general description the max8608y evaluation kit (ev kit) is a fully assem- bled and tested circuit board that evaluates the max8608y step-up dc-dc converter, which provides two output connections for either white led (wled) drive or organic led (oled) power at up to 85% effi- ciency. the ev kit operates from a 2.7v to 5.5v input and is configured to drive six surface-mount wleds with an output current of 25ma, as well as provide a regulated 25v output voltage (at up to 40ma) for oled power. the max8608y ev kit can also evaluate the max8608z, which does not feature the temperature (t a ) derating function. the t a derating function is offered only by the max8608y. either ic provides the flexibility of control-ling led brightness through an external analog or pwm dimming signal. features ? 2.7v to 5.5v input range ? wled drive up to 6 leds at 25ma ? oled drive at 25v (up to 40ma) ? high efficiency up to 85% ? analog or pwm dimming control ? 1mhz pwm switching frequency (selectable500khz) ? 14-pin tdfn package ? low-profile components (1.7mm max) ? fully assembled and tested evaluates: max8608y/max8608z max8608y evaluation kit ________________________________________________________________ maxim integrated products 1 19-3728; rev 1; 10/05 component list for pricing, delivery, and ordering information, please contact maxim/dallas direct! at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. ordering information part temp range ic package MAX8608YEVKIT 0? to +70? 14 tdfn, 3mm x 3mm designation qty description c1 1 1? ?0%, 35v x7r ceramiccapacitor (0805) taiyo yuden gmk212bj105kg c2 1 0.001? ?0%, 50v x7r ceramiccapacitor (0402) taiyo yuden umk105bj102kv c3 1 0.01? ?0%, 25v x7r ceramiccapacitor (0402) taiyo yuden tmk105bj103kv c4 1 4.7? ?0%, 6.3v x5r ceramiccapacitor (0603) murata grm188r60j475ke d1 1 200ma, 40v schottky diode (sod523) cmosh-4e lead free central semiconductor d2?7 6 white ledsnichia nscw215t designation qty description ju1 1 2-pin header ju2, ju3 2 3-pin headers ju4 0 3-pin header, not installed l1 1 22?, 250ma inductor (1210)murata lqh32cn220k53 r1 1 13.0 ? ?% resistor (0603) r2 1 475k ? ?% resistor (0402) r3 1 6.19k ? ?% resistor (0402) r4 1 10k ? ?% resistor (0402) r5 1 100k ? ?% resistor (0402) u1 1 max8608yetd (14-pin, 3mm x3mm) (top mark: aan ) ? shunts ? max8608y ev kit pc board part selection table part temperature derating max8608yetd yes max8608zetd no downloaded from: http:///
evaluates: max8608y/max8608z max8608y evaluation kit 2 _______________________________________________________________________________________ recommended equipment ? .7v to 5.5v, 1a power supply one voltmeter quick start the max8608y ev kit is fully assembled and tested.follow these steps to verify board operation. do not turn on the power supply until all connections arecompleted. for wled operation: 1) verify that a shunt is installed across pins 1-2 ofjumper ju3 to enable vouta. 2) verify that a shunt is installed across jumper ju1 to set full led brightness. 3) connect the positive terminal of the power supply to the vin pad. connect the ground terminal of thepower supply to the pgnd pad. 4) turn on the power supply and set it to 3.6v. 5) verify that all the white leds are lit. for oled operation: 1) verify that a shunt is installed across pins 1-2 ofjumper ju2 to enable voutb. 2) verify that a shunt is installed across pins 2-3 ofjumper ju3 to disable vouta. 3) connect the voltmeter across the voutb and gnd pads. 4) connect the positive terminal of the power supply to the vin pad. connect the ground terminal of thepower supply to the pgnd pad. 5) turn on the power supply and set it to 3.6v. 6) verify that the voltmeter reads 25v. detailed description the max8608y ev kit is a step-up dc-dc converteroptimized for driving either six wleds in series or pow- ering an oled display. the ev kit is powered by a 2.7v to 5.5v power supply and provides two output connec- tions, vouta and voutb. vouta is configured to deliver a 25ma driving current to six wleds, and voutb is configured to provide a 25v regulated output at 40ma for oled power. the max8608y features a t a derating function that automatically limits the wledcurrent at high temperatures in accordance with the derating curves of popular white leds. the t a derating function of the max8608y is only operational whenvouta is enabled. see the enable and output control section for output configuration. overvoltage protection is also provided to prevent the internal