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MIC4833 low noise dual 220 v pp el driver with output voltage slew rate control mlf and micro lead frame are registered trademark of amkor technologies micrel inc. ? 2180 fortune drive ? san jose, ca 95131 ? usa ? tel +1 ( 408 ) 944-0800 ? fax + 1 (408) 474-1000 ? http://www.micrel.com general description the MIC4833 is a low noise dual electroluminescent (el) panel driver used in backlighting applications. the MIC4833 converts a low dc voltage to a high dc voltage using a boost converter and then alternates the high dc voltage across the el panels using an h-bridge. the MIC4833 incorporates internal wave-shaping circuitry specifically designed to reduce audible noise emitted by el panels. the two el panels may be dimmed by applying a pwm signal to the device. the MIC4833 drives two outputs from a single inductor and requires a minimum number of passive components. it features an operating input voltage range of 2.3v to 5.8v, making it suitable for 1-cell li-ion and 2- or 3-cell alkaline/nicad/nimh battery applications. an external resistor may be used to adjust the output voltage slew rate to reduce audible noise. the MIC4833 features separate oscillators for the boost and h-bridge stages to allow independent control. external resistors set the operating frequencies of each stage allowing the el circuit to optimize efficiency and brightness. the MIC4833 is available in a 12 pin 3mmx3mm mlf ? package, and has an operating junction temperature range of ?40 c to +125 c. features ? drives two el panels, up to 4 in 2 each at full brightness ? independent input control for each of the two panels and allows pwm dimming. ? 220vpp regulated ac output waveform ? 2.3v to 5.8v dc input voltage ? wave-shaping circuit to reduce audible noise ? adjustable slew rate for audible noise reduction ? independently adjustable boost converter and el panel frequency ? single inductor to power both panels ? 0.1ua typical shutdown current ? 12 pin 3mmx3mm mlf ? package ? ?40 o c to +125 o c junction temperature range applications ? mobile phones ? mp3s/portable media players (pmp) ? clocks/ watches ? remote controls ? cordless phones ? gps devices ? pdas _________________________________________________________________________________________________ typical application ena vdd rsw rel enb 1.78m 220h MIC4833 332k gnd slew vin li ion 3v to 4.2v 0.01f ela elb com cs sw 50k 2.2nf 250v 10f vin li ion 3v to 4.2v high low high low high low el lamp a el lamp b october 2008 m9999-100308 (408) 955-1690 low noise dual el driver
micrel MIC4833 october 2008 2 m9999-100308 (408) 955-1690 ordering information part number package operating junction temp range lead finish MIC4833yml 12 pin 3mmx3mm mlf ? -40 c to +125 c pb-free / rohs compliant pin configuration enb cs 5 1 ena vdd rsw rel 12 slew ela elb com 11 10 9 2 3 4 8 ep gnd sw 6 7 12-pin 3mm 3mm mlf ? (ml) ? top view pin description pin number pin name pin function 1 ena el panel a enable pin: logic high enables ela and logic low disables ela output. 2 vdd dc input supply voltage: 2.3v to 5.8v 3 rsw rsw pin: sets internal boost converter switch frequency by connecting an external resistor (r sw ) to vdd. connecting the r sw resistor to gnd shuts down the device. 4 rel rel pin: sets internal h-bridge driver frequency by connecting an external resistor (r el ) to vdd. connecting the r el to gnd disables the el oscillator. 5 enb el panel b enable pin: logic high enables elb and logic low disables elb output. 6 gnd ground. 7 sw switch node: drain of internal high-voltage power mosfet for boost circuit. 8 cs regulated boost output: connect to the output capacitor of the boost regulator and to the ca thode of the diode. 9 com el output: common el output termi nal to both ela and elb. connect one end of each el panel to this pin. 10 elb el panel b output: connect the other end of the el panel b to this pin. 11 ela el panel a output: connect the other end of the el panel a to this pin. 12 slew optional resistor to set output curr ent drive to control slew rate of load. if left open, the default slew current limit is 5ma. epad hs pad heat sink pad. connect to ground externally.
