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microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 1 copyright ? 2003 rev. 1.0, 8/31/2004 www. microsemi . com lx1691a enhanced multi-mode ccfl controller p roduction d ata s heet tm ? description mircrosemi?s lx1691a is an enhanced direct drive ccfl (cold cathode fluorescent lamp) controller. its architecture is based on the lx1691. lx1691a based inverter modules can be designed for virtually any ccfl appliance from digital cameras and pda?s to big screen monitors and driver viewable automotive displays. new versatile dimming circuitry can accept digital and analog control inputs and provides six different dimming modes that control both lamp current amplitude and duty cycle, either simul- taneously or separately. designers can select normal or reverse polarity dimming and precisely program mini-mum and maximum lamp currents with resistors. the lx1691a fault shutdown feature is enhanced to include regulation and shutdown for over voltage and over current conditions. the lx1691a includes the microsemi proven and patented strike method that allows significant efficiency gains while guaranteeing strong striking power at all operating temperatures. our method sweeps strike frequency smoothly up to the unloaded resonant frequency of the lamp and high voltage transformer. this, coupled with the lx1691a?s active high output voltage regulation, produces just enough strike voltage without generating unpredictable high voltage spikes that cause arcing and component failures. competitive devices that simply switch to a higher frequency for striking do not have this ?real time? control over output voltage, and require much more attention to transformer design. the lx1691a is optimized for wide input voltage applications. it is identical to the lx1691 except it has a guaranteed minimum lamp strike interval of one second to meet notebook and monitor panel manufacturer?s specifications. the lx1691a includes feed forward compensation that provides improved regulation and transient response over an 7 ? 24 volt input supply range. the lx1691a can also be used with a fixed input supply and will produce performance equal to that of the lx1691. important: for the most current data, consult microsemi ?s website: http://www.microsemi.com key features ? simultaneous amplitude and duty cycle dimming modes ? resistor programmable min and max lamp currents ? digital dimming can synch to external or internal clocks ? 120 ms power on delay ? open or shorted lamp regulation & shutdown ? ?on chip? full wave lamp current rectifier ? 16 pin tssop package ? very stable oscillator with on- chip timing capacitor ? enhanced digital dimming resolution ? wide input voltage capable benefits ? low component count / module cost / and size ? high ?nits/watt? efficiency ? operates directly from a single li-ion cell ? industries safest and highest performing strike voltage generation (patented) ? tight operating frequency tolerance for easier system level rfi control product highlight 2 0 vdc t1 t2 brite_in dd_clk +3v traditional analog + t1 t2 _ 2 0 vdc brite_in dd_clk external digital t = 512 / dd_clk frequency + _ 2 0 vdc t1 t2 brite_in dd_clk direct pwm (analog) + t1 t2 _ 2 0 vdc brite_in dd_clk +3v internal digital t = 512 / lamp frequency + _ t lamp current (ma) lamp current (ma) lamp current (ma) lamp current (ma) t t t four of six dimming modes package order info t a ( c) m in v ddp m ax v ddp pw plastic tssop 16-pin -40 to +85 2.8v 5.5v LX1691AIPW pb-free note: available in tape & reel. append the lett ers ?tr? to the part number. (i.e. LX1691AIPW-tr) l l x x 1 1 6 6 9 9 1 1 a a
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 2 copyright ? 2003 rev. 1.0, 8/31/2004 www. microsemi . com lx1691a enhanced multi-mode ccfl controller p roduction d ata s heet tm ? absolute maximum ratings supply voltage ( v ddp ) ..................................................................................................... 6v digital input ( enable )....................................................................... -0.3v to v ddp +0.5v analog inputs ( i_sns, op_sns, vin_sns) clamped to +/- 10v. max peak current +/-100ma analog inputs ( brite_in )................................................................... -0.3v to v ddp +0.5v dim_mode input ................................................................................ -0.3v to v ddp +0.5v dd_clk digital i nput ........................................................................ 0.3v to v ddp +0.5v digital output ( a out , b out ) .................................................................. -0.3v to v ddp +0.5v analog outputs ( brite_r, i_r, ea_out,brite_out ) ....................... -0.3v to v ddp +0.5v operating temperatur e range ........................................................................ - 55 to 125c maximum junction te mperatur e ...............................................................................150c package peak temperature for solder reflow (40 seconds ma ximum exposure) ......... 255c (+5 -0) 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 v ddp op_sns vin_sns brite_in b out a out v dda i_sns dim_mode gnd dim_clk ea_out i_r enable 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 brite_out brite_r pw p ackage (top view) pb-free 100% matte tin lead finish thermal data pw plastic tssop 16-pin t hermal resistance - junction to a mbient , ja 99c/w junction temperature calculation: t j = t a + (p d x ja ). the ja numbers are guidelines for the therma l performance of the device/pc-board system. all of the above assume no ambient airflow. functional pin description p in n ame d escription gnd ground v ddp voltage input, 3.0 to 5.5v input range. v ddp is switched (see enable) to remo ve power from chip. an ldo regulator follows the switch and generates v dda (see v dda ). the output driver stages are powered directly from the v ddp input. care must be taken in po wer distribution design to minimize transients and noise coupling from v ddp to the v dda output. v dda analog v dda supply output. this output pin is used to connec t an external capacitor to stabilize and filter the on chip v dda ldo regulator. the input of the ldo is the switched v ddp supply. ldo output is normally 3.0v and is used to drive all circuitry except the output buffers at aout and bout. drop out voltage is typically 50mv (@ 25c) at 5ma, the average internal load. this output can supply up to a 5 ma external load. the output capacitor recommended is <1000nf of the ceramic dielectric type. a out a buffer n-fet driver output. 10k internal pull down, 100 ma peak current with 3 vdc applied to v ddp pin. b out b buffer n-fet driver output. 10k internal pull down, 100 ma peak current with 3 vdc applied to v ddp pin. dd_clk* digital dimming clock / dimming polarity. an input pin that may be selected to control burst frequency for digital dimming. this input can be forced to v dda or vss or any clock signal up to 1mhz. this pin is also used to control the dimming polarity when operating in the interna lly clocked digital dimming mo de*. if dim_mode is in the open condition (analog dimming mode) the dd_clk input is tied to v dda or open (internal pull-up) to select conventional dimming polarity. it is tied to ground for reverse polarity. conventional polarity means that lamp brightness increases with increasing voltage on the brit e_in pin. reverse polarity means that brightness decreases with increasing voltage. if dim_mode is open a nd a low frequency pulse is applied to dd_clk, lamp current amplitude is directly proportional to the volt age at brite_in, and its duty cycle follows the dd_clk waveform, e.g., current flows when dd_clk is high. in th is mode pulse count should be greater than fault count. p p a a c c k k a a g g e e d d a a t t a a
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 3 copyright ? 2003 rev. 1.0, 8/31/2004 www. microsemi . com lx1691a enhanced multi-mode ccfl controller p roduction d ata s heet tm ? functional pin description (continued) p in n ame d escription dim_mode* dimming mode input. this three state input pin places the ic in analog dimming mode, internal digital dimming mode, or external digital dimming mode. if the input is left open or forced to v dda / 2, analog mode is selected. if connected to v dda , digital dimming mode with an external clock from the dd_clk input controls the burst timing generator. burst frequency is the external clock frequency divided by 512. if dim_mode is connected to ground, digital dimming with an internal clock is sele cted. burst frequency in internal clock mode is lamp current frequency divided by 512, and burst duty cycle is directly proportional to the voltage at brite_in. op_sns over voltage & over current sense. this input pin co mbines the functionality of ov_sns and oc_sns in the lx1691. the op_sns input signal is a full wave ac voltage centered around ground that is proportional to lamp voltage. the op_sns input will be full wave rectif ied, then applied to a digital comparator with a 2v reference to cause peak voltage greater than 2v to di gitally reset the pwm logic on a pulse by pulse basis. frequency range of the input signal is 10khz to 500khz . normal operating voltage is less than 2v, and abnormal voltage can operate continuously as high as 7v peak under load fault conditions. transients under fault conditions can reach 10vpk. input voltage greater than 3v peak but less than 10v peak may cause saturation but will not cause malfunction, phase reversal, or reliability issues with the ic. vin_sns input voltage sense. this input pi n senses power supply amplitude and automatically adjusts the maximum pulse width of aout and bout to impr ove line transient response and regulation. an external resistor divider from the input power supply drives this pin. maximum du ty cycle is indirectly proportional to input voltage. maximum duty cycle versus vin slope can be varied by se lection of external resistor values and ratios. see application note for equations and design examples. i_sns current sense input. a full wave ac voltage input center ed around ground that is proportional to lamp current. the i_sns input is full wave rectified and amplified, t hen presented to the inverting input of the current error amplifier. during the strike mode the current sense input will regulate to 1v regardless of brite_in setting. frequency range of the input signal is 10 khz to 500k hz. normal operating voltage is less than 2v, and abnormal voltage can operate continuously as high as 7v peak under load fault conditions. transient under fault conditions can reach 10vpk. i nput voltages of up to 3v peak are lin early rectified. input voltage above 3v peak but less than 10v peak may cause saturation but do not cause malfunction, phase reversal, or reliability issues with the ic. ea_out error amp output. an external ca pacitor is connected from this pin to gnd to adjust loop response of the inverter module. this capacitor value can vary from 10pf to 5000pf in various applications. brite_in brightness control input. the input signal should be a dc voltage or a filtered high frequency pulse width modulated digital signal. active dc voltage range is 0.0 to 2.0v. on chip signal conditioning amplifiers clip inputs above 2v. enable chip enable input. if logic high, all functions are enabled. if logic low, internal power is disconnected from the v ddp pin, disabling all functions. maximum current into v ddp when enable < 0.3v, v ddp <5v, is 10a. enable may be connected directly to v ddp if the disable function is not used. i_r current reference resistor input. connects to an extern al resistor that determines the magnitude of internal bias currents. the nominal lamp frequency can be adjusted by varying this resistor value in the range of 40k to 100k ohms. i_r i_r r 1.00v i = *see dimming mode truth table for a summary of dimmi ng operation with respect to dd_clk & dim_mode inputs. p p a a c c k k a a g g e e d d a a t t a a
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 4 copyright ? 2003 rev. 1.0, 8/31/2004 www. microsemi . com lx1691a enhanced multi-mode ccfl controller p roduction d ata s heet tm ? functional pin description (continued) p in n ame d escription brite_out brightness reference current output. this variable curr ent source is the mirror of brite_r current multiplied by the brite_in signal and becomes the reference voltag e to the error amplifier when dim_mode is open or ? v dda . connecting an additional resistor to vdda determines minimum lamp current in order to prevent fault condition. a light sensor (lx1970) may be used in conjunction with brite_out to change amplitude of lamp current in response to ambient light intensity. v brite_out = v brite_in x brite_out/brite_r (when dd_clk is connected to v dda ) v brite_out = (2-v brite_in ) x brite_out/brite_r (when dd_clk is connected to gnd) when dim_mode is gnd or v dda , then brite_out has to be biased with an external resistor. brite_r dedicated bias resistor for brite_out curr ent source when dim_mode is open or ? v dda. connecting an additional resistor to vdda determines minimum burst duty cycle in digital dimming. a light sensor (lx1970) may be used in conjunction with brite_r to change burs t duty cycle in re sponse to ambient light intensity. dimming table description dim_ mode dd_ clk conditions reversed internal digital dimming internally clocked pwm burst generator, external input to brite_in low voltage at brite_in controls lamp current bu rst duty cycle. duty cycle is inversely proportional to voltage at brite_in. bu rst period is lx1691a oscillator frequency divided by 1024 (lamp current frequency divided by 512). an external voltage connected to the brite_out pin sets lamp current amplitude. conventional internal digital dimming internally clocked pwm burst generator, external input to brite_in 0v high voltage at brite_in controls lamp current burst duty cycle. duty cycle is directly proportional to voltage at brite_in. bu rst period is lx1691a oscillator frequency divided by 1024 (lamp current frequency divided by 512). an external voltage connected to the brite_out pin sets lamp current amplitude conventional external digital dimming externally clocked pwm burst generator, external input to brite_in vdda pulse voltage at brite_in controls lamp current burst duty cycle. duty cycle is directly proportional to voltage at brite_in. burs t period is dd_clk input divided by 512. an external voltage connected to the brite_out pin sets lamp current amplitude. reversed analog amplitude dimming low voltage at brite_in controls lamp current amplitude. amplitude is inversely proportional to voltage at brite_in. conventional analog amplitude dimming high voltage at brite_in controls lamp current am plitude. amplitude is directly proportional to voltage at brite_in. conventional analog amplitude dimming with external direct pwm control ? vdda or open pulse voltage at brite_in controls lamp current am plitude. amplitude is directly proportional to voltage at brite_in. burst period and duty cycle are directly proport ional to signal at dd_clk input pin. if held low, duty cycle is 0% (zero duty will cause a fault shut do wn. minimum duty to prevent fault shut down is lamp and tem perature dependent. user must characterize lamp to determine minimum duty cycle.). if held high, duty cycle is 100% (full brightness). p p a a c c k k a a g g e e d d a a t t a a
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 5 copyright ? 2003 rev. 1.0, 8/31/2004 www. microsemi . com lx1691a enhanced multi-mode ccfl controller p roduction d ata s heet tm ? recommended operating conditions lx1691a parameter min typ max units supply voltage (v ddp ) 2.8 5.5 v digital input (enable) 0 5.5 v analog inputs (i_sns, op_sns, vin_sns) -2 2 v pk brite_in linear dc voltage range 0 2 v brite_out, brite_r maximum source current 100 a digital inputs (dim_mode, dd_clk) 0 5.5 v internal oscillator frequency (i_r resistor range 42k to 175k) 60 250 khz maximum output gate charge (a out , b out ) 10 20 nc electrical characteristics (continued) unless otherwise specified, the following specifications apply over the operating ambient temperature -40 c t a 85 c except where otherwise noted. test conditions: v ddp =3.3 to 5.5 v, i_r =80.6k ? , brite_r = brite_out = 20k ? , op_sns = vin_sns = 0v, dd_clk = dim_mode = floating lx1691a parameter symbol test conditions min typ max units ` power power supply input voltage v _batt 2.8 5.5 v regulator output voltage v dda v ddp = 3.3 to 5.5v, i load = 0 madc 2.85 3.0 3.15 v v dda drop out voltage v dropout i load = 0 madc 50 150 mv v ddp operating current i bb c aout = c bout = 1000pf; f osc = 130khz 10 15 ma sleep mode current i dd_sleep v enable = 0.8v, v ddp = 5.5v 10 a ` enable input run threshold v th_enrun 1.5 2.8 v shutdown threshold v th_enshdn 0.8 1.1 v input high current i ih_enable enable = 2v 2 12 a input high current i ih_enable enable = 5v 35 80 a input low current i il_enable enable = 0v -1 0 1 a ` under voltage lockout startup threshold v th_uvlo run mode 2.55 2.8 v uvlo threshold shutdown mode 2.1 2.35 uvlo hysteresis v h_uvlo 200 mv ` bias block voltage at pin i_r v _ir 80.6k 0.975 1.025 v pin i_r max source current i max_ir 100 a voltage reference voltage (internal node) v 2p0 1.98 2.02 v ` output buffer block output sink current i sk_outbuf v aout , v bout = v ddp , v ddp = 3.3v 50 100 150 ma output source current i s_outbuf v aout , v bout = 0v, v ddp = 3.3v 50 100 150 ma output low voltage v ol_outbuf a out , b out =low , v ddp = 5v 0 0.4 v output high voltage v ohj_outbuf a out , b out = high, v ddp = 5v 4.9 5 v e e l l e e c c t t r r i i c c a a l l s s
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 6 copyright ? 2003 rev. 1.0, 8/31/2004 www. microsemi . com lx1691a enhanced multi-mode ccfl controller p roduction d ata s heet tm ? ] electrical characteristics (continued) lx1691a parameter symbol test conditions min typ max units ` ramp generator max strike / run frequency ratio f ramp_stk ratio to run frequency 3 maximum lamp run frequency f ramp_runmax lamp is ignited; i_r = 20k 250 262 khz lamp run frequency f lamp_run lamp is ignited, i_r = 80.6k, t a = 25 c 63 65 67 khz lamp run frequency f lamp_run lamp is ignited, i_r = 80.6k 61 65 69 khz lamp run frequency regulation over v ddp f lamp_reg 3.3 < v ddp < 5.5v 0.1 % internal digital dimming burst frequency f burst dim_mode = 0v, f lamp_run / 512, i_r = 80.6k 127 hz ` pwm block error amp transconductance g m_eamp 60 150 mho error amp output source current i s_eamp 100 a error amp output sink current i sk_eamp 100 a error amp output high voltage v h_eamp brite_out ? ea_in = 50mv 2.5 2.9 v error amp output low voltage v l_eamp ea_in ? brite_out = 50mv 0.015 0.5 v error amp input offset voltage v os_eamp 30 mv max duty cycle dc max 47 % ramp valley voltage r vv 100 mv ramp peak voltage r pv 2.1 v error amp output clamp threshold v eaout1 vinsns = 1.2v through 68k 1.68 v error amp output clamp threshold v eaout2 vinsns = 2.3v through 68k 1.26 v ` dd_clk input pull-up resistance to v dda 50 k ? input high threshold v th_dd_clk conventional dimming 1.6 2.0 v input low threshold v tl_dd_clk reverse dimming 0.4 0.9 v input high current i ih_dd_clk dd_clk = 5v; vddp=5v 45 70 a input low current i il_dd_clk dd_clk = 0v; vddp=5v -65 -100 a ` dim_mode input low state v tl_tri_ 0.4 0.85 v floating state v tf_tri 1.2 1.35 1.8 v high state v th_tri 2.35 2.8 v input high current i ih_tri dim_mode = 5v 70 120 a input low current i il_tri dim_mode = 0v -25 -50 a ` analog dimmer block brite_in input current brite_in ii brite_in = 0 to 5v -1 1 a brite_in = 0v 0 25 60 mv brite_in > 2.05v 1.95 2.0 2.10 v brite_ in < 0v 1.9 2.0 2.1 v conventional dimming brite_out brite_in > 2.05v 0 25 60 mv e e l l e e c c t t r r i i c c a a l l s s
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 7 copyright ? 2003 rev. 1.0, 8/31/2004 www. microsemi . com lx1691a enhanced multi-mode ccfl controller p roduction d ata s heet tm ? electrical characteristics (continued) lx1691a parameter symbol test conditions min typ max units ` digital dimmer block minimum duty cycle; brite_in = 0.1v 2 5 7 % maximum duty cycle; brite_in =1.90v 90 95 100 % conventional dimming duty cycle maximum duty cycle; brite_in 2.05v 100 % maximum duty cycle; brite_in = 0.0v 100 % maximum duty cycle; brite_in = 0.1v 90 95 100 % reverse dimming duty cycle minimum duty cycle; brite_in = 1.95v 2 5 7 % ` timing generator block number of lamp return current cycles before run mode n ignite to switch to run mode 4 cycles i_sns run mode checking interval lamp return current cycles 2048 cycles strike validation threshold to switch to run mode, t a =25c 700 mv pk fault comparator threshold run i_ sns open lamp fault detect, t a =25c 300 mv pk number of strike sweep attempts before fault shutdown n strk_fault flamp sweep cycles, i_sns = 0v_sns = 0v 14 power on delay before strike t d_pwron i_r = 80.6k 125 ms number of sweeping strike frequency steps per attempt 512 steps number of output pulses per striking step 16 cycles ` lamp feedback conditioning block i_sns = +2.5v 14 a i_sns input current i_sns iin i_sns = -2.5v -40 a op_sns input high threshold v th_op_sns active over protection 2.2 v pk op_sns input low threshold v tl_op_sns inactive over protection 1.8 v pk oc_sns = 10v 14 a op_sns input current oc_sns iin oc_sns = -2.5v -40 a i_sns = 0.3vdc, t a = 25c 0.3 v i_sns = 2.5vdc, t a = 25c 2.5 v i_sns = -0.3vdc, t a = 25c 0.3 v full wave rectifiers rms transfer i_sns rms i_sns = -2.5vdc, t a = 25c 2.5 v e e l l e e c c t t r r i i c c a a l l s s
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 8 copyright ? 2003 rev. 1.0, 8/31/2004 www. microsemi . com lx1691a enhanced multi-mode ccfl controller p roduction d ata s heet tm ? block diagram + _ + _ brite_in brite_r b r i t e _ o u t + - r + - r a b sel out mux ddclk >> high=normial analog dim >> 1v d i m _ m o d e a/d ddclk >> tbper>> >> digital dim, external >> digital dim, internal binary counter + _ voltage dac + - digital dim, external digital dim, internal analog dim >> q qb clk d d d c l k vdd >> o p _ s n s i s n s full wave rectifiers + - + - 2v binary counter binary counter vdd a b sel out mux 1v >> brite_out >> + - e a o u t r clk d q qb b o u t a o u t + - v d d a i _ r e n a b l e g n d binary counter current dac ram gen >> tbper >>2v v d d p vref bias normal polarity reverse polarity pwmgate direct digital dim 3.0v 1.5v 0v analog dim over current fault ignite + - v i n _ s n s << 1v 55k figure 1 ? simplified block diagram b b l l o o c c k k d d i i a a g g r r a a m m
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 9 copyright ? 2003 rev. 1.0, 8/31/2004 www. microsemi . com lx1691a enhanced multi-mode ccfl controller p roduction d ata s heet tm ? typical application gnd aout bout dd_clk dim_mode brite_out brite_r brite_in vddp vdda op_sns vin_sns i_sns ea_out i_r enable aout bout c2 1f 10v c3 0.1f 10v vdda j3 c5 100nf r7 47k r6 36k r5 20k r4 10k c4 10nf j4 j5 j1 r2 20k r3 120k j2 q3 dtc d1 5.6v q2 bc847a q1 dta c1 n/u f1 fuse r1 220 vddp op_sns r8 470 isns c6 10nf c7 nu r12 nu r11 80.6k c8 0.1f r10 49.9k r9 576k vins enable d2 5.1v r13 2.2k vins d3 1ss355 r14 120 c9 10f u2b u2a c11 2.2f t1 1:n r15 120 d4 1ss355 c10 0.1f aout d5 5.1v r16 2.2k vins d6 1ss355 r17 120 u3b u3a r18 120 d7 1ss355 c13 0.1f bout r19 82 d8 bav70wt1 c16 18nf r20 10k c14 10nf op_sns r21 2.2k c15 18pf 3kv c12 100nf r22 r isns vin vin gnd gnd +5v enable brite vdda u1 lx1691a optional +5v regualtor *brite_in divider op1: r3 sets minimum duty cycle op2: r6, r7 brite_in divider for 0 to 5v signal level figure 2 ? lx1691a inverter for notebook with 8v to 20v input voltage, various dimming configuration brite input control range (linear dcv) min. brite ?lo? = 100mv max. brite ?hi? = 2.0v burst rate frequency = 117 hz enable input off logic ?lo? <= 0.80v on logic ?hi? >= 1.7v dimming mode j1 j2 j3 j4 j5 r2 r3 r6 r7 c5 conventional internal digital dimmi ng s o o o s 20k op1 op2 op2 100nf reversed internal digital dimming o o o s s 20k op1 op2 op2 100nf conventional analog dimming s o o o o o o op2 op2 100nf reversed analog dimming o o o s o o o op2 op2 100nf external direct pwm dimming o s s o o o o o o o a a p p p p l l i i c c a a t t i i o o n n s s
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 10 copyright ? 2003 rev. 1.0, 8/31/2004 www. microsemi . com lx1691a enhanced multi-mode ccfl controller p roduction d ata s heet tm ? detailed description feature review on-chip ldo regulator an ldo regulator keeps critical analog control circuits operating optimally over the entire input vo ltage range. brightness control voltage and operating frequency are extremely stable. under voltage lockout if the battery input voltage is too low for the controller to function properly, it will turn itself off, preventing spurious operation. if the battery voltage falls to less than 1v where uvlo is no longer guaranteed, 10k pull down resistors on the a out and b out pins insure the external po wer fets cannot be biased on. power on delay a power up reset that delays a out and b out turn on for approximately 120 milliseconds after power is applied. this give extra time for the brite_in source voltage to stabilize so the lamp is not inadvertently powered up at high brightness and then suddenly lowered, creating an undesirable light flash. enhanced brite conditioning circuitry the brite_in pin offers a high impedance input with a linear control range of 0 to 2.0v the function of the pin depends on which of six dimming modes the controller is programmed. (see dimming table page 4) a new feature of the lx1691a allows the dd_clk input to control the burst frequency and duty cycle while the brite_in input controls the output current amplitude (see additional information below). digital or analog dimming modes a dim_mode input pin selects eith er analog or digital mode. in analog mode dc voltage at brite_in controls lamp current amplitude. in digital mode it controls digital dimming duty cycle. when in digital mode, the di mming burst frequency can be synchronous to lamp current by selec ting internal clocking, or to an external clock. with an external clock source, burst frequency will be the clocks frequency divided by 512. when using the internal clock source the burst frequency wi ll be the internal oscillator divided by 1024 which is equivalent to lamp current frequency divided by 512. brightness polarity and du al mode dimming control in analog dimming mode the ic can be programmed to either increase or decrease lamp current amplitude as a function of increasing signal at the brite_in pin by simply connecting the dd_clk input to v dda or ground (see dimming table). if simultaneous amplitude control and digital dimming is desired, apply a pwm signal to dd_clk. the lamp current waveform will exactly follow dd_clk (dd_clk is not divided in this mode); e.g., lamp current flows when dd_c lk is high and stops when it is low. in digital dimming mode, lamp cu rrent duty cycle is either directly or inversely proportional to dc input voltage at the brite_in pin, depending on the st ate of dd_clk. if external clock is selected, duty cycle will be directly proportional to voltage at brite_in and the burst period will be dd_clk period x 512. lamp current amplitude can be set and varied by applying a separate dc voltage at the brite_ out pin. this voltage can range from zero to 2.0 vdc. zero volts will produce zero current (and therefore a lamp fault). 2.0v will produce the maximum current as defined by the value of the cu rrent sensing resistor from i sns to gnd. strike voltage generation improved strike voltage generation circuits ramp strike voltage slowly to programmed maximum potential and hold it there for approximately 1400msec @65khz operating frequency. this insures a worst case lamp will stri ke at any temperature. strike potential is removed immediately wh en the lamp strikes or if the time limit is reached. strike detection the lx1691a includes a new lamp st rike detection scheme that saves a package pin and three external components. internal circuits monitor lamp current pulses at the i_sns input to determine if the lamp strikes and if it stay s ignited once operational. fault time out if the lamp fails to ignite within approximately 1400msec, or if it extinguishes after ignition, or if the clock signal at the dd_clk pin terminates when in external digital dim mode, the output drive is shut down. fault mode will also be invoked if the lamp is short circuited or left open for more than 350msec. on chip rectifiers integrating full wave rectifiers for each of two lamp inputs significantly