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power management ic fc suffix (pb-free) 98asa10787d 8-pin udfn 2x2 34726 ordering information device temperature range (t a ) package refer to table 1, device variations -25c to 85c 8-udfn bottom view document number: MC34726 rev. 2.0, 9/2010 freescale semiconductor advance information * this document contains certain information on a new product. specifications and information herein are subject to change without notice. ? freescale semiconductor, inc. , 2008-2010. all rights reserved. 300 ma high efficiency low quiescent current synchronous buck regulator with z-mode the 34726 is a high efficiency, low quiescent current (i q ), synchro - nous buck regulator, implementing freescale?s innovative z-mode ar - chitecture. freescale?s z-mode architecture greatly improves the ripple performance during light load currents, but still maintains a low quies - cent current of 65 a, at no loa d in ?sleepy? z-mode. the 34726 accepts an input voltage in the range of 2.7 to 5.5 v, making it ideally suited for single cell li-ion based applications. factory preset output voltages, ra nging from 0.8 to 3.3 v, reduce the number of requ ired auxiliary components. the part is able to provide 300 ma of continu ous load current across the input and the output voltage ranges. the 34726 switches at 2.0 mhz to allow the use of small, surface mount ind uctors and capacitors to save precious board space. the 34726 is available in the small, space saving, and low cost, 2x2 udf n-8 packages. the part is guar anteed for operation over the -25c to 85c temperature range. features ? 94% peak efficiency ?2.0 mhz switching frequency ? 2.7 to 5.5 v input voltage range ? automatic transition to energy savi ng light load z-mode (low ripple) ? fixed output voltage options from 0.8 to 3.3 v ?65 a qui escent current during sleepy z-mode ? 300 ma maximum continuous output current ? internal 2.0 ms soft start ? thermal and over-current protection ?0.1 a qu iescent current in shutdown (disabled) ? ultra thin 2x2 udfn package ? pb-free packaging designated by suffix code fc vin en sw fb gnd on off 2.7 ~ 5.5v 0.8 - 3.3v * 300ma 34726 c in c out l1 *programmable see table 1 figure 1. 34726 typical operating circuit
analog integrated circuit device data 2 freescale semiconductor 34726 device variations device variations table 1. device variations freescale part no. v in range output voltage (1) maximum load current switch frequency (mhz) (2) MC34726afc 2.7 - 5.5 v 1.2 v 300 ma 2.0 MC34726bfc 2.7 - 5.5 v 1.8 v 300 ma 2.0 MC34726cfc 3.6 - 5.5 v 3.3 v 300 ma 2.0 MC34726dfc 2.7 - 5.5 v 1.5 v 300 ma 2.0 MC34726efc 2.7 - 5.5 v 2.5 v 300 ma (3) 2.0 notes 1. output voltages of: 0.8 v, 0.9 v, 1.0 v, 1.1 v, 1.3 v, 1.4 v, 1.85 v, 2.0 v options available on request. contact freescale sales. 2. factory programmable at 2.0 mhz or 4.0 mhz. contact freescale sales for availability of the 4.0 mhz functionality. 3. the minimum input voltage must be higher than 2.8 v for 300 ma of load current.
analog integrated circuit device data freescale semiconductor 3 34726 internal block diagram internal block diagram + ? + ? + ? buck controller uvlo thermal shutdown current limit ref. vin pwm ref. osc. vin en sw (2) fb nc gnd (2) internal regulator soft start figure 2. 34726 simplifi ed internal block diagram
analog integrated circuit device data 4 freescale semiconductor 34726 pin connections pin connections vin gnd gnd en fb nc sw sw 2x2 udfn-8 (non ep) 1 2 3 45 6 7 8 transparent top view figure 3. 34726 pin connections table 2. 34726 pin definitions a functional description of each pin can be found in the functional pin description section beginning on page 10 . pin number pin name pin function formal name definition 1 vin input supply voltage input power input 2 gnd ground ground ground 3 gnd ground ground low noise ground 4 en input enable active high enable input 5 fb input feedback input feedback of the output voltage 6 nc n/a no connection internally not connected. connect to gnd externally 7 sw output switching node this terminal connects to the output inductor 8 sw output switching node this terminal connects to the output inductor
analog integrated circuit device data freescale semiconductor 5 34726 electrical characteristics maximum ratings electrical characteristics maximum ratings table 3. maximum ratings all voltages are with respect to ground unless otherwise no ted . exceeding these ratings may cause a malfunction or permanent damage to the device. ratings symbol value unit electrical ratings all pins voltages v in , v en , v fb , v sw -0.3 to 6.0 v esd voltage (1) human body model (hbm) machine model (mm) v esd 2000 200 v thermal ratings operating ambient temperature range t a -25 to +85 c storage temperature range t stg -25 to +150 c maximum lead temperature (2) , (3) t pprt note 3 c junction temperature operating junction temperature maximum junction temperature t j 125 +150 c thermal resistance (4) junction-to-case junction-to-ambient r jc r ja 104 122 c/w power dissipation continuous (derate 3.0 mw/c and over t a = 70c) p d 0.5 w notes 1. esd testing is performed in accordance with the human body model (hbm) (c zap = 100 pf, r zap = 1500 ), and the machine model (mm) (c zap = 200 pf, r zap = 0 ). 2. pin soldering temperature limit is for 10 seconds maximum dura tion. not designed for immersion so ldering. exceeding these lim its may cause malfunction or permanent damage to the device. 3. freescale?s package reflow capability m eets p b-free requirements for jedec standard j-std-020c. for peak package reflow temperature and moisture sensitivity levels (msl). go to www.free scale.com, search by par t number [e.g. remove prefixes/suffixe s and enter the core id to view all orderable parts. ( i.e. mc33xxxd enter 33xxx), and review parametrics. 4. device mounted on the freescale evb test board per jedec desd51-2.
analog integrated circuit device data 6 freescale semiconductor 34726 electrical characteristics static electrical characteristics static electrical characteristics table 4. static electric al ch aracteristics characteristics noted under conditions; 2.7 v v in 5.5 v, 0.8 v v out 3.3 v, -25 o c t a 85 o c, c in = c out = 4.7 f, l1 = 4.7 h (see figure 1 ), unless otherwise noted. the ty pical specifications are measur ed at the following conditions; t a = +25 o c, v in = 3.6 v, f sw = 2.0 mhz with the typical operating circuit (see figure 1 ), unless otherwise noted. characteristic symbol min typ max unit supply voltage v in 2.7 - 5.5 v output voltage (factory preset) v out 0.8 - 3.3 v output current i out 300 - - ma total supply current (5) regulator disabled i dis - 0.1 1.0 a quiescent current (switching) sleepy z-mode and i load = 0 ma i q - 65 85 a current limit current rising at high side i pk - 450 - ma output voltage accuracy (% of output voltage) overload and temperature v out -3% - 3% v out uvlo threshold (6) v in : 2.7 -5.5 v v in rising v in falling v uvlo - 2.5 - - 2.7 - v enable voltage regulator operating regulator shutdown v en 1.6 - - - - 0.4 v high side power mosfet on resistance v in = 3.6 v, v out = 1.8 v, t a = 40c , i load = 150 ma r ds(on)h - 250 - m low side power mosfet on resistance v in = 3.6 v, v out = 1.8 v, t a = 40c , i load = 150 ma r ds(on)l - 350 - m load regulation 1.0 ma < i load < 300 ma and v out = 1.8 v v out / i out - 0.5 - % line regulation v in = 2.7 to 5.5 v v out / v in - 0.5 - % start-up overshoot (% of output voltage) i load = 0 ma, v out = 1.8 v and c out = 4.7 f v sto - 3% - v out thermal shutdown threshold (junction temperature) t stdn - 140 - c thermal shutdown hysteres is (junction temperature) t hystr - 10 - c notes 5. maximum i dis measured at v in = 3.6 v and t a = 25c. 6. for a product with a v out of 3.3 v and a v in minimum less than 3.6 v, the v out value will track (drop below 3.3 v) v in down to a value of 2.5 v, where the uvlo shutdown mechanism will activate.
analog integrated circuit device data freescale semiconductor 7 34726 electrical characteristics dynamic electrical characteristics dynamic electrical characteristics table 5. dynamic electri cal cha racteristics characteristics noted under conditions; 2.7 v v in 5.5 v, 0.8 v v out 3.3 v, -20 o c t a 85 o c, c in = c out = 4.7 f, l1 = 4.7 h (see figure 1 ), unless otherwise noted. the ty pical specifications are measur ed at the following conditions; t a = +25 o c, v in = 3.6 v, f sw = 2.0 mhz with the typical operating circuit (see figure 1 ), unless otherwise noted. characteristic symbol min typ max unit switching frequency (7) f sw 1.8 2.0 2.2 mhz maximum duty cycle (8) measured from sw pin d max 95 - 100 % internal soft-start timer v out rise time t s - 2.0 - ms notes 7. f sw can be factory programmed to 20% of nominal 2.0 mhz. 8. the maximum duty limits the range of output voltages achievable for a g iven input voltage.
analog integrated circuit device data 8 freescale semiconductor 34726 electrical characteristics electrical performance curves electrical per formance curves 0.1 1 10 100 1000 0 20 40 60 80 100 efficiency (%) i load (ma) v in =2.7v v in =3.6v v in =5.5v figure 4. efficiency vs. load current v in = 3.6 v, v out = 1.8 v, t a =25 o c 2.5 3.0 3.5 4.0 4.5 5.0 5.5 -0.25 0.00 0.25 0.50 0.75 1.00 line regulation (%) v in (v) i load =0ma i load =100ma i load =300ma figure 5. line regulation v in is 2.7 v to 5.5 v and v out is 1.8 v, t a =25 o c 0 50 100 150 200 250 300 -0.25 0.00 0.25 0.50 0.75 load regulation (%) i load (ma) v in =2.7v v in =3.6v v in =5.5v figure 6. load regulation 1. 0 ma < i load < 300 ma, v out = 1.8 v v en (10 v/div) v out (200 mv/div) i l (200 ma/div) time: 500 s/div figure 7. start-up response i load = 0 ma, v out =1.2 v v out (1.0 v/div) v sw (2.0 v/div) i l (200 ma/div) time: 100 s/div figure 8. sleepy z-mode tm switching waveforms v in = 3.6 v, v out = 1.8 v and i load = 1.0 ma v out (1.0 v/div) v sw (2.0 v/div) i l (200 ma/div) time: 5.0 s/div figure 9. z-mode tm switching waveforms v in = 3.6 v, v out = 1.8 v and i load = 10 ma
v out (1.0 v/div) v sw (2.0 v/div) i l (200 ma/div) time: 500 ns/div analog integrated circuit device data freescale semiconductor 9 34726 electrical characteristics electrical performance curves figure 10. ccm switching waveforms v in = 3.6 v, v out = 1.8 v and i load = 150 ma v out (ac coupled, 500 mv/div) v sw (2.0 v/div) i load (100 ma/div) time: 200 s/div figure 11. load transient in sleepy z-mode tm v in = 3.6 v, i load =1.0 to 150 ma v out (ac coupled, 200 mv/div) v sw (2.0 v/div) i load (200 ma/div) time: 200 s/div figure 12. load transient in z-mode tm v in = 3.6 v, i load =10 to 300 ma v out (ac coupled, 50 mv/div) v sw (2.0 v/div) i load (100 ma/div) time: 200 s/div figure 13. load transient in ccm v in = 3.6 v, i load = 150 to 300 ma
analog integrated circuit device data 10 freescale semiconductor 34726 functional description introduction functional description introduction the 34726 is a high efficiency, synchronous, buck regulator, utilizing a voltage mode control architecture with feed forward. it is capable of providing a 300 ma load current for output voltages of 0.8 to 3.3 v, from a single input voltage rail between 2.7 and 5.5 v. in a buck converter, most of the losses at high output loads are due to conduction losses in the power train, but at light output loads, the conduction loss es are reduced and most of the losses become switching losses. using freescale?s z- mode architecture, the 34726, at light output loads, will smoothly transition into a lower switching frequency, thus improving its efficiency. functional pin description supply voltage input (vin) 2.7 to 5.5 v dc power input. bypass with a 4.7 p f ceramic capacitor as close as possible to the vin and gnd pins. ground (gnd) ground. enable (en) active high enable input. en is over-voltage protected to 6.0 v, independent of the supply voltage. drive with a logic high signal (or connect to vin) for normal operation. drive with a logic low signal, or connect to gnd will disable the 34726. feedback input (fb) feedback of the output voltage. switching node (sw) this terminal connects to the output inductor. the node internally connects the drain of both high side mosfet and low side mosfet. no connection (nc) internally not connected. connect to gnd externally.
analog integrated circuit device data freescale semiconductor 11 34726 functional description functional internal block description functional internal block description MC34726 - functional block diagram integrated supply oscillator mosfet control integrated supply internal regulator & reference control oscillator power mosfet driver undervoltage lockout power mosfet thermal shutdown soft start current limit figure 14. 34726 functional internal block diagram integrated supply internal regulator and reference the internal regulator and reference block steps down the high input voltage to lower voltage to power all the internal blocks, and provides the refe rence voltage for the other internal blocks. oscillator the oscillator block provides 2.0 mhz clock signal to the controll er. controller thermal shutdown the thermal shutdown block monitors the die temperature. once the die temperature reaches its threshold, this block turns off the device to prevent the further die temperature rise. soft-start the soft-start block controls the output voltage ramp after the device is enabled, to limit the in-rush current. the start-up time is internally set to approximately 2.0 ms, and is in dependent of input voltage, ou tput voltage, or load current. the soft-start sequence also occurs upon recovery from any fault condition. uvlo the uvlo block monitors the input voltage. once the input voltage is lower than the falling threshold voltage, this block turns off the device, to avoid unpredictable circuit behavior. current limit the current limit block monitors the inductor current. when the peak inductor current reaches its current limit, this block turns off the high side mosfet, to prevent the device and external components from damage. power-mosfet driver the power-mosfet-driver block controls the phase of the diver signals and enhances the drive capability of these. power-mosfet the power-mosfet block contains two power mosfets. one is a pmos that passes the current from the input to the output, and the ot her one is an nmos that provides the inductor current loop when pmos is turned off.
analog integrated circuit device data 12 freescale semiconductor 34726 functional device operation operational modes functional device operation operational modes z-mode operation the 34726 operates as a typical fixed frequency, pwm regulator, at moderate to heavy load currents. as the load is decreased, such that operation transitions from continuous conduction mode (ccm) to di scontinuous conduction mode (dcm), the duty cycle is reduced until it approaches 85% of the full load duty cycle. at this point the 34726 transitions into z-mode operation, where the z-mode factor is 0.85. in z- mode, the regulator skips puls es whenever the duty cycle is below 85% of the ccm duty cycle. as the load decreases, this pulse skipping reduces the switching frequency and the switching losses thus improving efficiency. for example, if a light load demanded a 30% duty cycle at 2.0 mhz, with z- mode this same load will require only (0.3/0.85) 2 x 2.0 mhz = 0.249 mhz switching frequency, he nce switching losses will be reduced by almost ten fold. figure 15 illustrates the transition to and the exit from z- mode. pwm z factor sw on time pwm_ref. v ramp v zerr figure 15. z-mode operation sleepy z-mode operation to improve low current effici ency, the 34726 transitions into the sleepy z-mode at load currents of approximately 1.0 ma and lower. this is accomplished by powering down in ternal circuit blocks to lower the device?s quiescent current. additionally, the oscillator frequency drops to 250 khz and the low side switch is turned off to emulate the operation of an asynchronous buck converter. detailed functional device operation over-current protection the 34726 implements two la yers of protection during overload conditions. the first is a current limit feature to prevent the device and exter nal components from damage. when the peak inductor current reaches the over-current limit, nominally 450 ma, the high side mosfet turns off to provide cycle by cycle protection. if the over-current condition persists and the die temperature surpasses the over- temperature protection (otp) threshold, this second layer of protection shuts down the device. short-circuit protection when a short-circuit condition occurs on the output, typical regulators will tend to operate at maximum duty cycle. this condition can saturate the inductor and produce severe peak currents, resulting in dam age to the device. the 34726 avoids this scenario by detecting output voltages below 0.5 v. upon detection, the part re-starts continuously until the short circuit condition is removed, or the part surpasses its otp threshold.
analog integrated circuit device data freescale semiconductor 13 34726 functional device operation operational modes over-temperature protection to limit its operating temperat ure, the 34726 shuts down if the junction temperature of the switching mosfet surpasses 140c. if the juncti on temperature subsequently drops to 130c, the 34726 restarts. soft-start operation to limit the in-rush current, an internal timer controls the output voltage ramp after the part is enabled. the start-up time is internally set to approximately 2.0 ms and is independent of input voltage, ou tput voltage, or load current. the soft-start sequence also occurs upon recovery from any fault condition. under-voltage lock-out the uvlo threshold is set to 2.7 v for rising v in , and to 2.5 v for falling v in . for a v out of 3.3 v or 2.5 v, the v out value will track v in below 3.6 v or 2.8 v until the 2.5 v falling v in threshold is reached. if the uvlo falling threshold is met, the part shuts down and will power-up again with soft-start, when the uvlo rising threshold is surpassed.
analog integrated circuit device data 14 freescale semiconductor 34726 typical applications application information typical applications application information input capacitor the input capacitor is used to minimize the input voltage transient that may cause instab ility when the load transient current is high. typically a 4.7 f x5r ceram ic capacitor is sufficient for most applications. output capacitor for stable operation and low output voltage ripple, an x5r ceramic capacitor of 4.7 f mini mum value is needed. depending on the load transient current, a larger capacitance may be required. inductor selection a 4.7 h low dc resistance inductor is typically used for the 34726 to guarantee the system stable operation. typical applications 1.2 v output dc/dc convertor figure 16 shows a typical application using 34726a. cin and cout are typically 4.7 f/x5r cera mic capacitors. l1 is typically a 4.7 h lo w dc resistance inductor. the fb connects to the output direct ly for monitoring the output voltage. normally, the en pin connects to the input supply directly to enable the regulator. vin en sw fb gnd on off 2.7 ~ 5.5 v 1.2 v 300 ma 34726a c in 4.7 f 4.7 h c out 4.7 f l1 figure 16. 1.2 v/300 ma dc/dc convertor
analog integrated circuit device data freescale semiconductor 15 34726 typical applications package dimensions package dimensions for the most current package revision, visit www.freescale.com and perform a keyword search using the ?98a? listed below. fc suffix 12-pin 98asa10787d revision a
fc suffix 12-pin 98asa10787d revision a analog integrated circuit device data 16 freescale semiconductor 34726 typical applications package dimensions
fc suffix 12-pin 98asa10787d revision a analog integrated circuit device data freescale semiconductor 17 34726 typical applications package dimensions
analog integrated circuit device data 18 freescale semiconductor 34726 revision history revision history revision date description of changes 1.0 5/2008 2.0 9/2009 ? initial release ? minor adjustments to the ordering information and device variations ? updated to match the current freescale format and style.
how to reach us: home page: www.freescale.com web support: http://www.freescale.com/support usa/europe or locations not listed: freescale semiconductor, inc. technical information center, el516 2100 east elliot road tempe, arizona 85284 1-800-521-6274 or +1-480-768-2130 www.freescale.com/support europe, middle east, and africa: freescale halbleiter deutschland gmbh technical information center schatzbogen 7 81829 muenchen, germany +44 1296 380 456 (english) +46 8 52200080 (english) +49 89 92103 559 (german) +33 1 69 35 48 48 (french) www.freescale.com/support japan: freescale semiconductor japan ltd. headquarters arco tower 15f 1-8-1, shimo-meguro, meguro-ku, tokyo 153-0064 japan 0120 191014 or +81 3 5437 9125 support.japan@freescale.com asia/pacific: freescale semiconductor china ltd. exchange building 23f no. 118 jianguo road chaoyang district beijing 100022 china +86 10 5879 8000 support.asia@freescale.com for literature requests only: freescale semiconductor literature distribution center p.o. box 5405 denver, colorado 80217 1-800-441-2447 or +1-303-675-2140 fax: +1-303-675-2150 ldcforfreescalesemiconductor@hibbertgroup.com freescale? and the freescale logo are trademarks of freescale semiconductor, inc. all other product or service names are the property of their respective owners. ? freescale semiconductor, inc. 2010. all rights reserved. MC34726 rev. 2.0 9/2010 information in this document is provided solely to enable system and software implementers to use freescale semiconductor products. there are no express or implied copyright licenses granted hereunder to design or fabricate any integrated circuits or integrated circuits based on the information in this document. freescale semiconductor reserves the right to make changes without further notice to any products herein. freescale semiconductor makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does freescale semiconductor assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. ?typical? parameters that may be provided in freescale semiconductor data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. all operating parameters, including ?typicals?, must be validated for each customer application by customer?s technical ex perts. freescale semiconductor does not convey any license under its patent rights nor the rights of others. freescale semiconductor products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other applications intended to support or sustain life, or for any other application in which the failure of the freescale semiconductor product could create a situation where personal injury or death may occur. should buyer purchase or use freescale semiconductor products for any such unintended or unauthorized application, buyer shall indemnify and hold freescale semiconductor and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that freescale semiconductor was negligent regarding the design or manufacture of the part.

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