BD9853AFV

Large Current External FET Controller Type Switching Regulators Single/Dual-output High-frequency Step-down Switching Regulator(Controller type) BD9853AFV No.09028EAT05 ●Description The BD9853AFV is a 2-ch synchronous DC/DC controller that can operate at a maximum switching frequency of 2MHz, enabling the use of a smaller external coil than conventional lower-frequency switching regulators. This makes the BD9853AFV a suitable choice for downsizing applications. ●Features 1) Synchronous Switching Regulator Controller 2channels 2) FET(Pch/Nch) Direct Drive 3) Adjustable Oscillator Frequency with External Resistor (Max. 2MHz) 4) Under Voltage Lockout Function (UVLO) 5) Thermal Shut Down Function (TSD) 6) Short Circuit Protection (SCP) 7) Independent ON/OFF Function in Each Channel with Soft Start Pin 8) SSOP-B16 Package SSOPB16 ●Applications TVSTB, PC, Portable CD・DVD,DVC etc. ●Absolute Maximum Ratings (Ta = 25℃) Parameter Supply Voltage (VCC-GND) VREGA-GND Voltage VCC-VREGB Voltage Power Dissipation Operating Temperature Range Junction Temperature Storage Temperature Range * Symbol Vcc VREGA VREGB Pd Topr Tjmax Tstg Limits 18 7 7 562(*1) -40 to +85 +150 -55 to +150 Unit V V V mW ℃ ℃ ℃ Reduced by 4.49mW for each increase in Ta of 1℃ over 25℃ (When mounted on a board 70×70×1.6tmm grass-epoxy PCB) ●Recommended Operating Conditions Parameter Supply Voltage Oscillator Frequency Symbol Vcc fosc Limits Min. 4.5 100 Typ. 12 1000 Max. 16 2000 Unit V KHz www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 1/16 2009.05 - Rev.A BD9853AFV ●Electrical Characteristics (Unless otherwise specified Ta=25℃,Vcc=12V,fosc=1000kHz,STB=3V) Limits Parameter Symbol Unit Min. Typ. Max. 【Whole Device】 Standby Current Circuit Current 【Regulator for Driver REGA】 Output Voltage Output Current Capability 【Regulator for Driver REGB】 Output Voltage Output Current Capability 【Oscillator】 Oscillator Frequency Oscillator Frequency Coefficient1 Oscillator Frequency Coefficient2 【Error Amplifier】 Threshold Voltage Input Bias Current Voltage Gain Max. Output Voltage Min. Output Voltage Output Sink Current Output Source Current 【PWM Comparator】 0% Threshold Voltage 100% Threshold Voltage * Technical Note Conditions Iccst Icc Vrega Irega Vregb Iregb － － 4.5 － VCC-5.5 100 0 3.2 5.0 － VCC-5.0 － 5 5.2 5.5 -100 VCC-4.5 － μA mA V mA V mA STB=0V INV1,INV2=2.5V Vrega > 4.5V Vregb < Vcc-4.5V RRT=8.2kΩ OUTH=2200pF,OUTL=1000pF Vcc=4.5 to 5V Vcc=5 to 18V fosc Dfosc1 Dfosc2 Vthea Ibias Av Vfbh Vfbl Isink Isource Vth0 Vth100 900 -2 -2 0.79 -230 60 Vrega-0.85 － 2 1.4 2.4 1000 0 0 0.80 -115 80 － － 11 -15 1.5 2.5 1100 2 2 0.81 － 100 － 0.85 -2 1.6 2.6 kHz % % V nA dB V V mA mA V V DC GAIN INV=2.5V, FB=2.5V INV=0V, FB=2.5V FB Voltage FB Voltage This product is not designed for the protection against radioactive rays. ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM ROHM www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 2/16 2009.05 - Rev.A BD9853AFV Technical Note ●Electrical Characteristics (Unless otherwise specified, Ta=25℃,Vcc=12V,fosc=1000kHz,STB=3V) Limits Parameter Symbol Unit Conditions Min. Typ. Max. 