View EC9219_9050398.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

tft- lcd dc-dc converters wi th operational amplifiers EC9219 p 1 / 14 2009/09/29 general description the EC9219 include a high-performance step-up regulator, and high-current operational amplifiers for active-matrix thin-film transistor (tft) liqui d-crystal displays (lcds). the step-up dc-dc converter provides t he regulated supply voltage for the panel source driver ics. the converter is a high-frequency (1.2mhz or 640khz) current-mode regulator with an integrated 18v n-channel mosfet that allows the use of ultra-small inductors and ceramic capacitors. it provides fast transient response to pulsed loads while achieving efficiencies over 85%. the EC9219 includes one operational amplifier. these amp lifiers are designed to drive the lcd backplane (vcom) and/or the gamma-correction divider string. the devices feature high output current (150ma), fast slew rate (17v/ s), wide bandwidth (12mhz), and rail-to-rail inputs and outputs the EC9219 are available in 14- pin thin tsop packages with a maximum thickness of 1mm for ultra-thin lcd panels. features z 2.6v to 5.5v input supply range z 1.2mhz or 640khz current-mode step-up regulator z fast transient response to pulsed load z high-accuracy output voltage ( 2% ) z built-in 18v, 1.6a, 0.16 ? n-channel mosfet z high efficiency (90%) z high-performance operational amplifiers z 17v/ s slew rate z 12mhz, -3db bandwidth z rail-to-rail inputs/outputs z thermal-overload protection applications z notebook computer displays , z lcd monitor panels , z automotive displays ordering information part no marking package EC9219i-g EC9219-g tssop14 green package EC9219g-g EC9219g tqfn16 green package
tft- lcd dc-dc converters wi th operational amplifiers EC9219 p 2 / 14 2009/09/29 name function out operational-amplifier output in + operational-amplifier non-inverting input sgnd analog ground. comp compensation pin. output of the internal error amplif ier. capacitor and resistor from comp pin to ground. fb voltage feedback pin. internal reference is 1.228v nominal. connect a resistor divider from vout. vout =1.228v (1 + r3 / r8). s ee typical application circuit. /sd shutdown control pin. pull shdn low to turn off the device, and soft-start internal reference voltage control pin, connect rc d elay circuit. pgnd power ground. lx switch pin. connect the inductor/catch diode to lx and minimize the trace area for lowest emi. vin analog power supply input pin. freq frequency select input. when freq is low, the oscillator frequency is set to 640khz. when freq is high the frequency is 1.2mhz. ss soft-start control pin. connect a capacito r to control the converter start-up. operational-amplifier power input. positive supply rail for the operational amplifiers. sup typically connected to dc-dc converter output. bypass sup to sgnd with a 0.1f capacitor. nc in - operational-amplifier inverting input
tft- lcd dc-dc converters wi th operational amplifiers EC9219 p 3 / 14 2009/09/29 absolute maximum rating ( t a = 25 ) v in to sgnd......................................................-0 .3v to +6v comp, fb, sd , freq to sgnd ........................ -0.3v to +6v pgnd to sgnd .......................................................... 0.3v lx to pg nd ....................................................-0 .3v to +18v sup,in+,in- to sg nd .....................................-0 .3v to +18v out maximum continuous output current ...... 150ma rms lx pin current ......................................................1.6a operating ambient temperature ......... -40 to +85 operating junction temperature ........................ +125 storage temper ature ......................... -65 to +150 lead temperat ure ............................................