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ep5348ui 400ma synchronous buck regulator with integrated inductor rohs compliant; halogen free www.enpirion.com description the ep5348ui delivers the optimal trade-off between footprint and efficien cy. it is a perfect alternative to replace less efficient ldos in space constrained applications that require improved efficiency. the ep5348ui is a 400ma powersoc which integrates mosfet switches, control, compensation, and the magnetics in a micro- qfn package. this highly integrated dcdc solution offers up to 46- points better efficiency than the comparable ldo. a significant reduction in power loss and improved thermals are achieved. it enables extended battery life and helps meet energy star requirements. integrated magnetics enables a tiny solution footprint, low output ripple, and high reliability, while maintaining high efficiency. the complete solution size is similar to an ldo and much smaller than a comparable dcdc. features ? integrated inductor technology ? 400ma continuous output current ? 2.0mm x 1.75mm x 0.9mm uqfn package ? small solution footprint ? efficiency, up to 90% ? v out range 0.6v to v in ? v drop_out ? short circuit and over current protection ? uvlo and thermal protection ? ic level reliability in a powersoc solution applications ? applications where poor ldo efficiency creates: o thermal challenges o battery life challenges o failure to meet energy star requirements ? space-constrained applications ? portable media player s and usb peripherals ep5348 10 f 0603 vout pvin agnd v in enable avin pgnd c out v out r a r b vfb 2.2 f 0603 c in c avin 0.1 f c a figure 1: typical application schematic 15 25 35 45 55 65 75 85 95 0.0 0.1 0.2 0.3 efficiency (%) load current (a) ep5348ui ldo = 46-points vin = 5.0v vout = 1.2v 05721 september 12, 2012 rev: c
ep5348ui ? enpirion 2012 all rights reserved, e&oe 2 www.enpirion.com ordering information part number package ep5348ui 14-pin qfn t&r EP5348UI-E ep5348ui evaluation board pin assignments (top view) figure 2: ep5348ui pin out diagram (top view) pin description pin name function 1, 13, 14 nc(sw) no connect ? these pins are internally connected to the common switching node of the internal mosfets. nc (sw) pins are not to be electrically connected to any external signal, ground, or voltage. however, they must be sold ered to the pcb. failure to follow this guideline may result in part malfunction or damage to the device. 2 pgnd power ground. connect this pin to the gr ound electrode of the input and output filter capacitors. 3, 8, 9 nc no connect: these pins may already be conne cted inside the device. therefore, they cannot be electrically connected to each other or to any external signal, voltage, or ground. they must however be soldered to the pcb. failure to follow this guideline may result in device damage. 4 vfb feedback pin for external voltage divider network. 5 agnd analog ground. this is the quiet ground for t he internal control circuitry, and the ground return for external feedback voltage divider 6, 7 vout regulated output voltage. refer to ap plication section for proper layout and decoupling. 10 enable output enable. enable = logic high; disable = logic low 11 avin input power supply for the controller ci rcuitry. connect to vin at a quiet point. 12 pvin input voltage for the mosfet switches. 05721 september 12, 2012 rev: c
ep5348ui ? enpirion 2012 all rights reserved, e&oe 3 www.enpirion.com absolute maximum ratings caution: absolute maximum ratings ar e stress ratings only. functional operation beyond the recommended operating conditions is not implied. stre ss beyond the absolute maximum ratings may cause permanent damage to the device. exposur e to absolute maximum rated conditions for extended periods may affect device reliability. parameter symbol min max units absolute maximum electrical ratings supply voltage ? pvin, avin, vout v in -0.3 6.0 v voltage on enable -0.3 v in + 0.3 v voltage on v fb -0.3 2.7 v esd rating (based on human body mode) 2000 v esd rating (charge device model) 500 v absolute maximum thermal ratings maximum operating junction temperature t j-abs 150 c storage temperature range t stg -65 150 c reflow temp, 10 sec, msl3 jedec j-std-020c 260 c recommended operating conditions parameter symbol min max units input voltage range v in 2.5 5.5 v output voltage range v out 0.6 v in -v do ? v operating ambient temperature t a -40 +85 c operating junction temperature t j -40 +125 c ? v do (drop-out voltage) is defined as (i load x dropout resistance). please see the ec table. thermal characteristics parameter symbol typ units thermal shutdown trip point t j-tp +155 c thermal shutdown trip point hysteresis 15 c thermal resistance: junction to ambient ?0 lfm ( note 1 ) ja 105 c/w note 1 : based on 2 oz. external copper layers and proper thermal design in line with eia/jedec jesd51-7 standard for high effective thermal conductivity boards. 