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rt8297b zqw evaluation board ug 8297b zqw - 00 april 2014 www.richtek.com purpose the rt8297b is a high - efficiency current mode synchronous step - down regulator that can deliver up to 1.5a output current from a wide input voltage range of 4v to 17v. this document explains the function and use of the rt8297b evaluation board (evb) and provides information to enable operation and modification of the evaluation board and circuit to suit individual requirements. table of contents purpose ................................ ................................ ................................ ................................ ....... 1 introduction ................................ ................................ ................................ ................................ .. 2 general product information ................................ ................................ ................................ ..... 2 key performance summary table ................................ ................................ ............................ 3 bench test setup conditions ................................ ................................ ................................ ....... 4 headers description and placement ................................ ................................ ................................ 4 test points ................................ ................................ ................................ ................................ .......... 4 power - up & measurement procedure ................................ ................................ .............................. 5 output voltage setting ................................ ................................ ................................ ....................... 5 schemat ic, bill of materials and board layout ................................ ................................ ............. 6 evb schematic diagram ................................ ................................ ................................ .......... 6 bill of materials ................................ ................................ ................................ ......................... 7 evb layout ................................ ................................ ................................ .............................. 8 other technical information ................................ ................................ ........ e` ! x`
rt8297b zqw evaluation board ug8297bzq w - 00 april 2014 www.richtek.com 2 introduction general product information general description the rt8297b is a high efficie ncy, monolithic synchronous step - down dc/dc converter that operates at 800k hz and delivers up to 1.5a output current from a 4v to 17v input supply. the rt8297b s current mode architecture allows the transient response to be optimized. cycle - by - cycle curren t limit provides protection against shorted outputs and soft - start eliminates input current surge during start - up. fault conditions also include output under voltage protection, output over voltage protection, and thermal shutdown. the low current (<5a) s hutdown mode provides output disconnect, enabling easy power management in battery - powered systems. the rt8297b is available in a wdfn - 8l 2x2 package. feature ? 4v to 17v input voltage range ? 1.5a output current ? internal n - mosfets ? current mode control ? fixed frequency operation : 800k hz ? output adjustable from 0.8v to 12v ? up to 95% efficiency ? internal compensation ? stable with low esr ceramic output capacitors ? cycle - by - cycle over current protection ? input under voltage lockout ? output under voltage protection ? outp ut over voltage protection ? power good indicator ? thermal shutdown protection
rt8297b zqw evaluation board ug8297bzq w - 00 april 2014 www.richtek.com 3 key performance summary table key features evaluation board number: pcb005_v1 default input voltage 12v max output current 1.5a default output voltage 3.3v default markin g & package type rt8297b zqw ( wdfn - 8l 2x2 ) operation frequency steady 800k hz at all load currents other key features 4v to 17v input voltage range power good indicator tiny wdfn - 8l 2x2 package protection over c urrent p rotection hiccup mode output under - v oltage & over - voltage protection thermal shutdown
