EVNB681-D-01A 26v, low i q , high current synchronous buck converter with 2-bit vid evaluation board EVNB681-D-01A rev. 1.0 www.monolithicpower.com 1 1/15/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. the future of analog ic technology description the nb681 is a fully integrated high frequency synchronous rectified step-down switch mode converter with 2-bit vid especially designed for v1.0a, vccio, primcore, edram and eopio for imvp8 applications. it offers very compact solution to achieve 6a continuous output current and 7.5a peak output current over a wide input supply range. the nb681 operates at high efficiency over a wide output current load rang based on mps proprietary switching loss reduction tech and internal low ron power mosfets adaptive constant-on-time (cot) control mode provides fast transient response and eases loop stabilization. the dc auto tune loop provides good load and line regulation. nb681 also provides a low power mode for power loss saving during the low power state and ultrasonic mode to avoid audible noise. full protection features include oc limit, ovp, uvp and thermal shut down. the converter requires minimum number of external components and is available in qfn 2x3 packages. features ? wide 4.5v to 26v operating input range ? v1.0a/vccio/pch/edram/eopio compatible for imvp8 ? output adjustable by 2-bit vid ? low power mode / 25ua low quiescent current ? 6a continous output current ? 7.5a peak output current ? selectable ultrasonic mode ? adaptive cot for fast transient ? dc auto tune loop ? stable with poscap and ceramic cap ? 1% reference voltage ? internal soft start and output discharge ? ocl, ovp, uvp protection and thermal shutdown ? latch off reset via en or power cycle applications ? notebook systems and tablet pc ? networking systems and server ? personal video recorders ? distributed power systems all mps parts are lead-free, halogen free, and adhere to the rohs directive. for mps green status, please visit mps website under quality assurance. ?mps? and ?the future of anal og ic technology? are registered trademarks of monolithic power systems, inc. EVNB681-D-01A evaluation board (l x w ) 85mm x 85mm board number mps ic number EVNB681-D-01A nb681 output current(a) 0.001 0.01 0.1 1 10 50 55 60 65 70 75 80 85 90 95 100 v in =5v v in =8.4v v in =12v v in =19v
EVNB681-D-01A, synchronous st ep-down converter ev board EVNB681-D-01A rev. 1.0 www.monolithicpower.com 2 1/15/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. evaluation bo ard schematic 22uf 1 2 c1b 0 r3 330uf(n s) c2a 22uf 2 1 c2c vin gnd gnd gnd 100nf c2g vo ut vout gnd gnd en sw 1 2 ns c2h 100nf c2b 100nf(n s) c1c vin bst pg 1.0uh 1 2 l1 1uf(ns) c7 gnd 3v3 vo ut 22uf 2 1 c2d 22uf 2 1 c2e gnd ns r5 3v3 100nf c1d 22uf(ns) 2 1 c2f 100k r12 20k r10 100k r7 ns r6 1uf c6 2 1 220nf c3 agnd nb681 vin 1 pg 13 vout 12 sw bst 9 3v 3 10 en 5 c0 4 8 mode 7 c1 3 agnd 11 pgnd 2 lp# 6 u1 nb681 22uf 1 2 c1a 20k r1 100nf(n s) c2i gnd 20k r2 3v3 mode lp# gnd 20k r11 gnd 3v3 c1 c0 c1 c0 2 1 3 c1 2 1 3 c0 20k r8 20k r9 gnd 3v3 lp# 2 1 3 lp# 0 r13 0 r14 ns r15 gnd gnd normal-connect agnd to rgnd near chip remote sense-connect agnd to pgnd at vout cap side agnd 1uf(ns) c8 gnd 100k r4a 150k r4b 2 1 3 m2 2 1 3 m1 47uf/35v c1e the agnd should be separate to pgnd in all the conditions unless they are finally connected together to vcc cap
