BD8966FVM_12

4.0V to 5.5V, 0.8A 1ch Synchronous Buck Converter integrated FET BD8966FVM ●General Description ROHM’s high efficiency step-down switching regulator BD8966FVM is a power supply designed to produce a low voltage including 1 volts from 5 /3.3 volts power supply line. Offers high efficiency with synchronous rectifier. Employs a current mode control system to provide faster transient response to sudden change in load. ●Features  Offers fast transient response with current mode PWM control system.  Offers highly efficiency for all load range with synchronous rectifier (Nch/Pch FET)  Incorporates soft-start function.  Incorporates thermal protection and ULVOfunctions.  Incorporates short-current protection circuit with time delay function.  Incorporates shutdown function ●Key Specifications  Input voltage range:  Output voltage range:  Output current:  Switching frequency:  Pch FET ON resistance:  Nch FET ON resistance:  Standby current:  Operating temperature range: ●Package MSOP8 4.0V to 5.5V 1.0V to 2.5V 0.8A(Max.) 1MHz(Typ.) 350μΩ(Typ.) 250μΩ(Typ.) 0μA (Typ.) -25℃ to +85℃ 2.90mm x 4.00mm x 0.83mm ●Applications Power supply for LSI including DSP, Micro computer and ASIC ●Typical Application Circuit VCC Cin EN VOUT ITH L VCC,PVCC SW ESR CO GND,PGND RO VOUT VOUT RITH CITH Fig.1 Typical application circuit ○Product structure：Silicon monolithic integrated circuit ○This product is not designed protection against radioactive rays. www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･14･001 1/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 BD8966FVM ●Pin Configuration (TOP VIEW) Datasheet Fig.2 Pin Configuration ●Pin Description Pin No. 1 2 3 4 5 6 7 8 Pin name ADJ ITH EN GND PGND SW PVCC VCC PIN function Output voltage detect pin GmAmp output pin/Connected phase compensation capacitor Enable pin(Active High) Ground Nch FET source pin Pch/Nch FET drain output pin Pch FET source pin VCC power supply input pin ●Block Diagram VCC EN 3 VREF 8 7 Current Comp. RQ Gm Amp. SLOPE VCC Soft Start OSC Driver Logic 5 PGND 4 GND 1 ADJ 2 ITH S CLK PVCC Current Sense/ Protect + Output 6 SW Input VCC UVLO TSD Fig.3 Block Diagram www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･15･001 2/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 BD8966FVM ●Absolute maximum Ratings Parameter VCC Voltage PVCC Voltage EN Voltage SW,ITH Voltage Power Dissipation 1 Power Dissipation 2 Operating temperature range Storage temperature range Maximum junction temperature *1 *2 *3 Datasheet Symbol VCC PVCC VEN VSW,VITH Pd1 Pd2 Topr Tstg Tjmax Ratings -0.3 to +7 -0.3 to +7 *1 *1 Unit V V V V mW mW ℃ ℃ ℃ -0.3 to +7 -0.3 to +7 387.5 587.4 *2 *3 -25 to +85 -55 to +150 +150 Pd should not be exceeded. Derating in done 3.1mW/℃ for temperatures above Ta=25℃. Derating in done 4.7mW/℃ for temperatures above Ta=25℃, Mounted on 70mm×70mm×1.6mm Glass Epoxy PCB. ●Operating Ratings(Ta=25℃) Parameter VCC Voltage PVCC Voltage EN Voltage SW average output current Output voltage Setting Range *4 Symbol VCC PVCC VEN Isw *4 *4 *4 Limits Min. 4.0 4.0 0 1.0 Typ. 5.0 5.0 Max. 5.5 5.5 VCC 0.8 2.5 Unit V V V A V VOUT Pd should not be exceeded. ●Electrical Characteristics ◎(Ta=25℃, VCC=5V, EN=VCC, R1=20kΩ, R2=10kΩ unless otherwise specified.) Limits Parameter Symbol Min. Typ. Max. Standby current ISTB 0 10 Bias current ICC 250 450 EN Low voltage VENL GND 0.8 EN High voltage VENH 2.0 VCC EN input current IEN 1 10 Oscillation frequency FOSC 0.8 1 1.2 Pch FET ON resistance RONP 350 600 Nch FET ON resistance RONN 250 500 ADJ voltage VADJ 0.78 0.80 0.82 ITH SInk current ITHSI 10 20 ITH Source Current ITHSO 10 20 UVLO threshold voltage VUVLO1 3.20 3.40 3.6 UVLO release voltage VUVLO2 3.25 3.50 3.80 Soft start time TSS 1.5 3 6 Timer latch time TLATCH 0.5 2 3 Unit µA µA V V µA MHz mΩ mΩ V µA µA V V ms ms Conditions EN=GND Standby mode Active mode VEN=5V PVCC=5V PVCC=5V VADJ=H VADJ=L VCC=4→0V VCC=0→4V VADJ=H SCP/TSD operated www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･15･001 3/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 BD8966FVM ●Typical Performance Curves Datasheet Fig.4 Vcc-Vout Fig.5 Ven-Vout Fig.6 Iout-Vout Fig.7 Ta-VOUT www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･15･001 4/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 BD8966FVM Datasheet Fig.8 Efficiency Fig.9 Ta-FOSC Fig.10 Ta-RONN, RONP Fig.11 Ta-VEN