micrel MIC4833 october 2008 3 m9999-100308 (408) 955-1690 absolute maximum rating (1) supply voltage (v dd )??????????..-0.5v to 6.5v output voltage (v cs ) ????..???.?... -0.5v to 130v switch node (v sw )??...????????.-0.5v to 130v enable voltage (v ena, v enb ) ..?...?????-0.5v to 6.5v voltage (v rel, v rsw, v slew ) ......???...?.?-0.5v to 6.5v ambient storage temperature (t s ) ?. ..... -65 c to +150 c esd rating (3) ?..????????..???esd sensitive operating range (2) supply voltage (v dd ) ..?????????...2.3v to 5.8v panel drive frequency (f el )?????..100hz to 1500hz switching mosfet frequency (f sw )?...35khz to 350khz enable voltage (v ena, v enb ) ????????...0v to v dd junction temperature range (t j ) ???-40 c to +125 c package thermal impedance ja mlf ? -12l ????????.................... 60 c/w electrical characteristics (4) t a =25 o c, v dd = 3.0v unless otherwise noted. bold values indicate -40 c t j 85 c. parameter symbol condition min typ max units supply voltage range v dd 2.3 5.8 v input supply current i dd r sw =high; v cs =105v; ela, elb, com, slew = open 152 220 a shutdown current i sd r sw =low; v dd =5.8v 0.1 1 a on-resistance of switching transistor r ds (on) i sw =100ma, v cs =105v 6.0 12.0 ? output voltage regulation v cs v dd =2.3v to 5.8v 90 109 120 v v dd =3.0v (r sw = 1.3m ? ) 25 35 45 khz v dd =3.0v (r sw = 450k ? ) 75 100 125 khz boost switching frequency f sw v dd =3.0v (r sw = 125k ? ) 250 350 450 khz v dd =3.0v (r el = 1.8 m ? ) ela, elb = open 175 235 295 hz ela, elb and com drive frequency f el vdd=3.0v (r el = 712k ? ) ela, elb = open 445 565 685 hz switching transistor duty cycle d 80 95 % slew = open 2.5 5 7.5 ma output current drive limit programmability i slew r slew =10k 7 10 13 ma enable logic threshold v ena , v enb 0.4 1.2 v enable logic hysteresis v hys 20 50 150 mv enable input current i ena , i enb 0.1 1 a notes: 1. exceeding the absolute maximum rating may damage the device. 2. the device is not guaranteed to function outside its operating rating. 3. devices are esd sensitive. handling pr ecautions recommended. human body model, 1.5k ? in series with 100pf. 4. specification for packaged product only.
micrel MIC4833 october 2008 4 m9999-100308 (408) 955-1690 typical characteristics 0 50 100 150 200 250 300 350 400 0 200 400 600 800 1000 1200 1400 switching frequency (khz) switching resistor (kohm) switching frequency vs sw resistor 0 200 400 600 800 1000 1200 1400 1600 012345 el frequency (hz) elresistor (mohm) el frequency vs el resistor 0 10 20 30 40 50 60 100 150 200 250 300 350 400 450 500 input current (ma) el frequency (hz) input current vs. el frequency (single el lamp) 4 in 2 3 in 2 2 in 2 1 in 2 v in = 3.6v f sw = 75khz 10 15 20 25 30 35 40 45 50 55 60 100 150 200 250 300 350 400 450 500 input current (ma) el frequency (hz) input current vs. el frequency (dual el lamp) 2 4 in 2 2 3 in 2 2 2 in 2 2 1 in 2 v in = 3.6v f sw = 75khz 0 20 40 60 80 100 120 140 160 0123456 switching frequency (khz) total lamp size (in 2 ) recommended switching frequency vs. total lamp size 150hz 200hz 300hz 400hz v in = 3.0v 0 5 10 15 20 25 30 35 40 22.533.544.555.56 input current (ma) input voltage (v) total input current vs. input voltage f sw = 122khz size = 1in 2 f el = 200hz c out = 2.2nf f sw = 100khz size = 2in 2 10 15 20 25 30 35 40 45 50 55 60 22.533.544.555.56 input current (ma) input voltage (v) total input current vs. input voltage f sw = 68khz size = 4in 2 f el = 200hz c out = 2.2nf f sw = 88khz size = 3in 2 30 35 40 45 50 55 60 65 70 75 80 22.533.544.555.56 input current (ma) input voltage (v) total input current vs. input voltage f sw = 47khz size = 6in 2 f el = 200hz c out = 2.2nf f sw = 55khz size = 5in 2 0 20 40 60 80 100 120 22.533.544.555.56 cs voltage (v) input voltage (v) cs voltage vs. input voltage f sw = 45khz f el = 200hz c out = 2.2nf 0 40 80 120 160 200 240 22.533.544.555.56 output voltage (v p-p ) input voltage (v) output voltage vs. input voltage f sw = 45khz f el = 200hz c out = 2.2nf 0 2 4 6 8 10 12 14 16 22.533.544.555.56 brightness (lux) input voltage (v) brightness vs. input voltage distance = 2 in f sw = 135khz f el = 225hz l = 220h
micrel MIC4833 october 2008 5 m9999-100308 (408) 955-1690 functional diagram sw oscillator sw driver pgnd 220h slew vref enb ena 0 vdd 0 vdd rel rsw vsense pgnd vcs output driver pgnd pgnd vcs output driver pgnd vcs output driver gnd gnd vdd vdd sw cs ela com 2.2nf elb driver logic & pwm dimming el oscillator el-b enable el-a enable output wave-shaping figure 1. MIC4833 block diagram