+260 stresses beyond those listed under ?absolute maximum ratings? ma y cause permanent damage to the device. these are stress ratings only, and functional operation of t he device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. ex posure to absolute maximum rating conditions for extended periods may affect device rel iability. electrical specifications v in = 3v, v sup = 10v ,fsel = gnd, t a =25 unless otherwise specified parameter symbol conditions min typ max unit v in supply range v in 2.6 5.5 v v in under voltage-lockout threshold v uvlo v in rising ,typical hysteresis = 40mv 2.25 2.38 2.52 v sd = v in ,v fb =1.3, not switching 0.4 1 ma quiescent current i in sd = v in ,v fb =comp, switching 4 5 ma shutdown supply current i in sd = sgnd include op. 0.1 1 ua input low level v il sd , freq ;v in = v to 5.5v 0.3v in v input high level v ih sd , freq ;v in = v to 5.5v 0.7v in v hysteresis sd , freq ;v in = v to 5.5v 0.1v in v freq input current freq =v in 1 na sd input current sd = v in 1 na temperature rising 130 c thermal shutdown hysteresis 30 c main step-up regulator output voltage range vmain v in 18 v freq=gnd 500 640 750 khz frequency fosc freq= v in , 1000 1200 1500 khz freq=gnd 85 90 95 % maximum duty cycle d freq= v in , 85 90 95 % fb regulation voltage v fb load=50ma 1.222 1.24 1.258 v fb line regulation v in = 2.6 v to 5.5v 0.5 % fb input bias current v fb =1.4 1 na voltage gain av fb to comp 1000 v/v swicth on-resistance r ds(on) 160 250 m lx leakage current i lx v lx =18v 1.8 ua lx current limit 2 a current-sense tran conductance rcs 0.047 v/a opeational amplifers sup supply range v sup 4.5 18 v sup supply current isup buffer configuration ,no load out=4v,vsup=8v 2.8 4 ma input offset voltage v os out= v sup /2 20 mv input bias current i bias out= v sup /2 2 50 na input common-mode range v cm 0 v sup v common-mode rejection ratio cmrr 50 70 db open-loop gain a v 75 100 db output voltage swing ,high v oh i out =5ma v sup -150 v sup -80 mv output voltage swing ,low v ol i out =-5ma 70 150 mv power-supply rejection ratio psrr 60 70 db
tft- lcd dc-dc converters wi th operational amplifiers EC9219 p 4 / 14 2009/09/29 parameter symbol conditions min typ max unit slew rate sr vin=4v,v in+ =6v,r l =2k ,c l =100 pf ,buffer configuration 10 17 v/s -3db bandwidth r l =2k ,c l =100 pf ,buffer configuration 12 mhz gain-bandwidth product gbp r l =2k ,c l =100pf buffer configuration 8 mhz block diagram EC9219 figure 1
tft- lcd dc-dc converters wi th operational amplifiers EC9219 p 5 / 14 2009/09/29 typical application circuit d1 bat54s 1 3 2 c15 47nf vin r4 nc r10 0 fb vcom c6 0.22uf fslc c3 0.22uf j1 vgff= -6v/20ma 1 vdd d3 bat54s 1 3 2 vin c2 0.1uf j5 con1 1 c13 10uf/16v/1206 c12 q2 2n3904 3 2 1 j2 vgon= +18v/20ma 1 c18 6.8nf r8 13k_1% c5 0.1uf u1 EC9219 1 2 3 4 5 6 7 14 13 12 11 10 9 8 opout in+ opgnd comp fb /shdn gnd in- opvsup opvcc ss freq in lx c4 0.1uf /shdn d5 fm220 1 2 c7 10uf/10v/1206 c16 10pf c1 0.1uf j6 con1 1 comp r3 87.6k_1% q1 2n3906 3 2 1 r11 1 3 2 r2 270 r7 nc r13 12k_1% vdd ss vdd c8 10uf/10v/1206 vdd=9.6v 0.2v c10 10uf/16v/1206 j3 con1 1 r12 13k_1% j7 con1 1 d2 6.8v lx c14 0.1uf c17 0.1uf c9 10uf/16v/1206 l1 10uh r1 1k c11 10uf/16v/1206 j4 con1 1 r9 20k r6 0 d4 18.8v r5 10.5k_1% lx vin vin figure 2
tft- lcd dc-dc converters wi th operational amplifiers EC9219 p 6 / 14 2009/09/29 typical operating characteristics typical application circuit, vin=3.3v, v main =9.6 ,v gon =18v , v goff =-6v , out=6v , freq=vin ta=25 unless otherwise noted.) no-load supply current vs. input voltage freq=640khz no-load supply current vs. input voltage freq=1.2mhz 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 2.533.544.555.5 input voltage(v) no-load supply current(ma) 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 2.533.544.555.5 input voltage no-load supply current(ma) output voltage vs. output curren efficiency vs. output current 9.8 9.85 9.9 9.95 10 10.05 10.1 0 50 100 150 200 250 300 output current(ma) output voltage(v) 50.00% 55.00% 60.00% 65.00% 70.00% 75.00% 80.00% 85.00% 90.00% 95.00% 1 10 100 1000 output current (ma) efficiency (%) 3.3v 5v vout=10v,vin=3.3v,l=10uh, freq=640khz vout=9.6v,l=10uh,freq=640khz fb voltage vs. temperature 1.222 1.227 1.232 1.237 1.242 1.247 1.252 1.257 -40-20020406080100120140 temperature() fb voltage(v)
tft- lcd dc-dc converters wi th operational amplifiers EC9219 p 7 / 14 2009/09/29 start-up waveform with soft-start start-up waveform with soft-start ch1: vin ch1:vin ch2:output voltage ch2:output voltage ch3:inductor current ch3:inductor current vin=3.3v,iout=10ma,freq=640khz, vin=3.3v,iout=200ma,freq=640khz, vout=10.6v,cout=30uf vout=10.6v,cout=30uf start-up waveform with soft-start start-up waveform with soft-start ch4: shdn ch1:shdn ch2:output voltage ch2:output voltage ch3:inductor current ch3:inductor current vin=3.3v,iout=10ma,freq=640khz, vin=3.3v,iout=200ma,freq=640khz, vout=9.6v,cout=30uf vout=9.6v,cout=30uf