www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･15･001 5/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 BD8966FVM Datasheet Fig.12 Ta-ICC Fig.13 Vcc-Fosc Fig.14 Soft start waveform Fig.15 SW waveform www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･15･001 6/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 BD8966FVM Datasheet Fig.16 Transient response Io=100→600mA(10µs) Fig.17 Transient response Io=600→100mA(10µs) www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･15･001 7/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 BD8966FVM Datasheet ●Application Information Operation BD8966FVM is a synchronous rectifying step-down switching regulator that achieves faster transient response by employing current mode PWM control system. ○Synchronous rectifier It does not require the power to be dissipated by a rectifier externally connected to a conventional DC/DC converter IC, and its P.N junction shoot-through protection circuit limits the shoot-through current during operation, by which the power dissipation of the set is reduced. ○Current mode PWM control Synthesizes a PWM control signal with a inductor current feedback loop add ed to the voltage feedback. ・PWM (Pulse Width Modulation) control The oscillation frequency for PWM is 1 MHz. SET signal form OSC turns ON a P -channel MOS FET (while a N-channel MOS FET is turned OFF), and an inductor current IL increases. The current comparator (Current Comp) receives two signals, a current feedback control signal (SENSE: Voltage converted from I L) and a voltage feedback control signal (FB), and issues a RESET signal if both input signals are identical to each other, and turns OFF the P-channel MOS FET (while a N-channel MOS FET is turned ON) for the rest of the fixed period. The PWM control repeats this operation. SENSE Current Comp RESET Level Shift Gm Amp. ITH OSC RQ FB SET S Driver Logic SW Load IL VOUT VOUT Fig.18 Diagram of current mode PW M control Current Comp SET PVCC SENSE FB GND GND GND IL(AVE) RESET SW IL VOUT VOUT(AVE) Fig.19 PWM switching timing chart www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･15･001 8/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 BD8966FVM Datasheet Description of Operation Soft-start function EN terminal shifted to “High” activates a soft -starter to gradually establish the output voltage with the current limited during startup, by which it is possible to prevent an overshoot of output voltage and an inrush current. ・Shutdown function With EN terminal shifted to “Low”, the device turns to Standby Mode, and all the function blocks including reference voltage circuit, internal oscillator and drivers are turned to OFF. Circuit current during standby is 0 μF (Typ.). ・UVLO function Detects whether the input voltage sufficient to secure the output voltage of this IC is supplied. of 300mV (Typ.) is provided to prevent output chattering. Hysteresis 100mV And the hysteresis width VCC EN VOUT Tss Soft start Standby mode Operating mode Standby mode Tss Tss Operating mode Standby mode Operating mode Standby mode UVLO UVLO EN UVLO Fig.20 Soft start, Shutdown, UVLO timing chart ・Short-current protection circuit with time delay function Turns OFF the output to protect the IC from breakdown when the incorporated current limiter is activated continuously for at least 1 ms. The output thus held tuned OFF may be recovered by restarting EN or by re-unlocking UVLO. EN Output OFF latch VOUT Limit IL 1msec Standby mode Standby mode Operating mode Operating mode EN Timer latch EN Fig.21 Short-current protection circuit with time delay timing chart www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･15･001 9/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 BD8966FVM Information on Advantages Advantage 1:Offers fast transient response with current mode control system. Conventional product (Load response IO=0.1A→0.6A) Datasheet BD8966FVM (Load response IO=0.1A→0.6A) VOUT 110mV VOUT 90mV IOUT IOUT Voltage drop due to sudden change in load was reduced . Fig.22 Comparison of transient response Advantage 2: Offers high efficiency with synchronous rectifier 100 EFFICIENCY: η [%] ・For heavier load: Utilizes the synchronous rectifying mode and the low on -resistance MOS FETs incorporated as power transistor. ON resistance of P-channel MOS FET : 350mΩ(Typ.) ON resistance of N-channel MOS FET : 250mΩ(Typ.) 90 【VOUT=1.5V】 80 70 60 50 40 30 20 10 0 1 10 100 1000 