Development Board EPC96 Quck Start Gude EPC6C V Hgh Current Pulsed Laser Dode Drver Revson.
DESCRIPTION The EPC96 development board s prmarly ntended to drve laser dodes wth hgh current pulses wth total pulse wdths as low as ns (% of peak). The board s shpped wth an EPC6C enhancement mode (egan ) feld effect transstor (FET), a V maxmum devce voltage capable of current pulses up to 7 A. The board does not nclude a laser dode, whch must be suppled by the user. The EPC96 s shpped wth an EPC6C ground-referenced egan FET drven by a Texas Instruments UCC76 gate drver. It ncludes multple optons for mountng laser dodes and can drve these va a dschargng capactor (as shpped) or drectly from a power bus. The prnted crcut board s desgned to mnmze the power loop nductance whle mantanng mountng flexblty for the laser dode. It ncludes multple on-board passve probes for voltages and dscharge capactor current, and equpped wth SMA connectons for nput and sensng desgned for ohm measurement systems. In addton, an optonal precson narrow pulse generator can be enabled by the user. The man FET footprnt can accommodate an EPCC V egan FET wth a pulse current ratng of up to A for users needng hgher current capablty. Fnally, the board can also be used for other applcatons requrng a ground-referenced egan FET, e.g. Class E amplfers or smlar. A complete block dagram of the crcut s gven n fgure, and a detaled schematc n fgure. For more nformaton on the EPC6C or EPCC egan FETs, please refer to the datasheets avalable from EPC at www.epc-co.com. The datasheet should be read n conjuncton wth ths quck start gude. NOTE: Verson. has component changes that can mprove some aspects of operaton. These are noted n the QSG where necessary. SETUP AND OPERATION Development board EPC96 s easy to set up to evaluate the performance of the EPC6C egan FET as a laser drver. Refer to fgure for connecton and measurement setup and follow the procedure below:. Revew laser safety consderatons. Observe all necessary laser safety requrements ncludng the use of personal protecton equpment (PPE) as requred. Refer to qualfed safety personnel as necessary.. Wth power off, nstall laser dode D wth the correct polarty followng dode manufacturer gudelnes. See secton Laser Dode Consderatons for further nformaton.. Wth power off, connect the nput power supply bus to +V BUS (J) and ground / return to V BUS (J).. Wth power off, connect the logc supply (7- V VDC) to +V7 n (J) and ground return to V7 n (J).. Wth power off, connect the sgnal pulse generator to the nput J. J s termnated wth Ω on the EPC96. The sgnal nput can handle up to. W RMS. 6. Connect the remanng measurement SMA outputs to an osclloscope, usng Ω cables and wth the scope nputs set to Ω mpedance. See secton Measurement Consderatons for more nformaton, ncludng the attenuaton values for each output. Table : Performance Summary (T A = C) EPC96 Demonstraton System EPC96 Symbol Parameter Condtons Mn Nom Max Unts V7 n V BUS V COMP Gate drve and logc supply Bus Input Voltage Range Input comparator threshold Input mpedance of J s Ω 7 V 8 V. V INPUT Input pulse range T Pn Input pulse wdth 6 ns SAFETY WARNING: Ths board s capable of drvng laser dodes to generate hgh peak power optcal pulses. Such pulses are capable of creatng permanent vson damage. User must follow proper laser safety procedures to prevent vson damage. Input (J) + V7 n V BUS + Narrow pulse generator (optonal) C, C, C, C, C SHUNT (J6) R, R, R, R, R6 CAP (J) V GDIN (J9) Fgure : Block dagram of EPC96 development board 7. Turn on the logc supply voltage to the requred value. 8. Turn on the bus voltage to the requred value (do not exceed the absolute maxmum voltage of 8 V). 9. Turn on the pulse source and observe swtchng operaton va the outputs and any addtonal desred probng. Laser dode output may be observed wth an approprate electro-optcal recever.. Once operatonal, adjust the bus voltage, nput pulse wdth, and pulse repleton frequency (PRF) as desred wthn the operatng range and observe the system behavor.. For shutdown, please follow steps n reverse. V GS (J) V OUT (J7) NOTE: Many of the waveforms n the laser drver can have transton speeds well under ns. It s recommended that the scope and probe bandwdth be at least GHz, and for hghest waveform fdelty, GHz or hgher s preferred. The use of standard scope probes wth sub-ghz bandwdths can result n waveforms that appear substantally slower than the actual behavor of the crcut. Dclmp D Q EPC EFFICIENT POWER CONVERSION CORPORATION WWW.EPC-CO.COM COPYRIGHT 7
