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ep53f8qi 1500 ma synchronous buck pwm dc-dc converter with integrated inductor rohs compliant; halogen free www.enpirion.com description the ep53f8qi provides hi gh efficiency in a very small footprint. featuri ng integrated inductor, the device delivers up to 1500ma of continuous output current. total solution footprint can be as little as 40mm 2 . output voltage is programmed via an external resistor divider prov iding a wide range of flexibility while maintaining a very small footprint. integration of the induc tor reduces conducted and radiated noise providing excellent compatibility with sensit ive rf and high speed data applications. features ? integrated inductor technology ? total solution footprint as small as 40 mm 2 ? 3 mm x 3 mm x 1.1 mm qfn package ? solution power density up to 140mw/mm 2 ? 1500 ma continuous output current ? high efficiency, up to 94 % ? low ripple voltage; 8 mv p-p typical ? power ok signal with 5 ma sink capability ? 2.4v to 5.5v input voltage range ? fast transient response ? 4 mhz fixed switching frequency ? low dropout operation: 100 % duty cycle ? under voltage lockout, over current, short circuit, and thermal protection ? rohs compliant; msl 3 260 c reflow application ? wireless wide area networking data cards. ? replacement of inefficient ldos ? noise sensitive applications such as rf, audio and video, and high speed io ? computing, computer peripherals, storage, networking, and instrumentation ? usb, dsl, stb, dvr, dtv, and ipc figure 1: typical application circuit product performance 25 35 45 55 65 75 85 95 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5 load current (a) efficiency (%) figure 2: efficiency, v in =5v, v out =3.7v 01542 4/3/2009 rev: a
ep53f8qi ? enpirion 2009 all rights reserved, e&oe 2 www.enpirion.com ordering information part number temp rating (c) package ep53f8qi-t -40 to +85 16-pin qfn t&r EP53F8QI-E qfn evaluation board pin assignments (top view) figure 3: pin diagram (top view) pin description pin name function 1, 15,16 nc(sw) no connect. these pins are internally connect ed to the common drain output of the internal mosfets. nc(sw) pins are not to be elec trically connected to any external signal, ground, or voltage. however, they must be so ldered to the pcb. failure to follow this guideline may result in part malfunction or damage. 2-3, pgnd input/output power ground. connect these pi ns to the ground electrode of the input and output filter capacitors. refer to layout considerations section for details. 4 avin2 analog input voltage. connect to avin1 only. 5 vfb feedback pin for external voltage divider network. connect a resistor divider to this pin to set the output voltage. use 100 k , 1% or better for the upper resistor. 6 nc no connect. 7,8 vout voltage and power output. connect these pins to output capacitor(s). 9 agnd analog ground for the controller circuits 10 avin1 analog voltage input for the controller circuits. connect this pin to pvin with a 10 resistor. connect a 1 uf capacitor between this pin and agnd. connect avin2 to this pin. 11 pok power ok with an open drain ou tp t. refer to power ok section. 12 enable input enable. a logic high signal on this pin ena bles the output and initiates a soft start. a logic low signal disables the output and discharg es the output to gnd. this pin must not be left floating. 13-14 pvin input power supply. connect to input suppl y. decouple with input capacitor(s) to pgnd. 01542 4/3/2009 rev: a
ep53f8qi ? enpirion 2009 all rights reserved, e&oe 3 www.enpirion.com absolute maximum ratings caution: absolute maximum ratings are 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. absolute maximum electrical ratings min max voltages on: pvin, avin, vout -0.3 v 6.5 v voltages on: enable, pok -0.3 v v in voltage on: vfb -0.3 v 2.7 v esd rating (human body model) 2 kv esd rating (charge device model) 500 v absolute maximum thermal ratings min max ambient operating range -40 c +85 c storage temperature range -65 c +150 c reflow peak body temperature msl3 (10 s) +260 c recommended operating conditions parameter symbol min max units input voltage range v in 2.4 5.5 v output voltage range v out 0.6 v in - v dropout ? v output current i load 0 1500 ma operating junction temperature t j -40 +125 c operating ambient temperature t a -40 +85 c ? v dropout is defined as (i load x dropout resistance) including temperature effect thermal characteristics parameter symbol min typ max units thermal shutdown (junction temperature) t sd 155 c thermal shutdown hysteresis t sdh 15 c thermal resistance: junction to ambient (0 lfm) ?? ja 55 c/w ?? based on a 2 oz. copper board and proper thermal des ign in line with jedec eij/jesd51 standards 01542 4/3/2009 rev: a