rt8297b zqw evaluation board ug8297bzq w - 00 april 2014 www.richtek.com 4 bench test setup conditions headers description and placement please carefully inspect the evb ic and external components, comparing them to the following bill of materials, to ensure that all compone nts are installed and undamaged. if any components are missing or damaged during transportation, please contact the distributor or send e - mail to evb_service@richtek.com . test points the evb is provided with t he test points and pin names listed in the table below. test point/ pin name signal comment (expected waveforms or voltage levels on test points) vin input voltage input voltage range= 4v to 17v vout output voltage default output voltage = 3.3v output v oltage range= 0.8v to 12v (see output voltage setting section for changing output voltage level) sw switching nod e test point sw waveform en enable test point enable signal. en is automatically pulled high (by r4) to enable operation. connect en lo w to disable operation. bs boot strap supply test point floating supply voltage for the high - side n - mosfet switch pg power good test point power good indicator v1 external voltage for pg external voltage terminal for pg pull - up voltage. gnd ground grou nd
rt8297b zqw evaluation board ug8297bzq w - 00 april 2014 www.richtek.com 5 power - up & measurement procedure 1. apply a 12v nominal input power supply (4v < v in < 17v) to the vin and gnd terminals. 2. the en voltage is pulled to logic high by r4 (100k to vin) to enable operation. drive en high (>2.5v) to enable operation or low (<0.4v) to disable operation. 3. verify the output voltage (approximately 3.3v) between vout and gnd. 4. connect an external load up to 1.5a to the vout and gnd terminals and verify the output voltage and current. output voltage setting set the output voltage with the resistive divider (r1, r2) between vout and gnd with the midpoint connected to fb. the output is set by the following formula: the installed v out capacitors (c4, c5) are 22 f, 16 v x5r ceramic types. do not exceed their operating voltage range and consider their voltage coefficient (capacitance vs. bias voltage) and ensure that the capacitance is sufficient to maintain stability and provide sufficient transient response for y our application. this can be verified by checking the output transient response as described in the rt 8297 ic datasheet. out r1 v = 0.8 x (1 + ) r2
rt8297b zqw evaluation board ug8297bzq w - 00 april 2014 www.richtek.com 6 schematic , bill of materials and board layout evb schematic diagram c1, c2: 10f/50v/x5r, 1206, tdk c3216x5r1h106k c4, c5: 22f/16 v/x5r, 1210, murata grm32er61c226k l1: 6.8 h taiyo yuden nr8040t 6r8n , dcr= 25 m cp1 short tp3 bs r3 100k tp5 v1 tp6 sw c10 nf tp7 pg gp2 gnd r6 nf c9 nf d3 nf c7 10nf c5 22uf gp1 vin tp1 gnd tp2 gnd gp3 vout gnd u1 wdfn-8l 2x2 sw 1 vin 2 boot 3 en 4 gnd 7,8,9 pgood 6 fb 5 tp4 en l1 6.8uh r1 47k r2 15k c1 10uf c4 22uf r4 100k c6 0.1uf c8 nf c2 10uf c3 0.1uf
rt8297b zqw evaluation board ug8297bzq w - 00 april 2014 www.richtek.com 7 bill of materials reference qty part number description package manufacture u1 1 rt8297b zqw dc - dc converter wdfn - 8l 2x2 r ichtek c1, c2 2 c3216x5r1h106k160ab 10 f/10%/50v/x5 r 1206 tdk ceramic capacitor c4, c5 2 grm32er61c226ke20# 22 f/10%/16v/x5r 1210 murata ceramic capacitor c7 1 grm32mr71h103ka01# 10nf/10%/50v/x7r 0 603 murata ceramic capacitor c3, c6 2 c1608x7r1h104k080aa 0.1 f/10%/50v/x7r 0 603 tdk ceramic capacitor c8, c9, c10 0 not installed 0 603 l1 1 nr8040t6r8n 6.8uh/3.7a/30%, dcr=25m, inductor 8mmx8mmx4mm taiyo yuden r1 1 47 k/1%, resistor 0 603 r2 1 15 k/1%, resistor 0 603 r3, r4 1 100k/1%, resistor 0 603 cp1 1 short d3, r6 0 not installed tp 6 test pin gp 4 golden pin
rt8297b zqw evaluation board ug8297bzq w - 00 april 2014 www.richtek.com 8 evb layout top view (1 st layer) bottom view (4 th layer)
rt8297b zqw evaluation board ug8297bzq w - 00 april 2014 www.richtek.com 9 component placement guide component side (1 st la yer) pcb layout component side (1 st layer)
rt8297b zqw evaluation board ug8297bzq w - 00 april 2014 www.richtek.com 10 pcb layout inner s ide ( 2 nd laye r ) pcb layout inner side ( 3 r d layer )
rt8297b zqw evaluation board ug8297bzq w - 00 april 2014 www.richtek.com 11 component placement guide bottom side (4 th layer) pcb layout bottom side (4 th layer)
rt8297b zqw evaluation board ug8297bzq w - 00 april 2014 www.richtek.com 12 more information for more information, please find the related datasheet or application notes from rich t ek website http://www.richtek.com . important notice for richtek evaluation board this document is for reference only, nothing contained in this document shall be construed as richteks warranty, express or implied, under contract, tort or statutory, with respect to the presentation herein. in no event shall richtek be liable to buyer or user for any and all damages including without limitation to direct, indirect, special, punitive or consequential damages.

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