【FET Driver】 On Resistance (OUT1H) On Resistance (OUT1L) On Resistance (OUT2H) On Resistance (OUT2L) Dead Time(Turn ON) Dead Time(Turn OFF) 【Control Block】 Threshold Voltage Sink Current 【Soft Start Block】 Soft Start Start-yo Voltage Vstasoft Standby Voltage Source Current Timer Start Voltage Threshold Voltage Standby Voltage Source Current Threshold Voltage Hysteresis Voltage * * RonP RonN RonP RonN RonP RonN RonP RonN tdtON tdtOFF Vstb Istb 1.6 1.7 1.6 1.7 1.6 1.7 1.6 1.7 30 25 0.6 6 0.2 － -3.2 0.50 2.2 1.21 -3.2 4.0 0.05 3.2 3.4 3.2 3.4 3.2 3.4 3.2 3.4 70 60 1.5 15 0.3 － -2.3 0.56 2.3 1.35 -2.3 4.15 0.1 4.8 5.1 4.8 5.1 4.5 5.1 4.8 5.1 120 115 2.4 30 0.4 40 -1.4 0.62 2.4 1.49 -1.4 4.30 0.15 Ω Ω Ω Ω Ω Ω Ω Ω ns ns V μA V mV μA V V V μA V V OUT=Hi OUT=Lo OUT=Hi OUT=Lo OUT=Hi OUT=Lo OUT=Hi OUT=Lo *OUTH,L H→L,OUTH=2200pF,OUTL=1000pF *OUTH,L H→L,OUTH=2200pF,OUTL=1000pF Output OFF when Vscp/SOFT＜Vstass SCP/SOFT Voltage Vscp/SOFT=0.6V INV Voltage SCP/SOFT Voltage SCP/SOFT Voltage (When soft start ends) SCP/SOFT=1.8V Vcc sweep down Vstsoft Isosoft Vtime Vthscp Vstscp Isoscp Vuvlo DVuvlo 【Short Circuit Protection (SCP)】 【Under Voltage Lockout (UVLO)】 This product is not designed for the protection against radioactive rays. Measurement of dead time Turn ON OUTH VCC-2.5V OUTL 2.5V OUTL tdtON VCC-2.5V OUTH Turn OFF 2.5V tdtOFF www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 3/16 2009.05 - Rev.A BD9853AFV ●Characteristic Data 100 90 80 Technical Note 70 60 50 40 30 20 10 0 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 2.6 OUTL OUTH FB VOLTAGE:VFB[V] 180 160 140 120 100 80 60 40 20 0 -20 -40 -60 -80 -100 -120 -140 -160 -180 0.01 Phase Gain 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 GAIN[dB]、PHASE[deg] FB SINK CURRENT[mA] 100 1000 10000 100000 ONDUTY[%] 0.1 1 10 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 4 FREQUENCY[KHz] FB VOLTAGE[V] Fig.1 FB VOLTAGE VS ON DUTY Fig.2 ERROR AMP OPEN LOOP Fig.3 FB SINK CURRENT 0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 -13 -14 -15 -16 -17 -18 -19 -20 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3 3.2 3.4 3.6 3.8 4 4.2 4.4 1000 950 900 850 800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 VCC=12V,18V 4 VCC=4.5V 1000 950 900 850 800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 OUTH SOURCE CURRENT:IOUT[mA] OUTH SINK CURRENT:IOUT[mA] FB SOURCE CURRENT[mA] VCC=12V,18V VCC=4.5V 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 FB VOLTAGE[V] (REGB-OUTH) VOLTAGE[V] (VCC-OUTH) VOLTAGE:[V] Fig.4 FB SOURCE CURRENT Fig.5 OUTH SINK CURRENT Fig.6 OUTH SOURCE CURRENT 1000 950 900 850 800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 VCC=12V,18V VCC=4.5V 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 1000 950 900 850 800 750 700 650 600 550 500 450 400 350 300 250 200 150 100 50 0 OUTL SOURCE CURRENT:IOUT[mA] OUTL SINK CURRENT:IOUT[mA] VCC=12V,18V VCC=4.5V 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 (OUTL-GND) VOLTAGE[V] (REGA-OUTL) VOLTAGE[V] Fig.7 OUTL SINK CURRENT Fig.8 OUTL SOURCE CURRENT www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 4/16 2009.05 - Rev.A BD9853AFV ●Block Diagram VCC VCC both channel ON/OFF STB REGA VCC REGB Technical Note 5V REGA FB1 VOUT1 VCC-5V REGB SOFT1 TSD VREF VCC VCC INV1 OUT1H Pch VOUT1 0.8V ⊿ｔ REGA REGB OUT1L Nch SCP/SOFT1 (Push-Pull) GND FB2 VOUT2 SOFT2 VCC INV2 OUT2H VCC 0.56V Pch VOUT2 SCP/SOFT2 RT 0.8V (Push-Pull) ⊿ｔ REGA REGB OUT2L Nch OSC GND GND Timer Latch Fig. 9 www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 5/16 2009.05 - Rev.A BD9853AFV ●Pin Configuration Technical Note Fig. 10 ●Pin Description Pin Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Pin Name VCC OUT1H OUT1L REGA RT FB1 INV1 SCP/SOFT1 SCP/SOFT2 INV2 FB2 GND STB OUT2L OUT2H REGB Input Supply Voltage High Side (Main) FET Driver Output Pin (CH1) Low Side (Synchronous) FET Driver Output Pin (CH1) Internal Regulator Output Pin (5V Output, 1uF Ceramic Capacitor