1/4 ● Structure ● Product name Silicon monolithic integrated circuit Boost DCDC converter for TV tuner ● Type BＤ8924G ● Package outline ● Block Diagram Fig. 1 Fig. 2 ● Features 1) For varactor voltage in the TV tuner. 2) Over current Protection circuit 3) SSOP-5 small size ◎ This chip is not designed to protect itself against radioactive rays. Absolute maximum ratings（Ta=25℃） Symbol Ratings Unit Maximum applied voltage1 Parameter Vmax1 7.0 V It applies to VIN terminal Maximum applied voltage 2 Vmax2 36 V It applies to SW, VOUT terminals Power dissipation Pd1 674.9 (Note1) Operating temperature range Topr -30 ～ +85 o C -55 ～ +150 o C Storage temperature range Tstr Condition mW At single unit (Note1) Pd derated at 5.4mW/℃ for temperature above Ta=25℃, mounted on 70mm×70mm×1.6mm glass-epoxy PCB. Operation condition（Ta=25℃） Parameter Power supply voltage range Symbol Ratings Unit VCC 4.5～5.5 V REV. A Condition VIN terminal voltage D 0 2/4 LOT NO. Fig. 1 Package outline Fig. 1 Package Outline Pin assigns NO. 1 2 3 4 5 Pin Name SW GND VOUT GND VIN I/O I O - Function Inductor connection terminal GND Boost voltage output GND Power supply input VIN SW VOUT OPEN PROTECT S Q1 Q R PWM comp. Control + + Current Sense + OSC GND Fig. 2 Block Diagram REV. A ERRAMP 3/4 (a) Iomax ≦ 2.0mA L1 47μH R1 1kΩ SBD to tuner A ICC VIN VIN SW BD8924 C1 10μF GND C3 0.1μF C2 1μF VOUT (b) 2mA < Iomax ≦ 4.0mA L1 68μH R1 1kΩ SBD to tuner ICC A VIN VIN C1 10μF SW BD8924 GND C2 1μF C4 15μF + C3 0.1μF VOUT Please use RC-LPF of R1 and C3 if you need to cut the noise. We do not guarantee the operation of circuit if you use LC filter. About recommended parts, please see the technical-note. Fig. 3 Recommended Circuit Electrical characteristic (Unless otherwise specified Ta=25℃、VIN=5V) Parameter Circuit current Oscillation frequency Output voltage range Maximum output current1 Maximum output current2 Oscillation beginning power-supply voltage Symbol Min. Typ. Max. Unit ICC fsw Vomax Iomax1 Iomax2 250 30.0 2.0 4.0 1.0 400 31.0 - 2.0 600 32.0 - mA kHz V mA mA Vst 4.2 - - V REV. A Condition VOUT=35V force Io=0mA L1=47uH, C2=1uF L1=68uH, C2=1uF, C4≧15uF VIN terminal voltage The oscillation is confirmed with SW pin. 4/4 Caution on use （1）Absolute Maximum Ratings An excess in the absolute maximum rating, such as supply voltage, temperature range of operating conditions, etc., can break down devices, thus making impossible to identify breaking mode such as a short circuit or an open circuit. If any special mode exceeding the absolute maximum ratings is assumed, consideration should be given to take physical safety measures including the use of fuses, etc. （2）The power supply and the GND lines Design PCB pattern to provide low impedance for the wiring between the power supply and the GND lines. Please take care about interference by common impedance of the wiring pattern when there are two or more power supply and GND line. For the GND line, please note the separation of the large current route and the small signal route including the external circuit. Furthermore, for all power supply 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. （3）GND voltage Make setting of the potential of the GND terminal so that it will be maintained at the minimum in any operating state. （4）Short circuit between terminals and erroneous mounting In order to mount ICs on a set PCB, pay thorough attention to the direction and offset of the ICs. Erroneous mounting can break down the ICs. Furthermore, if a short circuit occurs due to foreign matters entering between terminals or between the terminal and the power supply or the GND terminal, the ICs can break down. （5）Operation in strong electromagnetic field Be noted that using ICs in the strong electromagnetic field can malfunction them. （6）Input terminals In terms of the construction of IC, parasitic elements are inevitably formed in relation to potential. The operation of the parasitic 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 terminals a voltage lower than the GND respectively, so that any parasitic element will operate. Furthermore, do not apply a voltage to the input terminals when no power supply voltage is applied to the IC. In addition, even if the power supply voltage is applied, apply to the input terminals a voltage lower than the power supply voltage or within the guaranteed value of electrical characteristics. （7）External capacitor In order to use a ceramic capacitor as the external capacitor, determine the constant with consideration given to a degradation in the nominal capacitance due to DC bias and changes in the capacitance due to temperature, etc. （8）Thermal design Perform thermal design in which there are adequate margins by taking into account the permissible dissipation (Pd) in actual states of use. Moreover, please use it within the range where output Tr doesn't exceed the rated voltage and ASO. （9）Rush current In CMOS IC, when the power supply is turned on rush current might flow momentarily in logical internal irregular state. Therefore, note drawing the capacity of the power supply coupling, the power supply, and width and drawing the GND pattern wiring, please. （10）Test 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. （11）Content of material The application notes etc. are the design material to design the application, and no one of the content securing it. Please decide the application after it examines enough and it evaluates it including external parts. REV. A Notice Notes No copying or reproduction of this document, in part or in whole, is permitted without the consent of ROHM Co.,Ltd. The content specified herein is subject to change for improvement without notice. The content specified 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 specifications, 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 specified 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 specified herein is intended only to show the typical functions of and examples of application circuits for the Products. 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