not recommended for new design microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 1 copyright ? 2000 rev. 1.2a, 2005-01-27 www. microsemi . com lx1686 di g ital dimmin g ccfl controller ic p roduction d ata sheet integrated products description the lx1686 backlight controller ic provides all the control functions needed to implem ent microsemi?s direct drive inverters used to operate cold cathode fluorescent lamps (ccfl?s). this ic can be used to control single or multiple-lamp configurations. ccf l?s are used for back or edge lighting of liquid crystal flat panel displays (lcd?s) and typically find application in notebook computers, web browsers, automotive and industrial instrumentation, and entertainment systems. the lx1686 includes a pwm controlled lamp current burst circuit that can provide a > 100:1 dimming range from a simple zero to 2.5v potentiometer input. the pwm dimming burst rate is easily synchronized to the lcd panel?s frame rate to prevent interference from optical beat frequencies. safety and reliability features include a new dual feedback control loop that permits regulation of maximum lamp strike voltage as well as lamp current. regulating maximum lamp voltage permits the designer to provide for ample worst case lamp strike voltage while at the same time conservatively limit maximum open circuit voltage. an innovative new strike voltage generation technique enables the nodule designer to optimize high voltage transformer design for maximum operating efficiency with no power dissipating overhead to guarantee strike capability direct drive topology is a non- resonant, oscillator-controlled pwm regulation method. the lx1686 allows a wide choice of fixed operating frequencies to match lamp current frequency to the lamp?s most efficient operating point, and to minimize high frequency interference. important: for the most current data, consult microsemi ?s website: protected by u.s. patents 5,615,093; 5,923 ,129; 5,930,121; 6,198,234; patents pending product highlight 0 1 2 3 4 5 0 3045607590105 light output (nits) power used (watts) standard analog dimming inverter microsemi's rangemax key features ? rangemax? wide range dimming (>100:1) ? synchronizable to display video frequency ? high voltage feedback loop directly controls maximum open lamp ? micro-amp sleep mode ? user programmable fixed frequency operation ? under-voltage lockout feature with power-up reset ? built-in soft-start feature ? operates with 3.3v or 5v power supplies ? 100ma output drive capability applications ? notebooks ? instrumentation display ? desktop computer monitors ? low ambient light displays (used in aircraft, automobiles, and hand-held equipment) benefits ? extremely high efficiency from 3.3v to 5v power supplies ? lower cost than conventional buck / royer inverter topologies ? improved lamp strike capability ? improved over-voltage control package order info pw plastic tssop 24-pin t a ( c) rohs complaint / pb-free transition d/c: 0442 0 to 85 lx1686cpw -40 to 85 LX1686IPW note: available in tape & reel. append the letters ?tr? to the part number. (i.e. lx1686cpw-tr) l l x x 1 1 6 6 8 8 6 6 light emitted by a ccfl is proportional to the current flowing through it. there are two ways to control the curr ent: by adjusting the amplitude of a continuous ac current; or, as with rangemax technology, by varying the amount of time a burst of full curren t is present. rangemax technology frees the backlight inverter module designer to operate in a lower brightness and lower power consumpt ion mode than is possible with conventional amplitude control methods.
not recommended for new design microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 2 copyright ? 2000 rev. 1.2a, 2005-01-27 www. microsemi . com lx1686 di g ital dimmin g ccfl controller ic p roduction d ata sheet integrated products absolute maximum ratings supply voltage (vdd , vdd_p) .................................................................................. 6.5v digital input s ........................................................................................ -0.3 to vdd +0.5v analog inputs ........................................................................................ -0.3 to vdd +0.5v digital out puts...................................................................................... -0.3 to vdd +0.5v analog output s ..................................................................................... -0.3 to vdd +0.5v operating junction temperature ...............................................................................150c storage temperat ure ................................................................................... -65 c to 150c rohs / pb-free peak package solder reflow temperature (40 second maximum expo sure)..................................................................... 260c (+0,-5) note: exceeding these ratings could cause damage to th e device. all voltages are with respect to ground. currents are positive into, ne gative out of specified terminal package pin out vss afd_c vdd a out vss_p ramp_c ramp_r fvert pd_cr vco_c brt_pos brite dig_dim vdd_p tri_c olsns isns icomp vsns vcomp brt i_r enable b out 2 3 4 5 6 7 8 9 10 11 12 1 23 22 21 20 19 18 17 16 15 14 13 24 pw p ackage (top view) rohs / pb-free 100% matte tin lead finish thermal data pw p ackage thermal resistance - junction to ambient , ja 100 c/w junction temperature calculation: t j = t a + (p d x ja ). the ja numbers are guidelines for the ther mal performance of the device/pc-board system. all of the above assume no ambient airflow. p p a a c c k k a a g g e e d d a a t t a a
not recommended for new design microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 3 copyright ? 2000 rev. 1.2a, 2005-01-27 www. microsemi . com lx1686 di g ital dimmin g ccfl controller ic p roduction d ata sheet integrated products functional pin description p in n ame d escription aout output driver a. vss_p power ground for output drivers only. vss signal ground. afd_c connects to an external capacitor, c afd . forcing to ground or vdd will make the vco oscillate at approximately 50% of the maximum vco frequency. forcing to vdd/2 will make the vco oscillate at 2x the fvert frequency. ramp_c connects to external capacitor c ramp for setting direct drive pwm operating frequency. ramp_r connects to external resistor r ramp for setting direct drive pwm operating frequency. fvert vertical frequency reference digital input. has internal pull down. pd_cr phase detector filter. part of phase lock loop. connects to external capacitor and resistor network. vco_c connects to external capacitor c vco brt_pos brightness control polarity. has internal pull up. leave open or pull up to vdd for dimming brightness proportional to brite voltage, connect to ground for brightness inversely proportional to brite voltage. brite analog voltage input for brightness control. dig_dim digital dimming enable internal pull up. leave open or pull up to vdd for operating in digital dimming mode. connect to ground for analog dimming mode. enable chip enable internal pull up. high enables the chip. low disables. i_r current reference resistor. external resistor to ground (ri) determines internal capacitor c icomp . brt current error amplifier non-inverting input vcomp voltage error amplifier output. connects to ex ternal frequency compensation capacitor c vcomp . controls soft- start timing. vsns voltage error amplifier inverting input. icomp current error amplifier output. connects to external frequency compensation capacitor c icomp . isns current error amplifier inverting input. olsns open lamp sense input. tri_c connects to external capacitor c tri for setting strike frequency ramp slope. vdd vdd vdd_p dedicated vdd for output buffers only. bout output driver b. p p a a c c k k a a g g e e d d a a t t a a
not recommended for new design microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 4 copyright ? 2000 rev. 1.2a, 2005-01-27 www. microsemi . com lx1686 di g ital dimmin g ccfl controller ic p roduction d ata sheet integrated products electrical characteristics unless otherwise specified, the following specifications apply over the operating ambient temperature -0 c t a 85 c for the lx1686 c pw and -40c t a 85c for the LX1686IPW except where otherwise noted. test conditions: vdd = vdd_p = 3.0 to 5.5v, ri = 40k ? , c vco = 0.01f, c afd = 0.22f, c tri = 0.83f, c ramp = 208pf, r ramp = 15k ? , c pd = 0.22f, c pdb = 0.047f, r pd = 110k ? lx1686 parameter symbol test conditions min typ max units power supply voltage vdd vdd = vdd_p 3 5.5 v operating current i dd vdd = vdd_p = 5v 5 7 ma power supply voltage vdd_p vdd = vdd_p 3 5.5 v output buffer operating current i dd_p volsns = vdd = vdd_p = 5v, ca = cb = 1000pf 2 10 ma uvlo threshold v th_uvlo 2.7 2.9 v uvlo hysteresis v h_uvlo 160 mv ` direct drive ramp block triangular wave generator analog output peak voltage v p_tri 2.25 v triangular wave generator analog output valley voltage v v_tri 0.75 v triangular wave generator oscillation frequency f _tri 10 hz triangular wave generator oscillation charge current i chg_tri tri_c = 0v -2.3 -2.55 -2.9 a triangular wave generator oscillation discharge current i dischg_tri tri_c = 3v 2.3 2.65 2.9 a ramp generator analog output peak voltage v p_ramp 2.25 v ramp generator analog output valley voltage v v_ramp 0.75 v vdd = 3v 1.35 1.5 1.65 v ramp frequency change threshold v th_ramp_r vdd = 5.5v 1.55 1.65 1.85 v ramp generator oscillation frequency ? nominal f ramp v tri_c = 1.4v 84 100 116 khz ramp generator oscillation frequency ? maximum f ramp_hi v tri_c = 2.25v 170 200 256 khz olsns threshold voltage v th_olsns vdd = 3v 200 300 400 mv olsns hysteresis v h_olsns vdd = 3v 45 mv olsns-to-icomp propagation delay t d_olsns gbd 1 s ` digital dimmer block fvert input frequency capture range f r_fvert 45 200 hz fvert logic threshold v th_fvert design reference only vdd/2 v fvert input resistance r fvert design reference only 50 k ? vco analog output peak voltage v p_vco 2.5 v vco analog output valley voltage v v_vco 0.65 v vco forced source current f r_vco_i_src vpd_cr = 3v, vdd = 3v -6.4 -5.8 -5.2 a forced vco oscillation frequency f x_vco afc_c = 0v, cvco = 0.01f 250 hz auto-frequency detection response t d_afd fvert frequency is 200hz, vdd = 3v 1000 ms brite voltage range v r_brite 0 vdd v full-brightness brite input voltage v brite_full v brt_pos = vdd or float; brite = 2.5v 2.35 2.5 2.65 v vbrt_pos = 0v, brite = 0.5v 2.35 2.5 2.65 v full-darkness brite input voltage v brite_dark vbrt_pos = vdd or float, brite = 0.5v 0.35 0.5 0.65 v vbrt_pos = 0v, brite = 2.5v 0.35 0.5 0.65 v e e l l e e c c t t r r i i c c a a l l s s
not recommended for new design microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 5 copyright ? 2000 rev. 1.2a, 2005-01-27 www. microsemi . com lx1686 di g ital dimmin g ccfl controller ic p roduction d ata sheet integrated products electrical characteristics unless otherwise specified, the following specifications apply over the operating ambient temperature -0 c t a 85 c for the lx1686 c pw and -40c t a 85c for the LX1686IPW except where otherwise noted. test conditions: vdd = vdd_p = 3.0 to 5.5v, ri = 40k ? , c vco = 0.01f, c afd = 0.22f, c tri = 0.83f, c ramp = 208pf, r ramp = 15k ? , c pd = 0.22f, c pdb = 0.047f, r pd = 110k ? lx1686 parameter symbol test conditions min typ max units ` digital dimming block (continued) brite-to-icomp propagation delay t d_brite 300 ns brite_pos logic threshold vdd/2 v dig-dim logic threshold vdd/2 v ` direct drive pwm block isns threshold voltage range v r_isns dig_dim = vdd 0 2.5 v vamp transconductance g m_vamp vcomp = 1.25v 400 mho vamp output source current i s_vamp vcomp = 1.5v 10 50 110 a vamp output sink current i sk_vamp vcomp = 1.5v 15 70 120 a vamp output voltage range v r_vamp 0 vdd v vsns threshold voltage v th_vsns vcomp = vsns 1.12 1.25 1.38 v vcomp discharge current i d_vcomp vcomp = 0.5v, vdd = 3v 0.8 1.5 10 ma iamp transconductance g m_iamp brite = 0.5 ? 