View SM8136A_8297112.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

SM8136A seiko npc corporation ? white led driver ic overview the SM8136A is a charge pump type white led driver. it can drive 1 to 3 backlight white led connected in parallel, making it ideal for portable devices with small lcd. the charge pump switches between 1 bypass mode to 1.5 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 SM8136A 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 3-channel led drive current control circuit. features battery life extension by automatic charge pump switch between 1 to 1.5 according to the detec- tion of the led drive current controlling 1 to 3 lights of white led connected in parallel 1-wire input controlling on/off and brightness control by signal control- ling of en pin soft start circuit built-in input voltage range no-load current (i out = 0ma): 2.7 to 4.6v load current (i out = 60ma): 3.0 to 4.6v maximum output voltage: 5.0v (typ) maximum output current: 60ma (typ) quiescent current not-switching ( 1 mode): 0.3ma (typ) switching ( 1.5 mode): 1.0ma (typ) standby current: 0.01 a (typ) operating frequency (boost mode): 1.0mhz (typ) led drive current accuracy between channel: ?5.0% package: 12-pin qfn applications cellular phone pda portable games portable audio equipment handy terminal digital still camera digital video camera lcd panel back light white led driving ordering information pinout (top view) package dimensions (unit: mm) device package SM8136Ab 12-pin qfn en vout c1p din1 din2 din3 c1m c2m c2p nc gnd vin a b a s 0.10 8 ? c0.08 c0.30 msab 0.05 0.40 2 = 0.80 0.05 top view bottom view s 0.05 0.40 s 0.10 b s 0.40 2 = 0.80 0.05 2.00 0.07 0.18 0.05 2.00 0.07 0.60 0.60 1.00 1.00 0.70 0.05 0.25 0.07 0.75 max 0.05 max 11 12 12
SM8136A seiko npc corporation ? block diagram pin description number name i/o description 1 c1m charge pump boost capacitor connection 1m 2 c2m charge pump boost capacitor connection 2m 3 c2p charge pump boost capacitor connection 2p 4 c1p charge pump boost capacitor connection 1p 5 vout o led drive voltage output 6 en i enable/led drive current setting (high active) 7 din3 o led drive current control output 3 ( connect to ground when not used) 8 din2 o led drive current control output 2 ( connect to ground when not used) 9 din1 o led drive current control output 1 ( connect to ground when not used) 10 nc no connection 11 pgnd ground 12 vin supply voltage input vin en control logic current control & current detect mode control & output voltage control & protection c1p c1m c2p c2m vout din1 din2 din3 gnd charge pump nc (open at any time) 1/ 1.5
SM8136A 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 6.0 v input voltage range v en ?.3 to v in + 0.3 v output voltage range v din1 to 3 ?.3 to v in + 0.3 v v out 6.0 v vout output current i out 500 ma power dissipation p d 800 ( ta = 25 c) *1 *1. when mounted on a 4-layer board. 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 = 60ma 3.3 3.6 4.6 v input voltage range en v es logic-level inputs 0 ? v in v ambient temperature range ? ta ? 40 ? +85 c 0 200 400 600 800 1000 25 35 45 55 65 75 85 operating temperature [ c] power dissipation [mw]
SM8136A 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 1 vin i dd1 1.0 mode, i out = 0ma 0.3 1.0 ma quiescent current 2 i dd2 1.5 mode, i out = 0ma 1.0 2.0 ma output voltage vout v out 1.5 mode, v in = 3.6v, i out = 0ma 4.5 5.0 5.5 v 1.5 mode, v in = 3.0v, i out = 60ma 3.5 v maximum output current vout i out 1.5 mode 60 ma operating frequency c1m f osc 1.5 mode switching frequency 800 1000 1200 khz internal power-on reset time *1 *1. design guaranteed value en t por rest time from when power is applied 0.05 1.00 ms power-on rise time en, vin t pr en = vin, time from 0.3v to 2.7v 50 s soft start time din1 to 3 t ss en startup i led rising edge 2.00 3.00 ms led drive pin leakage current din1 to 3 i leak1 to 3 standby mode, din pin = 5.0v 0.01 1.00 a led drive current din1 to 3 i led1 to 3 1.0 mode (3-channel average value) 18.0 20.0 22.0 ma led drive current accuracy din1 to 3 ? i led 1.0 mode, relative accuracy between channels at i led maximum settings ?.0 +5.0 % led drive pin voltage din1 to 3 v din1 to 3 1.0 mode, i led = 20ma 120 mv 1.0 ? 1.5 mode switching threshold voltage vin v th1.0 to 1.5 vf (led) = 3.3v, i led = 20ma 3.46 v en hold time *1*2 *2. en t ceh time from when en = low until shutdown 0.50 1.00 1.50 ms en high-level input time *1 en t enh en input pulse high-level minimum pulsewidth 4.0 s en low-level input time *1*2 en t enl en input pulse low-level pulsewidth range 4.0 500 s 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 en when shutdown > 1.5msec en when dimming 4 sec to 500 sec