necessary) Oscillator Frequency Adjustment Pin with external Resistor Error Amplifier Output Pin (CH1) Error Amplifer Negative Input Pin (CH1) Short Circuit Protection・Soft Start Delay Time Setting Pin with External Capacitor (CH1) Short Circuit Protection・Soft Start Delay Time Setting Pin with External Capacitor (CH2) Error Amplifer Negative Input Pin (CH2) Error Amplifier Output Pin (CH2) Ground Pin ON/OFF Control Pin Low Side (Synchronous) FET Driver Output Pin (CH2) High Side (Main) FET Driver Output Pin (CH2) Internal Regulator Output Pin (VCC-5V Output, 1uF Ceramic Capacitor necessary) Pin Descriptions www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 6/16 2009.05 - Rev.A BD9853AFV Technical Note ●Block functional descriptions ・Triangular wave oscillator Connecting the resistor that sets the triangular wave oscillation frequency at the RT terminal generates the triangular wave, which is input into the CH1 and CH2 PWM comparator. ・Error amp The INV pin detects the output voltage, compares it to the programmed output voltage and amplifies the difference for output by the FB pin. (The 0.8V reference is the comparison voltage. The tolerance is 1.25%.) ・PWM comparator The PWM comparator converts the error amp (FB) voltage into a pulse width modulated waveform that goes to the FET driver and turns FET output ON. ・FET driver The push-pull FET driver directly drives the external MOSFET,providing high-side(OUT1H,OUT2H) switching at voltages between Vcc⇔REGB, and low-side switching in the 0⇔REGA voltage range. (REGA = 5V; REGB= VCC -5V internal power) ・Standby function The standby function enables output ON/OFF control by the STB pin. Output is ON when STB voltage is HIGH. With the STB pin set HIGH, the output ON/OFF for each channel can be independently controlled by one of the SCP/SOFT1, 2 pins. ・Soft Start/Short Circuit Protection (SCP) Connecting the external capacitor on the SCP/SOFT1, 2 pins sets the SCP delay time and soft start time. When STB is HIGH and the IC starts up, the capacitors on the SCP/SOFT1, 2 pins charge up at 2uA, stabilizing when the system reaches 1.3V. If load conditions change rapidly, causing the output voltage in either channel to fall to 70% or less of the set output voltage (INV voltage 0.56 or lower), the SCP/SOFT1, 2 external capacitors will charge further until output for both channels switches OFF at 2.3V. ・Under Voltage Lockout (UVLO) Under Voltage lockout prevents IC malfunctions that could otherwise occur due to intermittent or fluctuating power supply voltage, or insufficient voltage during start-up.When the VCC voltage falls to 4.1V or below, both channel outputs are turned OFF, while the SCP/SOFT1, 2 pins are simultaneously set LOW. The UVLO detection voltage includes 0.1V hysteresis width to prevent malfunctions from input voltage fluctuations. ・Thermal Shutdown (TSD) The TSD circuit protects the IC against thermal runaway and heat damage. ・The TSD thermal sensor detects junction temperature. When the temperature reaches the TSD threshold (175℃), the circuit switches the output of both channels OFF, and also switches REGA and REGB OFF. At the same time, it sets the SCP/SOFT1, 2 pins LOW. The hysteresis width (15℃) provided between the TSD function start temperature (threshold) and the stop temperature serves to prevent malfunctions from temperature fluctuations. www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 7/16 2009.05 - Rev.A BD9853AFV ●Timing Chart STB STB ON STB OFF Technical Note Output OFF at SCP/SOFT tdON - tdOFF The tdt turn-on