System Power Supply for TV Series FET Controller Type 3ch System Power Supply ICs No.09034EAT03 BD8621EFV ●Description BD8621EFV has realized the high performance and reliability required as a power supply for thin-screen TV. With built-in FET 1ch current mode control, the DC/DC Converter series has the advantage of high-speed load response and wide phase margin. Due to the high-speed load response, it is most suitable for TV-purpose processors with increasingly high performance, and due to the wide phase margin it leaves a good margin for board pattern & constant setting and so facilitates its application design. As a high-reliability design, it has various built-in protection circuits (overcurrent protection, output voltage abnormal protection, thermal protection, and off-latch function at the time of abnormality etc.), therefore as an advantage it does not easily damage in every possible abnormal condition such as all-pin short circuit test etc. and hence most suitable for thin-screen TV which requires the high reliability. ●Features 1) 3A output current 2) Low RDS(ON) internal switches (PchMOS:75mΩ，NchMOS:55mΩ) 3) ±1% reference voltage accuracy 4) Programmable frequency : 250kHz-1MHz 5) (Frequency in programmable by adjusting RT resistance or synchronizing with SYNCLK terminal.) 6) Terminal RT OPEN/SHORT detecting function 7) Over current protection function 8) Output over voltage/low voltage protection function (over : FB > VREF +60mV , low : FB < VREF -60mV) 9) Timer off latch function in abnormal circumstances 10) Thermal shutdown function 11) Under voltage protection 12) Soft start/start delay circuit 13) Soft start time out function 14) Protecting BUS function with terminal PDET 15) HTSSOP-B20 package www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 1/14 2009.05 - Rev.A Technical Note BD8621EFV ●Electrical characteristics (Unless otherwise noted Ta=25℃, VIN=3.3V, GND=0V) Specification value Parameter Symbol MIN TYP VIN supply current (operating) IQ_active 220 VIN supply current (standby) IQ_stby 0 Reference voltage (VREF) VREF 0.792 0.8 60 Output rise detection voltage VOVP 30 Output decrease detection voltage VLVP -60 -90 MAX 350 1 0.808 90 -30 UNIT Condition μA μA V mV VFB = 0.83V, VFC = 1V VEN = 0V mV Monitoring FB terminal Monitoring FB terminal VPDET< 0.3V RRT= 220kΩ ISW = 1A ISW = 1A Terminal PDET output current IPDET 0.4 mA Oscillation frequency fOSC 500 550 600 kHz Pch FET ON resistance RPFET 75 110 mΩ mΩ Nch FET ON resistance RNFET 55 90 UVLO voltage VUVLO 2.35 2.50 2.65 V SW leak current ILSW 0 1 μA VEN= 0V, VIN = 5.5V EN terminal H threshold voltage VENH 1.1 V EN terminal L threshold voltage VENL 0.4 V FC sink current IFCSI 10 20 μA FC source current IFCSO -20 -10 μA SS/DELAY terminal source current ISSSO 2 4 6 μA Terminal PDET pull-up resistor RPDET 100 170 250 kΩ VFB :FB terminal voltage, VEN :EN terminal voltage, VFC :FC terminal voltage, VPDET: PDET terminal voltage Current capability should not exceed Pd. www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 2/14 2009.05 - Rev.A Technical Note BD8621EFV ●Block Diagram Fig1 Block diagram ●Pin Description No. 1 2 Symbol SGND FB 3 PDET 4 5 6 7 8 9 10 11 12 13 14 SW SW PGND PGND PGND SW SW VIN VIN VIN VIN 15 16 17 18 19 20 Description Signal GND terminal Feed back terminal Explanation Small signal system GND Output voltage detection Off latch signal output Protecting BUS communication terminal Output terminal Switching output Power GND terminal GND for power MOSFET Output terminal Power Mos output Power supply input terminal Power supply input. The decoupling is done to PGND Synchronizable switching output terminal frequency with external clock EN Enable input ON/OFF control for device operation TEST Terminal for test SGND short in the set. Soft start adjustment capacity connection The soft start time is adjusted with the connected SS/DELAY terminal capacitor FC Error amplifier output Error amplifier phase compensation point Frequency adjustment resistance connection The switching frequency is set by the connected RT terminal resistance REG Internal Regulator www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 3/14 2009.05 - Rev.A Technical Note BD8621EFV ●Pin equivalence circuit diagram No. Symbol 1 SGND Explanation Terminal equivalent circuit diagram GND (connected 0V) VIN 2 FB Output voltage detection terminal 2 SGND 3 PDET Protecting BUS I/O terminal VIN 4,5,9,10 SW 54 56 97 10 Output terminal PGND 6,7,8 PGND 11,12,13,14 VIN Power GND (Same voltage as SGND) Power supply input terminal www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 4/14 2009.05 - Rev.A Technical Note BD8621EFV No. Symbol 15 REG 16 EN 17 TEST