Single-chip Type with Built-in FET type Switching Regulators Flexible Step-down Switching Regulator with Built-in Power MOSFET BD8646FV No.10027EAT44 ●Description The BD8646FV is a synchronous step-down switching regulator that integrates 2 low resistances N-channel MOSFETs. It achieves 2A continuous output current over a wide input supply range. Current mode operation provides fast transient response and easy phase compensation. ●Feature 1) Synchronous rectification with built-in FET type DC/DC converter 2) 2.0A output current 3) Range of operation power-supply voltage 4.5V～18V 4) Reference voltage FB 0.8V±1% 5) Programmable frequency 100kHz～600kHz 6) Over current protection function 7) Thermal shutdown function 8) Under voltage protection 9) Soft start time out function / Soft start delay circuit 10) Programmable OFFLATCH time ●Applications FPD,DVD,HDD Recorder,STB,Amusement,Other ●Absolute maximum rating (Ta=25℃) Parameter Input supply voltage Symbol Ratings Unit VIN 20 V VBOOT 28 V EN terminal voltage VEN GND-0.3 ～ VIN+0.3 V Input terminal voltage VINP GND-0.3 ～ 7 V SW terminal voltage VSW GND-0.3 ～ VIN+0.3 V Output current IOUT 2.5 A Power dissipation Pd 1.19*2 W BOOT terminal voltage *1 Operating temperature Topr -20 ～ 85 ℃ Storage temperature Tstg -55 ～ 150 ℃ *1 VINP Application terminal: SS/DELAY, FB, FC, RT, PSET *2 (70mm×70mm, thickness 1.6mm, and four layer glass epoxy substrates)When mounting substrate and the package back exposure part are connected with solder Operating at higher than Ta=25℃, 9.5mW shall be reduced per 1 ●Operating conditions Parameter Symbol Ratings Min. Typ. Max. Unit Input supply voltage VIN 4.5 - 18.0 V Output current IOUT - - 2.0 A * This product is not designed for protection against radioactive rays. www.rohm.com © 2010 ROHM Co., Ltd. All rights reserved. 1/13 2010.09 - Rev.A Technical Note BD8646FV ●Electrical characteristic (Unless otherwise noted Ta=25℃, VIN=12V, VEN = 3V) Parameter Symbol Limits Min. Typ. Max. UNIT Condition VIN supply current (operating) IQ_active - 1.5 2.5 mA VFB = 0.75V VIN supply current (standby) IQ_stby - 0.8 1.2 mA VEN = 0V Reference voltage (VREF) VFB 0.792 0.800 0.808 V Oscillation frequency fOSC 270 300 330 kHz RRT= 56kΩ High side FET ON resistance RHFET - 120 170 mΩ ISW = -1A Low side FET ON resistance RLFET - 120 170 mΩ ISW = 1A UVLO voltage VUVLO 3.8 4.0 4.2 V VIN Sweep SW leak current ILSW - 0 5 μA VEN= 0V EN terminal H threshold voltage VENH 1.6 - - V EN terminal L threshold voltage VENL - - 0.4 V SS/DELAY terminal source current ISSSO 2.8 4.0 5.2 μA VSS= 1V SS/DELAY – FB Offset voltage VSSFBOST 450 600 750 mV VSS= 1V PSET terminal source current IPSET 3.0 5.0 7.0 μA VPSET= 2V PSET terminal threshold voltage VPSET 0.8 1.0 1.2 V ● ● FB-FC Short VFB :FB terminal voltage,VEN :EN terminal voltage,VSS :SS/DELAY terminal voltage, VPSET :PSET terminal voltage, RRT :RT resistor Current capability should not exceed Pd. www.rohm.com © 2010 ROHM Co., Ltd. All rights reserved. 2/13 2010.09 - Rev.A Technical Note BD8646FV ●Reference data 0.820 0.810 0.815 VIN=12V VFB and FC [V] VFBとFC[V] 0.810 Ta=25℃ 0.805 VFBとFC[V] VFB and FC [V] 0.805 0.800 0.795 0.800 0.790 0.795 0.785 0.780 0.790 -20 -5 10 25 40 55 70 85 4 6 8 10 12 Ta [℃] Fig.1 Reference voltage – temperature characteristic 330 VIN=12V Ta=25℃ 320 310 fsw[kHz] fsw[kHz] 320 300 290 310 300 290 280 280 270 270 260 260 -20 -5 10 25 40 55 70 85 4 6 8 10 Ta [℃] 5.0 4.8 4.6 4.4 4.2 4.0 3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 12 14 16 18 VIN[V] Fig.3 Frequency – temperature characteristic Fig.4 Frequency – VIN characteristic 5.0 4.5 VIN=12V 4.0 Ta=25℃ 3.5 ICC[mA] ISS[μA] 18 340 330 3.0 2.5 2.0 1.5 1.0 0.5 0.0 -20 -5 10 25 40 55 70 85 4 6 8 10 Ta [℃] 12 14 16 18 VIN[V] Fig.5 SS/DELAY charge current - temperature characteristic Fig.6 Circuit Current – VIN characteristic 320 320 280 280 VIN=12V VIN=12V 240 SW_PGND[mΩ] 240 VIN_SW[mΩ] 16 Fig.2 Reference voltage – VIN characteristic 340 200 160 120 200 160 120 80 80 40 40 0 0 -20 -5 10 25 40 55 70 85 -20 Ta [℃] 10 25 40 55 70 85 Fig.8 Low side FET ON_R - temperature characteristic 320 320 280 280 240 -5 Ta [℃] Fig.7 Hi side FET ON_R - temperature characteristic 240 Ta=25℃ SW_PGND[mΩ] VIN_SW[mΩ] 14 VIN[V] 200 160 120 160 120 80 80 40 40 0 Ta=25℃ 200 0 4 6 8 10 12 14 16 18 4 VIN[V] www.rohm.com 8 10 12 14 16 18 VIN[V] Fig.9 Hi side FET ON_R - VIN characteristic © 2010 ROHM Co., Ltd. All rights reserved. 6 Fig.10 Low side FET ON_R – VIN characteristic 3/13 2010.09 - Rev.A Technical Note BD8646FV ●Block diagram FB 11 GND 10 FC 12 RT 13 PSET 14 EN 15 SS Softstart/Delay 9 NC OSC 8 CURRENT DET Protect time 5V BOOT 7 SW EN 6 PWM CONTROL NC 16 SW 5 NC 17 4 VIN 18 3 VIN 19 2 VIN 20 1 VOUT SW PGND PGND PGND Fig.11 Block diagram ●Pin assignment No. Symbol Description No. Symbol Description 1 PGND Power GND terminal 11 FB Feedback terminal 2 PGND Power GND terminal 12 FC Phase amends terminal 3 PGND 13 RT Frequency adjustment resistance connection terminal Power GND terminal 4 SW Switching output terminal 14 PSET 5 SW Switching output terminal 15 EN 6 SW Switching output terminal 16 NC - 7 BOOT Boot strap terminal 17 NC - 8 NC 9 SS/DELAY 10 GND - Adjust OFF LATCH time terminal Enable input 18 VIN Power supply input terminal Soft start adjustment capacity connection terminal 19 VIN Power supply input terminal Signal GND terminal 20 VIN Power supply input terminal ●Package outline dimension Product number BD8646 1PIN MARK Lot No. SSOP-B20W (Unit: mm) www.rohm.com © 2010 ROHM Co., Ltd. All rights reserved. 4/13 2010.09 - Rev.A Technical Note BD8646FV ●Operation description 1 Enable control The device can be controlled ON/OFF by EN terminal (15 pin) voltage. An internal circuit starts when VEN reaches 1.4V. When standing up of VIN is too steep (1msec or less), a defective start might be caused according to the state of Pascon between GND substrate pattern and power supply-when the terminal EN is short-circuited to the terminal VIN and it is used. VEN EN terminal VENH VENL 0 VSS VSSCLM SS terminal VSSTH 0 VO Output setting voltage 0 tSS Fig.12 ON/OFF transition wave form in EN controlling 2 Soft start time set function As for BD8646FV, output can do soft start without overshoot by charging soft start capacity (CSS) connected between SS/DELAY (9 pin) and GND (10 pin) terminal. Also, soft start time (tss) can be set by setting soft start capacity (CSS) arbitrarily. (Refer to 5-2 soft start time setting method) 3 OSC oscillation frequency setting function The output oscillation frequency can be set by connecting resistance between terminal RT (13 pin) and GND (range = 100kHz – 600kHz) The relation between RT terminal resistance and the oscillation frequency follows Fig.13. 10000 SW[kH z] 1000 100 10 1 10 100 1000 RT[kΩ] Fig.13 Oscillation frequency setting by RT resistance www.rohm.com © 2010 ROHM Co., Ltd. All rights reserved. 5/13 2010.09 - Rev.A Technical Note BD8646FV ●Protection function Protection circuit is effective for destruction prevention due to accident so that avoid using under continuous protection operation. 1 Low voltage protection function (LVP) The voltage of the terminal FB (11pin) is compared with internal reference voltage VREF. If FB terminal voltage falls below VLVP(= VREF -120mV) and the state continues, output changes to low voltage and the state is fixed. Table 1 output low voltage protection function EN terminal SS terminal >1.4V(typ) >VENH FB terminal ＜VLVP ＞VLVP Low voltage Protection function Low voltage Protection operation ON Effective OFF <1.4V(typ) - Invalidity OFF - - Invalidity OFF <VENL ※Low voltage protection function is available when SS terminal voltage becomes more than 1.4V (typ) in the transition to ON control (during soft start). 2 Over voltage protection function (OVP) The voltage of the terminal FB is compared with internal reference voltage VREF. If FB terminal voltage is over Vovp (=VREF +120mV) and the state is continues, output changes to low voltage and the state is fixed. Table 2 output low voltage protection function EN terminal SS terminal >1.4V(typ) >VENH FB terminal ＞VOVP ＜VOVP Low voltage Protection function Low voltage Protection operation ON Effective OFF <1.4V(typ) - Invalidity OFF - - Invalidity OFF <VENL ※Over voltage protection function is available when SS terminal voltage becomes more than 1.4V (typ) in the transition to ON control (during soft start). VFB VREF＋120ｍV FB terminal voltage VREF VREF-120ｍV 0 ON Protection OFF LVP OVP LVP Fig.14 Output voltage error detection range www.rohm.com © 2010 ROHM Co., Ltd. All rights reserved. 