is (OUTH,OUTL：H→L)70ns typ. Turn-off is OUTH,OUTL：L→H)70ns typ. Be sure to confirm that the process delay time does not pose problem in terms of the overall MOSFET delay. The following MOSFETs meet all of the selection criteria outlined above, and are recommended for use. Both are manufactured by ROHM. PCH: RSS040PO3 NCH: RSS065P03 www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 9/16 2009.05 - Rev.A BD9853AFV Technical Note Selecting the synchronous diode An extremely low forward voltage Schottky barrier diode should be employed as the synchronous diode. Selection of the specific diode to be used should be made in conformance with the following relative configurations for maximum forward current, reverse voltage and diode power dissipation. ・The maximum current rating is higher than the combined maximum load current and coil ripple current (⊿IL). ・The reverse voltage rating is higher than the VIN value. ・Power dissipation for the selected diode must be within the rated level. Synchronous diode power dissipation (Pdi) is expressed in the following formula: Pdi=Iout(MAX)×tdt×fosc×Vf Iout(MAX) : maximum load current, tdt： dead time 60ns typ,fosc : oscillation frequency, Vf：forward voltage Selecting the output/input coil The output coil and the output capacitor together form a second-order smoothing filter for the switch waveform and provide the DC output voltage. If a coil’s inductor value is low, its physical size is minimized, but the penalty is higher ripple current, with lowered efficiency and an increase in output noise. Conversely, a higher inductor value increases the size of the coil, but lowers the ripple current and, consequently. the output ripple current. Generally speaking, ripple current should be between 20% and 50% of output load current. The following equation is used to calculate the inductor value that corresponds to the ripple current value being employed. (VIN－VOUT) L= ⊿IL × VOUT VIN × 1 fOSC ⊿IL =(0.2 to 0.5)×IOUT , L：inductor value, VIN：maximum input voltage, VOUT：output voltage, ⊿IL：coil ripple current value fosc：oscillation frequency, IOUT：output load current Note that the current rating for the coil should be higher than IOUT(MAX)＋⊿IL. Selecting the input capacitor The input capacitor is the source of current that flows to the coil via the FET whenever the high side MOSFET is ON. In selecting an input capacitor, sufficient margin must be provided to accommodate capacitor pressure and the permissible ripple current. The expression below defines the effective value of the ripple current to the input capacitor. It should be used in determining the suitability of the capacitor in providing sufficient margin for the permissible ripple current. IRMS＝IOUT×√ (1－VOUT/VIN)×VOUT/VIN IRMS : effective value of the ripple current to the input capacitor IOUT : output load current Selecting the output capacitor The output capacitor should confine ESR and permissible ripple current within a stable region. Although incorporating a low-ESR capacitor will limit ripple voltage and load fluctuation, it can also hurt the stability of the feedback network. Therefore, in order to maintain a stable feedback loop when ceramic or other low-ESR capacitors are employed, special attention must be paid to providing an appropriate phase compensation scheme. A suitable output capacitor will satisfy the following formula for ESR. ESR≦⊿VL/⊿IL ⊿VL : permissible ripple voltage, ⊿IL : coil ripple current In addition, use the following formula to determine the effective value of the output