SM8136A seiko npc corporation ? functional description led drive current setting the SM8136A led drive current can be set using the en pin. the en input is used to enable/disable circuit operation. it also is used by a built-in counter that counts the number of input pulses in order to set the led current value. the built-in counter is a 4-bit counter for 16-step adjustment (data = 1 to 16). on the 16th pulse (data = 16), the led current drive circuit shuts down and led current is zero. on the 17th pulse (data = 1), the current returns to the maximum value. as the initial pulse (data = 1) sets the current to the maximum value, the device can also be used in applications that do not support pulsed input. en input signal and led current setting (initialization) on the ?st rising edge of en, the internal startup signal goes high and led current will start to ?w after the soft start time has elapsed. as the led current setting is adjusted by counting the number of input pulses on en, the en input voltage must be switched high low high repeatedly to set the current to a lower value. after the desired value is achieved, the en input voltage is held high to maintain the led current set- ting. if the en input goes low, the led current does not ?w. the en data input circuit operates even though the led current does not ?w during the soft start interval, but as long as the current value is set during the soft start interval the led drive circuits will start to drive the leds with that constant current setting. however, note that the setting is valid only after the power-on reset when the vin supply is applied. accordingly, allow 1ms or more after connecting the vin supply before setting the current value using the en input. led current setting is determined by the number of en input signal rising edges. furthermore, no led cur- rent ?ws until the soft start time has elapsed. table 1. en input pulse count and led current setting values data12345678910111213141516 en pulse count 12345678910111213141516 17 18 19 20 21 22 23 24 i led [ma] 20.00 18.7 17.3 16.0 14.7 13.3 12.0 10.7 9.3 8.0 6.7 5.3 4.0 2.7 1.3 0 en input signal and led current setting en input signal i led1-3 1 2 3 4 5 6 7 8 1 2 3 4 5 6 7 8
SM8136A seiko npc corporation ? v out output circuit mode switching the SM8136A output mode switches between 3 operating modes in response to the operating conditions. the modes are: standby mode, 1.0 mode (vin through mode), and 1.5 mode (1.5-times charge pump boost). the vout output switches automatically between these modes in response to the drive led characteristics and the overall power consumption. switching from 1.0 mode to 1.5 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 SM8136A normal startup procedure (after vin has been applied previously) is to switch from standby mode to the 1.0/ 1.5 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 use at en = vin when power is applied, the startup commences after the power-on reset (por) time (approximately 50 s) has elapsed. (1) when using at en = vin, rising time from 0.3v to 2.7v should set < 50 s. (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 en = vin 1.5 mode internal power on reset internal enable (ce) por time typ: 50 s (2) (3) soft start time standby mode (1) < 50 s 0.3v 2.7v
SM8136A seiko npc corporation ? immediately after startup, the device operates in 1.5 mode for a ?ed interval (soft start time: approximately 2ms) to set the current for leds connected to the din pins. (1) if the en signal is input after power is applied, the soft start time begins on the en rising edge. the en input signal for dimming is active during the soft start time. (2) the led drive starts immediately before the end of the led turn-on delay time. switching to standby mode the SM8136A operating mode switches from 1.0/ 1.5 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 auto- matically when the leds turn off in order to reduce current consumption. when en is low for longer than the ce hold time of 1.00ms (typ), the SM8136A switches to standby mode. in standby mode, the internal circuits are reset, hence the drive current settings must be re-entered to restart the device. soft start time and led current switching to standby mode, and en hold time en led current (1) (2) soft start time typ: 2ms led on dimming pulse enable vin vin high ce hold time typ: 1.00ms en led current 1.0 or 1.5 standby mode