micrel MIC4833 october 2008 6 m9999-100308 (408) 955-1690 functional description overview the MIC4833 is a high-voltage dual output el driver with a peak-to-peak ac output voltage of 220v capable of driving two 4 in 2 el panels. the MIC4833 drives el panels by converting a low dc input voltage to a dc high output voltage using the boost regulator circuit and then alternating the high dc voltage across the el panel using an h-bridge. input supply current for t he MIC4833 is typically 152a. the high voltage el driver has two internal oscillators to control the boost switchi ng frequency and the h-bridge driver frequency. both of the internal oscillators? frequencies can be individually programmed through external resistors to maximize efficiency and brightness of the el panel. the MIC4833 can be dimmed using a pwm signal applied to the rel pin with an external capacitor. an external resistor can be used to adjust the internal wave shaping circuit to reduce audible noise. r egulation referring to figure 1, power is initially applied to v dd . when the internal feedback voltage is less than the reference voltage, t he internal comparator enables switching in the boost circuit. when the boost regulator is switching, current flows through the inductor into the switch. the switching mosfet will typically turn on for 90 % of the switching period. during the on-time, energy is stored in the inductor. when the switching mosf et turns off, current flowing into the inductor forces the voltage across the inductor to reverse polarity. the voltage across the inductor rises until the external diode conducts and clamps the voltage at v out + v d1 . the energy in the inductor is then discharged into the c out capacitor. the internal comparator continues to turn the switching mosfet on and off until the internal feedback voltage is above the reference voltage. once the internal feedback voltage is above the reference voltage, the internal comparator disables switching. the control circui t will continue to turn the mosfet?s on and off to maintain a constant dc voltage at the cs pin. when the MIC4833 el driver is enabled, ela and elb will switch in opposit e states with com to achieve a 220v peak-to-peak ac output signal needed to drive the two el panels. switching frequency the switching frequency of the converter is controlled via an external resistor (r sw ) between rsw and vdd. the switching frequency increases as the resistor value decreases. in general, the lower the switching frequency, the greater the input current is drawn to deliver more power to the output. lowering the switching frequency can be used to drive larger panels. however, the switching frequency should not be so low as to allow the voltage at the switch node or the cs pin to exceed the absolute maximum voltage of those pins. for resistor value selections, see the ?typical characteristics: switching frequency vs. sw resistor? graph on page 4 or use the equation below. the switching frequency range is 35khz to 350khz, with an accuracy of 20%. () = mr 46 (khz)f sw sw el frequency the el panel frequency is controlled via an external resistor (r el ) connected between rel and vdd. the panel frequency increases as the resistor value decreases. in general, as the el panel frequency increases, the amount of current drawn from the battery will increase. the el panel brightness is dependent upon its frequency. for resistor value selections, see the ?typic al characteristics: el frequency vs. el resistor? graph on page 4 or use the equation below. the el panel frequency range is 100hz to 1500hz, with an accuracy of 20%. () () m ? el r 425 hz el f = enable function there are a few different ways to enable and disable the MIC4833. the boost regulator may be disabled by pulling the r sw resistor to ground. this turns off both the el panels by cutting power to the device completely. the el panels can also be turned off by pulling the r el resistor to ground. although this turns off the h-bridge and the el panels, the MIC4833 boost regulator will continue regulate. for individual panel control, the ena and enb pins can be used to enable ela and elb, respectively. pulling ena or enb high or low will turn ela and elb panels on or off.
micrel MIC4833 october 2008 7 m9999-100308 (408) 955-1690 figure 2. 150hz output waveform figure 3. 250hz output waveform figure 4. 350hz output waveform pwm dimming the MIC4833 may be dimmed by adding a shunt capacitor (c pwm ) to the rel pin, shown in figure 5. the duty cycle of the pwm signal changes the frequency of the el panel, thereby changing its brightness. increasing the pwm duty cycle increases the el frequency to a maximum set by r el (duty cycle = 100%). decreasing the pwm duty cycle decreases the el frequency. the pwm duty cycle should not be lowered to a level that may cause the el frequency to be lower than 100hz, since el frequencies lower than 100hz may cause the panel to flicker. the frequency of the pwm signal can range from 500hz to 50khz. the peak voltage of the pwm signal should be equal to vdd. r el c pwm 0.01f 0v vdd pwm 1khz rel pin figure 5. pwm dimming circuit slew resistor the MIC4833 is designed to reduce audible noise in el panels by the use of the internal wave-shaping circuit. to further reduce audible noise, a slew resistor (r slew ) can be added to limit the rate of change of the el driver output voltage by limiting the output current. a slower rate of change in voltage across the el panel creates less physical distortion in the material and therefore reduces the amount of audible noise. the lower the i slew , the slower the output voltage across the el panel will change. if r slew is not used, the i slew is by default 5ma, equivalent to using a 22k ? for r slew . r slew i slew open 5ma 125k ? 1ma 22k ? 5ma 10k ? 10ma table 1. slew resistor setting
micrel MIC4833 october 2008 8 m9999-100308 (408) 955-1690 application information the MIC4833 is designed to use an inductance with a value between 100h to 330h. choosing the right inductor is always a balance of size, inductance, efficiency, current rating and cost. a tdk (vls4012t-221m) 220h inductor is recommended based on size, efficiency and current rating. generally, the lower the inductance, the more current the inductor can handle. lowering the inductance allows the boost regulator to draw more input current to deliver more energy every switching cycle. as a result, a lower inductance may be used to drive larger panels or brighten similar sized panels. however, caution is required as using a low inductance with a low switching frequency may cause the voltage at the switch node and the cs pin to exceed the absolute maximum rating. if the application uses a low input voltage (2.3 to 3v), a lower value inductor, such as 100h, may be used in order to drive the el panel at maximum brightness. diode the diode must have a high reverse voltage (150v), since the output voltage at the cs pin can reach up to 130v. a fast switching diode with lower forward voltage and higher reverse voltage (150v), such as bav20ws/bas20w, can be used to enhance efficiency. output capacitor low esr capacitors should be used at the regulated boost output (cs pin), to minimize the switching output ripple voltage. the larger the output capacitance, the lower the output ripple at the cs pin. the reduced output ripple at the cs pin along with a low esr capacitor improves the efficiency of the MIC4833 circuit. selection of the capacitor value depends upon the peak inductor current, inductor size, and the load. the MIC4833 is designed for use with an output capacitance as low as 2.2nf. for minimum audible noise, the use of a c0g/npo dielectric output capacitor is recommended. tdk and avx offer c0g/npo dielectric capacitors in capacitances up to 2.7nf capacitance at 200v to 250v voltage rating in 0805 size. el panel terminals (ela, elb, com) the two el panels are connected from ela to com and elb to com. the ela and elb terminals are in phase with each other, while the com is out of phase with both ela and elb. since ela and com are out of phase, the high voltage generated by the boost regulator is alternated across ela and com by the h-bridge. the fre quency of each cycle is determined by r el . the alternating 220v peak-to- peak causes the el panel to emit light. similarly, the elb and com are also out of phase and allows a second el panel to be driven at the same time. both el panels may operate independently from each other and do not have to be the same size. for component selection, table 2 lists recommended values for various panel sizes up to a total of 8in 2 (for example, two 4in 2 panels). driving overly large panels will result in a dimmer display, but will not cause damage to the device.
micrel MIC4833 october 2008 9 m9999-100308 (408) 955-1690 application circuit ena vdd rsw rel enb rel 1.78m l1 220h MIC4833 rsw 332k gnd slew vin li ion 3v to 4.2v c1 0.01f ela elb com cs sw rslew 50k c3 2.2nf 250v c2 10f vin li ion 3v to 4.2v high low high low high low el lamp a el lamp b figure 6: typical li-ion powered MIC4833 circuit note: table 2 applies to circuit shown in figure 6. panel frequency (hz) 150 200 250 300 350 400 500 total panel area (inch 2 ) capacitance (nf) r el (m? ) 2.80 2.10 1.69 1.40 1.21 1.05 .850 r sw (k ? ) 324 340 357 383 392 402 442 0.4 2 f sw (khz) 138 132 126 118 116 112 102 r sw (k ? ) 357 365 392 422 442 475 511 1 5 f sw (khz) 125 122 116 108 102 95 88 r sw (k ? ) 402 453 487 549 590 649 681 2 10 f sw (khz) 112 100 92 83 76 70 66 r sw (k ? ) 464 511 590 698 768 909 1000 3 15 f sw (khz) 98 88 77 65 58 50 45 r sw (k ? ) 523 665 750 909 1000 1000 4 20 f sw (khz) 86 68 60 50 45 45 r sw (k ? ) 619 825 909 1000 5 25 f sw (khz) 72 55 50 45 r sw (k ? ) 698 953 1000 6 30 f sw (khz) 65 47 45 r sw (k ? ) 1000 8 40 f sw (khz) 45 table 2: recommended r sw & r el values for total panel sizes
micrel MIC4833 october 2008 10 m9999-100308 (408) 955-1690 bill of materials item part number manufacturer description qty c1 c1608x7r1a103k tdk (1) 0.01f ceramic capacitor, 10v, x7r, size 0603 1 c2 c1608x5r0j106k tdk (1) 10 f ceramic capacitor, 6.3v, x5r, size 0603 1 c3 c2012c0g2e2222j tdk (1) 0.0022f ceramic capacitor, 250v, c0g, size 0805 1 l1 vls4012t-221m tdk (1) 220h, 210ma i sat . (4mmx4mmx1.2mm) 1 d1 bas20-v-gs18 vishay (2) 200v/200ma hi-voltage switching diode 1 r1 or r sw crcw06033323fkeye3 vishay (2) 332k ? , 1%, 1/16w, size 0603 1 r2 or r el crcw06031784fkeye3 vishay (2) 1.78m ? , 1%, 1/16w, size 0603 1 r slew optional u1 MIC4833yml micrel (3) low noise dual 220vp-p el driver with output slew control 1 notes: 1. tdk: www.tdk.com 2. vishay: www.vishay.com 3. micrel, inc .: www.micrel.com
micrel MIC4833 october 2008 11 m9999-100308 (408) 955-1690 layout recommendation top layer bottom layer
micrel MIC4833 october 2008 12 m9999-100308 (408) 955-1690 package information 12-pin 3mm x 3mm mlf ? (ml) micrel, inc. 2180 fortune drive san jose, ca 95131 usa tel +1 (408) 944-0800 fax +1 (408) 474-1000 web http:/www.micrel.com the information furnished by micrel in this data sheet is believ ed to be accurate and reliable. however, no responsibility is a ssumed by micrel for its use. micrel reserves the right to change circuitry and specifications at an y time without notification to the customer. micrel products are not designed or authori zed for use as components in life support app liances, devices or systems where malfu nction of a product reasonably be expected to result in pers onal injury. life support devices or system s are devices or systems that (a) are in tended for surgical impla into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. a purchaser?s use or sale of micrel produc ts for use in life support app liances, devices or systems is a purchaser?s own risk and purchaser agrees to fully indemnify micrel for any damages resulting from such use or sale. can nt ? 2008 micrel, incorporated.

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