05721 september 12, 2012 rev: c
ep5348ui ? enpirion 2012 all rights reserved, e&oe 4 www.enpirion.com electrical characteristics note: t a = -40c to +85c unless otherwise noted. typical values are at t a = 25c, vin = 3.6v. c in = 2.2f 0603 mlcc, c out = 10f 0603. parameter symbol test conditions min typ max units operating input voltage range v in 2.5 5.5 v under voltage lock-out ? v in rising v uvlo_r 2.3 v under voltage lock-out ? v in falling v uvlo_f 2.2 v shut-down supply current i sd enable = low 3 a vfb voltage initial accuracy v fb t a = 25 c, v in = 3.6v; i load = 100ma ; 0.8v v out 3.3v 0.588 0.600 0.612 v line regulation v out_line 2.5v v in 5.5v 0.03 %/v load regulation v out_load 0a i load 400ma 0.48 %/a temperature variation v out_templ -40 c t a +85 c 24 ppm/ c feedback pin input current i fb note 1 <300 na output current i out 0 400 ma ocp threshold i lim 2.5v v in 5.5v 0.6v v out 3.3v 1.4 a output dropout resistance (note 1) voltage (note 1,2) r do v do_fl input to output resistance v inmin - v out at full load 520 208 780 312 m ? mv operating output voltage range v out v do = i out * r do 0.6 v in -v do v enable pin logic low v enlo 0.3 v enable pin logic high v enhi 1.4 v enable pin current i enable note 1 <200 na operating frequency f osc 9 mhz soft start operation v out rise time t rise from 0 to full output voltage 1.17 1.8 2.43 msec notes: 1 - parameter guaranteed by design 2 - v do_fl (full-load drop-out voltage) is defined as (maximum i out x dropout resistance) 05721 september 12, 2012 rev: c
ep5348ui ? enpirion 2012 all rights reserved, e&oe 5 www.enpirion.com typical performance characteristics efficiency vs. load current: v in = 3.3v, v out (from top to bottom) = 2.5, 1.8, 1.2v efficiency vs. load current: v in = 5.0v, v out (from top to bottom) = 3.3, 2.5, 1.8, 1.2v output ripple: v in = 3.3v, v out = 1.0v, iout = 400ma c in = 2.2 f/0603, c out = 10 f/0603 + 2.2uf/0603 output ripple: v in = 3.3v, v out = 1.0v, iout = 400ma c in = 2.2 f/0603, c out = 10 f/0603 + 2.2uf/0603 output ripple: v in = 5v, v out = 1.0v, iout = 400ma c in = 2.2 f/0603, c out = 10 f/0603 + 2.2uf/0603 output ripple: v in = 5v, v out = 1.0v, iout = 400ma c in = 2.2 f/0603, c out = 10 f/0603 + 2.2uf/0603 20 30 40 50 60 70 80 90 0 . 00 . 10 . 20 . 30 . 4 efficiency (%) load current (a) vin = 3.3v vout=2.5 vout=1.8 vout=1.2 top to bottom : 20 30 40 50 60 70 80 90 0 . 00 . 10 . 20 . 30 . 4 efficiency (%) load current (a) vin = 5.0v vout=3.3v vout=2.5v vout=1.8v vout=1.2v top to bottom : 20 mhz bw limit 500 mhz b w 20 mhz bw limit 500 mhz b w 05721 september 12, 2012 rev: c
ep5348ui ? enpirion 2012 all rights reserved, e&oe 6 www.enpirion.com load transient: v in = 3.3v, v out = 1.0v ch.1: v out , ch.2: i load 0 ? 400ma c in = 2.2 f/0603, c out = 10 f/0603 + 2.2uf/0603 load transient: v in = 5v, v out = 1.0v ch.1: v out , ch.2: i load 0 ? 400ma c in = 2.2 f/0603, c out = 10 f/0603 + 2.2uf/0603 power up/down at no load: v in /v out = 5.0v/1.2v, cout 10f, ch.1: enable, ch. 2: v out , ch.4: i out power up/down into 3 load: v in /v out = 5.5v/3.3v, cout 10f, ch.1: enable, ch. 2: v out , ch.4: i out 05721 september 12, 2012 rev: c