mosfet fromswitching when the converter output exceeds 27v. operating frequency selection (fsel) the max8608y ev kit provides the option to configurethe operating frequency of the step-up dc-dc convert- er. table 1 lists jumper ju4 settings for configuring the operating frequency. the ev kit is configured and shipped to operate at 1mhz. for operation at 500khz, cut the trace between pins 2 and 3 of jumper ju4, located on the solder side, and short pins 1 and 2. refer to the max8608y data sheet for selecting proper components when operating at 500khz. enable and output control the max8608y ic provides two enable inputs, enaand enb, to enable/disable the corresponding outputs, vouta and voutb. the ena input is set through jumper ju3 and the enb input is set through jumper ju2. the ena input has precedence over the enb input and thus, as long as the vouta output is enabled, the voutb output will be disabled. see table 2 for output configuration. controlling led intensity the led intensity can be controlled using the ctrlinput pc board pad on the ev kit. ctrl can be used either as an analog or a digital input. when using ctrl as an analog input, connect a 0 to 1.65v power supply shunt location fsel pin operating frequency 1-2 connected to vin (cut thetrace between pins 2-3 before shorting pins 1-2). 500khz 2-3 (default) connected to gnd with apc trace. 1mhz table 1. jumper ju4 function shunt location max8608y ev kit outputs ju2 (enb) ju3 (ena) voutb vouta 1-2 2-3 enabled disabled 1-2 1-2 disabled enabled 2-3 1-2 disabled enabled 2-3 2-3 shutdown mode table 2. jumper ju2 and ju3 functions downloaded from: http:///
to ctrl, where 0v corresponds to the dimmest ledsetting and 1.65v corresponds to full brightness. a digital pwm signal (up to 200khz) can also be con- nected directly to ctrl. in this case, the duty cycle controls the brightness of the leds, where 0% corre- sponds to zero led current and 100% is full bright- ness. the recommended pwm signal has a logic-low level of 0v and a logic-high level greater than 1.65v. pullup resistor r5 and jumper ju1 are provided so the ev kit can be used without applying a dimming signal to ctrl. with a shunt installed on jumper ju1 and no other connection to ctrl, the leds are set to full brightness. if ctrl is being driven, the shunt across jumper ju1 can be removed. see table 3 for jumper ju1 settings. remove the shunt across jumper ju1 when measuring quiescent current with the circuit in shutdown mode. evaluating the max8608z the max8608y ev kit can also evaluate the max8608zwhite led/organic led step-up dc-dc converter. the max8608y ic must be removed and replaced with the max8608z ic. refer to the max8608y/max8608z ic data sheet for detailed information about these parts. evaluates: max8608y/max8608z max8608y evaluation kit _______________________________________________________________________________________ 3 shunt location ctrl pin led intensity installed(default) connected to vinthrough resistor r5. full brightness not installed connect an externalanalog signal or pwm signal to the ctrl pad. adjustable table 3. jumper ju1 function component suppliers supplier phone fax website central semiconductor 631-435-1110 631-435-1824 www.centralsemi.com murata 770-436-1300 770-436-3030 www.murata.com nichia 248-352-6575 www.nichia.com taiyo yuden 408-573-4150 408-573-4159 www.t-yuden.com note: indicate that you are using the max8608y when contacting these component suppliers. downloaded from: http:///
evaluates: max8608y/max8608z max8608y evaluation kit 4 _______________________________________________________________________________________ vouta d2 d3 d4 d5 d6 d7 r36.19k 1% r2475k 1% r113 1% c20.001 f 50v voutb gnd 9 fbb 11 10 outb fba outa 13 c11 f 35v ovp 12 d1 14 lx l1 22 h 1 in pgnd fsel ena enb ctrl comp r410k c30.01 f ctrl ju1 r5100k 3 2 1 ju2 3 2 1 ju3 3 2 1 ju4 c44.7 f 6.3v 2 3 4 5 6 8 vin vin vin vin vin vin pgnd 7 gnd max8608y u1 figure 1. max8608y ev kit schematic downloaded from: http:///
maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 _____________________ 5 2005 maxim integrated products printed usa is a registered trademark of maxim integrated products, inc. evaluates: max8608y/max8608z max8608y evaluation kit figure 2. max8608y ev kit component placement guide component side figure 3. max8608y ev kit pc board layout?omponentside figure 4. max8608y ev kit pc board layout?older side downloaded from: http:///
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