1/4 rev. a structure silicon monolithic in tegrated circuit product name boost dcdc converter for tv tuner type b8924g package outline fig. 1 block diagram fig. 2 features 1) for varactor volta ge in the tv tuner. 2) over current protection circuit 3) ssop-5 small size this chip is not designed to prot ect itself against radioactive rays. absolute maximum ratingsta=25 parameter symbol ratings unit condition maximum applied voltage1 vmax1 7.0 v it applies to vin terminal maximum applied voltage 2 vmax2 36 v it applies to sw, vout ter minals power dissipation pd1 674.9 (note1) mw at single unit operating temperature range topr -30 +85 o c storage temperature range tstr -55 +150 o c (note1) pd derated at 5.4mw/ for temperature above ta=25, mounted on 70mm70mm1.6mm glass-epoxy pcb. operation conditionta=25 parameter symbol ratings unit condition power supply voltage range vcc 4.55.5 v vin terminal voltage
2/4 rev. a fig. 1 package outline pin assigns no. pin name i/o function 1 sw i inductor connection terminal 2 gnd - gnd 3 vout o boost voltage output 4 gnd - gnd 5 vin - power supply input fig. 2 block diagram 0 d lot no. fig. 1 package outline + + - osc control + - s qr sw gnd pwm comp. erramp vout vin current sense q1 open protect
3/4 rev. a vin vout gnd sw a vin c1 10f c2 1f sbd l1 47h icc c3 0.1f r1 1k to tuner vin vout gnd sw a vin c1 10f c2 1f sbd l1 68h icc c3 0.1f r1 1k to tuner c4 15f + (a) iomax Q 2.0ma (b) 2ma < iomax Q 4.0ma fig. 3 recommended circuit electrical characteristic (unless otherwise specified ta=25vi n=5v) parameter symbol min. ty p. max. unit condition circuit current icc - 1.0 2.0 ma vout=35v force oscillation frequency f sw 250 400 600 khz output voltage range vomax 30.0 31.0 32.0 v io=0ma maximum output current1 iomax1 2.0 - - ma l1=47uh, c2=1uf maximum output current2 iomax2 4.0 - - ma l1=68uh, c2=1uf, c4R15 uf oscillation beginning power-supply voltage vst 4.2 - - v vin terminal voltage the oscillation is confirmed with sw pin. please use rc-lpf of r1 and c3 if you need to cut the noise. we do not guarantee the operatio n of circuit if you use lc filt er. about recommended parts, please see the technical-note. bd8924 bd8924
4/4 rev. a caution on use 1absolute maximum ratings an excess in the absolute maximum rating, such as supply voltag e, temperature range of operating conditions, etc., can break d own devices, thus making impossible to identify breaking mode such as a shor t circuit or an open circuit. if any special mode exceeding the absolute maximum ratings is assumed, consideration should be given to ta ke physical safety measures including the use of fuses, etc. 2the power supply and the gnd lines design pcb pattern to provide low impedance for the wiring betw een the power supply and the gnd lines. please take care about interference by common impedance of the wiring pattern when there are two or mo re power supply and gnd line. for the gnd line, please note the separation of the large current route and the small signal rout e including the external circuit. furthermore, for all power su pply terminals to ics, mount a capacitor between the power supply and the gnd terminal . at the same time, in order to use an electrolytic capacitor, thoroughly check to be sure the characteristics of the capacitor to be used present no problem including the occurrence of capacity dropout at a low temperature, thus determining the constant. 3gnd voltage make setting of the potential of the gnd terminal so that it wi ll be maintained at the minimum in any operating state. 4short circuit between terminals and erroneous mounting in order to mount ics on a set pcb, pay thorough attention to t he direction and offset of the ics. erroneous mounting can brea k down the ics. furthermore, if a short circuit occurs due to foreign matters e ntering between terminals or between the terminal and the power supply or the gnd terminal, the ics can break down. 5operation in strong electromagnetic field be noted that using ics in the strong electromagnetic field can malfunction them. 6input terminals in terms of the construction of ic, parasitic elements are inev itably formed in relation to potential. the operation of the pa rasitic element can cause interference with circuit operation, thus resulting in a malfunction and then breakdown of the input terminal. therefore, pay thorough attention not to handle the input terminals, such as to apply to the input termi nals a voltage lower than the gnd respectively, so that any par asitic element will operate. furthermore, do not apply a voltage to the input terminals when no power supply volt age is applied to the ic. in addi tion, even if the power supply voltage is applied, apply to the input terminals a volta ge lower than the power supply voltage or within the guaranteed value of electrical characteristics. 7external capacitor in order to use a ceramic capacitor as the external capacitor, determine the constant with consideration given to a degradatio n in the nominal capacitance due to dc bias and changes in the capacitan ce due to temperature, etc. 8thermal design perform thermal design in which there are adequate margins by t aking into account the permissible dissipation (pd) in actual s tates of use. moreover, please use it within the range where output tr doesn' t exceed the rated voltage and aso. 9rush current in cmos ic, when the power supply is turned on rush current mig ht flow momentarily in logical internal irregular state. theref ore, note drawing the capacity of the power supply coupling, the power supply, an d width and drawin g the gnd pattern w iring, please. 10test terminal and unused terminal processing please process a test terminal and unused terminal according to explanations of the function manual and the application note, etc. to be unquestionable while real used. moreover, please inquire of the person in charge of our company about the terminal without the explanation especially. 11content of material the application notes etc. are the design material to design the application, and no one of the content securing it. please de cide the application after it examines enough and it evaluates it includ ing external parts.
r1010 a www.rohm.com ? 2010 rohm co., ltd. all rights reserved. notice rohm customer support system http://www.rohm.com/contact/ thank you for your accessing to rohm product informations. more detail product informations and catalogs are available, please contact us. notes no copying or reproduction of this document, in part or in whole, is permitted without the consent of rohm co.,ltd. the content specied herein is subject to change for improvement without notice. the content specied herein is for the purpose of introducing rohm's products (hereinafter "products"). if you wish to use any such product, please be sure to refer to the specications, which can be obtained from rohm upon request. examples of application circuits, circuit constants and any other information contained herein illustrate the standard usage and operations of the products. the peripheral conditions must be taken into account when designing circuits for mass production. great care was taken in ensuring the accuracy of the information specied in this document. however, should you incur any damage arising from any inaccuracy or misprint of such information, rohm shall bear no responsibility for such damage. the technical information specied herein is intended only to show the typical functions of and examples of application circuits for the products. rohm does not grant you, explicitly or implicitly, any license to use or exercise intellectual property or other rights held by rohm and other parties. rohm shall bear no responsibility whatsoever for any dispute arising from the use of such technical information. the products specied in this document are intended to be used with general-use electronic equipment or devices (such as audio visual equipment, ofce-automation equipment, commu- nication devices, electronic appliances and amusement devices). the products specied in this document are not designed to be radiation tolerant. while rohm always makes efforts to enhance the quality and reliability of its products, a product may fail or malfunction for a variety of reasons. please be sure to implement in your equipment using the products safety measures to guard against the possibility of physical injury, re or any other damage caused in the event of the failure of any product, such as derating, redunda ncy, re control and fail-safe designs. rohm shall bear no responsibility whatsoever for your use of any product outside of the prescribed scope or not in accordance with the instruction manual. the products are not designed or manufactured to be used with any equipment, device or system which requires an extremely high level of reliability the failure or malfunction of which may result in a direct threat to human life or create a risk of human injury (such as a medical instrument, transportation equipment, aerospac e machinery, nuclear-reactor controller, fuel- controller or other safety device). rohm shall bear no responsibility in any way for use of any of the products for the above special purposes. if a product is intended to be used for any such special purpose, please contact a rohm sales representative before purchasing. if you intend to export or ship overseas any product or technology specied herein that may be controlled under the foreign exchange and the foreign trade law, you will be required to obtain a license or permit under the law.
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