Single-chip Type with Built-in FET Switching Regulator Series Output 1.5A or Less High-efficiency Step-down Switching Regulator with Built-in Power MOSFET No.09027EAT29 BD9161FVM ●Description ROHM’s high efficiency step-down switching regulator BD9161FVM is a power supply designed to produce 1.2volts (low voltage) from 3.3volts power supply line. Offers high efficiency with our original pulse skip control technology and synchronous rectifier. Employs a current mode control system to provide faster transient response to sudden change in load. ●Features 1) Offers fast transient response with current mode PWM control system. 2) Offers highly efficiency for all load range with synchronous rectifier (Nch/Pch FET) 3) Incorporates 100% Duty function. 4) Incorporates soft-start function. 5) Incorporates thermal protection and ULVO functions. 6) Incorporates short-current protection circuit with time delay function. 7) Incorporates shutdown function Icc=0μA (Typ.) 8) Employs small surface mount package MSOP8 ●Use Power supply for HDD, DVS and for LSI of CPU, ASIC ●Absolute Maximum Rating (Ta=25℃) Parameter VCC voltage PVCC voltage EN Voltage Symbol Rating VCC -0.3～+7 *1 V *1 V PVCC -0.3～+7 Unit EN -0.3～+7 V SW,ITH -0.3～+7 V Power Dissipation 1 Pd1 387.5*2 mW Power Dissipation 2 Pd2 587.4*3 mW Power Dissipation 3 Topr -25～+85 ℃ Tstg -55～+150 ℃ Tjmax +150 ℃ SW, ITH Voltage Power Dissipation 4 EN voltage *1 Pd should not be exceeded. *2 Derating in done 3.1mW/℃ for temperatures above Ta=25℃. *3 Derating in done 4.7mW/℃ for temperatures above Ta=25℃,Mounted on 70mm×70mm×1.6mm Glass Epoxy PCB. ●Operating Conditions (Ta=25℃) Parameter Symbol VCC voltage PVCC voltage EN voltage Output Voltage Setting Range SW, ITH average output current VCC*4 PVCC*4 EN SW,ITH Isw*4 Limits Min. 2.5 2.5 0 1.0 - Typ. 3.3 3.3 - Max. 4.5 4.5 VCC 3.3 0.6 Unit V V V V A *4 Pd should not be exceeded. www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 1/13 2009.05 - Rev.A Technical Note BD9161FVM ●Electrical Characteristics ◎(Ta=25℃, VCC=PVCC=3.3V, EN=VCC, unless otherwise specified.) Limits Parameter Symbol Min. Typ. Standby current ISTB 0 Bias current ICC 200 EN Low voltage VENL GND EN High voltage VENH 2.0 VCC EN input current IEN 1 Oscillation frequency FOSC 0.8 1 Pch FET ON resistance RONP 0.35 Nch FET ON resistance RONN 0.37 Output voltage VOUT 0.784 0.8 ITH SInk current ITHSI 10 20 ITH Source Current ITHSO 10 20 UVLO threshold voltage VUVLO1 2.2 2.3 UVLO hysteresis voltage VUVLO2 2.22 2.35 Soft start time TSS 0.5 1 Timer latch time TLATCH 1 2 Output Short circuit Threshold Voltage VSCP 0.4 Max. 10 400 0.8 10 1.2 0.6 0.68 0.816 2.4 2.5 2 3 0.56 ●Block Diagram, Application Circuit 2.8±0.1 4.0±0.2 8 5 D 9 1 6 1 1 0.9Max. 0.75±0.05 0.08±0.05 0.475 4 +6 -4 PVCC=3.3V PVCC=3.3V VOUT =H VOUT =L VCC=H→L VCC=L→H SCP/TSD operated VOUT =H→L 3 8 Current Comp. R Q Gm Amp. S SLOPE +0.05 0.145 -0.03 VCC S CLK OSC UVLO Soft Start +0.05 0.22 -0.04 0.65 Standby mode Active mode VEN=3.3V 7 Lot No. 1PIN MARK EN=GND VREF 0.29±0.15 0.6±0.2 4 Max3.25(include.BURR) μA μA V V μA MHz Ω Ω V μA μA V V ms ms V Conditions VCC EN 2.9±0.1 Unit + ADJ 2 Output 6 SW Driver Logic PGND 5 4 SCP 1 PVCC 3.3V Input Current Sense/ Protect TSD 0.08 S VCC GND ITH MSOP8 (Unit:mm) Fig.1 BD9161FVM Dimension ●Pin No. & function table Pin No. 1 2 3 4 5 6 7 8 Pin name ADJ ITH EN GND PGND SW PVCC VCC www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. Fig.2 BD9161FVM Block Diagram PIN function Output voltage Feedback pin (Adjustable) 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 1/13 2009.05 - Rev.A Technical Note BD9161FVM ●Characteristics data(Reference data) 【VOUT=2.5V】 Ta=25℃ Io=0A 1.0 2.0 1.0 