tft- lcd dc-dc converters wi th operational amplifiers EC9219 p 8 / 14 2009/09/29 load-transient response switching waveform ch2: output voltage,ac-coupled ch1:output voltage,ac-coupled ch3:load current ch3:inductor current vin=3.3v,vout=10v,freq=640khz ch2:lx switching waveform figure 7. start-up waveform with soft-start vin=3.3v,vout=10v,iout=200ma,freq=640khz,l=10uh operational-amplifier rail-to-rail input/outpu operational-amplifier large-signal step response ch1: input signal ch1: input signal ch2:output signal ch2:output signal vsup:12v,rl:2k,cl:100p vsup:12v,rl:2k,cl:100p
tft- lcd dc-dc converters wi th operational amplifiers EC9219 p 9 / 14 2009/09/29 typical operating circuit the EC9219 typical operating circuit (figure 2) is a complete power-supply system for tft lcds. the circuit generates a +9.6v source-driver supply and + 18v and -6v gate-driver supplies. the input voltage range for the ic is from +2.6v to +5.5v. the listed l oad currents in figure 1 are available from a +4.5v to +5.5v supply. typical operating circuit recommended components,. applications information the EC9219 is a high frequency, high efficiency boos t regulator operated at constant frequency pwm mode. the boost converter stores energy from an input voltage source and deliver it to a higher output voltage. the input voltage range is 2.6v to 5.5v and output voltage range is 5v to 18v the switching frequency is selectable between 640khz and 1.2mhz allowing smaller inductors and faster transient response. an external compensation pin gives the us er greater flexibility in setting output transient response and tighter load regulation. the converter so ft-start characteristic can also be controlled by external c08 capacitor. the shdn pin allows the user to completely shut-down the device. main step-up regulator the main step-up regulator employs a current-mode, fixed-frequency pwm architecture to maximize loop bandwidth and provide fast transient response to pul sed loads typical of tft-lcd panel source drivers. the 1.2mhz switching frequency allows the use of low profile inductors and ceramic capacitors to minimize the thickness of lcd panel designs. th e integrated high-efficiency mosfet and soft-start function controls inrush currents. the output voltage c an be set from vin to 13v with an external resistive voltage-divider. the regulator controls the output voltage and the power delivered to the output by modulating the duty cycle (d) of the internal power mosf et in each switching cycle. the duty cycle of the mosfet is approximated by: main in main v v v d ? = figure 1 shows the functional diagram of the step-up regulator. an error amplifier compares the signal at fb to 1.228v and changes the comp output. the voltage at comp sets the peak inductor current. as the load varies, the error amplifier sources or sinks curr ent to the comp output accordingly to produce the inductor peak current necessary to service the load. to maintain stability at high duty cycles, a slope-compensation signal is summed with the current -sense signal. on the rising edge of the internal clock, the controller sets a flip-flop, turning on the n-channel mosfet and applying the input voltage across the inductor. the current through the inductor ramps up linearly, storing energy in its magnetic field. once the sum of the current-feedback signal and the lope compensation exceeds the comp voltage, the controller resets the flip-flop and turns off the mo sfet. since the inductor current is continuous, a transverse potential develops across the inductor that turns on the diode (d1). the voltage across the inductor then becomes the difference between the output voltage and the input voltage. this discharge condition forces the current through the inductor to ra mp back down, transferring the energy stored in the magnetic field to the output capacitor and the load. the mosfet remains off for the rest of the clock cycle.
tft- lcd dc-dc converters wi th operational amplifiers EC9219 p 10 / 14 2009/09/29 operational amplifiers the EC9219 has one operational amplif ier. the operational amplifiers ar e typically used to drive the lcd backplane (vcom) or the gamma-correction divider string. they feature 150m a output current, 17v/s slew rate, and 12mhz bandwidth. the rail-to-rail in put and output capability maximizes system flexibility. frequency selection the EC9219?s frequency can be user selected to operate at either 640khz or 1.2mhz. tie freq to gnd for 640khz operation. for a 1.2mhz switching frequency, tie freq to vin. under voltage lockout (uvlo) the under voltage-lockout (uvlo) circuit compares the input voltage at vin with the uvlo threshold to ensure the input voltage is high enough for reliable ope ration. the 100mv (typ) hysteresis prevents supply transients from causing a restart. once the input voltage exceeds the uvlo rising threshold, startup begins. when the input voltage falls below the uvlo fa lling threshold, the controller turns off the main step-up regulator, turns off the outputs, and disables t he switch control block; the operational amplifier outputs are high impedance. thermal-overload protection thermal-overload protection prevents excessive po wer dissipation from overheating the EC9219. when the junction temperature exceeds tj = +135 , a thermal sensor immediately activates the fault protection, which shuts down all outputs except the reference, a llowing the device to cool down. once the device cools down by approximately 30 , and reactivate the device. the ther mal-overload protection protects the controller in the event of fault conditions. for c ontinuous operation, do not exceed the absolute maximum junction temperature rating of tj = +125 . design procedure main step-up regulator inductor selection the minimum inductance value, peak current rating, and series resistance are factors to consider when selecting the inductor. thes e factors influence the co nverter?s efficiency, maximum output load capability, transient-response time, and output voltage ripple. size and cost are also important factors to consider. the maximum output current, input voltage, output voltage, and switching frequency determine the inductor value. very high inductance values minimi ze the current ripple and therefore reduce the peak current, which decreases core losses in the inducto r and rl losses in the entire power path. however, large inductor values also require more energy storage and more turns of wire, which increases size and can increase winding resistance losses in the inductor. low inductance values decrease the size but increase the current ripple and peak current. finding the best inductor involves choosing the best compromise between circuit efficiency, inductor size, and cost. the equations used here include a constant icr(inductor current ripple rate), which is the ratio of the i nductor peak-to-peak ripple current to the average dc inductor current at the full load curre nt. the best trade-off between inductor size and circuit efficiency for step-up regulators generally ha s an icr between 0.3 and 0.5. however, depending on the ac characteristics of the inductor core material and ratio of inductor resi stance to other power-path resistances, the best icr can shift up or down. if the inductor resistance is relatively high, more ripple can be accepted to reduce the number of turns requir ed and increase the wire diameter. if the inductor resistance is relatively low, increasing inductance to lower the peak current can decrease losses throughout the power path. if extremely thin high-re sistance inductors are used, as is common for lcd-panel applications, the best i cr can increase to between 0.5 and 1.0. once a physical inductor is chosen, higher and lower values of the inductor shou ld be evaluated for efficiency improvements in typical operating regions. calculate the approximate inductor value using the typical input voltage (vin), the maximum output current (imain(m ax)), the expected efficiency (
tft- lcd dc-dc converters wi th operational amplifiers EC9219 p 11 / 14 2009/09/29 i2r is a registered trademark of instrume nts for research and industry, inc. choose an available inductor value from an appropriate inductor family. calculate the maximum dc input current at the minimum input voltage (v in(min) ) using conservation of energy and the expected efficiency at that operating point ( ? min ) taken from the appropriate curve in the typical operating characteristics : calculate the ripple current at t hat operating point and the peak current required for the inductor: the inductor?s saturation current rating and the EC9219s? lx current limit (ilim) should exceed ipeak, and the inductor?s dc current rating should exce ed iin(dc,max). for good efficiency, choose an inductor with less than 0.1 ? series resistance. considering the typical operating circuit , the maximum load current (imain(max)) is 500ma with a 13v output and a typical input voltage of 5v. choosing an icr of 0.5 and estimating efficiency of 85% at this operating point: using the circuit?s minimum input voltage (4.5v) and estimating efficiency of 80% at that operating point: the ripple current and the peak current are: output-capacitor selection the total output voltage ripple has two components: the capacitive ripple caused by the charging and discharging of the output capacitance, and the ohmic ripple due to the capacitor?s equivalent series resistance (esr). where ipeak is the peak i nductor current (see the inductor selection section). for ceramic capacitors, the output voltage ripple is typically dominated by vripple(c). the voltage rating and temperature characteristics of the output capa citor must also be considered.