ep5348ui ? enpirion 2012 all rights reserved, e&oe 7 www.enpirion.com detailed description functional overview the ep5348ui requires only 2 small mlcc capacitors and a few small-signal components for a complete dc-dc converter solution. the device integrates mosfet switches, pwm controller, gate-drive, part of the loop compensation, and inductor into a tiny 2.0mm x 1.75mm x 0.9mm micro-qfn package. advanced package design, along with the high level of integration, pr ovides very low output ripple and noise. the ep5 348ui uses voltage mode control for high noise immunity and load matching to advanced 90nm loads. an external resistor divider is used to program output setting over the 0.6v to v in -v dropout as specified in the electrical characteristics table. the ep5348ui provides the industry?s highest power density of any 400ma dc-dc converter solution. the key enabler of this revolutionary integration is enpiri on?s proprietary power mosfet technology. the advanced mosfet switches are implement ed in deep-submicron cmos to supply very low switching loss at high switching frequencies and to allow a high level of integration. the semiconductor process allows seamless integration of all switching, control, and compensation circuitry. the proprietary magnetics design provides high-density/high-value magnetics in a very small footprint. enpirion magnetics are carefully matched to the control and compensation circuitry yielding an optimal solution with assured performance over the entire operating range. protection features in clude under-voltage lock- out (uvlo), over-current protection (ocp), short circuit protection, and thermal overload protection. integrated inductor the ep5348ui utilizes a proprietary low loss integrated inductor. the integration of the inductor greatly simplifies the power supply design process. the inherent shielding and compact construction of the integrated inductor reduces the noise that can couple into the traces of the printed circuit board. further, the package layout is optimized to reduce the electrical path length for the high di/dt currents that are always present in dc-dc converters. the integrated inductor provides the optimal solution to the complexi ty, output ripple, and noise that plague low power dc-dc converter design. control matched to sub 90nm loads the ep5348ui utilizes a type iii compensation network. voltage mode control is inherently impedance matched to the sub 90nm process technology that is used in today?s advanced ics. voltage mode control also provides a high degree of noise immunity at light load currents so that low ripple and high accuracy are maintained over the entire load range. the very high switching fr equency allows for a very wide control loop bandwidth and hence excellent transient performance. soft start internal soft start circuits limit the rate of output voltage rise when the device starts up from a power down condition, or when the ?enable? pin is asserted ?high?. digital control circuitry controls the v out rise time to ensure a smooth turn-on ramp. the ep5348ui has a fixed v out turn-on time. therefore, the ramp rate will vary with the output voltage setting. output voltage rise time is given in the electrical characteristics table. excess bulk capacitance on the output of the device can cause an over-current condition at startup. the maximum total capacitance on the output, including the out put filter capacitor, and bulk and decoupling capacitance at the load, is given as: c out_total_max = 9.333 x 10 -4 / v out the nominal value for the output filter capacitor is 10uf. see the applications section for more details. over current/short circuit protection the current limit function is achieved by sensing the current flowing through a sense p- 05721 september 12, 2012 rev: c
ep5348ui ? enpirion 2012 all rights reserved, e&oe 8 www.enpirion.com mosfet which is compared to a reference current. when this leve l is exceeded the p- fet is turned off and the n-fet is turned on, pulling v out low. this condition is maintained for approximately 0.5ms and then a normal soft start is initiated. if the over current condition still persists, this cycle will repeat. under voltage lockout during initial power up an under voltage lockout circuit will hold-off the switching circuitry until the in put voltage reaches a sufficient level to ensure proper operation. if the voltage drops below the uvlo threshold, the lockout circuitry will di sable the switching. hysteresis is included to prevent chattering between states. enable the enable pin provides a means to shut down the converter or enable normal operation. a logic low will disable the converter and cause it to shut down. a logic high will enable the converter into normal operation. note: the enable pin must not be left floating. thermal shutdown when excessive power is