Explanation Terminal equivalent circuit diagram Internal Regulator output voltage Enable terminal Using at test mode www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 5/14 2009.05 - Rev.A Technical Note BD8621EFV No. Symbol Explanation 18 SS /DELAY Soft start time adjustment terminal 19 FC Error amplifier compensation terminal 20 RT Oscillator frequency adjustment terminal www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. Terminal equivalent circuit diagram 6/14 2009.05 - Rev.A Technical Note BD8621EFV ●Operation description Enable control The device can be controlled ON/OFF by EN terminal (16 pin) voltage. An internal circuit starts when VEN reaches 1.1V. EN terminal voltage SS terminal voltage Output setting voltage Fig.2 ON/OFF transition wave form in EN controlling www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 7/14 2009.05 - Rev.A Technical Note BD8621EFV Soft start time set function As for BD8621EFV, output can do soft start without overshoot by charging soft start capacity (CSS) connected between SS and SGND terminal. Also, soft start time (tss) can be set by setting soft start capacity (CSS) arbitrarily. OSC oscillation frequency setting function The output oscillation frequency can be set by connecting resistance between terminal RT (20 pins) and SGND (range = 250kHz - 1MHz) The relation between RT terminal resistance and the oscillation frequency follows Fig.3. Frequency [kHz] 1000 10 10 100 1000 10000 RT terminal resistance [kΩ] Fig.3 RT resistance-oscillation frequency Switching frequency synchronization An internal transmitter of BD8621EFV can be synchronized with the external clock signal connected with the terminal SYNCLK (15 pins). The frequency of external clock can be set within the range of 250kHz-1MHz. In this case, please set the RT resistance that may become about -20% value of the external clock frequency. * Be short-circuited SYNCLK terminal to SGND when a frequency synchronous function is not used. www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 8/14 2009.05 - Rev.A Technical Note BD8621EFV ●Protection function Protection circuit is effective for destruction prevention due to accident so that avoid using under continuous protection operation. Low voltage protection function (LVP) The voltage of the terminal FB (2 pins) is compared with internal reference voltage VREF. If FB terminal voltage falls below VLVP(= VREF -60mV) and the state continues for 500us, output changes to low voltage and the state is fixed. In that case , PDET (3pin) output changes to L. Table 1 output low voltage protection function Low voltage protection Low voltage protection EN terminal SS terminal FB terminal function operation >VENH ＜VLVP >1.4V(typ) ON Effective ＞VLVP OFF <1.4V(typ) Invalidity OFF <VENL Invalidity OFF * 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). 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 +60mV) and the state is continues for 500usec, output changes to low voltage and the state is fixed. Table 2 output overvoltage protection function Over voltage Over voltage EN terminal SS terminal FB terminal protection function protection operation >VENH >1.4V(typ) ＞VOVP ON Effective ＜VOVP OFF <1.4V(typ) Invalidity OFF <VENL Invalidity OFF * 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＋60ｍV FB terminal voltage VREF VREF-60ｍV 0 ON Protection OFF LVP PDET terminal OVP LVP HIGH LOW Fig.4 Output voltage error detection range www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 9/14 2009.05 - Rev.A Technical Note BD8621EFV Under voltage lock out protection (UVLO) As for BD8621EFV, the power-supply voltage decrease detection protection circuit is built in. It the input voltage decrease below the UVLO voltage (2.5V typ), the device state changes to the standby mode (Moreover, to prevent the chattering of the output) hysteresis width of 100mV(typ) has been installed in the UVLO cancel voltage. 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. Terminal RT opening/short protection function is available if the state continue for 500usec, abnormal detection operates when the state continues about 500μsec(typ). Soft start time-out function If VSS doesn't exceed VSSTH within 64msec (typ) since a soft start began, BD8621EFV controls an off latch. Vo is fixed in a low level. Fig.5 Soft start time-out Thermal shut down function Thermal shut down circuit (TSD circuit) is built into BD8621EFV. 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. 