ep53f8qi ? enpirion 2009 all rights reserved, e&oe 4 www.enpirion.com electrical characteristics typical values for v in = 5v and t a =25c, unless otherwise noted. parameter symbol test conditions min typ max units operating input voltage v in 2.4 5.5 v under voltage lockout v uvlo v in going low to high 2.2 v under voltage lockout v uvlo v in going high to low 2.1 v vfb voltage initial accuracy v fb t a = 25 c; v in = 5v i load = 100 ma 0.588 0.600 0.612 v line regulation 2.4 v v in 5.5v 0.0031 %/v load regulation i load = 0 to 1.5a 0.420 %/a temperature variation -40c t a +85c 0.0012 %/c soft start slew rate 0.975 1.5 2.025 v/ms vfb, enable, pin input current (note 1) -40c t a +85c -40 +40 na logic low 0.0 0.4 v enable voltage threshold logic high 1.4 v in v pok upper threshold v out rising 111 % pok upper threshold v out falling 102 % pok lower threshold v out rising; percent of v out nominal 92 % pok lower threshold v out falling; percent of v out nominal 90 % pok low voltage i sink = 5 ma, -40c t a +85c 0.15 0.4 v pok pin v oh leakage current pok high, -40c t a +85c 500 na shutdown current enable low 14 a current limit threshold 2.4 v v in 5.5 v, -40c t a +85c 2.0 3.2 a dropout resistance 250 360 m operating frequency f osc 4 mhz note 1: vfb, enable pin input current specif ication is guaranteed by design. 01542 4/3/2009 rev: a
ep53f8qi ? enpirion 2009 all rights reserved, e&oe 5 www.enpirion.com typical performance characteristics ??? 25 35 45 55 65 75 85 95 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 load current (a) efficiency (%) efficiency vs. load current: v in = 5.0v, v out (from top to bottom) = 3.7, 2.5v, 1.8v, 1.2v 25 35 45 55 65 75 85 95 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 load current (a) efficiency (%) efficiency vs. load current: v in = 3.3v, v out (from top to bottom) = 2.5v, 1.8v, 1.2v output ripple: v in = 5v, v out = 3.7v, i load = 900ma output ripple: v in = 5v, v out = 3.7v, i load = 900ma output ripple: v in = 3.3v, v out = 1.8v, i load = 900ma output ripple: v in = 3.3v, v out = 1.8v, i load = 900ma 20 mhz bw limit 20 mhz bw limit 500 mhz bw 500 mhz bw 01542 4/3/2009 rev: a
ep53f8qi ? enpirion 2009 all rights reserved, e&oe 6 www.enpirion.com transient response: v in = 5.0v, v out = 1.2v load step 0 to 1.5a transient response: v in = 3.3v, v out = 1.8v load step 0 to 1.5a startup and shutdown waveform v in = 5.0v, v out = 3.7v, i load = 0ma startup and shutdown waveform v in = 5.0v, v out = 3.7v, i load = 900ma ??? application circuit in figure 1 used for typical performance characteristics. enable vout pok enable vout pok 01542 4/3/2009 rev: a
ep53f8qi ? enpirion 2009 all rights reserved, e&oe 7 www.enpirion.com functional block diagram dac vref (+) (-) error amp vfb vout package boundary p-drive n-drive uvlo thermal limit current limit soft start sawtooth gener ator (+) (-) pwm comp pvin enable pgnd logic compensation network nc (sw) pok pok avin bias figure 4: functional block diagram functional description the ep53f8qi leverages advanced cmos technology to provide high switching frequency, while also maintaining high efficiency. packaged in a 3 mm x 3 mm x 1.1 mm qfn, the ep53f8qi provides a high degree of flexibility in circuit design while maintaining a very small footprint. high switching frequency allows for the use of very small mlcc input and output filter capacitors. the converter uses voltage mode control to provide high noise immunity, low output impedance and excellent load transient response. most compensation components are integrated into the dev ice, requiring only a single external compensation capacitor. output voltage is progr ammed via an external resistor divider. output voltage can be programmed from 0.6v to v in -v dropout . pok monitors the output voltage and signals if it is within 10% of nominal. protection features include under voltage lockout (uvlo), over current protection, short circuit protection, and thermal overload protection. stability over wide range of operating conditions the ep53f8qi utilizes an internal compensation network and is designed to provide stable operation over a wide range of operating conditions. to improve transient performance or reduce output voltage ripple with dynamic loads you have the option to add supplementary capacitance to the output. the ep53f8qi is stable with up to 60 f of output capacitance without com pensation adjustment. additional output capacitance above 60 f can be accommodated with compensation adjustment depending on the application. the high switching frequency allows for a wide control loop bandwidth. 01542 4/3/2009 rev: a
ep53f8qi ? enpirion 2009 all rights reserved, e&oe 8 www.enpirion.com soft start the internal soft start circuit limits inrush current when the device st arts up from a power down condition or when the enable pin is asserted ?high?. digital control circuitry sets the v out ramp rate to minimi ze input voltage ripple and inrush current to ens ure a glitch-free start up. the soft start ramp ra te can be found in the electrical characteristics table. over current/short circuit protection when an over current condition occurs, v out is pulled low. this condition is maintained for a period of 1.2 ms and then a normal soft start cycle is initiated. if the over current condition still persists, this cycle will repeat. under voltage lockout an under voltage lockout circuit will hold off switching during initial power up until the input voltage reaches sufficient level to ensure proper operation. if the voltage drops below the uvlo threshold the lockout circuitry will again disable switching. hysteresis is included to prevent chattering betw een uvlo high and low states. enable the enable pin provides means to shut down the converter or initiate normal operation. a logic high will enable the converter to go through the soft start cycle and regulate the output voltage to the desir ed value. a logic low will allow the device to discharge the output and go into shutdown mode for minimal power consumption. when the output is discharged, an auxiliary nfet turns on and limits the discharge current to 300 ma or below. the enable pin must not be left floating. thermal shutdown when excessive power is dissipated in the device, its junction temper ature rises. once the junction temperature exceeds the thermal shutdown temperature, the thermal shutdown circuit turns off the c onverter, allowing the device to cool. when t he junction temperature decreases to a safe oper ating level, the device will be re-enabled and go through a normal startup process. the specific thermal shutdown junction temper ature and hysteresis can be found in the thermal characteristics table power ok the ep53f8qi provides an open drain output to indicate if the out put voltage stays within 92% to 111% of the set value. within this range, the pok output is allowed to be pulled high. outside this range, pok remains low. however, during transitions such as power up, power down, and dynamic voltage scaling, the pok output will not change state until the transition is complete for enhanced noise immunity. the pok has 5 ma sink capability for events where it needs to feed a digital controller with standard cmos inputs. when pok is pulled high, the pin leakage current is as low as 500 na maximum over temperature. this allows a large pull up resistor such as 100 k ? to be used for minimal current consumption in shutdown mode. the pok output can also be conveniently used as an enable input of the next stage for power sequencing of mu ltiple converters. 01542 4/3/2009 rev: a
ep53f8qi ? enpirion 2009 all rights reserved, e&oe 9 www.enpirion.com application information setting the output voltage figure 5: typical application circuit the ep53f8qi uses a simple resistor divider to program the output voltage. referring to figure 5, use 237 k ? , 1% or better for the upper resistor (ra). the value of the bottom resistor (rb) in k ? is given as: ? = k v rb out 6.0 2.142 where v out is the output voltage. rb should also be a 1% or better resistor. a 5.0pf mlcc capacitor is required in parallel with ra for compensation. input and output ca pacitor selection low esr mlc capacitors with x5r or x7r or equivalent dielectric should be used for input and output capacitors. y5v or equivalent dielectrics lose too much capacitance with frequency, dc bias, and temperature. therefore, they are not suitable for switch- mode dc-dc converter filtering, and must be avoided. the input filter capacitor requirement is a 10 f, 10v 0805 mlcc capacitor in parallel with a 680pf mlcc capacitor. the 680pf capacitor provides additional high frequency decoupling and is manditory. the 680pf capacitor must be placed closest to the ep53f8qi as shown in figure 5. the output filter capacitor requirement is a 22 f, 6.3v, 0805 mlcc for most applications. the output ripple can be reduced by using 2 x 22 f, 6.3v, 0805 mlc capacitors. avin decoupling avin should be connected to pvin using a 10? resistor. an 0402 or smaller case size is recommended for this resistor. a 1 f, 10 v, 0402 mlc capacitor should be connected from avin to agnd to provide high frequency decoupling for the control circuitry supply for optimal performance. pok pull up resi stor selection if the pok signal is required for the application. the pok pin must be pulled up through a resistor to any voltage source that can be as high as v in . the simplest way is to connect pok to the power input of the converter through a resistor. a 100 k ? pull up resistor is recommended for most applications for minimal current drain fr om the voltage source and good noise immunity. pok can sink up to 5ma. layout recommendation please refer to the ep53f8qi product page at www.enpirion.com for the most current device layout recommendation, gerber files, and other manufacturing guidelines. 01542 4/3/2009 rev: a
ep53f8qi ? enpirion 2009 all rights reserved, e&oe 10 www.enpirion.com recommended pcb footprint figure 6: ep53f8qi package pcb footprint 01542 4/3/2009 rev: a
ep53f8qi ? enpirion 2009 all rights reserved, e&oe 11 www.enpirion.com package and mechanical figure 7: ep53f8qi package dimensions contact information enpirion, inc. 685 route 202/206 suite 305 bridgewater, nj 08807 phone: 908-575-7550 fax: 908-575-0775 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. 01542 4/3/2009 rev: a

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