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mic4834 low noise dual 220 v pp el driver 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 october 2008 m9999-100808-a general description the mic4834 is a low noise dual electroluminescent (el) panel driver used in backlighting applications. the mic4834 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 mic4834 incorporates internal wave-shaping circuitry specifically designed to reduce audible noise emitted by el panels. with only one inductor the mic4834 can drive two outputs and requires a minimum number of passive components. it features an operating input voltage range of 2.3v to 5.8v, making it suit able for 1-cell li-ion and 2- or 3-cell alkaline/nicad/nimh battery applications. the mic4834 features separa te oscillators for the boost and h-bridge stages. the boost frequency may be adjusted with an external resistor to optimize efficiency and brightness. the h-bridge fre quency is internally preset to 225hz, to reduce the number of external components and layout space. the mic4834 is available in 10 pin 3mmx3mm mlf ? package as well as msop-10l, and has an operating junction temperature range of ?40 c to +125 c. features ? drives two el panels, up to 3 in 2 each at full brightness ? 220v pp regulated ac output waveform ? 2.3v to 5.8v dc input voltage ? wave-shaping circuit to reduce audible noise ? adjustable boost converter frequency ? single inductor to power both panels ? 0.1a typical shutdown current ? package options ? 10-pin 3mmx3mm mlf ? ? 10-pin msop ? ?40 o c to +125 o c junction temperature range applications ? mobile phones ? mp3/portable media players (pmp) ? clocks/ watches ? remote controls ? cordless phones ? gps devices ? pdas _________________________________________________________________________________________________ typical application low noise dual el driver
micrel mic4834 october 2008 2 m9999-100908-a ordering information part number package operating junction temp range lead finish MIC4834YML 10 pin (3mm x 3mm) mlf ? -40oc to +125oc pb-free / rohs-compliant mic4834ymm 10-pin msop -40oc to +125oc pb-free / rohs-compliant pin configuration 10-pin mlf ? - top view 10-pin msop ? 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 enb el panel b enable pin: logic high enables elb and logic low disables elb output. 5 gnd ground. 6 sw switch node: drain of internal high-voltage power mosfet for boost circuit. 7 cs regulated boost output: connect to the output capacitor of the boost regulator and to the cathode of the diode. 8 com el output: common el output terminal to both ela and elb. connect one end of each el panel to this pin. 9 elb el panel b output: connect the other end of the el panel b to this pin. 10 ela el panel a output: connect the other end of the el panel a to this pin. epad hs pad heat sink pad. connect to ground externally. mlf? package only.
micrel mic4834 october 2008 3 m9999-100908-a 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 rsw , v ena, v enb )................... -0.5v to 6.5v ambient storage temperature (t s ) ........... -65oc to +150oc esd rating (3) ........................................................................... esd sensitive operating range (2) supply voltage (v dd ) ........................................2.3v to 5.8v switching mosfet frequency (f sw ) ........ 35khz to 350khz enable voltage (v rsw , v ena, , v enb ) ....................... 0v to v dd junction temperature range (t j ) ............. -40 c to +125 c package thermal impedance 3mm x 3mm mlf ? ( ja )????????........ 60 c/w msop ( ja )????????......................... 206 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. symbol parameter condition min typ max units v dd supply voltage range 2.3 5.8 v i dd input supply current v rsw = high; v cs = 105v; ela, elb, com = open 152 220 a i sd shutdown current v rsw = low; v dd = 5.8v 0.1 1 a r ds (on) on-resistance of switching transistor i sw = 100ma, v cs = 105v 6.0 12.0 ? v cs output voltage regulation 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 f sw boost switching frequency v dd = 3.0v (r sw = 125k ? ) 250 350 450 khz f el ela, elb and com drive frequency v dd = 3.0v ela, elb, com = open 165 225 285 hz d switching transistor duty cycle 80 95 % i out output current drive limit 2.5 5 7.5 ma v ena , v enb enable logic threshold 0.4 1.2 v v hys enable logic hysteresis 20 50 150 mv i ena , i enb enable input current 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 mic4834 october 2008 4 m9999-100908-a 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 20 40 60 80 100 120 140 0123456 switching frequency (khz) total lamp size (in 2 ) recommended switching frequency vs. total lamp size 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 = 116khz size = 1in 2 f el = 225hz c out = 2.2nf f sw = 94khz size = 2in 2 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 = 62khz size = 4in 2 f el = 225hz c out = 2.2nf f sw = 82khz size = 3in 2 40 45 50 55 60 65 70 75 80 85 90 22.533.544.555.56 input current (ma) input voltage (v) total input current vs. input voltage f sw = 42khz size = 6in 2 f el = 225hz c out = 2.2nf f sw = 50khz 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 = 225hz 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 = 225hz 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 mic4834 october 2008 5 m9999-100908-a functional diagram figure 1. mic4834 block diagram functional description overview the mic4834 is a high-voltage dual output el driver with a peak-to-peak ac output voltage of 220v capable of driving two 3 in 2 el panels. the mic4834 drives el panels by converting a low dc input voltage to a high 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 the mic4834 is typically 152a. the high voltage el driver has two internal oscillators to control the boost switching frequency and the h-bridge driver frequency. the internal boost oscillator frequency can be individually programmed through an external resistor to maximize efficiency and brightness of the el panel. the h-bridge frequency is internally fixed at 225hz to reduce external component count. r egulation referring to figure 1, power is initially applied to v dd . when the internal feedback voltage is less than the reference voltage, the 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
micrel mic4834 october 2008 6 m9999-100908-a is stored in the inductor. when the switching mosfet turns off, current flowing into the inductor forces the voltage across the inductor to reverse polarity. the voltage across the inductor ri ses 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 circuit will continue to turn the mosfet?s on and off to maintain a constant dc voltage at the cs pin. when the mic4834 el driver is enabled, ela and elb will switch in opposite 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 by 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%. () = m r 46 (khz) f sw sw el frequency the mic4834 el panel frequency is internally fixed at 225hz. enable function there are a few different ways to enable and disable the mic4834. 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 r sw resistor must be pulled to vdd to enable the boost oscillator. if it is not equal to vdd, then the frequency set by r sw will be different the programmed value. for individual panel control, the ena and enb pins can be used to enable ela and elb, respectively. pulling ena or enb high (over 1.2v) or low (below 0.4v) will turn ela and elb panels on or off. figure 2. el panel waveform ? 2 1 in 2 figure 3. el panel waveform ? 2 2 in 2 figure 4. el panel waveform ? 2 3 in 2
micrel mic4834 october 2008 7 m9999-100908-a application information the mic4834 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. lowe ring 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 (2.3v to 3v), then 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 mic4834 circuit. selection of the capacitor value depends upon the peak inductor current, inductor size, and the load. the mic4834 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 capacitance up to 2.7nf 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 frequency of each cycle is internally fixed at 225hz. 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 6 in 2 (for example, two 3 in 2 panels). driving overly large panels will result in a dimmer display, but will not cause damage to the device.
micrel mic4834 october 2008 8 m9999-100908-a application circuit figure 6. typical li-ion powered mic4834 circuit note: table 2 applies to circuit shown in figure 6. total panel area (in 2 ) 0.4 1 2 3 4 5 6 capacitance (nf) 2 5 10 15 20 25 30 r sw (k ? ) 357 392 487 562 750 931 1100 f sw (khz) 128 116 94 82 62 50 42 table 2. recommended r sw values for total panel sizes 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 u1 MIC4834YML 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 mic4834 october 2008 9 m9999-100908-a layout recommendation (mlf ? ) top layer bottom layer
micrel mic4834 october 2008 10 m9999-100908-a layout recommendation (msop) top layer bottom layer
micrel mic4834 october 2008 11 m9999-100908-a package information 10-pin 3mm x 3mm mlf ? (ml)
micrel mic4834 october 2008 12 m9999-100908-a 10-pin msop (mm) 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 chan ge circuitry and specifications at any ti me without notification to the customer. micrel products are not designed or authorized for use as components in life suppor t appliances, devices or systems where malfu nction of a product can 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 implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significan t injury to the user. a purchaser?s use or sale of micrel produc ts for use in life support appliances, 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. ? 2008 micrel, incorporated.

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