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 for about 500μsec(typ), the output is fixed in a low level. www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 10/14 2009.05 - Rev.A Technical Note BD8621EFV Protecting BUS function with terminal PDET The terminal PDET (3 pins) monitors whether IC is normal or not. When IC becomes abnormal, the PDET output is reduced at "L" level with the output voltage fixed “L” level at the same time. Moreover, it is possible to make the output fix in a low level by compulsorily reducing the terminal PDET at "L" level from the outside. When two or more BD8621EFV is used in the application, this function prevents the IC from destroying, because one IC error transmits all other ICs by PDET line in the condition that PDET terminals are connected each other. Fig.6 Protecting BUS communication ※Please give the terminal PDET as OPEN when you do not use protecting BUS function. Error detection (off latch) release method BD8621EFV enters the state of an off latch when the protection function operates. To release the off latch state, EN terminal voltage should be changed to low level once time. www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 11/14 2009.05 - Rev.A Technical Note BD8621EFV ●Each characteristic reference data VIN = 5V Io = 3A Vout : 20mV/div VIN = 5V Vout : 100mV/div 1usec/div Io = 1A/div Fig.7 Output load response Fig.8 Output ripple 100 VIN = 2V/div VIN = 3.3V 90 Efficiency [%] 80 [%] 70 VOUT = 0.5V/div VIN = 5.0V 60 50 SS = 2V/div 効率 40 30 VOUT = 1.2V 20 10 10msec/div 0 10 100 1000 10000 Load current [mA] Fig.9 Efficiency Fig.10 Soft start OUTPUT VOLTAGE : Vo[V] 1.50 1.40 VIN = 5.0V VOUT = 1.2V 1.30 1.20 1.10 1.00 0.0000 0.5000 1.0000 1.5000 2.0000 2.5000 3.0000 LOAD CURRENT [A] 0.810 5.0 0.808 VIN = 3.3V S S C H A R G E C UR R E NT : Is s [μ A ] E R R OR A MP R E F E R E NC E VOL T A G E : VR E F [V] Fig.11 Regulation 0.806 0.804 0.802 0.800 0.798 0.796 0.794 0.792 4.8 VIN = 3.3V 4.5 4.3 4.0 3.8 3.5 3.3 0.790 -25 0 25 50 75 100 www.rohm.com 0 25 50 75 AMB IE NT T E MP E R AT UR E : T a [℃] Fig.12 Reference voltage - Temperature characteristic © 2009 ROHM Co., Ltd. All rights reserved. 3.0 -25 AMB IE NT T E MP E R AT UR E : T a [℃] 12/14 Fig.13 SS Charging current - Temperature characteristic 2009.05 - Rev.A 100 Technical Note BD8621EFV 600.0 600.0 590.0 590.0 F R E Q U E N C Y : F o s c [k H z ] Ta = 25℃ 580.0 FREQUENCY : Fosc [kHz] 570.0 560.0 550.0 540.0 530.0 520.0 510.0 VIN = 3.3V 580.0 570.0 560.0 550.0 540.0 530.0 520.0 510.0 500.0 500.0 2.5 3 3.5 4 4.5 5 5.5 -25 0 25 INPUT VOLTAGE : Vin [V] Fig.14 Switching frequency-power-supply voltage 75 100 Fig.15 Switching frequency-temperature characteristic 110.00 100.0 90.0 100.00 80.0 O N‐R E S IS T A NC E : R on [mΩ ] O N‐R E S IS T A NC E : R on [mΩ ] 50 AMB IE NT T E MP E R AT UR E : T a [℃] Ta = 25℃ 70.0 60.0 50.0 40.0 30.0 20.0 VIN = 3.3V 90.00 80.00 70.00 60.00 50.00 40.00 10.0 30.00 0.0 2.5 3 3.5 4 4.5 5 -25 5.5 0 Fig.16 PMOS on resistance-power-supply voltage 50 75 100 Fig.17 PMOS on resistance-temperature characteristic 90.00 100.0 90.0 80.00 80.0 O N‐R E S IS T A NC E : R on [mΩ ] O N‐R E S IS T A NC E : R on [mΩ ] 25 AMB IE NT T E MP E R AT UR E : T a [℃] INP UT VO L T AG E : V in [V] Ta = 25℃ 70.0 60.0 50.0 40.0 30.0 20.0 VIN = 3.3V 70.00 60.00 50.00 40.00 30.00 10.0 20.00 0.0 2.5 3 3.5 4 4.5 5 10.00 5.5 -25 0 INP UT VO L T AG E : Vin [V] Fig.18 NMOS on resistance-power-supply voltage 50 75 100 Fig.19 NMOS on resistance-temperature characteristic 400.0 1.00 VIN = 3.3V 0.90 350.0 0.80 Ta = 25℃ 300.0 CIRCUIT CURRENT: Icc [uA] E N VO L T A G E H IG H : VE NH [V] 25 AMB IE NT T E MP E R AT UR E : T a [℃] 0.70 0.60 0.50 0.40 0.30 0.20 250.0 200.0 VFB = 0.83V VFC = 1.0V SW = High 150.0 100.0 50.0 0.10 0.0 0.00 2.5 -25 0 25 50 75 100 AMB IE NT T E MP E R AT UR E : T a [℃] Fig.20 Terminal EN H voltage-temperature characteristic www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 13/14 3 3.5 4 4.5 5 5.5 INPUT VOLTAGE : Vin [V] Fig.21 Circuit current-power-supply voltage characteristic 2009.05 - Rev.A Technical Note BD8621EFV ●Ordering part number B D 8 Part No 6 2 1 E Part No. F V - Package EFV: HTSSOP-B20 E 2 Packaging and forming specification E2: Embossed tape and reel HTSSOP-B20 <Dimension> <Tape and Reel information> 6.5 ± 0.1 11 6.4 ± 0.2 4.4 ± 0.1 0.5 ± 0.15 1.0 ± 0.2 20 1 10 Embossed carrier tape Quantity 2500pcs Direction of feed 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) 0.17 +0.05 −0.03 S 0.08 S 1234 1234 1234 www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 1pin 1234 （Unit:mm) 1234 Reel 1234 0.2 +0.05 −0.04 1234 0.65 1234 1.0Max. 0.85 ± 0.05 0.08 ± 0.05 0.325 Tape Direction of feed ※When you order , please order in times the amount of package quantity. 14/14 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. 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