dissipated in the chip, the junction temperature rises. once the junction temperature exceeds the thermal shutdown threshold, the thermal shutdown circuit turns off the co nverter output voltage thus allowing the device to cool. when the junction temperature dec reases by 15c, the device will go through the normal startup process. application information output voltage programming ep5348 10 f 0603 vout pvin agnd v in enable avin pgnd c out v out r a r b vfb 2.2 f 0603 c in c avin 0.1 f c a figure 3: typical application circuit the ep5348ui uses a simple resistor divider to program the output voltage. referring to figure 3, use 200 k ? , 1% or better for the upper resistor (r a ). the value of the bottom resistor (r b ) in k ? is given as: nominal6.0 ) ( * vvfb vfbv rvfb r out a b = ? = a 5pf mlcc capacitor c a is also required in parallel with r a for compensation. input filter capacitor c in_min = 2.2f 0603 case size or larger. the input capacitor must use a x5r or x7r or equivalent dielectric formulation. y5v or equivalent dielectric formulations lose capacitance with fre quency, bias, and with temperature, and are not suitable for switch- mode dc-dc converter input filter applications. output filter capacitor c out_min = 10uf 0603 + 2.2uf 0603 mlcc when 4.5v v in 5.5v, and i out > 300ma. c out_min = 10uf 0603 mlcc for all other use cases. however, ripple performance can always be improved by adding a second 2.2uf or 1uf output capacitor for any operating condition. v out has to be sensed at the last output filter capacitor next to the ep5348ui. any additional bulk capacitance for load decoupling and byass has to be far enough from the v out 05721 september 12, 2012 rev: c
ep5348ui ? enpirion 2012 all rights reserved, e&oe 9 www.enpirion.com sensing point so that it does not interfere with the control loop operation. excess total capacitance on the output (output filter + bulk) can cause an over-current condition at startup. please see the soft st art section under functional overview for the maximum allowable bulk capacitance on the output rail. the output capacitor mu st use a x5r or x7r or equivalent dielectric formulation. y5v or equivalent dielectric formulations lose capacitance with frequency, bias, and temperature and are not suitable for switch- mode dc-dc converter output filter applications. ldo replacement the enpirion ep5348ui is a suitable replacement for inefficient ldos and can be used to augment the ldos in a pmu with minimum footprint impact. this integrated dcdc solution offers significantly better efficiency, and significant reduction in power loss. the resulting improved thermals and extended battery life helps meet energy star requirements. the tota l solution size is 25% smaller than a comparable ldo and half the footprint of a comparable dcdc. as the table below show s, ep5348ui provides the optimal trade-off between footprint and efficiency when compared to a traditional ldo: power-up/down sequencing during power-up, enable should not be asserted before pvin, and pvin should not be asserted before avin. the pvin should never be powered when avin is off. during power down, the avin should not be powered down before the pvin. tying pvin and avin or all three pins (avin, pvin, enable) together during power up or power down meets these requirements . pre-bias start-up the ep5348ui does not support startup into a pre-biased condition. be sure the output capacitors are not charged or the output of the ep5348ui is not pre-biased when the ep5348ui is first enabled. layout recommendations figure 4: top pcb layer critical components and copper for minimum footprint figure 5: bottom pcb layer critical components (r a , r b , c a ) & copper for minimum footprint vin (v) vout (v) load (ma) eff dcdc eff ldo ploss dcdc (mw) ploss ldo (mw) power saved (mw) 5.0 1.2 400 70.4% 24.0% 202 1520 1318 5.0 1.8 400 76.4% 36.0% 222 1280 1058 5.0 2.5 400 81.6% 50.0% 225 1000 775 5.0 3.3 400 87.7% 66.0% 185 680 495 3.3 1.2 400 77.1% 36.4% 143 840 697 3.3 1.8 400 83.3% 54.5% 144 600 456 3.3 2.5 400 88.2% 75.8% 134 320 186 05721 september 12, 2012 rev: c
