single output rbc models features 48v in , 12v/25a output quarter brick, regulated bus converter optimized for distributed power intermediate bus architectures (iba), the rbc- 12/25-d48 dc/dc bus converter series offer partially regulated outputs (?.5%, line and load) in an industry-standard quarter brick open frame package at excel- lent prices. the present trend in distributed power architectures (dpa) requires both high ef ciency and some regulation of the output voltage to reduce the risk of under voltage dropout. earlier unregulated bus converters were simply ratiometric ?c transformers. the fully isolated (1500vdc) rbc series accept a wide range 36 to 75 volt dc input (48v nominal) and convert it to an output of 12vdc at 25 amps maximum. this output then drives point-of-load (pol) converters such as our lsn, len, lsm or lqn series which feature precise load regulation. applications include 48v-powered datacom and telecom installations, base stations, cellular telephone repeaters and embedded systems. wideband output ripple and noise is a low 35mvp-p. low overall height of 0.39" (9.9 mm) ts tight card cages. the rbc s synchronous-recti er topology and xed frequency operation means excellent ef ciencies up to 93%, enabling ?o heatsink operation for most applica- tions up to +70 c (400 lfm air ow). ?o fan or zero air ow applications may use the optional base plate for cold surface mounting or natural-convection heatsinks. a wealth of electronic protection features include input undervoltage (uv) lockout, output current limit, short circuit hiccup, overtemperature shutdown and output overvoltage. available options include positive or negative polarity remote on/off control and the baseplate. assembled using iso-certi ed automated surface-mount techniques, the rbc series includes all fcc, ul, and iec emissions, safety and ammability certi cations. up to 300 watts total output power to 93% ultra-high ef ciency @ full load 48v input ( up to 36-75v range) 12v/25a output for intermediate bus architectures with pol converters synchronous-recti er topology 300khz xed switching frequency fully isolated, 1500v (basic) low 35mvp-p ripple/noise 2.3" x 1.45" x 0.39" quarter brick stable no-load condition thermal shutdown fully i/o protected iec/en/ul/cul60950 certi cation pending figure 1. simpli ed schematic # 5 2 2 % . 4 3 % . 3 % ( ) # # 5 0 ' ! 4 % $ 2 ) 6 % 6 / , 4 ! ' % 3 % . 3 % / 6 5 6 / 4 3 ( 5 4 $ / 7 . 3 7 ) 4 # ( ) . ' # / . 4 2 / , , % 2 6 ) . n 6 ) . 2 % - / 4 % / . / & & 6 / 5 4 n 6 / 5 4 preliminary www.cd4power.com rbc series page 1 of 6
rbc series regulated dc/dc bus converters rbc series page 2 of 6 www.cd4power.com mechanical specifications part number structure bus converter regulated nominal output voltage: 12 volts input voltage range: d48 = 36 to 75 volts (48v nominal) r bc 25 - / d48 - 12 b maximum rated output: current in amps n optional baseplate optional: on/off control n = negative polarity p = positive polarity note: not all model number combinations are available. contact c&d technologies for ordering assistance rohs-6 compliant* c - * contact c&d technologies (datel) for availability. " / 4 4 / - 6 ) % 7 ! " " " 0 ) . 3
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( 4 ( $ 8 $ 0 ! pin function p65 1 ?input 2 remote on/off 3 +input 4 ?output 5 +output i/o connections caution ? this converter is not internally fused. to avoid danger to persons or equipment and to retain safety certi? cation, the user must connect an external fast-blow input fuse as listed in the speci? cations. be sure that the pc board pad area and etch size are adequate to provide enough current so that the fuse will blow with an overload. start up considerations when power is ? rst applied to the dc/dc converter, there is some risk of start up dif? culties if you do not have both low ac and dc imped- ance and adequate regulation of the input source. make sure that your source supply does not allow the instantaneous input voltage to go below the minimum voltage at all times. even if this voltage depression is very brief, this may interfere with the on-board controller and pos- sibly cause a failed start. use a moderate size capacitor very close to the input terminals. you may need two parallel capacitors. a larger electrolytic or tantalum cap supplies the surge current and a smaller parallel low-esr ceramic cap gives low ac impedance. remember that the input current is carried both by the wiring and the ground plane return. make sure the ground plane uses adequate thick- ness copper. run additional bus wire if necessary.
rbc models regulated dc/dc bus converters rbc series page 3 of 6 www.cd4power.com performance/functional speci? cations input voltage: continuous 75 volts transient (100msec max.) 100 volts input reverse-polarity protection none, see notes output current ? current limited. devices can withstand an inde? nite output short circuit without damage. storage temperature ?55 to +125c lead temperature (soldering, 10 sec.) +280c these are stress ratings. exposure of devices to any of these conditions may adversely affect long-term reliability. proper operation under conditions other than those listed in the performance/functional speci? cations table is not implied. absolute maximum ratings typical at t a = +25c under nominal input voltage and full-load conditions unless noted. refer to required air? ow and derating curves for thermal speci? cations. [1] input input voltage range see ordering guide recommended external fuse 20 amp fast blow start-up threshold 35.5v undervoltage shutdown 34.0v min., 38.5 v max. overvoltage shutdown none [note 12] input current, nominal see ordering guide input current, v in = v min 9.14 amps max. input current, shut-down mode 2ma max. inrush transient 0.05a 2 -seconds re ected ripple current [2] 10map-p internal filter type pi ? lter reverse polarity protection none (see note 11) remote on/off control [5] positive logic on = +3.5 to +13.5 v. off = gnd. pin or 0 to +1v. negative logic on = gnd. pin or 0 to +1v. off = pin open or +3.5v to +13.5v. current 2ma max. output total output power [3] 306 watts max. setpoint accuracy (50% load) 2% of v nominal extreme accuracy [14] 11.4v min. to 12.6v max. output current [7] see ordering guide minimum load no minimum load ripple and noise (20mhz bandwidth) see ordering guide [8] line and load regulation [10] see ordering guide ef ciency see ordering guide isolation voltage (input/output) 1500vdc min. (input to baseplate) 1500vdc min. (baseplate to output) 1500vdc min. isolation resistance 100m isolation capacitance 1000pf isolation safety rating basic current limit inception (98% of v out ) 30 amps after warm up short circuit current [6] 5 amps (hiccup autorestart ? remove short for recovery) short circuit duration (+v out grd) continuous, no damage overvoltage protection 15vdc max. via magnetic feedback max. capacitive loading (resistive load) 10,000f, low esr 0.02 ohms temperature coef cient 0.02% per c dynamic characteristics dynamic load response 500sec, 50-75-50% load step (to within 2% of v out ) start up time (v in to v out regulated) 60msec (remote on to vout regulated) 20msec fixed switching frequency 300khz environmental calculated mtbf [4] tbd operating pcb temperature [13] +120c max. electronic thermal shutdown +125c min. operating temperature range [9] ?40 to +70c (no derating, full power, 400 lfm air? ow, vertical mount) operating temperature range see derating curves (with derating) storage temperature range ?55 to +125c relative humidity to 85% / +85c safety compliance ul60950, csa-c22.2 no.60950, iec/en60950 electromagnetic interference fcc part 15, en55022, conducted (may require external ? lters) or radiated physical outline dimensions see mechanical speci? cations pin material copper alloy over nickel underplate weight 1 ounce (28.4 grams) (1) all models are tested and speci? ed with 400 lfm air? ow, external 1 || 10f ceramic/tantalum output capacitors and no external input capacitor. all capacitors are low esr types. these capacitors are necessary to accommodate our test equipment and may not be required to achieve speci? ed performance in your applications. all models are stable and regulate within spec under no-load conditions. general conditions for speci? cations are +25c, v in = nominal, v out = nominal, full load. (2) input ripple current is tested and speci? ed over a 5 hz to 20 mhz bandwidth. input ? ltering is c in = 33f/100v tantalum, c bus = 220f/100v electrolytic, l bus = 12h. (3) note that maximum power derating curves indicate an average current at nominal input voltage. at higher temperatures and/or lower air? ow, the dc/dc converter will tolerate brief full current outputs if the total rms current over time does not exceed the derating curve. all derating curves are presented at sea level altitude. be aware of reduced power dissipation with increasing density altitude. (4) mean time before failure is calculated using the telcordia (belcore) sr-332 method 1, case 3, ground ? xed conditions, t pcboard = +25c, full output load, natural air convection. (5) the on/off control may be driven with external logic or by applying appropriate external voltages which are referenced to input common. the on/off control input should use either an open collector/open drain transistor or logic gate which does not exceed +13.5v. (6) short circuit shutdown begins when the output voltage degrades approximately 2% from the selected setting. (7) the outputs are not intended to sink appreciable reverse current. sinking excessive reverse current may damage the outputs. (8) output noise may be further reduced by adding an external ? lter. see i/o filtering and noise reduction. (9) all models are fully operational and meet published speci? cations, including ?cold start? at ?40c. (10) regulation speci? cations describe the deviation as the line input voltage or output load cur- rent is varied from a nominal midpoint value to either extreme. (11) if reverse polarity is accidentally applied to the input, a body diode will become forward biased and will accept considerable current. to ensure reverse input protection with full output load, always connect an external input fuse in series with the +v in input. use approxi- mately twice the full input current rating with nominal input voltage. (12) input overvoltage shutdown on 48v input models is normally deleted in order to comply with certain telecom reliability requirements. these requirements attempt continued operation despite signi? cant input overvoltage. (13) note that the converter may operate up to +120c pcb temperature with the baseplate installed. however, thermal self-protection occurs near +125c and there is a temperature gradient from high power components. therefore, +100c baseplate temperature is recom- mended to avoid thermal shutdown. (14) ?extreme accuracy? refers to all combinations of line and load regulation, output current, inititial setpoint accuracy and temperature coef? cient.
rbc series regulated dc/dc bus converters rbc series page 4 of 6 www.cd4power.com technical notes i/o filtering and noise reduction the rbc-12/25-d48 is tested and speci? ed with external output capacitors. these capacitors are necessary to accommodate our test equipment and may not be required to achieve desired performance in your application. the rbc-12/25-d48 is designed with high-quality, high-performance internal i/o caps, and will operate within spec in most applications with no additional external components . in particular, the rbc-12/25-d48 input capacitors are speci? ed for low esr and are fully rated to handle the units' input ripple currents. similarly, the internal output capacitors are speci? ed for low esr and full-range frequency response. in critical applications, input/output ripple/noise may be further reduced using ? ltering techniques, the simplest being the installation of external i/o caps. external input capacitors serve primarily as energy-storage devices. they minimize high-frequency variations in input voltage (usually caused by ir drops in conductors leading to the dc/dc) as the switching converter draws pulses of current. input capacitors should be selected for bulk capacitance (at appropriate frequencies), low esr, and high rms-ripple-current ratings. the switching nature of modern dc/dc's requires that the dc input voltage source have low ac impedance at the frequencies of interest. highly inductive source impedances can greatly affect system stability. your speci? c system con? guration may necessitate additional considerations. # ) . 6 ) . # " 5 3 , " 5 3 # ) . & % 3 2 m 7 k ( z # " 5 3 & % 3 2 m 7 k ( z , " 5 3 ( ) . 0 5 4 # / - - / . # 5 2 2 % . 4 0 2 / " % 4 / / 3 # ) , , / 3 # / 0 % n figure 2. measuring input ripple current output reverse conduction many dc/dc's using synchronous recti? cation suffer from output reverse conduction. if those devices have a voltage applied across their output before a voltage is applied to their input (this typically occurs when another power supply starts before them in a power-sequenced application), they will either fail to start or self destruct. in both cases, the cause is the "freewheeling" or "catch" fet biasing itself on and effectively becoming a short circuit. the rbc-12/25-d48 will withstand higher external sources several volts above the nominal output. however, if there is a chance of consistent over- voltage, users should provide an external voltage clamp or other protection. input fusing most applications and or safety agencies require the installation of fuses at the inputs of power conversion components. the rbc-12/25-d48 series may have an optional input fuse. therefore, if input fusing is mandatory, either a normal-blow or a fast-blow fuse with a value no greater than twice the maximum input current should be installed within the ungrounded input path to the converter. as a rule of thumb however, we recommend to use a normal-blow or slow- blow fuse with a typical value of about twice the maximum input current, calculated at low line with the converter's minimum ef? ciency. input overvoltage and reverse-polarity protection the rbc-12/25-d48 does not incorporate input reverse-polarity protection. input voltages in excess of the speci? ed absolute maximum ratings and input polarity reversals of longer than "instantaneous" duration can cause perma- nent damage to these devices. start-up time the v in to v out start-up time is the interval between the time at which a ramping input voltage crosses the lower limit of the speci? ed input voltage range and the fully loaded output voltage enters and remains within its speci? ed accuracy band. actual measured times will vary with input source impedance, external input capacitance, and the slew rate and ? nal value of the input voltage as it appears to the converter. the on/off to v out start-up time assumes the converter is turned off via the on/off control with the nominal input voltage already applied to the con- verter. the speci? cation de? nes the interval between the time at which the converter is turned on and the fully loaded output voltage enters and remains within its speci? ed accuracy band.
rbc models regulated dc/dc bus converters rbc series page 5 of 6 www.cd4power.com thermal considerations and thermal protection the typical output-current thermal-derating curves shown below enable designers to determine how much current they can reliably derive from each model of the rbc-12/25-d48 under known ambient-temperature and air-? ow conditions. similarly, the curves indicate how much air ? ow is required to reli- ably deliver a speci? c output current at known temperatures. the highest temperatures in rbc-12/25-d48's occur at their output inductor, whose heat is generated primarily by i 2 r losses. the derating curves were developed using thermocouples to monitor the inductor temperature and varying the load to keep that temperature below +110c under the assorted conditions of air ? ow and air temperature. once the temperature exceeds +125c (approx.), the thermal protection will disable the converter using the hiccup shutdown mode. distributed bus architecture a revolution is at hand for powering dedicated mixed circuit systems. instead of installing a single large isolated power supply or multiple isolated convert- ers, the new architecture uses one isolated power bus converter driving mul- tiple point-of-load non-isolated dc/dc converters which are positioned right where the power load is needed. while conceptually similar to having a single master power supply and distrubuted linear regulators, the bus converter figure 3. intermediate bus architecture undervoltage shutdown when the input voltage falls below the undervoltage threshold, the converter will terminate its output. however, this is not a latching shutdown mode. as soon as the input voltage rises above the start-up threshold, the converter will restore normal operation. this small amount of hysteresis prevents most uncommanded power cycling. since some input sources with higher output impedance will increase their output voltage greater than this hysteresis as soon as the load is removed, it is possible for this undervoltage shutdown to cycle inde? nitely. to prevent this, be sure that the input supply always has adequate voltage at full load. ) $ % ! , : % 2 /
) - 0 % $ ! . # % 6 / , 4 ! ' % 3 / 5 2 # % 6 / 5 4 n 6 / 5 4 % q u i v a l e n t i n t e r n a l s e r i e s r e s i s t a n c e figure 4. equivalent voltage source model thermal shutdown extended operation at excessive temperature will initiate overtemperature shutdown triggered by a temperature sensor inside the pwm controller. this operates similarly to overcurrent and short circuit mode. the inception point of the overtemperature condition depends on the average power delivered, the ambient temperature and the extent of forced cooling air? ow. remote on/off control the rbc-12/25-d48 may be turned off or on using the external remote on/off control. allow at least 15 milliseconds for either transition. this terminal consists of a digital input to the internal pwm controller athrough a protective resistor and diode. the on/off input circuit should be cmos logic referred to the ?input power terminal however ttl or ttl-ls logic will also work or a switch to ground. if preferred, you can even run this using a bipolar transistor in ?open collector? con? guration or an ?open drain? fet transistor. you may also leave this input unconnected and the converter will run whenever input power is applied. concept offers signi? cantly lower cost, higher ef? ciency and therefore lower temperatures, better reliability and longer service life. bulky, expensive heat sinks are eliminated and even a costly fan can be downsized or deleted. to achieve these results, the isolation is concentrated in the bus converter and the precise voltage regulation resides in the pol converters. since the high current power switching is located in the bus converter, designers can arrange the best possible noise shielding, isolation layout and thermal distribution. and, since most of the regulation is placed in the pol convert- ers, the total system offers very high ef? ciency, important for battery-operated and standby applictions. typically, datel?s surface mount pol converters are actually smaller than equivalent linear regulators, heat sinks and their discrete components. another bene? t to the distributed power architecture is that it eliminates digital crosstalk in tightly packed systems. a further advantage is that multiple power voltages are implemented simply by connecting pol?s with different output voltages. today?s modern systems require several low power voltages. many large asic?s, gate arrays and programmable logic are powered from 3.3 volts or lower. cpu?s use 2.5 or lower voltages at considerable current. and legacy logic or i/o ports may run from 5 volts. it makes sense to provide separate power converters for each of these sections. but they do not all need to be isolated, saving cost, board area and heat buildup.
sbc models regulated dc/dc bus converters ds-0564 08/07/2006 c&d technologies (datel), inc. makes no representation that the use of its products in the circuits described herein, or the us e of other technical information contained herein, will not infringe upon existing or future patent rights. the descriptions co ntained herein do not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. speci? cations are subject to change without notice. the datel logo is a registered trademark of c&d technologies, inc.. c&d technologies (ncl), ltd. milton keynes, united kingdom, tel: 44 (0) 1908 615232 internet: www.cd4power.com e-mail: ped.ltd@cdtechno.com c&d technologies (datel) s.a.r.l . montigny le bretonneux, france tel: 01-34-60-01-01 internet: www.cd4power.com e-mail: ped.sarl@cdtechno.com c&d technologies (datel) gmbh mnchen, germany tel: 89-544334-0 internet: www.cd4power.com e-mail: ped.gmbh@cdtechno.com c&d technologies kk tokyo, japan tel: 3-3779-1031, osaka tel: 6-6354-2025 int.: www.cd4power.jp email: sales_tokyo@cdtechno.com, sales_osaka@cdtechno.com china shanghai, people's republic of china tel: 86-50273678 internet: www.cd4power.com e-mail: shanghai@cdtechno.com c&d technologies (datel), inc. 11 cabot boulevard, mans? eld, ma 02048-1151 u.s.a. tel: (508) 339-3000 (800) 233-2765 fax: (508) 339-6356 www.cd4power.com email: sales@cdtechno.com iso 9001 registered rbc series page 6 of 6 www.cd4power.com
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