OPERATING PRINCIPLE The EPC96 s shpped as a capactve dscharge laser dode drver. Please refer to the block dagram (fgure ) and the schematc (fgure ). It has several possble modfcatons (secton MODIFICATIONS), but only the basc operaton wll be covered n ths secton. The EPC96 basc operatng prncple s to dscharge energy storage capactance {C, C, C, C, C} through the laser dode, and then recharge {C, C, C, C, C} through the resstor bank {R, R, R, R6}. The dscharge s controlled va an nput pulse that s delvered to SMA connector J, whch s termnated n Ω. As shpped, ths pulse s delvered to gate drver U. When the nput goes hgh, the gate drver turns on Q, allowng {C, C, C, C, C} to dscharge through the laser dode D. When the nput goes low, Q turns off. If there s current remanng n the power loop, dodes D, D can conduct and help prevent overvoltage of the laser and FET. Measurements of many of the man waveforms can be made through the SMA test ponts provded, and addtonal test ponts are provded. These test ponts can provde waveform measurements wth equvalent bandwdths up to GHz. As a result, they have requrements and propertes that dffer from most conventonal osclloscope probes. More detals on the usage of these test ponts s provded n secton Measurement Consderatons. LASER DIODE CONSIDERATIONS Laser dode D (suppled by the user) s mounted on the rght-hand sde of the EPC96. The board s desgned to accommodate both throughhole laser dodes and surface mount laser dodes. It s desgned to allow mountng of laser dodes such that the laser beam can be emtted ether perpendcular or parallel to the plane of the PCB. Fgure shows some example mountng confguratons. The power loop nductance, ncludng that of the laser dode, s a prmary factor that determnes the shape of the laser pulse. Consderable effort Sgnal generator Demonstraton System EPC96 V7 n V BUS Note polarty + + Fgure : Connecton and measurement setup Laser dode Osclloscope ( Ω nputs) has been made to mnmze power loop nductance whle maxmzng the choce of laser dode and ts orentaton. The dscharge caps, current sense resstors, and the egan FET must all be mounted n close proxmty to mnmze nductance. As a result, the user must take care not to damage any components when mountng the laser or changng other components n the power loop. Laser dode current pulses can result n peak powers of several hundred watts. Laser dodes for ldar applcatons are desgned wth ths n mnd, but thermal lmtatons of the laser package mean that pulse wdths, duty cycles, and pulse repetton frequency lmtatons must be observed. Read laser dode data sheets carefully and follow any manufacturers recommendatons. Ths board has been tested wth the followng laser dodes: SPL PL9 and SPL PL9_ from OSRAM Opto Semconductor (https://www. osram.com/os/) and DPEGWS9H and TPGADS9H from Exceltas (http://www.exceltas.com). Fgure : Laser dode mountng optons: Leaded laser n standard through-hole poston (upper left), edge-mounted leaded laser wth both leads top-sde (lower left), edge-mounted leaded laser wth anode top-sde and cathode bottom-sde (upper rght) and surface-mount laser (lower rght). EPC EFFICIENT POWER CONVERSION CORPORATION WWW.EPC-CO.COM COPYRIGHT 7
MEASUREMENT CONSIDERATIONS SMA jacks are provded to measure several voltages n the crcut, ncludng gate drve nput, Q gate voltage, Q dran voltage, charge voltage of the energy storage cap, and the sense voltage of the dscharge cap current measurement shunt. All measurement ponts are desgned to be termnated n Ω, hence when vewng waveforms, the osclloscope nputs should be set to a Ω nput. Ideally, unused nputs should be also termnated wth a Ω load to prevent the probes from creatng addtonal resonances. The Q dran voltage and the dscharge cap sense voltage have on-board termnatons to greatly reduce ths effect, and n practce, the remanng resonances may be small or otherwse tolerable. It s recommended that the user verfy ths for ther own requrements. All sense