ts19377 2a buck (step-down) wled driver 1/7 version: a11 so p - 8 general description ts19377 consists of step-down switching regulator w ith pwm control. these devise include a reference v oltage source, oscillation circuit, error amplifier, inter nal pmos and etc. ts19377 provides low-ripple power, high efficiency, and excellent transient characteristics. the pwm c ontrol circuit is able to the duty ratio linearly from 0 u p to 100%. an enable function, an over current prot ect function and short circuit protect function are built inside, an d when ocp or scp happens, the operation frequency will be reduced. also, an internal compensation block is bu ilt in to minimum external component count. with the addition of an internal p-channel power mo s, a coil, capacitors, and a diode connected extern ally, these ics can function as step-down switching regulators. they serve as ideal power supply units for portabl e devices when coupled with the sop-8 package, providing such outstanding features as low current consumption. s ince this converter can accommodate an input voltage up to 23v, it is also suitable for the operation via a n ac adapter. features input voltage range 3.6v~23v output voltage: 0.25v~vcc 2a switch output current duty ratio: 0%~100% pwm control 330khz switching frequency enable/disable functions current limit and thermal shutdown short circuit protections built-in internal sw p-ch mos application white led backlighting white led driving multiple led driving led lighting equipment ordering information part no. package packing ts19377cs rlg sop-8 2.5kpcs / 13 reel note: g denotes halogen free product. block diagram vcc oscillator circuit reference voltage pwmswitched control circuit + - vss v en en comp fb thermal shutdown sw current limit pin definition : 1. fb 8. gnd 2. en 7. gnd 3. comp 6. sw 4. vcc 5. sw
ts19377 2a buck (step-down) wled driver 2/7 version: a11 absolute maximum rating parameter symbol limit unit v cc pin voltage v cc v ss - 0.3 to v ss + 25 v feedback pin voltage v fb v ss - 0.3 to v cc v on/off pin voltage v en v ss - 0.3 to v cc + 0.3 v switch pin voltage v sw v ss - 0.3 to v cc + 0.3 v power dissipation pd internally limited mw storage temperature range t st -40 to +150 c operating temperature range t op -40 to +125 c operating supply voltage v op +3.6 to +23 v thermal resistance from junction to case jc 25 c/w electrical specifications (v in =12v, t a =25 o c, unless otherwise noted) parameter symbol conditions min typ max units feedback voltage v fb i out =0.2a 0.24 0.25 0.26 v quiescent current i ccq v fb =1.2v force driver off -- 3 5 ma feedback bias current i fb i out =0.1a -- 0.1 0.5 ua shutdown supply current i sd v en =0v -- 2 10 ua switch current i sw 2.5 -- -- a line regulation v out /v out v cc =5v~23v, i out =0.2a -- 1 2 % load regulation v out /v out i out =0.1 to 2a -- 0.2 0.5 % oscillation frequency f osc 260 330 400 khz en pin logic input threshold voltage v sh high (regulator on) 2.0 -- -- v v sl low (regulator off) -- -- 0.8 en pin input current i sh v en =2.5v (on) -- 20 -- ua i sl v en =0.3v (off) -- -10 -- ua internal mosfet r dson r dson v cc =5v, v fb =0v -- 100 140 m v cc =12v, v fb =0v -- 70 100 efficiency effi v out = 5v i out =1a -- 91 -- % i out =2a -- 91 -- thermal shutdown temp t sd -- 140 -- c
ts19377 2a buck (step-down) wled driver 3/7 version: a11 typical application circuit a: 1w/3w led*1 for dc input vout vcc r1 100k u1 ax2002/a 1 2 3 4 5 6 7 8 fb en comp vcc sw sw vss vss d7 led r2 0.75r/0.33r r4 4.7k c4 1u l1 22uh (10uh for ax2002a) d6 1n4148 d5 b240a c3 0.1u r5 100k c2 22u c1 4.7u option 1w/3w recommend bill of material: i led r2 c2 r5 l1 350ma 0.715 87.5mw 100uf 0.22k 68uh 750ma 0.333 189mw 220uf 0.47k 1000ma 0.250 250mw 330uf 0.47k b: 1w/3w led*1 for ac input no output capacitor vout u1 ax2002/a 1 2 3 4 5 6 7 8 fb en comp vcc sw sw vss vss d2 led r2 c5 l1 d5 b240a r5 100nf c2 ac 12v in ac d4 ac d3 ac d2 ac d1 c3 0.1u i led r2 c2 r5 l1 350ma 0.715 87.5mw 100uf 0.22k 68uh 750ma 0.333 189mw 220uf 0.47k 1000ma 0.250 250mw 330uf 0.47k
ts19377 2a buck (step-down) wled driver 4/7 version: a11 function descriptions pwm control the ts19377 consists of dc/dc converters that emplo y a pulse-width modulation (pwm) system. in convert ers of the ts19377, the pulse width varies in a range from 0 to 100%, according to the load current. the ripp le voltage produced by the switching can easily be removed thr ough a filter because the switching frequency remai ns constant. therefore, these converters provide a low -ripple power over broad ranges of input voltage an d load current. setting i led current application circuit item shows the basic applicatio n circuit with ts19377 adjustable output version. t he external resistor sets the led output current according to t he following formula: i led =(0.25v/r2) resistor select for led output current setting i led r2 350ma 0.715 87.5mw 750ma 0.333 189mw 1000ma 0.250 250mw rds (on) current liming the current limit threshold is setting by the inter nal circuit. compensation please refer the table of application circuit. for dc input, the option circuit for compensation is co nnecting r4 and a 1n4148 diode to v out . in order to protect short circuit and thermal shu tdown release for led.
ts19377 2a buck (step-down) wled driver 5/7 version: a11 electrical characteristics curve figure 1. quiescent current vs. temperature figure 2. shutdown current vs. temperature figure 3. feedback voltage vs. temperature figure 4. feedback voltage vs. input voltage figure 5. frequency vs. temperature figure 6. efficiency vs. output current
ts19377 2a buck (step-down) wled driver 6/7 version: a11 sop-8 mechanical drawing marking diagram y = year code m = month code for halogen free product ( o =jan, p =feb, q =mar, r =apl, s =may, t =jun, u =jul, v =aug, w =sep, x =oct, y =nov, z =dec) l = lot code sop-8 dimension dim millimeters inches min max min max. a 4.80 5.00 0.189 0.196 b 3.80 4.00 0.150 0.157 c 1.35 1.75 0.054 0.068 d 0.35 0.49 0.014 0.019 f 0.40 1.25 0.016 0.049 g 1.27bsc 0.05bsc k 0.10 0.25 0.004 0.009 m 0o 7o 0o 7o p 5.80 6.20 0.229 0.244 r 0.25 0.50 0.010 0.019
ts19377 2a buck (step-down) wled driver 7/7 version: a11 notice specifications of the products displayed herein are subject to change without notice. tsc or anyone on its behalf, assumes no responsibility or liability for any erro rs or inaccuracies. information contained herein is intended to provide a product description only. no license, express or implied, to any intellectual property rights is granted by this document. except as provided in tscs terms and co nditions of sale for such products, tsc assumes no liability wh atsoever, and disclaims any express or implied warr anty, relating to sale and/or use of tsc products includi ng liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, cop yright, or other intellectual property right. the products shown herein are not designed for use in medical, life-saving, or life-sustaining applica tions. customers using or selling these products for use i n such applications do so at their own risk and agr ee to fully indemnify tsc for any damages resulting from such i mproper use or sale.
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