ep5348ui ? enpirion 2012 all rights reserved, e&oe 10 www.enpirion.com figures 4 and 5 show cr itical pcb top and bottom layer components and traces for a minimum-footpint recommended ep5348 layout with enable tied to v in . alternate enable configuratio ns need to be connected and routed according to specific customer application. this layout c onsists of four layers. for the other 2 layers and the exact dimensions, please see the gerber files at www.enpirion.com . the recommendations given below are general guidelines. customers may need to adjust these according to their own layout and manufacturing rules. recommendation 1: input and output filter capacitors should be placed on the same side of the pcb, and as cl ose to the ep5348ui package as possible. they should be connected to the device with very short and wide traces. do not use thermal reliefs or spokes when connecting the capacitor pads to the respective nodes. the +v and gnd traces between the capacitors and the ep5348ui should be as close to each other as possible so that the gap between the two nodes is minimized, even under the capacitors. recommendation 2: the system ground plane should be the first layer immediately below the surface laye r. this ground plane should be continuous and un-interrupted below the converter and the input/output capacitors. please the gerber files at www.enpirion.com . recommendation 3: multiple small vias should be used to connect ground terminal of the input capacitor and out put capacitors to the system ground plane. it is preferred to put these vias along the edge of the gnd copper closest to the +v copper. these vias connect the input/output filter capacitors to the gnd plane, and help reduce paras itic inductances in the input and output curr ent loops. see figure 4. if the two vias ca nnot be put under c in or c out , then put two vias right after the capacitors next the v in and v out vias. recommendation 4: as figure 5 shows, r a , r b , and c a have been placed on the back side to minimize the footprint. these components also need to be close to the vfb pin (see figures 3, 4 and 5). the vfb pin is a high- impedance, sensitive node. keep any trace connected to this node as short and thin as possible. whenever possible, connect r b directly to the agnd pin instead of going through the gnd plane. in the layout shown above, r b goes to the via next to agnd pin using a dedicated trace on layer 3 not shown here. see gerber files at www.enpirion.com . recommendation 5 : avin is the power supply for the small-signal cont rol circuits. it should be connected to the input vo ltage at a quiet point. in figure 4 this connection is made at the vias just before c in . there is an additional decoupling capacitor c avin for avin which is connected between the device pin and the gnd plane. recommendation 6: the via to the right of pin 2 underneath the device hel ps to minimize the parasitic inductances in the input and output loop ground connections. recommendation 7: the top layer 1 metal under the device must not be more than shown in figure 4. as with any switch-mode dc/dc converter, try not to run sensitive signal or control lines underneath the converter package on other layers. recommendation 8: the v out sense point should be just after the last output filter capacitor. keep the sens e trace short in order to avoid noise coupling into the node. 05721 september 12, 2012 rev: c
ep5348ui ? enpirion 2012 all rights reserved, e&oe 11 www.enpirion.com recommended pcb footprint figure 6: en5348ui package pcb footprint package and mechanical figure 7 en5348ui package dimensions dimensions in mm 05721 september 12, 2012 rev: c
ep5348ui ? enpirion 2012 all rights reserved, e&oe 12 www.enpirion.com contact information enpirion, inc. perryville iii corporate park 53 frontage road, suite 210 hampton, nj 08827 phone: +1 908-894-6000 fax: +1 908-894-6090 www.enpirion.com enpirion reserves the right to make changes in circuit design and/or specif ications at any time without notice. information fur nished by enpirion is believed to be accurate and reliable. enpirion assumes no respons ibility for its use or for infringement of patents or other th ird party rights, which may result from its use. enpirion products are not authorized for us e in nuclear control systems, as critical components in life su pport systems or equipment used in hazardous environment without the ex press written authority from enpirion. 05721 september 12, 2012 rev: c

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