VCC=3.3V Ta=25℃ Io=0A 0.0 0 1 2 3 INPUT VOLTAGE:VCC[V] 4 1 0 1.20 1.10 2.50 2.49 2.48 70 60 50 40 30 2.47 20 2.46 10 2.45 0 Fig. 6 Ta-VOUT Fig.7 Efficiency 35 45 55 65 75 1 85 2.0 0.35 1.8 1.6 EN VOLTAGE:VEN[V] VCC=3.3V PMOS 0.25 NMOS 0.20 0.15 0.10 0.00 5 15 25 35 45 55 65 75 0.50 0.40 0.30 0.20 1000 -25 -15 -5 5 15 25 35 45 55 65 75 85 TEMPERATURE:Ta[℃] Fig.8 Ta - Fosc 1.2 VCC=3.3V VCC=3.3V 1.4 1.2 1.0 0.8 0.6 0.0 -5 0.60 1.1 1 0.9 0.2 VCC=3.3V -25 -15 0.70 0.10 0.4 0.05 0.80 FREQUENCY:FOSC[MHz] 25 VCC=3.3V 0.90 0.00 TEMPERATURE:Ta[℃] 15 0.40 0.30 【VOUT=2.5V】 VCC=3.3V Ta=25℃ 10 100 OUTPUT CURRENT:IOUT[mA] 5 3 VCC=3.3V 1.00 FREQUENCY:FOSC[MHz] 2.51 -5 1 2 OUTPUT CURRENT:IOUT [A] Fig.5 Iout-Vout 80 2.52 -25 -15 VCC=3.3V Ta=25℃ 4 90 EFFICIENCY:η[%] 2.53 1.0 Fig.4 Ven-Vout 【VOUT=2.5V】 VCC=3.3V Io=0A 2.54 OUTPUT VOLTAGE:VOUT[V] 2 3 EN VOLTAGE:VEN[V] 100 2.55 2.0 0.0 0 Fig.3 Vcc-Vout ON [Ω] OUTPUT VOLTAGE:VOUT[V] 2.0 0.0 ON RESISTANCE:R 【VOUT=2.5V】 【VOUT=2.5V】 OUTPUT VOLTAGE:VOUT[V] OUTPUT VOLTAGE:VOUT[V] 3.0 3.0 3.0 85 TEMPERATURE:Ta[℃] Fig.9 Ta-VEN www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. -25 -15 -5 5 15 25 35 45 55 65 TEMPERATURE:Ta[℃] Fig.10 Ta-ICC 2/13 75 85 0.8 2.5 3 3.5 4 INPUT VOLTAGE:VCC [V] 4.5 Fig.11 Vcc-Fosc 2009.05 - Rev.A Technical Note BD9161FVM ●Characteristics data(Reference data) – Continued 【SLLMTM control 【VOUT=2.5V】 VCC=PVCC =EN VOUT=2.5V】 SW VOUT VCC=3.3V Ta=25℃ Io=0A VCC=3.3V Ta=25℃ Fig.12 Soft start waveform 【100% Duty VOUT=2.5V】 SW VOUT VOUT 【PWM control VCC=3.3V Ta=25℃ Fig.14 SW waveform Io=500mA Fig.13 SW waveform Io=10mA VOUT=2.5V】 【VOUT=2.5V】 【VOUT=2.5V】 VOUT VOUT SW VOUT VCC=2.7V Ta=25℃ Fig. 15 SW waveform Io=600mA www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. IOUT IOUT VCC=3.3V Ta=25℃ Fig. 16 Transient response Io=250→500mA(10μs) 3/13 VCC=3.3V Ta=25℃ Fig.17 Transient response Io=500→250mA(10μs) 2009.05 - Rev.A Technical Note BD9161FVM ●Information on advantages Advantage 1：Offers fast transient response with current mode control system. Conventional product (VOUT of which is 2.5 volts) BD9161FVM (Load response IO=250mA→500mA) VOUT VOUT 40mV 98mV IOUT IOUT Voltage drop due to sudden change in load was reduced by about 50%. Fig.18 Comparison of transient response Advantage 2： Offers high efficiency for all load range. ・For lighter load: TM Utilizes the current mode control mode called SLLM for lighter load, which reduces various dissipation such as switching dissipation (PSW), gate charge/discharge dissipation, ESR dissipation of output capacitor (PESR) and on-resistance dissipation (PRON) that may otherwise cause degradation in efficiency for lighter load. Achieves efficiency improvement for lighter load. 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: 0.35 Ω (Typ.) ON resistance of N-channel MOS FET: 0.37 Ω (Typ.) SLLMTM ② 50 ① PWM TM ①inprovement by SLLM system ②improvement by synchronous rectifier 0 0.001 0.01 0.1 Output current Io[A] 1 Fig.19 Efficiency Achieves efficiency improvement for heavier load. Offers high efficiency for all load range with the improvements mentioned above. Advantage 3： ・Supplied in smaller package due to small-sized power MOS FET incorporated. ・Allows reduction in size of application products ・Output capacitor Co required for current mode control: 10 μF ceramic capacitor ・Inductance L required for the operating frequency of 1 MHz: 4.7 μH inductor Reduces a mounting area required. VCC 15mm Cin CIN RITH DC/DC Convertor Controller L RITH L VOUT 10mm CITH Co CO CITH Fig.20 Example application www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 4/13 2009.05 - Rev.A Technical Note BD9161FVM ●Operation BD9161FVM is a synchronous rectifying step-down