miniature, 2w isolated regulated dc/dc converters dcr02 series features ul1950 recognized dip-18 and gull-wing (1) packages 55w/in 3 (3.3w/cm 3 ) power density device-to-device synchronization thermal protection 1000vrms isolation 400khz switching 125 fits at 55 c short-circuit protected 12v, 24v inputs 5v outputs note: (1) gull-wing package available q1 2001. description dcr02 family is a series of high-efficiency, input- isolated, output-regulated dc/dc converters. in addi- tion to 2w nominal, galvanically-isolated output power capability, this range of dc/dcs offer very low out- put noise, and high accuracy. the dcr02 family is implemented in standard molded ic packaging, giving standard jedec outlines suit- able for high-volume assembly. the dcr02 is manufactured using the same technol- ogy as standard ic packages, thereby achieving very high reliability. applications point-of-use power conversion digital interface power ground loop elimination power-supply noise reduction input controller ldo regulator enable v rec sync v s error v out 0v in 0v out dcr02 dcr02 copyright ?2000, texas instruments incorporated sbvs028 printed in u.s.a. december, 2000 www.ti.com
dcr02 series 2 sbvs028 specifications at t a = +25 c, v s = nominal, i o = 10ma, c o = 0.1 f, unless otherwise specified. dcr02 series parameter conditions min typ max units output setpoint dcr021205 5v dcr022405 5v setpoint accuracy 0.5 2.0 % maximum output current dcr021205 400 ma dcr022405 400 ma output short-circuit protected duration infinite line regulation dcr021205 1 mv/v dcr022405 1 mv/v over line and load dcr021205 10ma to 400ma load, 4.5v to 5.5v line 1.0 2.5 % dcr022405 10ma to 400ma load, 4.5v to 5.5v line 1.0 2.5 % versus temperature ?0 c to +70 c 1.0 % ripple and noise dcr0212 ripple 20mhz bandwidth, 50% load (1) 18 mvp-p dcr0212 noise 100mhz bandwidth, 50% load (1) 20 mvp-p dcr0224 ripple 20mhz bandwidth, 50% load (1) 18 mvp-p dcr0224 noise 100mhz bandwidth, 50% load (1) 25 mvp-p input nominal voltage (v s ) dcr021205 12 v dcr022405 24 v voltage range ?0 +10 % supply current dcr021205 i o = 0ma 15 ma i o = 10ma 23 ma i o = 400ma 250 ma dcr022405 i o = 0ma 15 ma i o = 10ma 17 ma i o = 400ma 129 ma reflected ripple current dcr021205, dcr022405 mhz bandwidth, 100% load 8 map-p c in = 2.2 f, c filter = 1 f isolation voltage 1s flash test 1 kvrms 60s test, ul1950 (2) 1 kvrms input/output capacitance 25 pf output enable control logic high input voltage 2.0 v rec v logic high input current 2.0 < v enable < v rec 100 na logic low input voltage ?.2 0.5 v logic low input current 0 < v enable < 0.5 100 na dcr021205 v dcr022405 v error flag logic high open collector leakage v error = 5v 10 a logic low output voltage sinking 2ma 0.4 v thermal shutdown junction temperature temperature activated 150 c temperature deactivated 130 c synchronization pin max external capacitance on sync pin 3pf internal oscillator frequency 720 800 880 khz external synchronization frequency 720 880 khz external synchronization signal high 2.5 2.5 5.0 v external synchronization signal low 0 0.4 v temperature range operating ?0 +70 c note: (1) c in = 2.2 f, c filter = 1 f, c out = 0.1 f. (2) during ul approval only.
dcr02 series 3 sbvs028 electrostatic discharge sensitivity this integrated circuit can be damaged by esd. burr-brown recommends that all integrated circuits be handled with appropriate precautions. failure to observe proper handling and installation procedures can cause damage. esd damage can range from subtle performance degrada- tion to complete device failure. precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. input voltage: dcr0212 .......................................................................................... 15v dcr0224 .......................................................................................... 29v storage temperature ...................................................... ?0 c to +125 c lead temperature (soldering, 10s) ................................................. 270 c absolute maximum ratings dcr02 basic model number: 1w product voltage input: 12v in voltage output: 5v out package code: p = 18-pin plastic dip, p-u = dip-18 gull wing (1) note: (1) p-u available q1 2001. ordering information 12 05 (p) package specified drawing temperature package ordering transport product package number range marking number (1) media dcr021205p dip-18 218-1 ?0 c to +70 c dcr021205p dcr021205p rails dcr022405p dip-18 218-1 ?0 c to +70 c dcr022405p dcr022405p rails dcr021205p-u (2) dip-18 gull wing 218-2 ?0 c to +70 c dcr021205p-u dcr021205p-u/700 tape and reel dcr022405p-u (2) dip-18 gull wing 218-2 ?0 c to +70 c dcr022405p-u dcr022405p-u/700 tape and reel note: (1) models with a slash (/) are available only in tape and reel in the quantities indicated (e.g., /700 indicates 700 dev ices per reel). ordering 700 pieces of ?cr021205p-u/700?will get a single 700-piece tape and reel. (2) p-u available q1 2001. package/ordering information pin definitions pin # pin name description 1v s voltage input 2 nc no connection 7v rec rectified output 80v out output ground 9v o voltage output 10 dnc do not connect 11 enable output voltage enable 12 error error flag active low 17 0v in input ground 18 sync synchronization input top view dip pin configuration dcr02 1 2 7 8 9 18 17 12 11 10 v s nc v rec 0v out v o sync 0v in error enable dnc
dcr02 series 4 sbvs028 functional description overview the dcr02 series offers isolation from an unregulated power supply operating from a choice of input voltages. the dcr02s provide a variety of regulated output voltages at a nominal output power of 2w. power stage the input supply is chopped at a frequency of 400khz (internal oscillator divided by 2), which is used to drive the center-tapped toroidal transformer. rectification the transformer? output is full wave rectified and smoothed by the external capacitor connected to v rec . regulator the internal low dropout regulator provides a well-regulated output voltage throughout the operating range of the device. oscillator and watchdog the dcr02 uses an internal saw-tooth generator to provide the 800khz on-board oscillator that is used to drive the power switching circuit. the operation of the oscillator is monitored by the watchdog, which will tri-state the output driver circuit if the oscillator fails, or if the sync pin is taken low, (shutdown mode). when the sync pin is returned high, normal operation resumes. synchronization if more than one dcr02 is being used, beat frequencies and other electrical interference can be generated. this is due to the small variations in switching frequencies between the converters. the dcr02 overcomes this by allowing devices to be synchronized to one another. up to eight devices can be synchronized by connecting the sync pins together, with care being taken to minimize the capacitance of tracking. significant stray capacitance on the sync pin will have the effect of reducing the frequency of the internal oscillator. if this is large, the dcr02 may be taken out with its optimized operating parameters, and saturation of the magnetics may result, damaging the device. if devices are synchronized, it should be noted that all devices will draw maximum current simultaneously at start up. this can cause the input voltage to dip. should it fall below the minimum input voltage, the devices may not start up. a 2.2 f capacitor (low esr) should be connected as close to the device input pins as possible. if more than eight devices are required to be synchronized, it is recommended that external synchronization be used. details are contained in burr-brown? application bulletin ab-153 (literature number sbaa035) available at www.ti.com. construction the dcr02 is manufactured using the same technology as standard ic packages. there is no substrate within the package. the dcr02 is constructed using a driver ic, low- dropout voltage regulator, rectifier diodes, and a wound magnetic toroid, all mounted on a leadframe. the dcr02 requires no special pcb assembly processing, as there is no solder within the package. the result is an isolated dc/dc converter with inherently high reliability. additional functions disable/enable the dcr02 can be disabled or enabled by driving the sync pin using an open drain cmos gate. if the sync pin is pulled low, the dcr02 will be disabled. the disable time depends upon the external loading. the internal disable function is implemented in 2 s. removal of the pull down will enable the dcr02. capacitance loading on the sync pin should be minimized in order to prevent a reduction in the internal oscillator? frequency. see application bulletin ab-153, ?xternal syn- chronization of the dcp01/02 series of dc/dc convert- ers? this document contains information on how to null the effects of additional capacitance on the sync pin. the oscillators frequency can be measured at v rec , as this is the fundamental frequency of the ripple component. output enable/disable the regulated output of the dcr02 can be disabled by pulling the enable pin low. holding the enable pin high enables the regulated output voltage, thus allowing the output to be controlled from the isolated side. error flag the dcr02 has an error pin which provides a ?ower good?flag, as long as the internal regulator is in regulation. decoupling ripple reduction due to the very low forward resistance of the dmos switching transistors, high current demands are placed upon the input supply for a short time. by placing a good quality low equivalent series resistance (esr) capacitor of 2.2 f close to the ic supply input pins, the effects on the power supply can be minimized. the high switching frequency of 400khz allows relatively small values of capacitors to be used for filtering the recti- fied output voltage. a good quality low esr capacitor of 1 f placed close to the v rec pin and output ground will reduce the ripple. it is not recommended that the dcr02 be fitted using an ic socket as this will degrade performance. the output at v rec is full wave rectified and produces a ripple of 800khz.
dcr02 series 5 sbvs028 figure 1. dcr02 with a single output. figure 2. self-synchronizing dcr02s with a dual output. it is recommended that a 0.1 f low esr capacitor is connected close to the output pin and ground to reduce noise on the output. the capacitor values listed are minimum values. if lower ripple is required, the filter capacitor should be increased in value to 0.47 f. note: as with all switching power supplies, the best performance is only obtained with low esr capacitors connected close to the switcher. if low esr capacitors are not used, the esr will generate a voltage drop when the capacitor is supplying the load power. often a larger capaci- tor is chosen for this purpose when a low esr smaller capacitance would perform as well. pcb layout ripple and noise careful consideration should be given to the layout of the pcb in order for the best results to be obtained. the dcr02 is a switching power supply and as such can place high peak current demands on the input supply. in order to avoid the supply falling momentarily during the fast switching pulses, ground and power planes should be used to track the power to the input of dcr02; this will also serve dcr 02 v out v rec v in c in (1) c out = 0.1 f c filter = 1 f v o1 0 v out 0v v s 0v note: (1) 2.2 f capacitor with low esr. dcr 02 v out v rec v in v o1 0 v out 0v v s sync 0v dcr 02 v out v rec v in v o2 0 v out 0 v out 0 v out 0v v s sync 0v note: (1) 2.2 f capacitor with low esr. c in (1) c out = 0.1 f c in (1) c out = 0.1 f c filter = 1 f c filter = 1 f to reduce noise on the circuit. if this is not possible, the supplies must be connected in a star formation, with the tracks made as wide as possible. if the sync pin is being used, the tracking between device sync pins should be short to avoid stray capacitance. if the sync pin is not being used, it is advisable to place a guard ring (connected to input ground) around this pin to avoid any noise pickup. the output should be taken from the device using ground and power planes. this will ensure minimum losses. a good quality low esr capacitor placed as close as practicable across the input will reduce reflected ripple and ensure a smooth start up. a good quality low esr capacitor placed as close as practicable across the rectifier output terminal and output ground will give the best ripple and noise performance. thermal management due to the high power density of this device, it is advisable to provide a ground plane on the output. the output regula- tor is mounted on a copper leadframe, and a ground plane will serve as an efficient heatsink.
important notice texas instruments and its subsidiaries (ti) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. all products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, patent infringement, and limitation of liability. ti warrants performance of its products to the specifications applicable at the time of sale in accordance with ti's standard warranty. testing and other quality control techniques are utilized to the extent ti deems necessary to support this warranty. specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements. customers are responsible for their applications using ti components. in order to minimize risks associated with the customer's applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. ti assumes no liability for applications assistance or customer product design. ti does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of ti covering or relating to any combination, machine, or process in which such products or services might be or are used. ti's publication of information regarding any third party's products or services does not constitute ti's approval, license, warranty or endorsement thereof. reproduction of information in ti data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations and notices. representation or reproduction of this information with alteration voids all warranties provided for an associated ti product or service, is an unfair and deceptive business practice, and ti is not responsible nor liable for any such use. resale of ti's products or services with statements different from or beyond the parameters stated by ti for that product or service voids all express and any implied warranties for the associated ti product or service, is an unfair and deceptive business practice, and ti is not responsible nor liable for any such use. also see: standard terms and conditions of sale for semiconductor products. www.ti.com/sc/docs/stdterms.htm mailing address: texas instruments post office box 655303 dallas, texas 75265 copyright ? 2001, texas instruments incorporated
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