2.6v 70 200 700 mho iamp output source current i s_iamp icomp = 1.5v, vdd = 3v -15 -40 -80 a iamp output sink current i sk_iamp icomp = 1.5v, vdd = 3v 20 60 100 a iamp output voltage range v r_iamp 0 vdd v vcmp input offset voltage v os_vcmp vcomp = 1.25v, vdd = 3v -10 3 10 mv vcomp-to-output propagation delay t d_vcomp vdd = 3v 250 500 ns icmp input offset voltage v os_icmp icomp = 0.5 to 2.25v, vdd = 3v -10 3 10 mv icomp-to-output propagation delay t d_icomp brite = 1.25v, ramp_c = 2v, vdd = 3v 1100 ns ` output buffer block output sink current i sk_outbuf aout, bout = vdd = 3v 25 45 85 ma aout, bout = 1v, vdd = 3v 20 35 85 ma output source current i sout_buf aout, bout = 0v, vdd = 3v -35 -50 85 ma aout, bout = 2v, vdd = 3v -20 -40 85 ma ` bias control block voltage at pin i_r v ir .975 1.02 v pin i_r maximum source current i max_ir design reference only 50 a vbg output resistance r o_vbg design reference only 10 k ? enable logic threshold ? 3v v en3v vdd = 3v 1.5 1.9 2.4 v enable logic threshold ? 5.5v v en5.5 vdd = 5.5v 2.7 3.2 3.6 v enable threshold hysteresis ? 3v v h_en3 450 mv enable threshold hysteresis ? 5.5v v h_en5.5 350 mv e e l l e e c c t t r r i i c c a a l l s s
not recommended for new design microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 6 copyright ? 2000 rev. 1.2a, 2005-01-27 www. microsemi . com lx1686 di g ital dimmin g ccfl controller ic p roduction d ata sheet integrated products block diagram c pd r pd c pdn c afd c vco pd_cr fvert afd_c vco_c brite brt_pos dig_dim phase detector auto freq. detect vco burst comparator 50k 50k 0-3v ena voltage error amp voltage comparator current comparator brt isns vsns vcomp icomp output steering logic vdd_p aout bout vss_p c vcomp c icomp a b clk out ramp_c ramp_r tri_c olsns vss i_r enable vdd triangle wave gen. open lamp comparator ignite ramp_dout c ramp r ramp2 r ramp1 c tri ri ena pwr_gd 2.50v vdd_sw vdd vdd 1.5v 300mv 255mv vdd q q vamp iamp vcomp icomp 2.5v 0v 1.25v + - + - + + + + - - - - dimming control pwm controllers output drivers bias generator, uvlo, and v ref pwm ramp generator 0.5 - 2.5v current error amp b b l l o o c c k k d d i i a a g g r r a a m m
not recommended for new design microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 7 copyright ? 2000 rev. 1.2a, 2005-01-27 www. microsemi . com lx1686 di g ital dimmin g ccfl controller ic p roduction d ata sheet integrated products package dimensions pw 24-pin thin small shrink outline (tssop) c 1 2 3 p d e f a g h l b m seating plane note: 1. dimensions do not include mold flash or protrusions; these shall not exceed 0.155mm(.006?) on any side. lead dimension shall not include solder coverage. m illimeters i nches dim min max min max a 0.85 0.95 0.033 0.037 b 0.19 0.30 0.007 0.012 c 0.09 0.20 0.0035 0.008 d 7.70 7.90 0.303 0.311 e 4.30 4.50 0.169 0.177 f 0.65 bsc 0.025 bsc g 0.05 0.15 0.002 0.005 h ? 1.10 ? .0433 l 0.50 0.75 0.020 0.030 m 0 8 0 8 p 6.25 6.50 0.246 0.256 *lc ? 0.10 ? 0.004 m m e e c c h h a a n n i i c c a a l l s s
not recommended for new design microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 8 copyright ? 2000 rev. 1.2a, 2005-01-27 www. microsemi . com lx1686 di g ital dimmin g ccfl controller ic p roduction d ata sheet integrated products notes production data ? information contained in this document is proprietary to microsemi and is current as of publication date . this document may not be modified in any way without the express written consent of microsemi. product processing does not necessarily include testing of all parameters. microsemi reserves the right to change the configuration and performance of the product and to discontinue product at any time. n n o o t t e e s s
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