switching regulator that achieves faster transient response by employing current mode PWM control system. It utilizes switching operation in PWM (Pulse Width Modulation) mode for TM heavier load, while it utilizes SLLM (Simple Light Load Mode) operation for lighter load to improve efficiency. ○Current mode PWM control Synthesizes a PWM control signal with a inductor current feedback loop added 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 IL) 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. TM ・SLLM (Simple Light Load Mode) control When the control mode is shifted from PWM for heavier load to the one for lighter load or vise versa, the switching pulse is designed to turn OFF with the device held operated in normal PWM control loop, which allows linear operation without voltage drop or deterioration in transient response during the mode switching from light load to heavy load or vise versa. Although the PWM control loop continues to operate with a SET signal from OSC and a RESET signal from Current Comp, it is so designed that the RESET signal is held issued if shifted to the light load mode, with which the switching is tuned OFF and the switching pulses are thinned out under control. Activating the switching intermittently reduces the switching dissipation and improves the efficiency. ・100% Duty control Max duty is 100%. (@ Pch MOS FET always ON) In usual PWM control, in case output voltage cannot keep (ex, drop of input voltage), oscillation frequency becomes lower and finally it becomes 100% duty. The output voltage is a value that depends only by on a voltage hang from the input voltage to Pch MOS FET, and can keep the output voltage even with the low input voltage. SENSE Current Comp VOUT Level Shift FB RESET SET Gm Amp. ITH R Q S IL Driver Logic VOUT SW Load OSC Fig.21 Diagram of current mode PWM control PVCC Current Comp SENSE PVCC SENSE Current Comp FB FB SET GND SET GND RESET GND RESET GND SW GND SW IL GND IL(AVE) IL 0A VOUT VOUT VOUT(AVE) VOUT(AVE) Not switching Fig.23 SLLM Fig.22 PWM switching timing chart www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 5/13 TM switching timing chart 2009.05 - Rev.A Technical Note BD9161FVM ●Description of operations ・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 0μF (Typ.). ・UVLO function Detects whether the input voltage sufficient to secure the output voltage of this IC is supplied. And the hysteresis width of 50 mV (Typ.) is provided to prevent output chattering. Hysteresis 50mV VCC EN VOUT Tss Tss Tss Soft start Standby mode Operating mode Standby mode Standby mode Operating mode UVLO UVLO Operating mode EN Standby mode UVLO Fig.24 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 the fixed time (TLATCH) or more. 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 Timer latch EN Operating mode EN Fig.25 Short-current protection circuit with time delay timing chart www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 6/13 2009.05 - Rev.A Technical Note BD9161FVM ●Switching regulator efficiency Efficiency ŋ may be expressed by the equation shown below: POUT ×100[%]= POUT η= VOUT×IOUT ×100[%]= ×100[%] Vin×Iin Pin POUT+PDα Efficiency may be improved by reducing the switching regulator power dissipation factors PDα 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) 2 2 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[H]：Switching frequency, V[V]：Gate driving voltage of FET) 2 Vin ×CRSS×IOUT×f 3)PD(SW)= (CRSS[F]：Reverse transfer capacitance of FET, IDRIVE[A]：Peak current of gate.) IDRIVE 2 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. Power dissipation:Pd [mW] 1000 800 600 400 P=IOUT2×(RON) RON=D×RONP+(1-D)×RONN ①Using an IC alone θj-a=322.6℃/W ②mounted on glass epoxy PCB θj-a=212.8℃/W D：ON duty (=VOUT/VCC) RONP：ON resistance of P-channel MOS FET RONN：ON resistance of N-channel MOS FET IOUT：Output current ②587.4mW ①387.5mW 200 0 0 25 50 75 85 100 125 150 Ambient temperature:Ta [℃] Fig.26 Thermal derating curve (MSOP8) If VCC=3.3V, VOUT=2.5V RONP=0.35Ω, RONN=0.37Ω IOUT=0.6A, for example, D=VOUT/VCC=2.5/3.3=0.758 RON=0.758×0.35+(1-0.758)×0.37 =0.2653+0.08954 =0.35484[Ω] 2 P=0.6 ×0.35484 ≒127.7[mV] As RONP is greater than RONN in this IC, the dissipation increases as the ON duty becomes greater. With the consideration on the dissipation as above, thermal design must be carried out with sufficient margin allowed. www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 7/13 2009.05 - Rev.A Technical Note BD9161FVM ●Selection of components externally connected 1. Selection of inductor (L) IL 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. ΔIL VCC (VCC-VOUT)×VOUT [A]・・・(1) L×VCC×f Appropriate ripple current at output should be 20～30% more or less of the maximum output current. ΔIL=0.25×IOUTmax. [A]・・・(2) ΔIL= IL VOUT L Co L= (VCC-VOUT)×VOUT ΔIL×VCC×f [H]・・・(3) (ΔIL: Output ripple current, and f: Switching frequency) Fig.27 Output ripple current * 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=3.3V, VOUT=2.5V, f=1MHz, ΔIL=0.25×0.6A=0.15A (3.3-2.5)×2.5 L≧ 0.15×3.3×1M ≧4.04μ * 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 ΔVOUT=ΔIL×ESR [V]・・・(4) Co (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.28 Output capacitor Inappropriate capacitance may cause problem in startup. A 10μF to 100μF ceramic capacitor is recommended. 3. Selection of input capacitor (Cin) VCC 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): Cin VOUT L Co IRMS=IOUT× √VOUT(VCC-VOUT) VCC [A]・・・(5) < Worst case > IRMS(max.) When VCC is twice the Vout, IRMS= IOUT 2 Fig.29 Input capacitor If VCC=3.3V, VOUT=2.5V, and IOUTmax.=0.6A √2.5(3.3-2.5) IRMS=0.6× =0.284[ARMS] 5 A low ESR 10μF/10V ceramic capacitor is recommended to reduce ESR dissipation of input capacitor for better efficiency. www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 8/13 2009.05 - Rev.A Technical Note BD9161FVM 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.) 1 2π×RO×CO 1 fz(ESR)= 2π×ESR×CO fp= A Gain [dB] fp(Max.) 0 fz(ESR) IOUTMin. Phase [deg] IOUTMax. Pole at power amplifier When the output current decreases, the load resistance Ro increases and the pole frequency lowers. 0 -90 fp(Min.)= 1 2π×ROMax.×CO [Hz]←with lighter load fp(Max.)= 1 2π×ROMin.×CO [Hz]←with heavier load Fig.30 Open loop gain characteristics A fz(Amp.) 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.) Gain [dB] 0 Phase [deg] 0 fz(Amp.)= -90 1 2π×RITH.×CITH Fig.31 Error amp phase compensation characteristics Cin VCC EN VOUT L VCC,PVCC SW ESR VOUT ITH VOUT GND,PGND RO CO RITH CITH Fig.32 Typical application Stable feedback loop may be achieved by canceling the pole fp (Min.) produced by the output capacitor and the load resistance with CR zero correction by the error amplifier. fz(Amp.)= fp(Min.) 1 2π×RITH×CITH www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. = 1 2π×ROMax.×CO 9/13 2009.05 - Rev.A Technical Note BD9161FVM 5. Determination of output voltage The output voltage VOUT is determined by the equation (6): VOUT=(R2/R1+1)×VADJ・・・(6) 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～3.3V ) L Output 6 SW Co R2 1 ADJ R1 Use 1 kΩ～100 kΩ resistor for R1. If a resistor of the resistance higher than 100 kΩ is used, check the assembled set carefully for ripple voltage etc. Fig.33 Determination of output voltage ●BD9161FVM Cautions on PC Board layout 1 ADJ VCC 8 2 ITH PVCC 7 3 EN SW 6 4 GND PGND 5 RIN RITH VCC CIN EN CITH ③ ① L VOUT CO ② GND Fig.34 Board layout ① ② ③ For the sections drawn with heavy line, use thick conductor pattern as short as possible. Lay out the input ceramic capacitor CIN closer to the pins PVCC and PGND, and the output capacitor Co closer to the pin PGND. Lay out CITH and RITH between the pins ITH and GND as neat as possible with least necessary wiring. ●Recommended component lists with above applications Symbol Part Value L RIN CIN CO Coil Resistance Ceramic capacitor Ceramic capacitor Ceramic capacitor CITH RITH Resistance 4.7μH 10Ω 10μF 10μF VOUT=1.0V VOUT=1.2V VOUT=1.5V VOUT=1.8V VOUT=2.5V VOUT=1.0V VOUT=1.2V VOUT=1.5V VOUT=1.8V VOUT=2.5V 820pF 560pF 470pF 470pF 330pF 6.8kΩ 8.2kΩ 12kΩ 12kΩ 15kΩ Manufacturer TDK Sumida ROHM Kyocera Kyocera murata murata murata murata murata ROHM ROHM ROHM ROHM ROHM Series VLF5014AT-4R7M1R1 CMD6D11B MCR03 Series CM316X5R106K10A CM316X5R106K10A GRM18 Series GRM18 Series GRM18 Series GRM18 Series GRM18 Series MCR03 Series MCR03 Series MCR03 Series MCR03 Series MCR03 Series * The parts list presented above is an example of recommended parts. Although the parts are sound, actual circuit characteristics should be checked on 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 considered in establishing these margins. When switching noise is substantial and may impact the system, a low pass filter should be inserted between the VCC and PVCC pins, and a schottky barrier diode established between the SW and PGND pins. www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 10/13 2009.05 - Rev.A Technical Note BD9161FVM ●I/O equivalence circuit PVCC ・SW pin ・EN pin PVCC PVCC 10kΩ EN SW ・ITH pin ・ADJ pin VCC 10kΩ ADJ ITH Fig.36 I/O equivalence circuit www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 11/13 2009.05 - Rev.A Technical Note BD9161FVM ●Cautions on use 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 fuses. 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 orientation 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 37: ○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. Resistor Transistor (NPN) Pin A Pin B C Pin B B E Pin A N P + N P P + N Parasitic element N P+ B N P P substrate Parasitic element GND P C + N E Parasitic element P substrate Parasitic element GND GND GND Other adjacent elements Fig.37 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 that resistance to the wiring pattern and voltage fluctuations due to a large current will cause no fluctuations in voltages of the small-signal GND. Pay attention not to cause fluctuations in the GND wiring pattern of external parts as well. www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 12/13 2009.05 - Rev.A Technical Note BD9161FVM ●Ordering part number B D 9 1 6 1 Part No. Part No. F V M - Package FVM:MSOP8 T R Packaging and forming specification TR: Embossed tape and reel (MSOP8) MSOP8 <Tape and Reel information> 2.8±0.1 4.0±0.2 8 7 6 5 0.6±0.2 +6° 4° −4° 0.29±0.15 2.9±0.1 (MAX 3.25 include BURR) Tape Embossed carrier tape Quantity 3000pcs Direction of feed TR The direction is the 1pin of product is at the upper right when you hold ( reel on the left hand and you pull out the tape on the right hand ) 1 2 3 4 1PIN MARK 1pin +0.05 0.145 –0.03 0.475 0.08±0.05 0.75±0.05 0.9MAX S +0.05 0.22 –0.04 0.08 S Direction of feed 0.65 Reel (Unit : mm) www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 13/13 ∗ Order quantity needs to be multiple of the minimum quantity. 2009.05 - 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, 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 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 © 2009 ROHM Co., Ltd. All rights reserved. R0039A