high power factor & accuracy constant current led driver EC4188B e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 1 o f 10 4c26 n - rev.p001 general description the EC4188B i s a highly - integrated, low startup current, aver age current mode, one cycle control pfc and f ixed switching frequency pwm controller. these func tions enable the led driver to easily meet the accuracy average led current and high power factor requirements. the integrated functions also include the led short protection, open protection, and internal over temperature protection. the comp pin controls the duty by connected an rc compensation network to ground and forming the closed loop feedback control. to protect the external power mosfet from being damaged by suppl y over voltage, the EC4188B out pin voltage is clamped to about 15v. the ec4188 b improves the performance and reduces the cost of the led driver. it is a 6 - pin sot23 - 6l package. features high power factor by one cycle co ntrol accuracy constant current low bom cost linear dimming on dim pin average current / fixed frequency control gate output voltage clamp led open protection (ovp) led short protection (scp) over current protection (ocp) internal otp protection 300ma driving capability for out pin fa st start current incompatible electronic ballast and inductance ballast applications e26/27, t8 led tube others led lighting applications pin assignments pin description pin no. name function 1 vcc power supply pin 2 gnd ground pin 3 out the output driver for driving the external mosfet 4 dim dimming control pin by input a dc voltage 5 comp feedback compensation network 6 cs current sense pin, connect to sense the mosfet current
high power factor & accuracy constant current led driver EC4188B e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 2 o f 10 4c26 n - rev.p001 orderi n g information part number package marking marking information EC4188B nb3r sot23 - 6l 4188 b lllll 1. 4188 part no, typ ical application circuit
high power factor & accuracy constant current led driver EC4188B e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 3 o f 10 4c26 n - rev.p001 absolute maximum ratings parameter value supply voltage vcc 30v dim,comp, cs - 0.3 to 7v out 15v junction temperature 150 operating ambient temperature - 20 ~85 storage temperature range - 65 ~150 sot 23 - 6 l package thermal resistance (junction to ambient) 250 /w power dissipation (sot 23 - 6 l , at ambient temperature = 85 ) 250mw lead temperature (all pb free packages, soldering, 10 sec) 260 esd voltage protection, machine model 200v esd voltage protection, human body model 2kv electrical characteristics (vcc = 15.0v & t a = +25 parameters pin min. typ. max. unit supply voltage startup current (vcc=uvlo on - 1v) 1 8 15 ua operating current (with 1nf load on out pin) ,v comp =2.5v 1 2 3 ma operating current (with 1nf load on out pin) protection triggered (ocp,ovp,scp,otp 1 0.7 1.1 ma uvlo(off) 1 6 7 8 v uvlo(on) 1 14 15 16 v ovp level on vcc pin 1 29.5 31.5 33.5 v ovp de - bounce time 1 40 us voltage feedback feedback reference voltage 5 0.19 5 0.2 00 0.205 v tran - conductance 5 120 us output sink current 5 12 ua output source current 5 12 ua current sensing input over voltage protection 6 0.8 v open loop voltage, cs pin open 6 5 v leading - edge blanking time 6 410 ns delay to output 6 100 220 ns switching frequency switching frequency - 42 45 48 khz maximum duty - 90 % frequency jitter range +/ - 4 % temp. stability( - 40c ~ 125c) - 6 % voltage stability (vcc = 11v~25v) - 1 %
high power factor & accuracy constant current led driver EC4188B e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 4 o f 10 4c26 n - rev.p001 electrical characteristics (vcc = 15.0v & t a = +25 parameters pin min. typ. max. unit gate driver output rising time, load capacitance = 1000pf 3 160 320 ns falling time, load capacitance = 1000pf 3 80 16 0 ns vgate - clamp (vcc = 25v ) 3 13.5 15 v dim input section saturation threshold voltage 4 3.0 v linear dimming range 4 0.3 3 v led current off threshold voltage 4 0.5 v current source 4 270 300 330 ua otp section otp trip point - 150 otp release point 130 otp threshold level 20 otp de - bounce time - 80 us note 1. ovp, ocp,scp,otp auto recovery type.