reduces lamp feedb ack component count. rectification accuracy is improved with high performance on chip rectifiers to provide better lamp current and voltage regulation. complete fault protection in addition to the lamp fault time out, maximu m output voltage and current under all fault conditions is regulated. open circuit voltage can never go higher than th e preset maximum strike potential and total current from the circuit is safely limited with a scaling resistor. ul safety specifications can now be easily met in any application. familiar magnetics the lx1691a can use the same magnetics as all other direct drive controllers. refer to application note 13 for transformer design and power fet selection criteria. with external high side fet drivers, the lx1691a can be used in full bridge resonant mode applic ations. it can employ industry standard high voltage transformers commonly used in notebook computers and desktop monitors. please see separate application note for more details. d d e e s s c c r r i i p p t t i i o o n n
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 11 copyright ? 2003 rev. 1.0, 8/31/2004 www. microsemi . com lx1691a enhanced multi-mode ccfl controller p roduction d ata s heet tm ? detailed description (continued) lx1691a operation four operating modes: power on delay, strike, run, and fault modes are employed by the lx1691a. upon power up or enable going true, power on delay is automatically invoked. immediately after termination of power on delay, or enable going true, strike mode is entered. after a successful strike, e.g., lamp is ignited, run mode is entere d. if ignition is unsuccessful, or if the lamp extinguishes while r unning, fault mode is entered. lamp ignition is determined by monitoring the lamp current feedback voltage at pin i_sns. lamp current cycles are counted from the beginning of strike mode. if 4 or more complete cycles occur the lamp is declared ignited. if less than 4, the lamp is considered not ignited and strike mode continues until ignition is detected or strike time out (approximately 1400ms) is reached. after run mode is entered lamp current pulse count is sampled several times a second to dete rmine that the lamp has not inadvertently extinguished. if lamp current pulses are counted in each sample, run mode is maintained. otherwise, fault mode is entered. strike mode can be entered only once for each on/off cycle of either v ddp or enable. this insures that even intermittent lamp failures cannot cause th e module to continuously output maximum strike voltage. during strike, operating frequenc y is swept from the normal run value approximately to 3x run frequency. this will excite the unloaded resonant frequency of th e transformer and lamp load to generate the required lamp striking voltage. if the lamp has not ignited after about 1400ms, a fault is declared and the a & b outputs are shut off. if while strike frequency is swee ping, the over voltage or over current voltage set point at op_s ns is detected the, strike frequency will hold at the present frequency value until either the lamp strikes or the timeout is reached. this causes maximum strike potential to be continuous ly impressed across the lamp for the entire strike period. the only way to re-initiate the strike process is to either cycle vddp or enable off and on. if ignition is successful, ramp frequency immediately returns to its programmed run value. power on delay mode all functions are ac tivated except that aout and bout are inhibited. delay is in the 120ms ec range and is determined by a counter. power on delay is activated at every v ddp power up sequence and enable sequence. strike mode entered from power on delay, or upon an enable sequence. control of the ramp generator frequency is switched to the dac output. frequency is increased from its normal run value to up to three times that value for up to 14 sweeps if while strike frequency is sweeping, the set points at op_s ns is detected, strike frequency will freeze at the present value until either the lamp strikes or the timeout is reached. strike mode is terminated by reaching 14 sweep counts or by detecting lamp ignition. if strike is successful, run mode is entered. if unsucce ssful, fault mode is entered. run mode entered only by detection of a successful strike. frequency control is immediately switched to a fixed reference that sets the programmed run frequency. the la mp current cycle counter is monitored to insure at least 4 cu rrent cycles received during each period. if less than 4, the lamp is considered extinguished and the fault mode is entered. fault mode fault mode may be entered from e ither strike or run mode as described above. in fault mode, the a & b output buffers are forced low. fault mode may be cleared by cycling enable off then on, or by removing and applying v ddp . design procedure selecting the i_r resistor value this resistor determines the value of several internal reference currents that control timing. it must be chosen first, and will be in the range of 40 to 120k ohms. we use an 80.6k, 1% low tcr value in our designs to set nomi nal lamp current frequency to 65khz. the output frequency is approximated by the following formula: r i_r = 5.24e9 / f lampout/hz . driving the brite_in input the brite_in input circuitry includes on-chip active voltage clamps that ignore input voltage greater than 2.0v. input impedance is very high so it can also be driven from a 100k potentiometer with no offset error. brite_in can be a dc voltage, or a higher frequency externally filter pwm the brite_in input has a linear active range between 0.0 and 2.0v selecting resistor for vin_sns divider the lx1691a includes feed forward compensation that provides improved regulation and transient response over an 7 ? 24 volt input supply range. the vin_sns has internal 55k gain resistor. with external battery vo ltage divider, it will clamp eaout max level properly in accordance with input supply voltage. vin_sns pin is compared with internal 1v, and the clamp slope is controlled by external divider re sistor. recommended resistor value are r6 = 576k 1%, r12=49.9k 1%. d d e e s s c c r r i i p p t t i i o o n n
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 12 copyright ? 2003 rev. 1.0, 8/31/2004 www. microsemi . com lx1691a enhanced multi-mode ccfl controller p roduction d ata s heet tm ? ivddp over temperature vdda over temperature 6.2 6.4 6.6 6.8 7.0 7.2 7.4 7.6 -40 -20 0 20 40 60 80 100 ambient temperature (c) ivddp current (ma) 3.15v 5.0v 5 . 5 v ivddp over temperature 2.965 2.970 2.975 2.980 2.985 2.990 -40 -20 0 20 40 60 80 100 ambient temperature (c) vdda voltage (v) 3.15v 5.0v 5 . 5 v vdda over temperature vdda dropout voltage i_r voltage over temperature 0 25 50 75 100 125 150 -40 -20 0 20 40 60 80 100 ambient temperature (c) dropout voltage (v) 0m a 5m a vdda dropout voltage over temperature 980 985 990 995 1000 1005 1010 -40 -20 0 20 40 60 80 100 ambient temperature (c) i_r voltage (v) 80.6k 10k i_r voltage over temperature enable threshold over temp uvlo threshold over temp 0.8 1.0 1.2 1.4 1.6 1.8 2.0 -40 -20 0 20 40 60 80 100 ambient temperature (c) threshold voltage (mv) vt turn-on vt turn-off enable threshold over temperature 2.2 2.3 2.4 2.5 2.6 2.7 2.8 -40 -20 0 20 40 60 80 100 ambient temperature (c) threshold voltage (v) vt turn-on vt turn-off uvlo threshold over temperature c c h h a a r r t t s s
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 13 copyright ? 2003 rev. 1.0, 8/31/2004 www. microsemi . com lx1691a enhanced multi-mode ccfl controller p roduction d ata s heet tm ? lamp freq over temperature fwrect transfer offset 63.5 64 64.5 65 65.5 66 66.5 -40 -20 0 20 40 60 80 100 ambient temperature (c) threshold voltage (v) n t c p tc lamp frequency over temperature -75 -50 -25 0 25 50 75 -2.5 -1.5 -0.5 0.5 1.5 2.5 isns voltage (v) offset voltage (mv) ea i n fwrect transfer offset fault threshold over temp striking threshold over temp 255 260 265 270 275 280 285 -40 -20 0 20 40 60 80 100 ambient temperature (c) threshold voltage (mv) run fault threshold over temperature 680 683 686 689 692 695 698 -40 -20 0 20 40 60 80 100 ambient temperature (c) threshold voltage (mv) st rike striking threshold over temperature vdac peak over temperature vdac valley over temperature 1.86 1.87 1.88 1.89 1.90 1.91 1.92 -40 -20 0 20 40 60 80 100 ambient temperature (c) vdac peak voltage (mv) vth vdac peak over temperature 84.5 86.5 88.5 90.5 92.5 94.5 96.5 -40-200 20406080100 ambient temperature (c) vdac valley voltage (mv) vth vdac valley over temperature c c h h a a r r t t s s
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 14 copyright ? 2003 rev. 1.0, 8/31/2004 www. microsemi . com lx1691a enhanced multi-mode ccfl controller p roduction d ata s heet tm ? mechanical drawing pw 16-pin thin small shrink outline (tssop) c p e a g h l b m seating plane d f 123 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 4.90 5.10 0.192 0.200 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 note: 1. dimensions do not include mold flash or protrusions; these shall not exceed 0. 155mm(.006?) on any side. lead dimension shal l not include solder coverage. m m e e c c h h a a n n i i c c a a l l s s
microsemi integrated products 11861 western avenue, garden grove, ca. 92841, 714-898-8121, fax: 714-893-2570 page 15 copyright ? 2003 rev. 1.0, 8/31/2004 www. microsemi . com lx1691a enhanced multi-mode ccfl controller p roduction d ata s heet tm ? 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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