must not exceed 80ma. iset rset gnd rset vs. i led max 0 10 20 30 40 50 0 100 rset [k ? ] 200 300 400 500 i led max [ma]
sm8135a seiko npc corporation ? (2) setting led current using pwm signal input on en the en input is used to enable/disable circuit operation, but it can also be switched at speed using a pwm sig- nal input to set the average led drive current value. when using pwm signal input on en only for dimming control, the average led drive current is given by the multiplication of the maximum current value (i led max ) set by rset and the pwm signal on duty percentage. i led = i led max on duty [%] the pwm signal on duty is de?ed in the following ?ures (?wm duty?. the pwm signal operating fre- quency range is 10khz to 100khz (10 s to 100 s per period), and the allowable duty range is 10 to 100%. however, led drive current that can be set by pwm signal has lower limit (= 2ma). when setting current to 2ma or less, even if the signal on duty is within the allowable range, the current between pins varies widely. dimming control with pwm signal pwm duty en duty100% duty50% duty10% duty25% high low turn on (i led max ) i led max turn off (0) i led turn off (0) 0 i led = i led max 25% i led = i led max 10% i led = i led max 50% on interval on off off interval 1period 10 sec 1period 100 sec duty [%] = on interval/1period i led = i led max duty [%]
sm8135a seiko npc corporation ? v out output circuit mode switching the sm8135a output mode switches between 4 operating modes in response to the operating conditions. the modes are: standby mode, 1.0 mode (vin through mode), 1.5 mode (1.5-times charge pump boost), and 2.0 mode (2.0-times charge pump boost). speci?ally, the use of 1.0 mode, 1.5 mode, and 2.0 mode allows the vout output to be adjusted automatically to match drive led characteristics. switching between 1.0 mode, 1.5 mode, and 2.0 mode is controlled automatically by an internal circuit. the operating mode cannot be speci?d by an external control signal. startup: internal reset time and soft start time the sm8135a normal startup procedure (after vin has been applied previously) is to switch from standby mode to the 1.0/ 1.5/ 2.0 operating modes when the en enable input goes high. the soft start time (described on the following page) begins after switching to the operating mode using en. (1) vin is high, en is low (standby mode) (2) switches to an operating mode when en goes high (soft start time begins) if the vin supply voltage is applied when en is high level, startup commences after the power-on reset (por) time (approximately 50 s) has elapsed. (1) vin voltage rises when power is applied. (2) power-on reset (por) circuit resets internal circuits approximately 50 s after the power is applied. (3) if en is high when power is applied, the internal circuits start operating when the internal ?e?signal ris- ing edge occurs after the power-on reset time. if en is low when power is applied, the ?e?rising edge occurs simultaneously with the ?st rising edge. normal startup internal reset operation when power is applied (power-on reset) soft start time vin en vin high enable on (1) (2) standby mode v in power source 1.5 mode internal power on reset internal enable (ce) por time typ: 50 s (1) (2) (3) soft start time standby mode
sm8135a seiko npc corporation ? immediately after startup, the device operates in 1.5 mode for a ?ed interval (soft start time: approximately 1.43ms) to set the current for leds connected to the din pins. after the soft start time has elapsed, the leds are turned on. approximately 2ms is required for the led drive current to reach the set drive value. (1) if the en signal is input after power is applied, the soft start time begins on the en rising edge. the pwm signal input for dimming is active during the soft start time. (2) after the soft start time (1.43ms) has elapsed, the leds are turned on. approximately 2ms is required for led drive current to reach set values. switching to standby mode the sm8135a switches from 1.0/ 1.5/ 2.0 mode to standby mode if en goes low and stays low for an interval of 1.00ms (typ). this function is used to switch the internal circuits to standby mode automatically when the leds turn off in order to reduce current consumption. if en is low for longer than the enable hold time of 1.00ms (typ), the sm8135a switches to standby mode. in standby mode, the internal circuits are reset. soft start time and led current en input signal and internal enable signal ?e en input signal led current (1) (2) typ: 1.43ms soft start time led on typ: 2ms ce hold time typ: 1.00ms en led current 1.0 or 1.5 standby mode
sm8135a seiko npc corporation ? boost mode auto-switching the sm8135a switches between 1.0 mode (vin through mode), 1.5 mode (1.5-times charge pump boost), and 2.0 mode (2.0-times charge pump boost) automatically in response to the operating state to reduce current consumption. the switching transition ?w chart is shown in the following ?ure. this section describes the boost mode switching in response to insuf?ient led drive current level detection. the next section describes the mode reset functions. initially, when the led drive current begins to ?w, oper- ation begins in 1.0 mode at the set current value if possible, without boosting the input voltage vin. if the set current value cannot be attained in 1.0 mode due to a vin voltage drop or an increase in the set current value, a low-current detector circuit connected to each led drive circuit is activated that switches the vout output to 1.5 mode automatically, and the charge pump circuit starts boosting the voltage by 1.5 times. if the set cur- rent value still cannot be attained, the led drive circuits are switched to 2.0 mode, and the charge pump starts boosting the voltage by 2 times. boost mode switching ?w chart led on 1.0 mode i led judgment 1.5 mode i led judgment 1.5 mode 1.0sec i led judgment sufficient insufficient insufficient 1.0sec 2.0 mode sufficient i led judgment insufficient sufficient insufficient mode reset 1.5 1.0 mode reset 2.0 1.5 sufficient
sm8135a seiko npc corporation ?0 in 1.0 mode, v in = v out . however, the v out output does not always reach the electrical characteristics typi- cal rating of 4.9v. however, as long as an insuf?ient current condition is not detected, 1.0 mode operation continues. in other words, v out may drop below 4.9v if suf?ient led drive current is ?wing to counter the led forward-bias voltage drop vf. the longer the device can operate in the high output ef?iency 1.0 mode, the lower the total current consumption and the longer the battery drive time can be extended. furthermore, the more that low vf leds and lower led drive current are used, the longer the device can operate automatically in 1.0 mode. the led low-current detector circuit switches the output boost mode whenever a single insuf?ient current condition is detected among the 4 channel led drive currents, hence drive leds with small vf variation should be used to increase overall ef?iency. if, after startup, a led connection to the din pins is switched on/off, the led current detection circuit will operate incorrectly and normal boost mode switching does not occur. also, if led drive current control using a dim pin is not used, the low-current detector circuit does not operate and the boost mode does not switch to either 1.5 or 2.0 mode. v in voltage drop and v out output voltage v out mode switching time comparison due to drive led ?f?variation v in input voltage v out mode v out output voltage 4.9v 1.0 mode 1.5 mode 1.0 1.5 threshold 1.5 2.0 threshold lack of led current detect 2.0 mode high high vf led low vf led vin input low 1.0 mode (high efficiency) 1.5 mode 1.0 mode (high efficiency) 2.0 mode (low efficiency) 1.5 mode (low efficiency) 2.0 mode
sm8135a seiko npc corporation ?1 mode reset function vf increases immediately after the led current starts to ?w, and then decreases as the led temperature increases due to the heating effect of the current ?w. it can take about 10 seconds for the led temperature to stabilize and for vf to reach equilibrium, and vf may ?ctuate more than 200mv. the vf ?ctuation is affected by the ambient temperature and led current setting, and has a large affect on the automatic mode switching voltage tolerances. to counter the effects of vf ?ctuation, the sm8135a outputs a mode reset sig- nal once every 1.0 seconds which automatically switches the output mode to 1.0, and then a determination is made whether to make the 1.0 1.5 mode switch. (1) mode reset signal is output once every 1.0 seconds. (2) mode switches from 1.5 to 1.0 mode on the rising edge of the mode reset signal. (3) a 200 s (max) mode hold time begins after switching to 1.0 mode. led drive current insuf?ient state is detected but the mode is not switched during this interval. (4) led drive current insuf?ient signal is ignored during the mode hold time, but normal mode switching operation resumes when the mode hold time elapses. switching from 1.5 mode to 1.0 mode due to mode reset signal mode hold l: hold v out output voltage i led detector mode reset 1.0sec/cycle 1.0 mode min 80 s max 200 s i led detector ignore 4.9v v out mode (1) (2) (3) (4) 1.5 mode 1.5 mode
sm8135a seiko npc corporation ?2 a mode hold signal of 200 s (max) duration is output immediately after switching to 1.0 mode. the v out output is held in 1.0 mode and any led drive current insuf?ient detection signal is ignored during the mode hold signal output. for example, if the v in voltage drops and the v out output voltage in 1.0 mode cannot provide suf?ient current to drive the leds, a led drive current insuf?ient condition occurs momentarily due to the mode reset. the led low-current detector circuit outputs a led drive current insuf?ient signal imme- diately after switching modes, but during the mode hold time the device stays in 1.0 mode and does not switch to 1.5 mode. consequently, the v out voltage drops and the led brightness decreases during the 85 s (min) to 200 s (max) mode hold time. however, a 200 s decrease in the brightness is not a problem as it is not perceptible to the human eye. v out drop due to mode reset signal (between 1.5 and 1.0 mode) mode reset mode hold (l: hold) i led detector (h: lack ) v out output voltage v in input voltage 1.0sec 1.0 1.5 threshold 4.9v v out mode max 200 s
sm8135a seiko npc corporation ?3 the mode reset operation when in 2.0 mode performs boost mode switching between 2.0 mode and 1.5 mode. mode switching directly from 2.0 mode to 1.0 mode does not occur. (1) mode switches from 2.0 to 1.5 mode on the rising edge of the mode reset signal. (2) a 200 s (max) mode hold time begins after switching to 1.5 mode. led drive current insuf?ient state is detected but the mode is not switched during this interval. (3) led drive current insuf?ient signal is ignored during the mode hold time, but normal mode switching operation resumes when the mode hold time elapses. the mode reset function periodically tests the boost mode to try to maximize the duration of operation in the higher ef?iency 1.0 and 1.5 modes in order to extend battery drive time. thermal shutdown circuit (overtemperature protection circuit) the sm8135a features a thermal shutdown circuit that operates whenever the ic temperature exceeds approx- imately 170 c for whatever reason, stopping the v out output. v out output recommences when the ic temper- ature falls below approximately 150?. switching from 2.0 mode to 1.5 mode due to mode reset signal mode hold (l: hold) v out output voltage i led detector mode reset 1.0sec/cycle min 80 s max 200 s i led detector ignore 4.9v v out mode 2.0 mode 1.5 mode 2.0 mode
sm8135a seiko npc corporation ?4 peripheral parts about the external capacitors the best capacitors for use with the sm8135a are multi-layer ceramic capacitors. when selecting a multi-layer ceramic capacitor, only x5r and x7r dielectric types are strongly recommended, since the loss of capacitance in various conditions is less than other types such as z5u and y5v. the much loss of capacitance in various conditions may cause the output voltage unstable. about the input capacitor "c4" the parts layout of pcb may merely cause the ? out ?output voltage unstable. in this case, increasing the ?4?input capacitance value or adding another capacitor on the vin input line is effective to solve the unsta- ble output voltage. table. the eia three digit "tc" code lower temperature limit high temperature limit maximum allowable capacitance change from + 25 c (0v dc) x = ? 55 c 5 = + 85 c f = ?7.5% y = ? 30 c 6 = + 105 c p = ?10% z = + 10 c 7 = + 125 c r = ?15% 8 = + 150 c s = ?22% t = + 22%/ ? 33% u = + 22%/ ? 56% v = + 22%/ ? 82% for example : x5r
sm8135a seiko npc corporation ?5 typical application circuits led 4, i led = 20ma, without dimming note. if the driving led is less than 4 pcs, unused din pins should be connect to gnd. on/off control is performed using enable signal input on en with a ?ed led current determined by resistor rset. vin control logic tsd current control & current detect mode control & output voltage control & protection c1p c1m c2p c2m vout din1 din2 din3 iset din4 gnd pgnd nc (open at any time) c4 = 1 f 2.7 to 4.6v c1 = 1 f c2 = 1 f c3 = 1 f rset = 120k ? charge pump 1/ 1.5/ 2 20ma 4 en gnd
sm8135a seiko npc corporation ?6 led 4, i led max = 20ma, pwm pulse input dimming on en note. if the driving led is less than 4 pcs, unused din pins should be connect to gnd. dimming and on/off control is performed using pwm pulse input on en with a maximum led current determined by resistor rset (see p.6 ?etting led current using pwm signal input on en?. the pwm control signal duty ratio must be in the range 10 to 100% (see ?lectrical characteristics?. the pwm control signal frequency must be in the range 10khz to 100khz (see ?lectrical characteristics?. vin control logic tsd current control & current detect mode control & output voltage control & protection c1p c1m c2p c2m vout din1 din2 din3 iset din4 gnd pgnd nc (open at any time) c4 = 1 f 2.7 to 4.6v c1 = 1 f c2 = 1 f c3 = 1 f rset = 120k ? max 20ma 4 charge pump 1/ 1.5/ 2 en 10khz to 100khz gnd
sm8135a seiko npc corporation ?7 led 3, i led max = 20ma, pwm pulse input dimming on en note. if the driving led is less than 4 pcs, unused din pins should be connect to gnd. dimming and on/off control is performed using pwm pulse input on en with a maximum led current determined by resistor rset (see p.6 ?etting led current using pwm signal input on en?. the pwm control signal duty ratio must be in the range 10 to 100% (see ?lectrical characteristics?. the pwm control signal frequency must be in the range 10khz to 100khz (see ?lectrical characteristics?. vin control logic tsd current control & current detect mode control & output voltage control & protection c1p c1m c2p c2m vout din1 din2 din3 iset din4 (connect to ground) gnd pgnd nc (open at any time) c4 = 1 f 2.7 to 4.6v c1 = 1 f c2 = 1 f c3 = 1 f rset = 120k ? max 20ma 3 charge pump 1/ 1.5/ 2 en 10khz to 100khz gnd
sm8135a seiko npc corporation ?8 led 2, i led max = 29.3ma, pwm pulse input dimming on en note. if the driving led is less than 4 pcs, unused din pins should be connect to gnd. dimming and on/off control is performed using pwm pulse input on en with a maximum led current determined by resistor rset (see p.6 ?etting led current using pwm signal input on en?. the pwm control signal duty ratio must be in the range 10 to 100% (see ?lectrical characteristics?. the pwm control signal frequency must be in the range 10khz to 100khz (see ?lectrical characteristics?. vin control logic tsd current control & current detect mode control & output voltage control & protection c1p c1m c2p c2m vout din1 din2 din3 (connect to ground) iset din4 (connect to ground) gnd pgnd nc (open at any time) c4 = 1 f 2.7 to 4.6v c1 = 1 f c2 = 1 f c3 = 1 f rset = 82k ? max 29.3ma 2 charge pump 1/ 1.5/ 2 gnd en 10khz to 100khz
sm8135a seiko npc corporation ?9 footprint pattern 3.6 0.1 0.5 3 = 1.5 0.05 0.5 3 = 1.5 0.05 2.2 0.1 2.2 0.1 3.6 0.1 0.25 0.05 0.7 0.1 0.32
sm8135a seiko npc corporation ?0 nc0602ae 2007.01 please pay your attention to the following points at time of using the products shown in this document. the products shown in this document (hereinafter ?roducts? are not intended to be used for the apparatus that exerts harmful in?ence on human lives due to the defects, failure or malfunction of the products. customers are requested to obtain prior written agreeme nt for such use from seiko npc corporation (hereinafter ?pc?. customers shall be solely responsible for, and indemnify and hold npc free and harmless from, any and all claims, damages, losses, expenses or lawsuits, due to such use without such agreement. npc reserves the right to change the speci?ations of the products in order to improve the characteristic or reliability thereof. npc makes no claim o r warranty that the contents described in this document dose not infringe any intellectual property right or other similar right owned by third parties. therefore, npc shall not be responsible for such problems, even if the use is in accordance with the descriptions provided in t his document. any descriptions including applications, circuits, and the parameters of the products in this document are for reference to use the products, and shall not be guaranteed free from defect, inapplicability to the design for the mass-production products without further te sting or modi?ation. customers are requested not to export or re-export, directly or indirectly, the products to any country or any ent ity not in compliance with or in violation of the national export administration laws, treaties, orders and regulations. customers are req uested appropriately take steps to obtain required permissions or approvals from appropriate government agencies. seiko npc corporation 15-6, nihombashi-kabutocho, chuo-ku, tokyo 103-0026, japan telephone: +81-3-6667-6601 facsimile: +81-3-6667-6611 http://www.npc.co.jp/ email: sales @ npc.co.jp

▲Up To Search▲

Price & Availability of SM8135AB

	To Download SM8135AB Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .