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general description the max13253 is a 1a, push-pull, transformer driver designed to provide a simple solution for low-emi isolated power supplies. the max13253 has an internal oscillator and operates from a single +3.0v to +5.5v supply. the transformers secondary-to-primary winding ratio defines the output voltage, allowing selection of virtually any iso - lated output voltage with galvanic isolation. the max13253 features an integrated oscillator driving a pair of n-channel power switches. the driver includes pin-selectable spread-spectrum oscillation and a well- controlled slew rate to reduce emi. the max13253 can optionally be driven by an external clock to further man - age emi. internal circuitry guarantees a fixed 50% duty cycle to prevent dc current flow through the transformer, regardless of which clock source is used. the max13253 operates with up to 1a of continuous current and features integrated protection including fault detection, overcurrent protection, and thermal shutdown. the max13253 includes a low-current shutdown mode to reduce the overall supply current to less than 5a (max) when the driver is disabled. the max13253 is available in a small 10-pin (3mm x 3mm) tdfn package and is specified over the -40c to +125c temperature range. features and benefts simple, flexible design ? + 3.0v to +5.5v supply range ? low r on 300m (max) at 4.5v ? up to 90% efficiency ? provides up to 1a to the transformer ? internal or external clock source ? internal oscillator frequency: 250khz or 600khz ? optional spread-spectrum oscillation ? -40 oc to +125oc temperature range integrated system protection ? fault detection and indication ? overcurrent limiting ? undervoltage lockout ? thermal shutdown saves space on board ? small 10-pin tdfn package (3mm x 3mm) applications power meter data interface isolated fieldbus interface medical equipment isolated analog front-end isolated usb power 19-6600; rev 1; 4/13 ordering information appears at end of data sheet. for related parts and recommended products to use with this part, refer to www.maximintegrated.com/max13253.related . typical operating circuit evaluation kit available fa ul t 1f 1f 10f 5v v dd en clk spr d hiclk t1 gnd pgnd t2 isolated v out 1ct:1.3ct max13253 max13253 1a, spread-spectrum, push-pull, transformer driver for isolated power supplies
maxim integrated 2 electrical characteristics (v dd = +3.0v to +5.5v, t a = t min to t max , unless otherwise noted. typical values are at v dd = +5.0v and t a = +25oc.) (note 2) note 1: package thermal resistances were obtained using the method described in jedec specification jesd51-7, using a four-layer board. for detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial . (all voltages referenced to gnd.) v dd , fault , clk, hiclk, sprd, en .................... -0.3v to +6v t1, t2 ................................................................. -0.3v to +16.5v t1, t2 maximum continuous current .............................. +1.75a fault maximum continuous current ............................. +50ma continuous power dissipation (t a = +70oc) tdfn (multilayer board) (derate 24.4mw/oc above +70oc) .......................... 1951.2mw tdfn (single-layer board) (derate 18.5mw/oc above +70oc) .......................... 1481.5mw operating temperature range .......................... -40oc to +125oc junction temperature ...................................................... +150oc storage temperature range ............................. -65oc to +150c lead temperature (soldering, 10s) ................................. +300c soldering temperature (reflow) ....................................... +260c stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to ab solute maximum rating conditions for extended periods may affect device reliability. package thermal characteristics (note 1) tdfn (multilayer) junction-to-ambient thermal resistance ( ja ) .......... 41c/w junction-to-case thermal resistance ( jc ) ................. 9c/w tdfn (single layer) junction-to-ambient thermal resistance ( ja ) .......... 54c/w junction-to-case thermal resistance ( jc ) ................. 9c/w absolute maximum ratings parameter symbol conditions min typ max units dc characteristics supply voltage range v dd 3.0 5.5 v supply current i dd v en = 0v, v clk = 0v, v sprd = 0v, t1 and t2 not connected v hiclk = 0v 1.1 1.8 ma v hiclk = v dd 2.1 3.5 disable supply current i dis v en = v dd , t1, t2, clk, sprd, hiclk connected to gnd or v dd (note 3) 5 a driver output resistance r o i out = 500ma v dd = 3.0v 160 350 m v dd = 4.5v 145 300 undervoltage lockout threshold v uvlo v dd rising 2.6 2.75 2.9 v undervoltage lockout threshold hysteresis v uvlo_hyst 250 mv t1, t2 current limit i lim 3.0v < v dd < 3.6v 1.1 1.3 1.5 a 4.5v < v dd < 5.5v 1.2 1.4 1.6 t1, t2 leakage current i lkg v en = v dd , v clk = 0v; t1, t2 = 0v or v dd -1 +1 a max13253 1a, spread-spectrum, push-pull, transformer driver for isolated power supplies www.maximintegrated.com
maxim integrated 3 electrical characteristics (continued) (v dd = +3.0v to +5.5v, t a = t min to t max , unless otherwise noted. typical values are at v dd = +5.0v and t a = +25oc.) (note 2) note 2: all units are 100% production tested at t a = +25oc. specifications over temperature are guaranteed by design. note 3: disable supply current includes output switch-leakage currents. parameter symbol conditions min typ max units logic signals (clk, en , hiclk, sprd, fault ) input logic-high voltage v ih 2 v input logic-low voltage v il 0.8 v input leakage current i il en , clk, sprd, hiclk = 0v or 5.5v -1 +1 a sprd pulldown current i pd v sprd = v dd 5 10 20 a fault output logic-low voltage v ol i sink = 10ma 0.4 v fault leakage current i lkgf v fault = 5.5v, fault deasserted 1 a ac characteristics switching frequency f sw figure 2, v clk = 0v, v sprd = 0v v hiclk = 0v 237 250 263 khz v hiclk = v dd 564 600 636 frequency spread d f sw figure 1, v sprd = v dd 4 % spread modulation rate f mod figure 1, v sprd = v dd v hiclk = 0v f sw /12 khz v hiclk = v dd f sw /28 clk input frequency f ext 200 2000 khz clk to t1, t2 propagation delay t pd t1/t2 switching low 230 ns t1, t2 duty cycle d internal or external clocking 50 % t1, t2 slew rate t slew figure 2 200 v/s crossover dead time t dead figure 2 50 ns watchdog timeout t wdog 20 35 55 s protection thermal-shutdown threshold t shdn +160 oc thermal-shutdown hysteresis t shdn_hys 30 oc max13253 1a, spread-spectrum, push-pull, transformer driver for isolated power supplies www.maximintegrated.com
maxim integrated 4 figure 1. frequency spread timing diagram figure 2. t1, t2 timing diagram if sprd = gn d (dither amount = 0%) time 8% dither amount +4% of f sw -4% of f sw f sw 1 f mod 50pf 100i v dd t1, t2 2 x v dd t1 0v 0v 2 x v dd t2 t dead t dead max13253 1a, spread-spectrum, push-pull, transformer driver for isolated power supplies www.maximintegrated.com
maxim integrated 5 typical operating characteristics (v dd = +5v, t a = +25c, unless otherwise noted.) supply current vs. external clock frequency max13253 toc01 external clock frequency (mhz) supply current (ma) 1.8 1.6 0.4 0.6 0.8 1.2 1.0 1.4 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0 0.2 2.0 switching frequency vs. temperature max13253 toc02 temperature (c) switching frequency (khz) 105 80 30 55 5 -20 260 310 360 410 460 510 560 610 660 210 -45 130 hiclk = v dd hiclk = gnd clk = gnd sprd = gnd current limit vs. temperature max13253 toc03 temperature (c) current limit (a) 105 80 55 30 5 -20 1.1 1.2 1.3 1.4 1.5 1.6 1.0 -45 130 v dd = 5v v dd = 3.3v t1 / t2 output voltage low vs. output current max13253 toc04 output current (a) t1 / t2 output voltage low (v) 0.8 0.6 0.4 0.2 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20 0 0 1.0 v dd = 5v v dd = 3.3v fault output voltage low vs. sink current max13253 toc05 sink current (ma) 30 20 10 20 40 60 80 100 120 140 160 180 200 0 0 40 fault is asserted fault output voltage low (mv) isolated output voltage vs. load current max13253 toc06 load current (a) isolated output voltage (v) 0.6 0.4 0.2 1 2 3 4 5 6 7 8 9 10 0 0 0.8 clk = gnd hiclk = gnd sprd = gnd 1:1:1.3:1.3 halo tgm-h240v8lf transformer isolated output voltage vs. load current max13253 toc07 load current (a) isolated output voltage (v) 0.5 0.4 0.3 0.2 0.1 1 2 3 4 5 6 7 8 9 10 11 12 0 0 0.6 clk = gnd hiclk = gnd sprd = gnd 1:1:2:2 halo tgm-h260v8lf transformer max13253 1a, spread-spectrum, push-pull, transformer driver for isolated power supplies www.maximintegrated.com
maxim integrated 6 typical operating characteristics (continued) (v dd = +5v, t a = +25c, unless otherwise noted.) efficiency vs. load current max13253 toc10 load current (a) efficiency (%) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 75 80 85 90 95 70 0 0.8 clk = gnd hiclk = gnd sprd = gnd 1:1:1.3:1.3 halo tgm-h240v8lf transformer v dd = 4.5v v dd = 5v v dd = 5.5v efficiency vs. load current max13253 toc08 load current (a) efficiency (%) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 80 82 84 86 88 90 78 0 0.9 clk = gnd hiclk = gnd sprd = gnd 1:1:1.3:1.3 halo tgm-h240v8lf transformer t a = +25c t a = +125c t a = +85c t a = -40c efficiency vs. load current max13253 toc11 load current (a) efficiency (%) 0.5 0.4 0.3 0.2 0.1 75 80 85 90 95 70 0 0.6 clk = gnd hiclk = gnd sprd = gnd 1:1:2:2 halo tgm-h260v8lf transformer t a = +125c t a = +85c t a = +25c t a = -40c max13253 toc09 load current (a) efficiency (%) efficiency vs. load current 75 80 85 90 95 70 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 hiclk = gnd hiclk = vdd clk = gnd sprd = gnd 1:1:1.3:1.3 halo tgm-h240v8lf transformer efficiency vs. load current max13253 toc12 load current (a) efficiency (%) 0.6 0.5 0.4 0.3 0.2 0.1 70 75 80 85 90 95 65 0 0.7 clk = gnd sprd = gnd 1:1:2:2 halo tgm-h260v8lf transformer hiclk = vdd hiclk = gnd efficieny vs. load current max13253 toc13 load current (a) efficiency (%) 0.6 0.5 0.4 0.3 0.2 0.1 70 75 80 85 90 95 65 0 0.7 clk = gnd hiclk = gnd sprd = gnd 1:1:2:2 halo tgm-h260v8lf transformer v dd = 3.0v v dd = 3.3v v dd = 3.6v switching waveforms max13253 toc14 t1 5v/div t2 5v/div 0v 0v 1s /div clk = gnd hiclk = gnd sprd = gnd rload = 1k? max13253 1a, spread-spectrum, push-pull, transformer driver for isolated power supplies www.maximintegrated.com
maxim integrated 7 pin description pin confguration pin name function 1 v dd power-supply input. bypass v dd to gnd with a 1f capacitor as close as possible to the device. 2 clk clock input. connect clk to gnd to enable internal clocking. apply a clock signal to clk to enable external clocking. 3 hiclk internal oscillator frequency select input. drive hiclk high to set the internal oscillator to a 600khz switching frequency. drive hiclk low to set the internal oscillator to a 250khz switching frequency. 4 en active-low enable input. drive en low to enable the device. drive en high to disable the device. 5 sprd spread-spectrum enable input. drive sprd high to enable 4% spread spectrum on the internal oscillator. drive sprd low or leave it unconnected to disable spread spectrum. sprd does not have any effect when an external clock is used. 6 fault active-low fault open-drain output. the fault open-drain transistor turns on when an overcurrent or overtemperature condition occurs. 7 gnd logic and analog ground 8 t2 transformer drive output 2 9 pgnd power ground. the transformer primary current fows through pgnd. ensure a low-resistance connection to ground. 10 t1 transformer drive output 1 ep exposed pad. internally connected to gnd. connect ep to a large ground plane to maximize thermal performance; not intended as an electrical connection point. 1 34 10 8 7 t1 t2 gnd 2 9 pgnd 5 + 6 faul t v dd hiclk en clk sprd *ep tdfn top view *exposed pad?connect to gn d max13253 max13253 1a, spread-spectrum, push-pull, transformer driver for isolated power supplies www.maximintegrated.com
maxim integrated 8 functional diagram detailed description the max13253 is an integrated primary-side trans - former driver for low-emi isolated power-supply circuits. an on-board oscillator, protection circuitry, and internal mosfets provide up to 1a of drive current to the primary windings of a center-tapped transformer. the max13253 features an internal oscillator for autonomous operation and an external clock source input to synchronize multiple max13253 devices. regardless of the clock source used, an internal flip-flop stage guarantees a fixed 50% duty cycle to prevent dc current flow in the transformer. the max13253 operates from a single +3.0v to +5.5v supply and includes undervoltage lockout for controlled startup. overcurrent protection and thermal shutdown circuitry provides additional protection against excessive power dissipation. isolated power-supply application the max13253 allows a versatile range of secondary- side rectification circuits (see figure 3 ). the primary-to- secondary transformer winding ratio can be chosen to adjust the isolated output voltage. the max13253 allows up to 1a of current into the primary transformer winding with a supply voltage up to +5.5v. clock source either the internal oscillator or an external clock provides the switching signal for the max13253. connect clk to ground to select the internal oscillator. provide an external signal to clk to automatically select external clocking. internal oscillator mode the max13253 includes an internal oscillator with a guar - anteed 50% duty cycle. drive the hiclk input high to set the internal oscillator frequency to 600khz (typ). drive the hiclk input low to set the internal oscillator frequency to 250khz (typ). the max13253 features spread-spectrum oscillation for reducing emi peaks. drive the sprd input high to enable spread spectrum on the internal oscillator. drive the clk sprd hiclk v dd en drive r t1 t2 uvlo mux flip- flop v uvlo current limit osc 10a watchdo g fault gnd pgnd max13253 max13253 1a, spread-spectrum, push-pull, transformer driver for isolated power supplies www.maximintegrated.com
maxim integrated 9 sprd input low or leave unconnected to disable spread spectrum on the internal oscillator. sprd has an internal 10a pulldown to ground. external clock mode the max13253 provides an external clock mode for syn - chronizing multiple max13253 devices. apply an external clock source to the clk input to enable external clock mode. an internal flip-flop divides the external clock by two in order to generate a switching signal with a guaran - teed 50% duty cycle. as a result, the max13253 outputs switch at one-half of the external clock frequency. t1 and t2 switch on the rising edge of the external clock signal. sprd has no effect when an external signal is applied to clk. watchdog when the max13253 is operating in external clock mode, a stalled clock can cause excessive dc current to flow through the primary winding of the transformer. the max13253 integrates internal watchdog circuitry to prevent damage from this condition. the internal oscilla - tor provides the switching signal to the driver whenever the period between edges on clk exceeds the watchdog timeout period of 20s (min). slew-rate control the t1 and t2 drivers feature a controlled slew rate to limit emi. disable mode the max13253 includes a pin-selectable disable mode to reduce current consumption. in disable mode the device consumes less than 5a (max) of supply current. the t1 and t2 outputs are high impedance in disable mode. power-up and undervoltage lockout the max13253 provides an undervoltage lockout feature to ensure controlled power-up state and prevent opera - tion before the oscillator has stabilized. on power-up and during normal operation, if the supply voltage drops below the v uvlo , the undervoltage-lockout circuit forces the device into disable mode. the t1 and t2 outputs are high impedance in disable mode. overcurrent limiting the max13253 features overcurrent limiting to protect the ic from excessive currents when charging large capaci - tive loads or driving into short circuits. current limiting is achieved in two stages: internal circuity monitors the out - put current and detects when the peak current rises above 2a. when the 2a limit is exceeded, internal protection cir - cuitry is immediately enabled, reducing the output current and regulating it to the 1.4a (typ) current-limit threshold. the max13253 monitors the driver current on a cycle-by- cycle basis, and the driver output current is regulated to the current-limit threshold until the short is removed. the max13253 can dissipate large amounts of power during overcurrent limiting, causing the ic to enter ther - mal shutdown. fault output the fault output is asserted low during an overcurrent or overtemperature fault. fault is an open-drain output. thermal shutdown the max13253 is protected from overtemperature dam - age by integrated thermal-shutdown circuitry. when the junction temperature (t j ) exceeds +160oc (typ), the device is disabled and fault is asserted. fault is asserted for the duration of either an overcurrent or over - temperature event. the device resumes normal operation when t j falls below +130c (typ). figure 3. secondary-side rectification topologies + v out = nv in - v d 1ct : nct v d = diode forw ard vo ltage - t1 t2 t1 t2 t1 t2 v in (a) push-pull rectifica tion + v out = 2(nv in - v d ) 1ct : nct v d = diode forw ard vo ltage - v in (b) vol ta ge doubler + v out = nv in - 2v d 1ct : nct v d = diode forw ard vo ltage - v in (c) full-w a ve rectifie r max13253 1a, spread-spectrum, push-pull, transformer driver for isolated power supplies www.maximintegrated.com
maxim integrated 10 applications information power dissipation the power dissipation of the device is approximated by: p d = (r o x i pri 2 ) + (i dd x v dd ) where r o is the resistance of the internal fet drivers and i pri is the load current flowing into t1 and t2. ensure that the power dissipation of the max13253 is kept below the absolute maximum ratings for proper operation. high-temperature operation when the max13253 is operated under high ambient temperatures, the power dissipated in the package can raise the junction temperature close to the thermal shut - down threshold. under such temperature conditions, the power dissipation should be held low enough that the junction temperature observes a factor of safety margin. the maximum junction temperature should be held below +140c. use the packages thermal resistance to calcu - late the junction temperature. power-supply decoupling bypass v dd to ground with a 1f ceramic capacitor as close as possible to the device. connect at least 10f between v dd and ground as close as possible to the primary-side center tap of the trans - former. this capacitor helps to stabilize the voltage on the supply line and protects the ic against large voltage spikes on v dd. output voltage regulation for many applications, the unregulated output of the max13253 circuit meets output voltage tolerances. this configuration represents the highest efficiency possible. when the load currents on the transformers second - ary side are low, the output voltage of the rectifier can strongly increase. to protect downstream circuitry, limit the output voltage when operating the circuit under low load conditions. if the minimum output load current is less than approximately 5ma, connect a zener diode from the output node of the rectifier to ground to limit the output voltage to a safe value. for applications requiring a regulated output voltage, maxim provides several solutions. in the following exam - ples, assume a tolerance of 10% for the input voltage. example 1: 5v to isolated, unregulated 6v in the circuit of figure 4 , the max13253 is used to gener - ate an isolated 6v output. for a minimum input voltage of 5v, the output voltage of the rectifier is approximately 6v. example 2: 3.3v to isolated, regulated 5v in the circuit of figure 5 , the max8881 low-dropout lin - ear regulator regulates the isolated output voltage to 5v. a 1:2 center-tapped transformer is used to step-up the secondary side voltage from a 3.3v input. for a minimum input voltage of 3.3v, the output voltage of the rectifier is approximately 5v. figure 4. 5v to isolated, unregulated 6v application circuit fa ul t 1f 1f 10f 5v v dd en clk sprd hiclk t1 gnd pgnd t2 5v iso output 1ct:1.3ct max13253 max13253 1a, spread-spectrum, push-pull, transformer driver for isolated power supplies www.maximintegrated.com
maxim integrated 11 isolated usb/rs-485/rs-232 isolated applications the max13253 can provide isolated power for usb/ rs-485/rs-232 applications. the 1a output current capa - bility of the max13253 allows multiple rs-485/rs-232 transceivers to operate simultaneously. pcb layout guidelines as with all power-supply circuits, careful pcb layout is important to achieve low switching losses and stable operation. connect the exposed pad to a solid copper ground plane for optimum thermal performance. the traces from t1 and t2 to the transformer must be low-resistance and low-inductance paths. locate the transformer as closely as possible to the max13253 using short, wide traces. if possible, use a power plane for all v dd connections to the max13253 and the primary-side of the transformer. if a power plane is not available, avoid damage to the ic by ensuring that the current flowing through the primary-side center tap of the transformer does not flow through the same trace that connects the supply pin of the max13253 to the v dd source, and connect the primary-side center tap to the v dd supply using a very low-inductance connection. when the internal oscillator is used, it is possible for high frequency switching on t1 and t2 to couple into the clk circuitry through pcb parasitic capacitance. this capaci - tive coupling can induce duty cycle errors in the oscillator, resulting in a dc current through the transformer. for proper operation, ensure that clk has a solid ground connection. exposed pad for optimal thermal performance, ensure that the exposed pad has a low thermal resistance connection to the ground plane. failure to provide a low thermal impedance path to the ground plane results in excessive junction temperatures when dissipating high power. component selection transformer selection transformer selection for the max13253 can be simpli - fied by the use of the et product. the et product relates the maximum allowable magnetic flux density in a trans - former core to the voltage across a winding and switching period. inductor magnetizing current in the primary wind - ing changes linearly with time during the switching period of the max13253. each transformer has a minimum et product, though not always stated on the transformer data sheet. ensure that the transformer selected for use with the max13253 has an et product of at least et = v dd / (2 x f sw ) for each half of the primary winding, where f sw is the minimum switching frequency of the t1 and t2 ouputs. select a transformer with sufficient et product for each half of the primary winding to ensure that the transformer does not saturate during operation. saturation of the magnetic core results in significantly reduced inductance of the primary, and therefore in a large increase in current flow. this can cause the current limit to be reached even when the lo ad is not high. figure 5. 3.3v to isolated, regulated 5v application circuit fa ul t shdn in 1f 1f 10f 3.3v v dd 4.7f 5v iso output en clk sprd hiclk t1 gnd gnd out pgnd t2 1ct:2ct max13253 max8881 fb max13253 1a, spread-spectrum, push-pull, transformer driver for isolated power supplies www.maximintegrated.com
maxim integrated 12 for example , when the internal oscillator is used to drive the outputs and hiclk is low, the required transformer et product to the center tap for an application with v dd (max) = 5.5v, is 13.1v-s. an application with v dd (max) = 3.3v has a transformer et product to the center tap requirement of 7.9v-s. in addition to the constraint on et product, choose a trans - former with low leakage inductance and low dc-winding resistance. power dissipation of the transformer due to the copper loss is approximated as: p d_tx = i load 2 x (r pri /n 2 + r sec ) where r pri is the dc winding resistance of the primary, and r sec is the dc winding resistance of the second - ary. in most cases, an optimum is reached when r sec = r pri /n 2 . for this condition, the power dissipation is equal for the primary and secondary windings. as with all power-supply designs, it is important to opti - mize efficiency. in designs incorporating small trans - formers, the possibility of thermal runaway makes low transformer efficiencies problematic. transformer losses produce a temperature rise that reduces the efficiency of the transformer. the lower efficiency, in turn, produces an even larger temperature rise. to ensure that the transformer meets these requirements under all operating conditions, the design should focus on the worst-case conditions. the most stringent demands on et product arise for maximum input voltage, minimum switching frequency, and maximum temperature and load current. additionally, the worst-case values for transform - er and rectifier losses should be considered. the primary must be center-tapped; however the second - ary winding may or may not be center-tapped, depending on the rectifier topology used. the phasing between pri - mary and secondary windings is not critical. the transformer turns ratio must be set to provide the minimum required output voltage at the maximum antici - pated load with the minimum expected input voltage. in addition, include in the calculations an allowance for the worst-case losses in the rectifiers. since the turns ratio determined in this manner will ordinarily produce a much higher voltage at the secondary under conditions of high input voltage and/or light loading, be careful to prevent an overvoltage condition from occurring. transformers for use with the max13253 are typically wound on a high-permeability magnetic core. to minimize radiated electromagnetic emissions, select a toroid, pot core, e/i/u cor e, or equivalent. diode selection the high switching speed capability of the max13253 necessitates high-speed rectifiers. ordinary silicon signal diodes such as the 1n914 or 1n4148 can be used for low- output current levels (less than 50ma), but at high output current levels, their reverse recovery times might degrade efficiency. at higher output currents, select low forward- voltage schottky diodes to improve efficiency. ensure that the average forward current rating for the rectifier diodes exceeds the maximum load current of the circuit. for surface-mount applications, schottky diodes such as the b230a, mbrs230, and mbrs320 are recommended. table 1. component manufacturers suggested external component manufacturers manufacturer component website halo electronics transformers www.haloelectronics.com diodes inc. diodes www.diodes.com murata americas capacitors www.murataamericas.com max13253 1a, spread-spectrum, push-pull, transformer driver for isolated power supplies www.maximintegrated.com
maxim integrated 13 ordering information chip information process: bicmos +denotes lead(pb)-free/rohs-compliant package. * ep = exposed pad package information for the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. package type package code outline no. land pattern no. 10 tdfn-ep t1033+1 21-0137 90-0003 part temp range pin-package MAX13253ATB+ -40c to +125c 10 tdfn-ep* max13253 1a, spread-spectrum, push-pull, transformer driver for isolated power supplies www.maximintegrated.com
? 2013 maxim integrated products, inc. 14 revision history revision number revision date description pages changed 0 3/13 initial release 1 4/13 updated toc parameters, updated figure 4, replaced figure 5, updated output voltage regulation section 5, 6, 10, 11 maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integrated product. no circuit patent licenses are implied. maxim integrated reserves the right to change the circuitry and specifcations without notice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. maxim integrated and the maxim integrated logo are trademarks of maxim integrated products, inc. max13253 1a, spread-spectrum, push-pull, transformer driver for isolated power supplies for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds website at www.maximintegrated.com.

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