tft- lcd dc-dc converters wi th operational amplifiers EC9219 p 12 / 14 2009/09/29 input-capacitor selection the input capacitor (cin) reduces the current pea ks drawn from the input supply and reduces noise injection into the ic. a 10 f ceramic capacitor is used in the typical applications circuit (figure 2) because of the high source impedance seen in typical lab setups. actual applications usually have much lower source impedance since the step-up regulator often runs directly fr om the output of another regulated supply. typically, cin can be r educed below the values used in the typical applications circuit . ensure a low-noise supply at vin by using adequate cin. alternately, greater voltage variation can be tolerated on cin if vin is decoupled fr om cin using an rc low-pass filter. rectifier diode the EC9219s? high switching frequency demands a high-speed rectifier. schottky diodes are recommended for most applications because of their fast recovery time and low forward voltage. in general, a 2a schottky diode complements the internal mosfet well. output-voltage selection the output voltage of the main step-up regulator can be adjusted by connecting a resistive voltage-divider from the output (vmain) to agnd with the center tap connected to fb (see figure 2). select r2 in the 10k ? to 50k ? range. calculate r1 with the following equation: 1) - v vmain ( r8 r3 fb = where vfb, the step-up regulator?s feedback set poi nt, is 1.228v. place r3 and r8 close to the ic. loop compensation the EC9219 incorporates an trans conductance amplifier in its feedback path to allow the user some adjustment on the transient response and better regulation. the EC9219 uses current mode control architecture which has a fast current sense loop and a slow voltage feedback loop. the fast current feedback loop does not require any compensation. t he slow voltage loop must be compensated for stable operation. the compensation network is a series rc net work from comp pin to ground. the resistor sets the high frequency integrator gain for fast transient re sponse and the capacitor sets the integrator zero to ensure loop stability. for most applications, the compens ation resistor in the range of 10k to 100k and the compensation capacitor in the range of 1nf to 0.22uf. pc board layout and grounding careful pc board layout is important for proper oper ation. use the following guidelines for good pc board layout: z minimize the area of high-current loops by plac ing the inductor, the out put diode, and the output capacitors near the input capacitors and near the lx and pgnd pins. the high-current input loop goes from the positive terminal of the input capacitor to the inductor, to the ic?s lx pin, out of pgnd, and to the input capacitor?s negative terminal. the high-current output loop is from the positive terminal of the input capacitor to the inductor, to the output di ode (d5), and to the positive terminal of the output capacitors, reconnecting between the output capacitor and input capacitor ground terminals. connect these loop components with short, wide connections. av oid using vias in the high-current paths. if vias are unavoidable, use many vias in parallel to reduce resistance and inductance. z create a power-ground island (pgnd) consisting of the input and output capacitor grounds, pgnd pin, and any charge-pump component s. connect all of these together with short, wide traces or a small ground plane. maximizing the width of the power-gro und traces improves efficiency and reduces output voltage ripple and noise spikes. create an analog ground plane (sgnd) consisting of the sgnd pin, all the feedback-divider ground connections, the co mp and ss capacitor ground connections. connect the sgnd and pgnd islands. make no other conn ections between these separate ground planes.
tft- lcd dc-dc converters wi th operational amplifiers EC9219 p 13 / 14 2009/09/29 z place all feedback voltage-divider resistors as close to their respective feedback pins as possible. the divider?s center trace should be kept short. placing the resistors far away causes their fb traces to become antennas that can pick up switching noise. take care to avoid running any feedback trace near lx or the switching nodes in the charge pumps. z place the vin pin bypass capacitors as close to the device as possible. t he ground connection of the vin bypass capacitor should be connected directly to the sgnd pin with a wide trace. z minimize the length and maximize the width of the traces between the output capacitors and the load for best transient responses. z minimize the size of the lx node while keeping it wide and short. keep the lx node away from feedback nodes (fb) and analog ground. us e dc traces to shield if necessary. refer to the EC9219 demo board for an example of proper pc board layout. package dimension tssop-14 unit:mm
tft- lcd dc-dc converters wi th operational amplifiers EC9219 p 14 / 14 2009/09/29 tqfn-16

▲Up To Search▲

Price & Availability of EC9219

	To Download EC9219 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .