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ec4304 1a, hysteretic, high brightness led driver with internal switch e-cmos corp. ( www.ecmos.com.tw ) page 1 of 13 4b25n-rev.f005 general description features the ec4304 is a high-efficiency continuous mode ind uctive step-down converter which drives n-channel mosfet a nd it is designed for driving single or multiple serie s connected leds from a voltage source higher than the led volt age. it operates from input supply between 7v and 40v and provides and externally adjustable output current t o 1a which is depending on supply voltage and external components. this ec4304 includes the output switch and high-sid e output current sensing circuit, which uses an exter nal resistor to set the output current. the adj pin will accept either a dc voltage or a pw m waveform. this will provide either a continuous or gated output current depending upon the control frequency . the pwm filter components contains a soft-start rising time setting. the soft-start time can be increased by us ing an external capacitor from the adj pin to ground. appl ying a 0.2v or lower to the adj pin turns the output off a nd switches the device into a low current standby stat e. operates from 7v to 40v supply voltage internal 40v ndmos switch output current 1a single pin on/off and brightness control using dc voltage or pwm ec4304 to 95% efficiency typical +/-5% led current accuracy input under voltage lockout sot23-5l dfn 3x3 8l sot89-5l package rohs compliant and halogen-free applications automotive led lighting high power led lighting indicator and emergency lighting architectural lighting low voltage industrial lighting signage and decorative led lighting functional block diagram
ec4304 1a, hysteretic, high brightness led driver with internal switch e-cmos corp. ( www.ecmos.com.tw ) page 2 of 13 4b25n-rev.f005 pin configuration typical application pin name pin function lx drain of ndmos switch. gnd ground for the ic. all voltages levels are measured with respect to t his pin. adj multi-function on/off and brightness control pin: -analog signal input for analog control of pwm dimm ing. -pwm signal input for digital pwm dimming. isense current sense pin: sense led string current. vin power supply input pin. connect a nominal (7v~40v) power supply to this pin . the power- on-reset (por) function monitors the input v oltage by this pin. it is recommended that a decoupling capacitor (4.7 f or higher x7r ceramic capacitor) be connected to the gnd for noise decoupling.
ec4304 1a, hysteretic, high brightness led driver with internal switch e-cmos corp. ( www.ecmos.com.tw ) page 3 of 13 4b25n-rev.f005 ordering/ marking information part number package marking marking information EC4304ANT2R sot23-5 4304a llllll llllll is lot no ec4304anfnr dfn3x3-8 ec4304anb9r sot89-5l 4304a ywlll yw date code lll lot no
ec4304 1a, hysteretic, high brightness led driver with internal switch e-cmos corp. ( www.ecmos.com.tw ) page 4 of 13 4b25n-rev.f005 functional description the ec4304 is a simple high-efficiency, continuous mode inductive step-down converter. the device oper ates with an input voltage range from 7v to 40v and delivers ou tput current 1a. a high- side current-sense resisto r sets the output current and a dedicated pwm dimming input enables p ulsed led dimming over a wide range of brightness l evels. a high- side current-sensing scheme and an on-board current - setting circuitry minimize the number of external components which is required while delivering led current with +5% a ccuracy, using a 1% sense resistor. adjusting output current the device contains a low pass filter between the a dj pin and the threshold comparator and an internal current limiting resistor between adj and the internal reference vol tage. this allows the adj pin to be overdriven with either dc or pulse signals to change the vsense switching threshold an d adjust the output current. details of the differe nt modes of adjusting output current are given in the applicati ons section by: the value of the output current is 1a at 0.1 (0.5a at 0.2 ) and this is a calculated output current when the adj terminal is 1.25v floating. shutdown mode taking the adj pin to a voltage below 0.2v for more than approximately 100 s will turn off the output, and supply current will fall to a low standby level of 20 a nominal. soft-start the device has inbuilt soft-start action due to the delay through the pwm filter. an external capacito r from the adj pin to ground will provide additional soft-start delay, by increasing the time taken for the voltage on this pin to rise to the turn-on threshold and by slowing down the rate of rise of t he control voltage at the input of the comparator. with no external capacitor, the time taken for the output to reach 90% of its final value is approxima tely 500 s. adding capacitance increases this delay by approximately 0 .5ms/ nf. inherent open-circuit led protection if the connection to the led(s) is open-circuited, the coil is isolated from the lx pin of the chip, s o the chip will not be damaged. unlike in many boost converters, where the back emf may damage the internal switch by forcing the drain above its breakdown voltage.
ec4304 1a, hysteretic, high brightness led driver with internal switch e-cmos corp. ( www.ecmos.com.tw ) page 5 of 13 4b25n-rev.f005 absolute maximum rating supply input voltage, v in (note 1) ----------------------------------------- ------------- -0.3v to + 45v isense voltage, v isense --------------------------------------------------- --------------- +0.3v to -5v(measured with respect to v in ) lx output voltage, v lx -------------------------------------------------- ----------------- -0.3v to + 45v adjust pin input voltage, v adj -------------------------------------------------- ---------- -0.3v to + 6v switch output current, i lx -------------------------------------------------- --------------- 1.2a operation temperature range ----------------------- ----------------------------------- -40 c to +125 c storage temperature range ------------------------- ------------------------------------ -55 c to +150 c junction temperature ------------------------------ ---------------------------------------- 150 c lead temperature (soldering, 10 sec) -------------- ----------------------------------- 260 c esd rating (note 2) hbm (human body mode) ----------------------------- ---------------------------- 4kv mm (machine mode) --------------------------------- -------------------------------- 200v thermal information package thermal resistance (note 3) sot23-5l ja -------------------------------------------------- ---------------------- 250c/w sot23-5l jc -------------------------------------------------- ---------------------- 100c/w sot89-5l ja --------------------------------------------------- --------------------- 175c/w sot89-5l jc -------------------------------------------------- ---------------------- 58c/w package thermal resistance (note 4) dfn3x3-8l ja -------------------------------------------------- ---------------------- 70c/w dfn3x3-8l jc --------------------------------------------------- -------------------- 8.2c/w power dissipation, p d @ t a = 25c sot23-5l ------------------------------------------ ----------------------------------- 0.4w dfn3x3 8l ----------------------------------------- ------------------------------------ 1.4w sot89-5l ------------------------------------------ ----------------------------------- 0.7w recommended operation conditions operating junction temperature range (note 5) ----- ----------------------------- -40c to +125c operating ambient temperature range --------------- ------------------------------- -40c to +85c note 1. stresses listed as the above absolute maxi mum ratings may cause permanent damage to the devi ce. these are for stress ratings. function al operation of the device at these or any other co nditions beyond those indicated in the operational sections of the specif ications is not implied. exposure to absolute maxim um rating conditions for extended periods may remain possibil ity to affect device reliability. note 2. devices are esd sensitive. handling precaut ion recommended. note 3. ja is measured in the natural convection at t a = 25c on a low effective thermal conductivity tes t board of jedec 51-3 thermal measurement standard. note 4. ja is measured at t a = 25 c on a high effective thermal conductivity four-lay er test board per jedec 51-7. jc is measured at the exposed pad of the package. note 5. the device is not guaranteed to function ou tside its operating conditions.
ec4304 1a, hysteretic, high brightness led driver with internal switch e-cmos corp. ( www.ecmos.com.tw ) page 6 of 13 4b25n-rev.f005 electrical characteristics (v in = 12v, t a = 25 , unless otherwise specified) parameter symbol test conditions min typ max units supply input supply voltage range v in 7 - 40 v vin por threshold v inrth v in rising - 4.95 - v vin por threshold v infth v in falling - 4.8 - v quiescent current with output off i_q off adj pin grounded - 20 40 a quiescent current with output switching i_q on adj pin floating f = 250khz - 0.5 1.0 ma isense pin current sense threshold voltage v sense isense pin with respect to vin, adj = 1.25v 95 100 105 mv isense input current isense v sense = vin-0,1 - - 1.0 a reference reference voltage v ref adj pin voltage - 1.25 - v reference voltage temperature coefficient - 50 - ppm/v adj pin adj pin for dc control level v adj 0.3 - 2.5 v adj to switch device from on state to off state v adj_off v adj falling 0.15 0.2 0.25 v adj to switch device from off state to on state v adj_on v adj rising 0.2 0.25 0.3 v 0 < v adj < vref 135 - 250 k adj to vref resistance r adj v adj > vref+100mv 13.5 - 25 k adj pin low frequency duty cycle range dpwm (lf) pwm frequency < 500hz 10 - 100 % adj pin high frequency duty cycle range dpwm (hf) pwm frequency >10khz 16 - 100 % lx pin lx switch current i lxmean ec4304a - - 1 a
ec4304 1a, hysteretic, high brightness led driver with internal switch e-cmos corp. ( www.ecmos.com.tw ) page 7 of 13 4b25n-rev.f005 parameter symbol test conditions min typ max units lx r ds_on r lx @i lx = 1a, ec4304a - 0.3 0.6 lx leakage current - - 5 a minimum switch on time t on_min lx switch on - 240 - ns minimum switch off time t off_min lx switch off - 200 - ns recommended minimum switch on time t on_min_rec - 800 - ns frequency operation frequency f lx adj pin floating, l=33 h (0.093 ) i out = 1a @ vled=3.6v driving 1led - 280 - khz recommended maximum operation frequency f lxmax - - 1 mhz duty cycle range of output switch of operation frequency d lx 30 - 70 % internal comparator propagation delay tpd - 50 - ns soft-start soft-start time time taken for output current to reach 90% of final value after voltage on adj pin has risen above 0.3v. - 500 - s
ec4304 1a, hysteretic, high brightness led driver with internal switch e-cmos corp. ( www.ecmos.com.tw ) page 8 of 13 4b25n-rev.f005 typical operation characteristics
ec4304 1a, hysteretic, high brightness led driver with internal switch e-cmos corp. ( www.ecmos.com.tw ) page 9 of 13 4b25n-rev.f005 typical operation characteristics
ec4304 1a, hysteretic, high brightness led driver with internal switch e-cmos corp. ( www.ecmos.com.tw ) page 10 of 13 4b25n-rev.f005 typical operation characteristics
ec4304 1a, hysteretic, high brightness led driver with internal switch e-cmos corp. ( www.ecmos.com.tw ) page 11 of 13 4b25n-rev.f005 package information sot23-5l
ec4304 1a, hysteretic, high brightness led driver with internal switch e-cmos corp. ( www.ecmos.com.tw ) page 12 of 13 4b25n-rev.f005 sot89-5l package informa tion dimensions in millimeters symbols min nom max a2 1.40 1.50 1.60 b 0.38 --- 0.47 b1 0.37 0.40 0.43 c 0.36 --- 0.46 c1 0.35 0.38 0.41 a 0.46 --- 0.56 a1 0.45 0.48 0.51 d 0.36 --- 0.46 d1 0.35 0.38 0.41 d 4.30 4.50 4.70 d1 1.70ref e 4.00 4.20 4.40 e1 2.30 2.50 2.70 e 1.50bsc l1 0.80 1.00 1.20
ec4304 1a, hysteretic, high brightness led driver with internal switch e-cmos corp. ( www.ecmos.com.tw ) page 13 of 13 4b25n-rev.f005 package information dfn3x3-8l

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