OUTPUT CURRENT:IOUT[mA] 10000 VCC=5V Ta=25℃ Fig.23 Advantage 3:・Supplied in smaller package due to small-sized power MOS FET incorporated. ・Output capacitor Co required for current mode control:10μF ceramic capacitor ・Inductance L required for the operating frequency of 1 MHz: 4.7μH inductor Reduces a mounting area required. VCC 15mm Cin CIN DC/DC Convertor Controller RITH CITH RITH L VOUT Co 10mm CITH CO L Fig.24 Example application www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･15･001 10/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 BD8966FVM Switching Regulator Efficiency Efficiency ŋ may be expressed by the equation shown below: η= VOUT×IOUT Vin×Iin ×100[%]= POUT Pin ×100[%]= POUT POUT+PDα ×100[%] Datasheet Efficiency may be improved by reducing the switching regulator power dissipation factors P Dα as follows: Dissipation factors: 2 1) ON resistance dissipation of inductor and FET:PD(I R) 2) Gate charge/discharge dissipation:PD(Gate) 3) Switching dissipation:PD(SW) 4) ESR dissipation of capacitor:PD(ESR) 5) Operating current dissipation of IC:PD(IC) 1)PD(I R)=IOUT ×(RCOIL+RON) (RCOIL[Ω]:DC resistance of inductor, RON[Ω]:ON resistance of FET, IOUT[A]:Output current.) 2)PD(Gate)=Cgs×f×V (Cgs[F]:Gate capacitance of FET, f[Hz]:Switching frequency, V[V]:Gate driving voltage of FET) 3)PD(SW)= Vin ×CRSS×IOUT×f IDRIVE 2 2 2 2 (CRSS[F]:Reverse transfer capacitance of FET, IDRIVE[A]:Peak current of gate.) 4)PD(ESR)=IRMS ×ESR (IRMS[A]:Ripple current of capacitor、ESR[Ω]:Equivalent series resistance.) 5)PD(IC)=Vin×ICC (ICC[A]:Circuit current.) Consideration on Permissible Dissipation and Heat Generation As this IC functions with high efficiency without significant heat generation in most applications, no special consideration is needed on permissible dissipation or heat generation. In case of extreme conditions, however, including lower input voltage, higher output voltage, heavier load, and/or higher temperature, the permissible dissipation and/or heat generation must be carefully considered. For dissipation, only conduction losses due to DC resistance of inductor and ON resistance of FET are considered. Because the conduction losses are considered to play the leading role among other dissipation mentioned above including gate charge/discharge dissipation and switching dissipation. P=IOUT ×(RCOIL+RON) RON=D×RONP+(1-D)RONN D:ON duty (=VOUT/VCC) RCOIL:DC resistance of coil RONP:ON resistance of P-channel MOS FET RONN:ON resistance of N-channel MOS FET IOUT:Output current If VCC=5V, VOUT=1.5V, RCOIL=0.15Ω, RONP=0.35Ω, RONN=0.25Ω IOUT=0.8A, for example, D=VOUT/VCC=1.5/5=0.3 RON=0.3×0.35+(1-0.3)×0.25 =0.105+0.175 =0.28[Ω] P =0.8 ×(0.15+0.28) ≒275.2[mW] 2 2 1000 ①using an IC alone θj-a=322.6℃/W Power dissipation:Pd [mW] 800 ①587.4mW ②mounted on glass epoxy PCB θj-a=212.8℃/W 600 400 ②387.5mW 200 0 0 25 50 75 85 100 125 150 Fig. 25 As RONP is greater than RONN in this IC, the dissipation increases as the ON duty b ecomes greater. With the consideration on the dissipation as above, thermal design must be carried out with sufficient margin allowed. www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･15･001 11/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 BD8966FVM Selection of Components Externally Connected 1. Selection of inductor (L) IL ΔIL VCC Datasheet The inductance significantly depends on output ripple current. As seen in the equation (1), the ripple current decreases as the inductor and/or switching frequency increases. [A]・・・(1) L×VCC×f Appropriate ripple current at output should be 30% more or less of the maximum output current. ΔIL=0.3×IOUTmax. [A]・・・(2) (VCC-VOUT)×VOUT L= ΔIL×VCC×f [H]・・・(3) ΔIL= (VCC-VOUT)×VOUT IL VOUT L Co Fig.26 Output ripple current (ΔIL: Output ripple current, and f: Switching frequency) * Current exceeding the current rating of the inductor results in magnetic saturation of the inductor, which decreases efficiency. The inductor must be selected allowing sufficient margin with which the peak current may not exceed its current rating. If VCC=5V, VOUT=1.5V, f=1MHz, ΔIL=0.3×0.8A=0.24A, for example, (5-1.5)×1.5 L= 0.24×5×1M =4.375μ → 4.7[μH] * Select the inductor of low resistance component (such as DCR and ACR) to minimize dissipation in the inductor for better efficiency. 2. Selection of output capacitor (CO) VCC Output capacitor should be selected with the consideration on the stability region and the equivalent series resistance required to smooth ripple voltage. Output ripple voltage is determined by the equation (4)： VOUT L ESR Co ΔVOUT=ΔIL×ESR [V]・・・(4) (ΔIL: Output ripple current, ESR: Equivalent series resistance of output capacitor) *Rating of the capacitor should be determined allowing sufficient margin against output voltage. Less ESR allows reduction in output ripple voltage. Fig.27 Output capacitor As the output rise time must be designed to fall within the soft -start time, the capacitance of output capacitor should be determined with consideration on the requirements of equation (5): TSS×(Ilimit-IOUT) Tss: Soft-start time Co≦ ・・・(5) Ilimit: Over current detection level, 2A(Typ) VOUT In case of BD8966FVM, for instance, and if VOUT=1.5V, IOUT=0.8A, and TSS=1ms, Co≦ 1m×(2-0.8) 1.5 Inappropriate capacitance may cause problem in startup. A 10 μF to 100 μF ceramic capacitor is recommended. ≒800[μF] www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･15･001 12/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 BD8966FVM 3. Selection of input capacitor (Cin) VCC Datasheet Cin Input capacitor to select must be a low ESR capacitor of the capacitance sufficient to cope with high ripple current to prevent high transient voltage. The ripple current IRMS is given by the equation (5): VOUT L IRMS=IOUT× Co √ OUT(VCC-VOUT) V VCC [A]・・・(5) IOUT < Worst case > IRMS(max.) 2 If VCC=5.0V, VOUT=1.5V, and IOUTmax.=0.8A IRMS=0.8× √ (5-1.5) 5 5 =0.67[ARMS] When Vcc is twice the VOUT, IRMS= Fig.28 Input capacitor A low ESR 10µF/10V ceramic capacitor is recommended to reduce ESR dissipation of input capacitor for better efficiency. 4. Determination of RITH, CITH that works as a phase compensator As the Current Mode Control is designed to limit a inductor current, a pole (phase lag) appears in the low frequency area due to a CR filter consisting of a output capacitor and a load resistance, while a zero (phase lead) appears in the high frequency area due to the output capacitor and its ESR. So, the phases are easily compensated by adding a zero to the power amplifier output with C and R as described below to cancel a pole at the power amplifier. fp(Min.) A Gain [dB] fp(Max.) 0 fz(ESR) IOUTMin. 0 Phase [deg] -90 IOUTMax. 1 2π×RO×CO 1 fz(ESR)= 2π×ESR×CO fp= Pole at power amplifier When the output current decreases, the load resistance Ro increases and the pole frequency lowers. fp(Min.)= 1 [Hz]←with lighter load 2π×ROMax.×CO 1 2π×ROMin.×CO [Hz] ←with heavier load Fig.29 Open loop gain characteristics fp(Max.)= A fz(Amp.) Gain [dB] 0 0 Phase [deg] Zero at power amplifier Increasing capacitance of the output capacitor lowers the pole frequency while the zero frequency does not change. (This is because when the capacitance is doubled, the capacitor ESR reduces to half.) -90 fz(Amp.)= Fig.30 Error amp phase compensation characteristics 1 2π×RITH×CITH www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･15･001 13/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 BD8966FVM Datasheet Stable feedback loop may be achieved by canceling the pole fp (Min.) produced by the out put capacitor and the load resistance with CR zero correction by the error amplifier. fz(Amp.)= fp(Min.) 1 2π×RITH×CITH = 1 2π×ROMax.×CO 5. Determination of output voltage The output voltage VOUT is determined by the equation (7): VOUT=(R2/R1+1)×VADJ・・・(7) VADJ: Voltage at ADJ terminal (0.8V Typ.) With R1 and R2 adjusted, the output voltage may be determined as required. (Adjustable output voltage range: 1.0V to 2.5V) Use 1 kΩ to 100 kΩ resistor for R1. If a resistor of the resistance higher than 100 kΩ is used, check the assembled set carefully for ripple volta ge etc. 4.7µH 6 SW 1 ADJ R1 10µF R2 Output Fig.31 Determination of output voltage BD8966FVM Cautions on PC Board Layout VCC 1 ADJ EN 8 EN 2 VCC 3 RITH ③ CITH PVCC 7 ① VOUT 5 GND PGND CIN ② Co ITH SW 6 L 4 GND Fig.32 Layout diagram ① For the sections drawn with heavy line, use thick conductor pattern as short as possible. ② Lay out the input ceramic capacitor CIN closer to the pins PVCC and PGND, and the output capacitor Co closer to the pin PGND. ③ Lay out CITH and RITH between the pins ITH and GND as near as possible with least necessary wiring. www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･15･001 14/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 BD8966FVM Recommended Components Lists on Above Application Symbol Part Value L CIN CO CITH Coil Ceramic capacitor Ceramic capacitor Ceramic capacitor 4.7µH 10µF 10µF 750pF VOUT=1.0V VOUT=1.2V VOUT=1.5V VOUT=1.8V VOUT=2.5V Datasheet RITH Resistance 18kΩ 22kΩ 22kΩ 27kΩ 36kΩ Manufacturer Sumida TDK Kyocera Kyocera murata ROHM ROHM ROHM ROHM ROHM Series CMD6D11B VLF5014AT-4R7M1R1 CM316X5R106K10A CM316X5R106K10A GRM18series MCR10 1802 MCR10 2202 MCR10 2202 MCR10 2702 MCR10 3602 * The parts list presented above is an example of recommended parts. Although the parts are sound, actual circuit characteristics should be checked o n your application carefully before use. Be sure to allow sufficient margins to accommodate variations between external devices and this IC when employing the depicted circuit with other circuit constants modified. Both static and transient characteristics should be con sidered in establishing these margins. When switching noise is substantial and may impact the system, a low pass fil ter should be inserted between the VCC and PVCC pins, and a schottky barrier diode established between the SW and PGND pins. I/O Equivalence Circuit ・EN pin ・SW pin PVCC PVCC PVCC EN SW ・ADJ pin VCC ・ITH pin VCC 10kΩ ADJ ITH Fig.33 I/O equivalence circuit www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･15･001 15/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 BD8966FVM Datasheet ●Operational Notes 1. Absolute Maximum Ratings While utmost care is taken to quality control of this product, any application that may exceed some of the absolute maximum ratings including the voltage applied and the operating temperature range may result in breakage. If broken, short-mode or open-mode may not be identified. So if it is expected to encounter with special mode that may exceed the absolute maximum ratings, it is requested to take necessary safety measures physically including insertion of fu ses. 2. Electrical potential at GND GND must be designed to have the lowest electrical potential In any operating conditions . 3. Short-circuiting between terminals, and mismounting When mounting to pc board, care must be taken to avoid mistake in its orien tation and alignment. Failure to do so may result in IC breakdown. Short-circuiting due to foreign matters entered between output terminals, or between output and power supply or GND may also cause breakdown. 4. Operation in Strong electromagnetic field Be noted that using the IC in the strong electromagnetic radiation can cause operation failures. 5. Thermal shutdown protection circuit Thermal shutdown protection circuit is the circuit designed to isolate the IC from thermal runaway, and not intended to protect and guarantee the IC. So, the IC the thermal shutdown protection circuit of which is once activated should not be used thereafter for any operation originally intended. 6. Inspection with the IC set to a pc board If a capacitor must be connected to the pin of lower impedance during inspection with the IC set to a pc board, the capacitor must be discharged after each process to avoid stress to the IC. For electrostatic protection, provide proper grounding to assembling processes with special care taken in handling and storage. When connecting to jigs in the inspection process, be sure to turn OFF the power supply before it is connected and removed. 7. Input to IC terminals + This is a monolithic IC with P isolation between P-substrate and each element as illustrated below. This P-layer and the N-layer of each element form a P-N junction, and various parasitic element are formed. If a resistor is joined to a transistor terminal as shown in Fig 34. ○P-N junction works as a parasitic diode if the following relationship is satisfied; GND>Terminal A (at resistor side), or GND>Terminal B (at transistor side); and ○if GND>Terminal B (at NPN transistor side), a parasitic NPN transistor is activated by N-layer of other element adjacent to the above-mentioned parasitic diode. The structure of the IC inevitably forms parasitic elements, the activation of which may cause interference among circuits, and/or malfunctions contributing to breakdown. It is therefore requested to take care not to use the device in such manner that the voltage lower than GND (at P-substrate) may be applied to the input terminal, which may result in activation of parasitic elements. Fig.34 Simplified structure of monorisic IC 8. Ground wiring pattern If small-signal GND and large-current GND are provided, It will be recommended to separate the large -current GND pattern from the small-signal GND pattern and establish a single ground at the reference point of the set PCB so t hat resistance to the wiring pattern and voltage fluctuations due to a large current will cause no fluctuations in voltages of th e small-signal GND. Pay attention not to cause fluctuations in the GND wiring pattern of external parts as well. 9. Selection of inductor It is recommended to use an inductor with a series resistance element (DCR) 0.1 Ω or less. Note that use of a high DCR inductor will cause an inductor loss, resulting in decreased output voltage. Should this condition continue for a specified period (soft start time + timer latch time), output short circuit protection will be activated and output will be latched OFF. When using an inductor over 0.1Ω, be careful to ensure adequate margins for variation between external devices and this IC, including transient as well as static characteristics. Furthermore, in any case, it is recommended to start up the output with EN after supply voltage is within operation range. Status of this document The Japanese version of this document is formal specification . A customer may use this translation version only for a reference to help reading the formal version. If there are any differences in translation version of this document formal version takes priority www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･15･001 16/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 BD8966FVM ●Ordering Information Datasheet B D 8 9 6 6 F V M - TR Packaging and forming specification TR: Embossed tape and reel Package FVM: MSOP8 ●Physical Dimension, Tape and Reel information ●Marking Diagram MSOP8(TOP VIEW) Part Number Marking D 6 8 9 6 LOT Number 1PIN MARK www.rohm.com © ROHM Co., Ltd. All rights reserved. TSZ22111･15･001 17/17 TSZ02201-0J3J0AJ00060-1-2 02.MAR.2012. Rev.001 Datasheet Datasheet Notice ●Precaution for circuit design 1) The products are designed and produced for application in ordinary electronic equipment (AV equipment, OA equipment, telecommunication equipment, home appliances, amusement equipment, etc.). If the products are to be used in devices requiring extremely high reliability (medical equipment, transport equipment, aircraft/spacecraft, nuclear power controllers, fuel controllers, car equipment including car accessories, safety devices, etc.) and whose malfunction or operational error may endanger human life and sufficient fail-safe measures, please consult with the ROHM sales staff in advance. If product malfunctions may result in serious damage, including that to human life, sufficient fail-safe measures must be taken, including the following: [a] Installation of protection circuits or other protective devices to improve system safety [b] Installation of redundant circuits in the case of single-circuit failure 2) The products are designed for use in a standard environment and not in any special environments. Application of the products in a special environment can deteriorate product performance. Accordingly, verification and confirmation of product performance, prior to use, is recommended if used under the following conditions: [a] Use in various types of liquid, including water, oils, chemicals, and organic solvents [b] Use outdoors where the products are exposed to direct sunlight, or in dusty places [c] Use in places where the products are exposed to sea winds or corrosive gases, including Cl2, H2S, NH3, SO2, and NO2 [d] Use in places where the products are exposed to static electricity or electromagnetic waves [e] Use in proximity to heat-producing components, plastic cords, or other flammable items [f] Use involving sealing or coating the products with resin or other coating materials [g] Use involving unclean solder or use of water or water-soluble cleaning agents for cleaning after soldering [h] Use of the products in places subject to dew condensation The products are not radiation resistant. Verification and confirmation of performance characteristics of products, after on-board mounting, is advised. In particular, if a transient load (a large amount of load applied in a short period of time, such as pulse) is applied, confirmation of performance characteristics after on-board mounting is strongly recommended. Avoid applying power exceeding normal rated power; exceeding the power rating under steady-state loading condition may negatively affect product performance and reliability. De-rate Power Dissipation (Pd) depending on Ambient temperature (Ta). When used in sealed area, confirm the actual ambient temperature. Confirm that operation temperature is within the specified range described in product specification. Failure induced under deviant condition from what defined in the product specification cannot be guaranteed. 3) 4) 5) 6) 7) 8) ●Precaution for Mounting / Circuit board design 1) When a highly active halogenous (chlorine, bromine, etc.) flux is used, the remainder of flux may negatively affect product performance and reliability. 2) In principle, the reflow soldering method must be used; if flow soldering method is preferred, please consult with the Company in advance. Regarding Precaution for Mounting / Circuit board design, please specially refer to ROHM Mounting specification ●Precautions Regarding Application Examples and External Circuits 1) If change is made to the constant of an external circuit, allow a sufficient margin due to variations of the characteristics of the products and external components, including transient characteristics, as well as static characteristics. 2) The application examples, their constants, and other types of information contained herein are applicable only when the products are used in accordance with standard methods. Therefore, if mass production is intended, sufficient consideration to external conditions must be made. Notice - Rev.001 Datasheet Datasheet ●Precaution for Electrostatic This product is Electrostatic sensitive product, which may be damaged due to Electrostatic discharge. Please take proper caution during manufacturing and storing so that voltage exceeding Product maximum rating won't be applied to products. Please take special care under dry condition (e.g. Grounding of human body / equipment / solder iron, isolation from charged objects, setting of Ionizer, friction prevention and temperature / humidity control). ●Precaution for Storage / Transportation 1) Product performance and soldered connections may deteriorate if the products are stored in the following places: [a] Where the products are exposed to sea winds or corrosive gases, including Cl2, H2S, NH3, SO2, and NO2 [b] Where the temperature or humidity exceeds those recommended by the Company [c] Storage in direct sunshine or condensation [d] Storage in high Electrostatic 2) Even under ROHM recommended storage condition, solderability of products out of recommended storage time period may be degraded. It is strongly recommended to confirm solderability before using products of which storage time is exceeding recommended storage time period . Store / transport cartons in the correct direction, which is indicated on a carton as a symbol. Otherwise bent leads may occur due to excessive stress applied when dropping of a carton. Use products within the specified time after opening a dry bag. 3) 4) ●Precaution for product label QR code printed on ROHM product label is only for internal use, and please do not use at customer site. It might contain a internal part number that is inconsistent with an product part number. ●Precaution for disposition When disposing products please dispose them properly with a industry waste company. ●Precaution for Foreign exchange and Foreign trade act Since concerned goods might be fallen under controlled goods prescribed by Foreign exchange and Foreign trade act, please consult with ROHM in case of export. ●Prohibitions Regarding Industrial Property 1) Information and data on products, including application examples, contained in these specifications are simply for reference; the Company does not guarantee any industrial property rights, intellectual property rights, or any other rights of a third party regarding this information or data. Accordingly, the Company does not bear any responsibility for: [a] infringement of the intellectual property rights of a third party [b] any problems incurred by the use of the products listed herein. 2) The Company prohibits the purchaser of its products to exercise or use the intellectual property rights, industrial property rights, or any other rights that either belong to or are controlled by the Company, other than the right to use, sell, or dispose of the products. Notice - Rev.001