capacitance permissible ripple current, and select a capacitor that allows sufficient margin to accommodate this value. IRMS =⊿IL/2√3 IRMS : effective value of ripple current to the output condenser, ⊿IL : coil ripple current Setting the soft start time To prevent output voltage startup overshoot on either channel, the capacitors connected to the SCP/SOFT 1, 2 pins – in a discharged state at power-on – are gradually charged during a delay interval, thus providing a soft start. The soft start period is the time from when the standby pins go from LOW to HIGH, starting the charge, to the time that the output voltage reaches the programmed setting. The soft start time is calculated in the following equation: tsoft＝ 0.8[V] (typ)×Cscp/soft F］ ［ Isosoft (typ: 2.3μA)[A] tsoft : soft start time, Cscp/soft : SCP/SOFT pin connection capacitance, Isosoft : charge current www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 10/16 2009.05 - Rev.A BD9853AFV Technical Note Setting the Short Circuit Protection (SCP) delay time When the soft start is complete for each channel, the output voltage stabilizes at the set value 1.35V(typ) for the SCP/SOFT1, 2 pins. When any type of short circuit occurs, the voltage at the point of the fault is reduced. In this case, when voltage at the INV pin falls to 0.56V(typ) or below, the SCP comparator sensor detects the short and further charges the SCP/SOFT pins for the shorted channel from the 1.35V(typ) level. When the SCP/SOFT pins are charged to 2.3V(typ), the Pch/Nch MOSFET is switched OFF. The elapsed time from the occurrence of the output short to the point the external FET switches OFF is calculated with the following formula: 0.95[V](typ)×Cscp/soft［F］ tscp＝ Isosofc (typ: 2.3μA)[A] tscp : SCP delay time, Cscp/soft : SCP/SOFT pin connection capacitance,Isoscp : charge current * If the current more than the capacity of power supply when the short between VOUT and GND occurs, input voltage starts to fall and under voltage lockout (UVLO) is activated at Vin < 4.15 V (typ.). The UVLO has FET driver output (OUT1H, OUT2H, OUT1L, OUT2L) off and external FETs become off. When external FETs are not operating, input voltage returns because of the short between VOUT and GND and the UVLO is canceled. But input voltage starts to fall again because the UVLO is not activated. There is possibility that a series of behavior “output short → input voltage fall → UVLO activated → external FETs off → input voltage returns → UVLO canceled → output short”. So please make provision like inserting FUSE in input line. Pin conditions with the only single channel use Pin conditions are shown in the following, when the only single channel out of 2 channels is used. Use only CH1 ・SCP/SOFT2, INV2 ⇒ GND short ・FB2, OUT2H, OUT2L ⇒ OPEN Use only CH2 ・SCP/SOFT1, INV1 ⇒ GND short ・FB1, OUT1H, OUT1L ⇒ OPEN ●Application example VCC VCC VCC 1μF 4.7μF 0.1μF REGB OUT2H OUT2L STB GND FB2 INV2 SCP/SOFT2 4.7μF RSS040P03 (ROHM) 1 2 3 1μF 4 8.2kΩ VCC OUT1H OUT1L REGA RT FB1 INV1 SCP/SOFT1 16 15 14 13 12 11 10 9 0.015μF RSS040P03 (ROHM) VOUT1 (3.3V) 4.7μH C6-K3L (MITSUMI) 4.7μH C6-K3L (MITSUMI) VCC RB081 L-20 220pF 3.3kΩ VOUT2 (2.5V) 10kΩ 120pF 22kΩ 10μF (ceramic） RB081 L-20 (ROHM) 5 RSS065 10kΩ 680pF NO3 7 (ROHM) 6 10μF (ceramic） 100kΩ 15kΩ 68pF 100kΩ RSS065 NO3 (ROHM) (ROHM) 39kΩ 8 0.015μF 47kΩ www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 11/16 2009.05 - Rev.A BD9853AFV ●I/O Equivalent Circuit OUT1H(2),OUT2H(15) Max ratings：7V(from VCC or REGB) VCC Technical Note OUT1L(3),OUT2L(14) Max ratings：7V REGA VCC REGA(4) Max ratings：7V VCC OUT1H OUT2H OUT1L OUT2L REGA REGB RT(5) Max ratings：7V REGA FB1(6),FB2(11) Max ratings：7V REGA VCC INV1(7),INV2(10) Max ratings：10V VCC VCC INV1 INV2 RT SCP/SOFT1(8),SCP/SOFT2(9) Max ratings：7V VREF REGA VCC STB(13) Max ratings：18V VCC REGB(16) Max ratings：7V(fromVCC) VCC REGB STB SCP/SOFT1 SCP/SOFT2 www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 12/16 2009.05 - Rev.A BD9853AFV ●Recommended Board Patterns Technical Note VOUT PMOS L CIN GND(IC) N MOS INV SBD COUT GND(others) There are two current loops at the behavior of switching regulator. When laying a pattern on the board, put these elements near to minimize these current loops and make the lines as short and wide as possible. And connect all GND lines at one point to reduce effects caused by above current noise to other lines. a pattern example of switching part L COUT SBD P MOS NMOS C IN Place following parts with attention about patterns VCC CREGB REGB GND CVCC 1 2 3 VCC REGB 16 15 14 CREGA 4 5 6 7 8 REGA RT 13 12 11 10 9 GND RRT ・Place CVCC, CREGA, RRT, CREGB as near to the pin as possible. ・Pattern area has to be small enough to reduce parasitic capacitance with RT terminal. www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 13/16 2009.05 - Rev.A BD9853AFV Technical Note ●Notes for use 1) Absolute maximum ratings Use of the IC in excess of absolute maximum ratings such as the applied voltage or operating temperature range may result in IC deterioration or damage. Assumptions should not be made regarding the state of the IC (short mode or open mode) when such damage is suffered. A physical safety measure such as a fuse should be implemented when use of the IC in a special mode where the absolute maximum ratings may be exceeded is anticipated. 2) GND potential Ensure a minimum GND pin potential in all operating conditions. In addition, ensure that no pins other than the GND pin carry a voltage lower than or equal to the GND pin, including during actual transient phenomena. 3) Thermal design Use a thermal design that allows for a sufficient margin in light of the power dissipation (Pd) in actual operating conditions. 4) Inter-pin shorts and mounting errors Use caution when orienting and positioning the IC for mounting on printed circuit boards. Improper mounting may result in damage to the IC. Shorts between output pins or between output pins and the power supply and GND pin caused by the presence of a foreign object may result in damage to the IC. 5) Operation in a strong electromagnetic field Use caution when using the IC in the presence of a strong electromagnetic field as doing so may cause the IC to malfunction. 6) Thermal shutdown circuit (TSD circuit) This IC incorporates a built-in thermal shutdown circuit (TSD circuit). The TSD circuit is designed only to shut the IC off to prevent runaway thermal operation. Do not continue to use the IC after operating this circuit or use the IC in an environment where the operation of the thermal shutdown circuit is assumed. 7) Testing on application boards When testing the IC on an application board, connecting a capacitor to a pin with low impedance subjects the IC to stress. Always discharge capacitors after each process or step. Ground the IC during assembly steps as an antistatic measure, and use similar caution when transporting or storing the IC. Always turn the IC's power supply off before connecting it to or removing it from a jig or fixture during the inspection process. 8) Common impedance Power supply and ground wiring should reflect consideration of the need to lower common impedance and minimize ripple as much as possible (by making wiring as short and thick as possible or rejecting ripple by incorporating inductance and capacitance). 9) Applications with modes that reverse VCC and pin potentials may cause damage to internal IC circuits. For example, such damage might occur when VCC is shorted with the GND pin while an external capacitor is charged. It is recommended to insert a diode for preventing back current flow in series with VCC or bypass diodes between VCC and each pin. Bypass diode Back current prevention diode VCC Output Pin 10) Pin short and mistake fitting Do not short-circuit between OUT pin and VCC pin, OUT pin and GND pin, or VCC pin and GND pin. When soldering the IC on circuit board, please be unusually cautious about the orientation and the position of the IC. 11) Timing resistor and capacitor Timing resistor connected between RT and GND, has to be placed near RT terminal. And pattern has to be short enough. www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 14/16 2009.05 - Rev.A BD9853AFV Technical Note 12) IC pin input This monolithic IC contains P+ isolation and PCB layers between adjacent elements in order to keep them isolated. P/N junctions are formed at the intersection of these P layers with the N layers of other elements to create a variety of parasitic elements. For example, when a resistor and transistor are connected to pins as shown in following chart,  the P/N junction functions as a parasitic diode when GND > (Pin A) for the resistor or GND > (Pin B) for the transistor (NPN).  Similarly, when GND > (Pin B) for the transistor (NPN), the parasitic diode described above combines with the N layer of other adjacent elements to operate as a parasitic NPN transistor. The formation of parasitic elements as a result of the relationships of the potentials of different pins is an inevitable result of the IC's architecture. The operation of parasitic elements can cause interference with circuit operation as well as IC malfunction and damage. For these reasons, it is necessary to use caution so that the IC is not used in a way that will trigger the operation of parasitic elements, such as by the application of voltages lower than the GND (PCB) voltage to input and output pins. Resistance (PinA) (PinB) Transistor (NPN) Ｂ Ｃ Ｎ Ｐ Ｎ ＋ (PinA) Parasitic diode ＧＮＤ ＧＮＤ Ｅ Ｐ Ｎ Ｐ ＋ Ｐ Ｎ Ｎ ＋ Ｐ Ｐ ＋ (PinB) Ｎ Ｂ Ｃ Ｅ Ｎ P substrate Parasitic diode ＧＮＤ P substrate ＧＮＤ Parasitic elementals Other adiacent components ＧＮＤ Parasitic diode ●Power Dissipation Reduction 1000 POWER DISSIPATION ： Pd(mW) 800 ※IC mounted on a ROHM standard board (70mm X 70mm X 1.6mm, glass epoxy) 600 400 200 0 0 25 50 75 100 125 150 175 AMBIENT TEMPERATURE：Ta(℃) www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 15/16 2009.05 - Rev.A BD9853AFV ●Ordering part number Technical Note B D 9 Part No. 8 5 3 A F V - E 2 Part No. Package FV: SSOP-B16 Packaging and forming specification E2: Embossed tape and reel SSOP-B16 5.0±0.2 16 9 Tape Quantity Embossed carrier tape 2500pcs E2 The direction is the 1pin of product is at the upper left when you hold 6.4±0.3 4.4±0.2 0.3Min. Direction of feed ( reel on the left hand and you pull out the tape on the right hand ) 1 8 0.15±0.1 1.15±0.1 0.10 0.1 0.65 0.22±0.1 1pin (Unit : mm) Direction of feed Reel ∗ Order quantity needs to be multiple of the minimum quantity. www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 16/16 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