measurement SMAs, except for the shunt measurement, use the transmsson lne probe prncple to obtan waveform fdelty at sub-ns tme scales. They have been verfed to produce near-dentcal results to a Tektronx P98 GHz transmsson lne probe. As a result of ther desgn, they have a bult-n attenuaton factor. In addton, the mpedance of the probes can be relatvely small, and as a result, the test ponts for hgh voltage measurements nclude a DC blockng capactor. If long pulse wdths are used, these test ponts may yeld erroneous results, and an external probe should be used. The current shunt s desgned to estmate the dscharge capactor current. Substantal effort has been made to reduce the nductve effects of the current shunt, but t should be used for estmaton only, snce the shunt nductance wll dstort the measured waveforms at the sub-ns tme scale. If a more accurate shunt waveform measurement s desred, the shunt resstors may be replaced wth ones that provde hgher accuracy. Ths s lkely to requre hgher resstor values, whch can contrbute to errors n the capactor voltage measurement and n ncreased power dsspaton. Fnally, note that the capactor current also ncludes the current due to D, D, and PCB capactance. Table summarzes the propertes of the SMA test ponts for ease of reference. MODIFICATIONS Narrow pulse generator: Demonstraton System EPC96 Many sgnal generators cannot produce an accurate, short pulse. The EPC96 ncludes a narrow pulse generator based on the Lnear Technologes LT7 ultrafast dual comparator. Ths pulse generator requres an nput pulse of at least ns, and wll produce a shorter pulse of fxed duraton, ndependent of the length of the nput pulse. To use the pulse generator nstead of drectly usng the nput pulse, remove Ω resstors R and R (remove both to prevent unwanted reflectons at ether gate drver or nput comparator), and add a Ω resstor to the empty footprnt for R8. The nternal pulse generator shps wth a pulse wdth of ~8 ns. R, R, and R can be changed to change the pulse wdth. Increasng the combned value of R, R, and R wll shorten the output pulse, and decreasng the combned value wll lengthen t. Other modfcatons: Whle dodes D and D can provde some protecton to FET Q and laser D, they have parastc nductance and capactance that can reduce performance at the very fastest speeds. Based on customer feedback, these dodes are not populated n Verson. boards. For very fast pulses and low nductance laser dodes, ths results n mproved optcal pulses. However, f one s usng a laser dode wth hgh nductance (> nh), one may consder replacng one or both of these dodes for mproved relablty. The value of the shunt resstors can be ncreased up to a pont to mprove the dscharge cap current sense accuracy. Note that accurate measurement of current whle nsertng extremely low nductance nto the power loop s extremely challengng, and many factors must be consdered. For the lowest possble nductance, the resstors can be mounted upsde down or replaced wth copper fol f no sensng s needed. The footprnt for Q can accommodate the EPCC egan FET f hgher currents are desred. The hgher gate charge of the larger FET wll reduce the maxmum speed, but wll approxmately double the current capablty. For nformaton on changng the FET, please see http://epc-co.com/epc/desgnsupport/assemblyresources.aspx. The value of the energy storage cap {C, C, C, C, C} can be modfed as desred, as well as the recharge resstor {R, R, R, R6}. In the extreme case, the resstor may be reduced to Ω for cases where a capactve dscharge pulse s not desred. Table : Propertes of SMA test ponts Desgnator PCB label Descrpton J CAP Dscharge capactor voltage (VCHARGE on schematc) J6 SHUNT Dscharge shunt voltage Attenuaton factor DC blockng cap LF tme constant Internal Ω termnaton V/V nf μs YES.7 A/V (V.) 9.8 A/V (V.) NO N/A NO J7 V OUT Q dran voltage V/V nf μs YES J9 V GDIN Gate drve nput NO N/A NO J V GS Q gate voltage NO N/A NO EPC EFFICIENT POWER CONVERSION CORPORATION WWW.EPC-CO.COM COPYRIGHT 7
Demonstraton System EPC96 Logc Supply 7.DC - VDC U MCP7T-E/MC. V, ma DFN IN OUT Logc Supply Regulator Fgure : Full schematc EPC96. LDAR Pulse Demonstraton Board GGNNDD V7n Man Supply Input J PULSE_IN R8 R. R6 Vout J7 C µf, C µf, C µf, R9 VBUS J8 EMPTY x." Male Vert. R7 R TP C nf, Vgate TP TP Vdran R k _ VBUS C9 µf, R7 _V FB Ω, 7 ma U LT79CS6 VDD C8 pf, C pf, C7 nf, C6 pf, U A VCC 6 B NC Y NC7SZ8L6X R8 EMPTY TP R VCHARGE C7 nf, PLS_IN -IN SHDN 6 +IN OUT C6 nf, R 6 _ U LT7IDD +IN A -IN A -IN B +IN B VDD OUT A OUT B 8 7 6 C nf, C nf, EP R7 k FB Ω, 7 ma C pf, V C pf, V C pf, V R 6 R k R 6 FB Ω, 7 ma FB Ω, 7 ma VDD U LDO UCC76DRVT VREF C nf, 6 V VSS 6 EP PLS_IN R 9 VGDIN Gate drve nput sense VGS R.9 k R.9 k R.9 k R6.9 k C µf, V C6 µf, V C7 µf, V C8 µf, V C pf, V C pf, V VSHUNT C nf, V R k EPC6C V, 8 A, 6 mω R9 R J J 776- C.7 µf, J FB6 Ω, 7 ma R9 R J9 R 9 J C nf, V Z sngle core R8 k R 9.9 Dran voltage test Gate voltage sense Dscharge cap voltage sense Shunt voltage sense J6 VBUS V7n x." Male Vert. Z sngle core R. R. FB Ω, 7 ma R - HOLE - HOLE - HOLE - HOLE SPL PL9 D EMPTY 9 nm, W, A CAP SHUNT TP TP6 GD prop delay Z sngle core GD prop delay Z sngle core Z sngle core Z sngle core Z sngle core Hgh voltage Hgh voltage R. R6. Z sngle core J 776- D V, ma D V, ma For Verson. of the EPC96, D and D are not populated. FD FD FD Local Fducals MB MB MB MB MB MB6 MB7 MB8 Note: For Verson. of the EPC96, value of R-R6 s. Ω Dran voltage sense EPC EFFICIENT POWER CONVERSION CORPORATION WWW.EPC-CO.COM COPYRIGHT 7
Demonstraton System EPC96 Table : Bll of Materals - EPC96 Reference Part Descrpton Quantty Manufacturer Part # C.7 µf,, XR 6 C68XRE7K8AC C, C, C, C9 µf,, X7R 6 UMK7AB7KA-T C, C6, C7, C8 µf, V, X7S 8 TDK CGAJX7SAKAE C, C nf, V, CG 6 TDK C68CGAJ8AC C, C, C, C, C pf, V, CG TDK CCGAJBA C6, C7, C, C, C, C7 nf,, X7R 6 CX7REKBB C8 pf,, CG CCGHCBA C nf, 6 V, X7R 6 C86X7RCMAC C, C6 nf,, X7R GCM88CHJA6D D, D Schottky V, ma BATKFILM D Laser dode, W, peak 9 nm EMPTY FB, FB, FB, FB, FB, FB6 Ω, 7 ma, ferrte bead TDK 6 MPZSET J, J Termnal block screw type THT -poston.8 mm ptch 776- J, J, J6, J7, J9, J SMA jack straght SM 6 Molex 7- J. Male Vert." 68-6HLF J8. Male Vert." EMPTY Q V, 8 A, 6 mω EPC6C R, R, R Sze ERJ-GERX R, R, R, R6.9 k, %,.67 W, 6 resstor ERJ-P8J9V R, R7, R k resstor 6 % RMCF6FTK R8, R Vshay PHP 6 wde resstor PHP6EBST R9, R, R6, R7 Sze ERJ-RKFX R Sze ERJ-RKF9R9X R, R, R, R, R6 Sze RLS-R-F (V.) RLS-R-F (V.) R7 Sze ERJ-RKFRX R8, R9 Ω 6 MCT6MCFP R, R, R 6 resstor 6 % RMCF6FT6R R8 Sze EMPTY R9, R Sze RC6JCS R, R Sze ERJ-RKF9X TP, TP, TP, TP, TP, TP6 6 Keystone, U, ma, DFN MCP7T-E/MC U Dual. ns comparator RRO LT79CS6 U Dual. ns comparator RRO LT7IDD U TnyLogc UHS nput AND NC7SZ8L6X U egan gate drver wth LDO UCC76DRVT 6 EPC EFFICIENT POWER CONVERSION CORPORATION WWW.EPC-CO.COM COPYRIGHT 7
For More Informaton: Please contact nfo@epc-co.com or your local sales representatve Vst our webste: www.epc-co.com Sgn-up to receve EPC updates at bt.ly/epcupdates or text EPC to 88 EPC Products are dstrbuted through Dg-Key. www.dgkey.com Demonstraton Board Notfcaton The EPC96 board s ntended for product evaluaton purposes only and s not ntended for commercal use. Replace components on the Evaluaton Board only wth those parts shown on the parts lst (or Bll of Materals) n the Quck Start Gude. Contact an authorzed EPC representatve wth any questons. Ths board s ntended to be used by certfed professonals, n a lab envronment, followng proper safety procedures. Use at your own rsk. As an evaluaton tool, ths board s not desgned for complance wth the European Unon drectve on electromagnetc compatblty or any other such drectves or regulatons. As board bulds are at tmes subject to product avalablty, t s possble that boards may contan components or assembly materals that are not RoHS complant. Effcent Power Converson Corporaton (EPC) makes no guarantee that the purchased board s % RoHS complant. The Evaluaton board (or kt) s for demonstraton purposes only and nether the Board nor ths Quck Start Gude consttute a sales contract or create any knd of warranty, whether express or mpled, as to the applcatons or products nvolved. Dsclamer: EPC reserves the rght at any tme, wthout notce, to make changes to any products descrbed heren to mprove relablty, functon, or desgn. EPC does not assume any lablty arsng out of the applcaton or use of any product or crcut descrbed heren; nether does t convey any lcense under ts patent rghts, or other ntellectual property whatsoever, nor the rghts of others.