EVNB681-D-01A, synchronous st ep-down converter ev board EVNB681-D-01A rev. 1.0 www.monolithicpower.com 3 1/15/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. EVNB681-D-01A bill of materials qty des value description package manufacture manufacture_pn 2 c1a, c1b 22 f ceramic capacitor;25v;x5r; 1206 murata grm21br61e226ke15 2 c1d,c2g 100nf ceramic capacitor;50v;x7r; 0603 murata grm188r71h104ka93d 1 c1e 47 f ceramic capacitor;35v smd avx taje476k035rnj 6 c1c,c2a,c2 b,c2f,c2h, c2i ns 3 c2c,c2d,c2 e 22 f ceramic capacitor;6.3v;x5r 0805 murata grm21br60j226me39l 1 c3 220nf capacitor;25v;x5r 0402 murata grm155r61e224ka87d 1 c6 1 f ceramic capacitor;6.3v;x5r; 0603 murata grm188r60j105ka01d 2 c7,c8 ns 6 r1,r2,r8,r9 ,r10,r11 20k film resistor;1% 0402 yageo rc0402fr-0720kl 1 r3 0 film resistor;1% 0603 yageo rc0603fr-070rl 2 r13,r14 0 film resistor;1% 0402 yageo rc0402fr-070rl 3 r5,r6,r15 ns 3 r4a,r7,r12 100k resistor;1 %;1/16w 0402 yageo rc0402fr-07100kl 1 r4b 150k resistor;1%;1/16w 0402 yageo rc0402fr-07150kl 1 l1 1 h inductor;1uh;8.5m; 9.5a smd toko fdve0603-1r0m 1 d1 ns 1 u1 nb681 nb681 qfn2*3 mps nb681 5 c1,c0,lp#,m 1,m2 450301 014042 switch dip 450301014042
EVNB681-D-01A, synchronous st ep-down converter ev board EVNB681-D-01A rev. 1.0 www.monolithicpower.com 4 1/15/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. printed circuit board layout figure 1?top layer and silk figure 2?inner layer 1 figure 3?inner layer 2 figure 4?bottom layer
EVNB681-D-01A, synchronous st ep-down converter ev board notice: the information in this document is subject to change wi thout notice. users should warra nt and guarantee that third party intellectual property rights are not infringed upon w hen integrating mps products into any application. mps will not assume any legal responsibility for any said applications. EVNB681-D-01A rev. 1.0 www.monolithicpower.com 5 1/15/2015 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2015 mps. all rights reserved. quick start guide 1. connect the positive and negative terminals of the load to the vout and gnd pins, respectively. 2. preset the one power supply output between 4.5v and 24v as vin, and another power supply to 3.3v as external 3.3v vcc, and then turn off the power supply. 3. connect the positive and negative terminals of the vin power supply output to the vin and gnd pins, respectively. 4. connect the positive and negative terminals of the power 3.3v supply output to the 3v3 and agnd pins, respectively. 5. turn both the vin and 3v3 power supply on. the nb681 will automatically startup. 6. to use the enable function, apply a digital input to the en pin. drive en to 3.3v to turn on the regulator or less than 0.4v to turn it off. 7. refer to the ds for 2-bit vid, lp# mode and usm mode operation. vid table mode lp# c0 c1 vout(v) 0 x x 0 1 0 0 0.85 1 1 0 0.875 1 0 1 0.95 vccio m1=1,m2=1 rmode=0 ? 1 1 1 0.975 0 x x 0.7 1 0 0 0.85 1 1 0 0.9 1 0 1 0.95 vcc_primcore(pch) m1=0,m2=0 (rmode=float ) 1 1 1 1 0 x x 0 1 0 0 0.8 1 1 0 0.95 1 0 1 1 edram/eopio m1=0,m2=1 (rmode=100k ) 1 1 1 1.05 0 x x 0 1 0 0 1 1 1 0 1.05 1 0 1 1.15 others m1=1,m2=0 rmode=150k 1 1 1 1.2
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