6/13 2010.09 - Rev.A Technical Note BD8646FV 3 Under voltage lock out protection (UVLO) As for BD8646FV, the power-supply voltage decrease detection protection circuit is built in. It the input voltage decrease below the UVLO voltage (4.0V typ), the device state changes to the standby mode (Moreover, to prevent the chattering of the output) hysteresis width of 300mV(typ) has been installed in the UVLO cancel voltage. 4 RT terminal open/short protection function (RTO/RTS) RT terminal opening/short protection function prevent the clock from abnormal oscillation. If RT terminal open/short protection function is detected, output voltage changes to low level and is fixed. 5 Soft start time-out function If VSS doesn't exceed VSSTH within 64msec (typ) since a soft start began, BD8646FV controls an off latch. Vo is fixed in a low level. VSSTH SS terminal 0V about 64msec（typ） Fig.15 Soft start time-out 6 Thermal shut down function Thermal shut down circuit (TSD circuit) is built into BD8646FV. When the temperature of the chip exceeds Tjmax=175, the DC/DC converter is fixed in a low voltage. TSD function is aimed to shut down IC from thermal reckless driving under an abnormal state to exceed Tjmax=175. It aims at neither protection nor the guarantee of the set. Therefore, please do not use this function to protect the set. 7 Over current protection function The over current protection function has been achieved by limiting the current that flows on high side MOSFET. The current is controlled in every one cycle of the switching frequency. When an abnormal state continues, the output is fixed in a low level. 8 Error detection (off latch) release method BD8646FV enters the state of an off latch when the protection function operates. To release the off latch state, VIN terminal voltage should be changed to less than UVLO level (=4.0V [typ] ) once time. www.rohm.com © 2010 ROHM Co., Ltd. All rights reserved. 7/13 2010.09 - Rev.A Technical Note BD8646FV ●External parts setting method 1 Output voltage setting method The output voltage can be arbitrarily set by external resistance. (R1 R2) Vo VREF R2 Please select the constant of R1 and R2 by this expression. Please select the current that flows to R1 and R2 to become much smaller than output current. Vo R1 FB R2 VREF=0.8V Fig.16 Output voltage setting circuit 2 Soft start time setting method BD8646FV can soft start without overshoot because of a charge current to the soft start capacitance (CSS). The soft start time can be set by connecting soft start capacity (CSS). When the EN terminal voltage is set VIN_EN or more, the charge to the capacity between SS/DELAY and GND terminal is begun. The output voltage becomes soft start in proportion to a SS/DELAY terminal voltage rising. When the SS/DELAY terminal voltage exceeds VSSTH, the output voltage is fixed in a setting value. Please set soft start time (tss) in 1msec-52.5msec. TVO TW EN( 50μs) VOST( 0.6 V ) CSS (VSSTH VOST ) CSS ISS( 4μA ) ISS( 4μA ) ① ② ③ VENH EN terminal 0V ① TWEN (=50µsec) SS terminal Output setting voltage 0V VSSTH(=1.4V[typ]) VOST(=0.6V[typ]) ② TWENSPEC Min. Typ. Max. 35µsec 50µsec 75µsec ③ 0V TVO Fig.17 Soft start www.rohm.com © 2010 ROHM Co., Ltd. All rights reserved. 8/13 2010.09 - Rev.A Technical Note BD8646FV 3 Selection of inductor (L) Please select the value of the inductor according to the following expressions. L (VIN VOUT ) VOUT [H] ⊿IL VIN f (⊿ IL: Output ripple current , f: Switching frequency) IL ※Please have and select an enough margin so that the current peak should not exceed the ratings current value of the inductor. △IL Fig.18 Current of output ripple 4 Selection of input capacitor (Cin) Please use a low ESR input capacitor which can be used with high voltage and ripple current to prevent a big transition voltage. ※Please put on the input capacitor near side by VIN-PGND. 5 Selection of diode Please have and set the margin enough to the current rating of the diode for the maximum load current. Moreover, please similarly have and set the margin enough to a ratings reverse-voltage for the maximum input voltage. FB FC R1 C1 Fig.19 Phase amends part external circuit chart 6 OFFLATCH time setting method If it continues abnormal state, BD8646FV output become low voltage and state is fixed. In this case, the OFFLATCH time can be set by connecting capacitor between PSET and GND. Please select the value of OFFLATCH time according to the following expression. Please set OFFLATCH time in 200usec～5msec. TTM = CPSET IPSET(5µA typ) [sec]・・・(11) To release the off latch state, EN or VIN terminal voltage should be changed to low level once time. www.rohm.com © 2010 ROHM Co., Ltd. All rights reserved. 9/13 2010.09 - Rev.A Technical Note BD8646FV ●Typical application 【Condition】 VOUT = 1.2V / 2A fosc = 300kHz OFFLATCH time = 500µsec 220p 10k FB 11 GND 10 20k FC 12 SS/DELAY Softstart/Delay 9 2200p 11k 0.033µ RT 13 56k PSET 14 2000p EN 15 NC 16 NC OSC 8 5V CURRENT DET Protect time BOOT 7 SW EN PWM CONTROL 6 0.1µ SW 5 6.8µ VOUT 22µ×2pcs SW NC 17 4 VIN 18 3 VIN 19 2 VIN 20 1 PGND PGND PGND 22µ Fig.20 Typical application www.rohm.com © 2010 ROHM Co., Ltd. All rights reserved. 10/13 2010.09 - Rev.A Technical Note BD8646FV ●I/O equivalence circuit 4, 5 ,6PIN(SW) 7PIN(BOOT) 9PIN(SS/DELAY) VIN VREG5 50kΩ SS/ DELAY SW BOOT 50kΩ 2kΩ SW GND 11PIN(FB) 12PIN(FC) VIN VIN 13PIN(RT) VIN 10kΩ 10kΩ FB VIN FC 5kΩ 50kΩ 1kΩ 400Ω 2k Ω RT 10kΩ SGND SGND SGND GND GND PGND 14PIN(PSET) 15PIN(EN) VIN VIN 50kΩ PSET EN 100kΩ 330kΩ 2kΩ GND GND GND GND 600kΩ GND www.rohm.com © 2010 ROHM Co., Ltd. All rights reserved. 11/13 GND 2010.09 - Rev.A Technical Note BD8646FV ●Note for use 1. About the absolute maximum rating Attention is brushed off enough to the quality control, it is likely to destroy when the absolute maximum rating such as impressed voltages (VCC_IN,DCIN) and ranges (Topr) of the operating temperature as it is exceeded, the mode of breakings of the short or the opening, etc. cannot be specified, and examine it in this IC to give physical measures for safety such as fuses when a special mode that exceeds the absolute maximum rating is assumed. 2. GND pin voltage GND terminal should be connected the lowest voltage, under all conditions. And all terminals except SW should be under GND terminal voltage under all conditions including transient situations. If a terminal exists under GND,it should be inserting a bypass route. 3. Power dissipation If IC is used on condition that the power loss is over the power dissipation, the reliability will become worse by heat up, such as reduced output current capability. Also, be sure to use this IC within a power dissipation range allowing enough of margin. 4. Input supply voltage Input supply pattern layout should be as short as possible. 5. About the short and the miss-installation between terminals Note the direction and the miss-registration of IC enough when you install it in the set substrate. IC might destroy it as well as reversely connecting the power supply connector when installing it by mistake. Moreover, there is fear of destruction when the foreign body enters between terminals, the terminal, the power supply, and grandeur and it is shortcircuited. 6. About operation in strong electromagnetic field In use in strong electromagnetic field, note that there is a possibility of malfunctioning. 7. About the inspection by the set substrate It is likely to suffer stress to IC and discharge electricity every one process when you connect the capacitor with the pin with low impedance when inspecting it in the set substrate. Moreover, detach it after connecting after the power supply is turned off without fail when detaching it to G in the inspection process, inspecting, and turning off the power supply. n addition, be give the earth to the assembly process as a static electricity measures, and careful enough when it transports and you preserve it. 8. About each input terminal This IC is a monolithic IC which has a P+ isolations and P substrate to isolate elements each other. This P layer and an N layer in each element form a PN junction to construct various parasitic elements. For instance, the potential difference operates in resistance as shown in the figure below when resistance and the transistor connect it with the terminal and the playground (GND) >(terminal B) joint of PN operates as a parasitic diode in playground (GND) >(terminal A) transistor (NPN). In addition, the NPN transistor of parasitism works with N layer of the element of the above-mentioned parasitic diode and the neighborhood and others in transistor (NPN). A parasitic element in IC composition is inevitably formed because of the potential relation. A parasitic element can operate, the interference with the circuit operation be caused, it malfunction, and, consequently, it cause destruction. Therefore, do not do the usage that a parasitic element operates as a voltage that is lower than the playground (GND;P substrate) is impressed to the input terminal enough. Moreover, do not impress the voltage to the input terminal when you do not impress the power-supply voltage to IC. Give each input terminal to me the voltage below the power-supply voltage or in the guarantee value of an electric characteristic when you similarly impress the powersupply voltage. Example of IC of simple structure 9. Earth wiring pattern If small signal GND and large current GND exist, disperse their pattern. In addition, for voltage change by pattern wiring impedance and large current not to change voltage of small signal GND, each ground terminal of IC must be connected at the one point on the set circuit board. As for GND of external parts, it is similar to the above-mentioned. 10. About each output terminal We recommend to put Diode for protection purpose in case of output pin connected with large load of impedance or reserve current occurred at initial and output off. 11. Thermal Shut Down Circuit A temperature control is built in the IC to prevent the damage due to overheat. Therefore, the outputs are turned off when the thermal circuit works. 12. Over Output Current Protection SW Output terminal has over current protection circuit of 4A, with prevents IC from being damage by short circuit at over current. However, It is recommend not to use that continuously operates the protection circuit (For instance, always the load that greatly exceeds the output current ability is connected or the output is short-circuited, etc.) in these protection circuits by an effective one to the destruction prevention due to broken accident. www.rohm.com © 2010 ROHM Co., Ltd. All rights reserved. 12/13 2010.09 - Rev.A Technical Note BD8646FV ●Ordering part number B D 8 Part No. 6 4 6 F Part No. V - Package F: SSOP-B20W E 2 Packaging and forming specification E2: Embossed tape and reel SSOP-B20W <Tape and Reel information> 6.5 ± 0.2 Embossed carrier tape Quantity 2000pcs 0.3Min. Direction of feed 1 E2 The direction is the 1pin of product is at the upper left when you hold ( reel on the left hand and you pull out the tape on the right hand ) 10 0.15 ± 0.1 0.11 1.7 ± 0.2 Tape 11 6.1 ± 0.2 8.1 ± 0.3 20 0.1 0.65 0.22 ± 0.1 1pin Reel (Unit : mm) www.rohm.com © 2010 ROHM Co., Ltd. All rights reserved. 13/13 Direction of feed ∗ Order quantity needs to be multiple of the minimum quantity. 2010.09 - 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. 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 specified in this document are intended to be used with general-use electronic equipment or devices (such as audio visual equipment, office-automation equipment, communication devices, electronic appliances and amusement devices). The Products specified 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, fire or any other damage caused in the event of the failure of any Product, such as derating, redundancy, fire 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, aerospace machinery, nuclear-reactor controller, fuelcontroller 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 specified 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. Thank you for your accessing to ROHM product informations. More detail product informations and catalogs are available, please contact us. ROHM Customer Support System http://www.rohm.com/contact/ www.rohm.com © 2010 ROHM Co., Ltd. All rights reserved. R1010A