1 ? ISL8009AEVAL1Z: 1.5a synchronous buck regulator with integrated mosfets description the ISL8009AEVAL1Z kit is intended for use by individuals with requirements for point- of-load applications sourcing from 2.7v to 5.5v. the isl8009eval1z evaluation board demonstrates the performance of the isl8009a low quiescent current mode converter. the isl8009a is offered in a 2mmx3mm 8 ld dfn package with 1mm maximum height. the complete converter occupies less than 1cm 2 area. key features ? high efficiency synchronous buck regulator with up to 95% efficiency ? 2ms reset timer ? soft discharge output cap during disable ? 2.7v to 5.5v supply voltage ? 3% output accuracy over-temperature/load/line ? 1.5a guaranteed output current ? 17a quiescent supply current in pfm mode ? selectable forced pwm mode and pfm mode ? less than 1a logic controlled shutdown current ? 90% maximum duty cycle for lowest dropout ? internal current mode compensation ? internal digital soft-start ? peak current limiting, short circuit protection ? over-temperature protection ? enable ? small 8 ld 2mmx3mm dfn ? pb-free (rohs compliant) recommended equipment the following materials are recommended to perform testing: ? 0v to 10v power supply with at least 5a source current capability, battery, notebook ac adapter ? two electronic loads capable of sinking current up to 5a ? digital multimeters (dmms) ? 100mhz quad-trace oscilloscope ? signal generator quick setup guide 1. ensure that the circuit is co rrectly connected to the supply and loads prior to applying any power. 2. connect the bias supply to vin. plus terminal to p4(vin) and negative retu rn to p5(gnd). 3. verify that position is on for sw1. 4. turn on the power supply. 5. verify the output voltage is 1.8v for v out evaluating the other output voltage the isl8009aevaliz kit output is preset to 1.8v; however, output voltages can be adjusted from 0.8v to 3.3v by following equations 1 and 2: let?s set r 1 = 124k : if desired output is 0.8v then short r 1 and open r 2 . mode control the isl8009a has a skip pin that controls the operation mode. when the skip pin is driven to low or shorted to ground, the regulator operates in a forced pwm mode. the forced pwm mode remains the fixed pwm frequency at light load instead of entering the skip mode. table 1. switch 1 settings sw1 skip function 1 pwm fixed pwm frequency at light load 3 pfm force continuous mode sw2 enable on/off control 1 off disable v out 3 on enable v out v out 0.8 1 r 1 r 2 ------ - + ?? ?? ?? = (eq. 1) r 2 r 1 () v out 0.8 --------------- - ?? ?? 1 ? ------------------------------ - = (eq. 2) october 9, 2008 an1388.1 application note caution: these devices are sensitive to electrosta tic discharge; follow proper ic handling procedures. 1-888-intersil or 1-888-468-3774 | intersil (and design) is a registered trademark of intersil americas inc. copyright intersil americas inc. 2008. all rights reserved all other trademarks mentioned are the property of their respective owners.
2 an1388.1 october 9, 2008 schematic 9 d1 2 1 3 4 3 4 5 1 3 22 1 2 1 1 2 2 1 1 2 open p1 1 rsi r3 100k a vin r5 2k 2 21 31 2n7002 q1 2 a pg 1 p3 r4 100k 1 d 2 vin 2 r6 100k skip p2 1 1 2 r9 open 3 pfm pwm sw2 1 a 1 2 vin 2 r7 100k en 1 1 p6 2 r8 open 3 on/ex sw1 1 off a 1 p4 p5 1 vin c1 10 f c2 10 f 1 1 22 1 a 2 1 2 3 4 en por skip vin en por skip isl8009airz-t 9 a e rsi vfb gnd lx j1 1 4 53 u1 a 5 6 7 8 a l1 2 2.2 h 2 r1 124k 1 c4 220pf 1 2 1 c5 10 f a 2 r2 100k 1 a j2 1 2 p7 p8 1 1 c6 10f 2 543 1 rsi application note 1388
3 an1388.1 october 9, 2008 table 2. component list ref des qty value tol. voltage package part number manufacturer description c1, c2, c5, c6 4 10f 10% 10v 1206 grm31cr71a106ka01l-t murata cap, smd, 1206, 10f, 10v, 10%, x7r, rohs, monolithic c4 1 220pf 5% 50v 0603 h1045-00221-50v5-t venkel cap, smd, 0603, 220pf, 50v, 5%, c0g, rohs l1 1 2.2h 20% 7.6x6 dr73-2r2-r cooper electronic tech. coil-pwr inductor, smd, 7.6x6, 2.2h, 20%, 4.15a, rohs d1 1 2mmx1.25mm ltst-c170ckt liteon/vishay led-gaas red, smd, 2mmx1.25mm, 100mw, 40ma, 10mcd, rohs u1 1 2x3 isl8009airz intersil ic-1.5a sync buck regulator, 8p, dfn, 2x3, rohs q1 1 - 60v n-channel 2n7002-7-f-t diodes, inc. transistor, n-channel, 3 ld sot-23, 60v, 115ma, rohs r2-r4, r6, r7 5 100k 1% 100v 0603 h2511-01003-1/10w1-t res, smd, 0603, 100k, 1/10w, 1%, tf, rohs r1 1 124k 1% 100v 0603 h2511-01243-1/10w1-t yageo res, smd, 0603, 124k,1/10w,1%, tf, rohs r5 1 2k 1% 100v 0603 h2511-02001-1/10w1-t koa res, smd, 0603, 2k, 1/10w, 1%, tf, rohs r8, r9 0 100v 0603 h2511-dnp res, smd, 0603, dnp-place holder, rohs sw1, sw2 2 - - - - gt11mscbe-t c&k components switch-toggle, smd, ultramini, 1p, spst mini application note 1388
4 an1388.1 october 9, 2008 ISL8009AEVAL1Z board layout figure 1. top components figure 2. top layer etch application note 1388
5 intersil corporation reserves the right to make changes in circuit design, software and/or specifications at any time without n otice. accordingly, the reader is cautioned to verify that the application note or technical brief is current before proceeding. for information regarding intersil corporation and its products, see www.intersil.com an1388.1 october 9, 2008 figure 3. bottom layer components (mirrored) figure 4. bottom layer etch (mirrored) ISL8009AEVAL1Z board layout (continued) application note 1388
|