high power factor & accuracy constant current led driver EC4188B e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 5 o f 10 4c26 n - rev.p001 function block
high power factor & accuracy constant current led driver EC4188B e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 6 o f 10 4c26 n - rev.p001 typical performance characteristics
high power factor & accuracy constant current led driver EC4188B e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 7 o f 10 4c26 n - rev.p001
high power factor & accuracy constant current led driver EC4188B e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 8 o f 10 4c26 n - rev.p001 application information start - up current the typical start - up current is around 8ua. very low start - up current allows the pwm controller to increase the value of s tart - up resistor and then reduce the power dissipation on it. uvlo (under voltage lockout) a hysteresis uvlo comparator is implemented in ec4188 b, then the turn - on and turn - off thresholds level are fixed at 15v and 7v respectively. this hysteresis shown in fig.11 ensures that the start - up capacitor will be adequate to supply the chip during start - up. for quickly startup the led driver, the start - up resistor should be m atched with the startup capacitor. due to the low uvlo on level, so the turn - on delay time will also never greater than the general pwm ic. oscillator the maximum duty - cycle o f internal oscillator is up to 90% for driving high led voltage string. the frequency of the oscillator is fixed to 45khz by internal setting. leb (leading - edge blanking) each time the power mosfet is switched on , a turn - on spike will inevitably occur at the sense resistor. to avoid fault trigger, a 410ns leading - edge blanking time is built in. conventional rc filtering can therefore be omitted. during this blanking period, the current - lim it comparator is disabled and can not switch off the gate driver. ocp (over current protection) the EC4188B has a n over current protection function on cs pin. an internal circuit detects the current level, when the c urrent is larger than a threshold level, the gate output will keep on low level. then vcc decreases below u vlo off level, the controller resets again. ovp (over voltage protection) on vcc to prevent the led driver from being damaged, the ec4188 b is implemented an ovp function on vcc. when the vcc voltage is higher than the ovp threshold voltage 31.5v, the output gate driver circuit will be shut d own immediately to stop the switching of power mosfet. the vcc pin ovp function is an auto recovery type pr otection (latch off type optional). if the ovp condition happens, the pulses will be stoppe d and never recovery unless the vcc pin voltage is down to the uvlo off level. the EC4188B is wo rking in an auto - recovery mode as shown in fig. 12.
high power factor & accuracy constant current led driver EC4188B e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 9 o f 10 4c26 n - rev.p001 gate clamp/soft driving driver is clamped to 15v by an internal clamping circuit. those damages usually come from undesired over - voltage gate signals. under the conditions listed below, the gate output will turn off immediately to protect the power circuit. the EC4188B also has soft driving function to minimize emi. the typical application for dim pin is shown in fig. 13. the ntc thermistor is setting as an external otp protection. in the dim pin, there is one comparator for latch - of f mode protection. while the voltage on t his pin is lower t han 0.3v, the EC4188B will shut down. when the voltage is in the ran ge of 0.3 to 3.0v, the ec4188 b is operating on the line ar dimming range. while the voltage is higher than 3.0v, the ec4188 b is operating on the normal status. it also could let this pin open when the function is not required for the user.
high power factor & accuracy constant current led driver EC4188B e - c m o s c o r p . ( ww w . e c m o s . c o m . t w ) p a g e 10 o f 10 4c26 n - rev.p001 package information sot23 - 6l p ack a ge out l ine dimensions note: 1. followed from jedec to - 178 ab. 2. dimension d and e1 do not include mold flash, protrusions or gate bu rrs. mold flash, protrusions or gate burrs shall not exceed 10 mil per side symbol sot 23 - 6l millimeters inches min. max. min. max. a 1.45 0.057 a1 0.00 0.15 0.000 0.006 a2 0.90 1.30 0.035 0.051 b 0.30 0.50 0.012 0.020 c 0.08 0.22 0.003 0.009 d 2.70 3.10 0.106 0.122 e 2.60 3.00 0.102 0.118 e1 1.40 1.80 0.055 0.071 e 0.95 bsc 0.037 bsc e1 1.90 bsc 0.075 bsc l 0.30 0.60 0.012 0.024 o 8 o 0 o 8 o
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