SM8136A seiko npc corporation ? switching from 1.0 mode to 1.5 mode when the leds are on and can be driven at the ?ed current value set by the en pulse input without needing to boost the vin input voltage, the vout output operates in 1.0 mode. in other words, if suf?ient current ?ws to counter the led forward-bias voltage drop vf, it means the vout voltage may drop below 5.0v. the longer that the driver output operates in the more ef?ient 1.0 mode, the lower the total power consumption and the longer the battery life can be extended. also, by using leds with low vf and a lower led drive cur- rent setting, the longer the device can operate automatically in 1.0 mode. if the vin voltage drops and the led current drops below the ?ed current setting in 1.0 mode, an undercur- rent detection circuit connected to each led drive circuit activates and automatically switches the vout out- put mode to 1.5 mode that uses a charge pump to boost the voltage by a factor of 1.5. the led undercurrent detection circuit switches the output mode when it detects an undercurrent condition on any one of the three channels. accordingly, there should be as low a variation as possible in drive led vf values in order to improve overall ef?iency. (1) the vin voltage drops below the 1.5 mode threshold value. (2) when the voltage drops below the 1.5 mode threshold, the i led detection circuit raises an i led undercur- rent signal. (3) the vout output switches to 1.5 mode in response to the i led undercurrent signal. (4) the vout voltage drops below 5.0v but still supplies suf?ient current until reaching the 1.5 switching threshold. note that if the leds connected to the din pins are switched after startup, the led connection detection cir- cuit will operate incorrectly and the correct mode switching functions cannot occur. v out mode switching interval comparison due to drive led ?f?variation v in voltage drop and v out output voltage high high vf led low vf led vin low 1.0 mode (high efficiency) 1.5 mode 1.0 mode (high efficiency) (low efficiency) 1.5 mode (low efficiency) v in voltage v out mode v out voltage 5.0v 1.0 mode 1.5 mode 1.0 1.5 threshold i led detector lack of led current detect (1) (2) (3) (4)
SM8136A seiko npc corporation ? switching from 1.5 mode to 1.0 mode the led vf increases immediately after the led current starts to ?w, and then decreases as the led temper- ature increases due to the heating effect of the current ?w. it can take about 10 seconds or more for the led temperature to stabilize and for vf to reach equilibrium, and vf may ?ctuate more than 200mv. the vf ?c- tuation 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 SM8136A outputs a mode reset signal once every 1.0 seconds which automatically switches the output mode to 1.0, and then a determi- nation 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 voltage i led detector mode reset 1.0sec/cycle min 80 s max 200 s i led detector ignore 5.0v v out mode (1) (2) (3) (4) 1.5 mode 1.0 mode 1.5 mode
SM8136A seiko npc corporation ?0 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 mode reset (1 sec/cycle) mode hold (l: hold) low i led detector (h: low i led ) v out voltage v in voltage 1.0sec 5.0v max 200 s v out mode (h: 1.5, l: 1.0) 1.0 1.5 threshold
SM8136A seiko npc corporation ?1 peripheral parts about the external capacitors the best capacitors for use with the SM8136A 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. 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 recommended parts list manufacture part number capacitance [ f] dimensions [mm] wl t tdk c1608jb1c105k 1.0 1.6 0.8 0.8 murata grm188b11a105ka61 1.0 1.6 0.8 0.8
SM8136A seiko npc corporation ?2 typical application circuits led 3 note. if the driving led is less than 3 pcs, unused din pins should be connect to gnd. the high-level and low-level pulsewidths for the pulse input on en must be 4.0 s or longer (see ?lectrical characteristics?. 1 f 1 f1 f 1 f vin en control logic current control & current detect mode control & output voltage control & protection c1p c1m c2p c2m vout din1 din2 din3 gnd charge pump 20ma 3 1/ 1.5
SM8136A seiko npc corporation ?3 led 2 note. if the driving led is less than 3 pcs, unused din pins should be connect to gnd. the high-level and low-level pulsewidths for the pulse input on en must be 4.0 s or longer (see ?lectrical characteristics?. 1 f 1 f1 f 1 f vin en control logic current control & current detect mode control & output voltage control & protection c1p c1m c2p c2m vout din1 din2 din3 gnd charge pump 1/ 1.5 20ma 2
SM8136A seiko npc corporation ?4 footprint pattern 1.0 0.30 0.4 2=0.80 0.05 1.0 1.4 0.1 2.6 0.1 0.18 0.05 thermal via 0.6 0.1 0.4 2=0.80 0.05 1.4 0.1 2.6 0.1
SM8136A seiko npc corporation ?5 nc0717ae 2008.12 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 SM8136A

	To Download SM8136A Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .