BD8629FS

System Power Supply for TV Series FET Controller Type 3ch System Power Supply ICs BD8629FS No.09034EAT07 ●Description BD8629FS 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) High efficiency in all load area 2) 2.0A output current 3) Low RDS(ON) internal switches (PchMOS:170mΩ, NchMOS:130mΩ) 4) ±1% reference voltage accuracy 5) Programmable frequency : 250kHz-1MHz 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) SSOP-A16 package www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 1/11 2009.05 - Rev.A BD8629FS ●Electrical characteristic (Unless otherwise noted Ta=25℃, VIN=5.6V) Technical Note Specification value UNIT Condition MIN TYP MAX VIN supply current (operating) IQ_active 1.3 2.0 mA VFB = 0.83V, VFC = 1V VEN = 0V μA VIN supply current (standby) IQ_stby 350 700 Reference voltage (VREF) VREF 0.792 0.8 0.808 V Output rise detection voltage VOVP 30 60 90 mV Monitoring FB terminal Output decrease detection voltage VLVP -90 -60 -30 mV Monitoring FB terminal Terminal PDET output current IPDET 1 mA VPDET< 0.5V ROSC = 220kΩ Oscillation frequency fOSC 500 550 600 kHz Pch FET ON resistance RPFET 170 240 mΩ ISW = 1A Nch FET ON resistance RNFET 130 200 mΩ ISW = -1A UVLO voltage VUVLO 3.8 4.0 4.2 V μA SW leak current ILSW 0 1 VEN= 0V, VIN = 6V EN terminal H threshold voltage VENH 2.0 V EN terminal L threshold voltage VENL 0.5 V μA SS/DELAY terminal source current ISSSO 2 4 6 VFB :FB terminal voltage, VEN :EN terminal voltage, VFC :FC terminal voltage, VPDET: PDET terminal voltage Current capability should not exceed Pd. Parameter Symbol Permissible loss 1 (70mm×70mm, thickness 1.6mm, and one layer glass epoxy substrates) When mounting substrate Permissible loss ： PD [W] 0.75 0.5 0.25 0 0 25 50 75 100 125 150 Surrounding temperature ： Ta [℃] Fig. 1 heat decrease curve www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 2/11 2009.05 - Rev.A BD8629FS ●Block Diagram 14 SS/DELAY VIN Technical Note 16 RT 15 FC 13 EN 12 REG 11 10 REG OSC en enable PWM CONTROL REG VIN REG Detec t Abnor ma l Volt ag e and Star t error Er r A M P SG D 1 N PDET 3 SW 4 S hut Down REG 5 6 6 7 SW Pre drive FB 2 Fig.2 Block diagram ● Pin description No. Symbol 1 SGND 2 FB 3 4 5 6 7 8 9 10 11 12 13 14 15 16 PDET SW PGND PGND SW SW VIN VIN VIN REG EN Description Signal GND terminal Feed back terminal Off latch signal output Output terminal Power GND terminal Output terminal Power supply input terminal Explanation Small signal system GND Output voltage detection Reset output Switching output GND for power MOSFET Power Mos output Power supply input. The decoupling is done to PGND Internal regulator ON/OFF control for device operation The soft start time is adjusted with the connected capacitor Error amplifier phase compensation point The switching frequency is set by the connected resistance Internal regulator Enable input Soft start adjustment capacity connection SS/DELAY terminal FC Error amplifier output Frequency adjustment resistance connection RT terminal www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. ND PG 8 9 3/11 2009.05 - Rev.A BD8629FS ●Pin equivalence circuit diagram No. Symbol 1 SGND Technical Note Explanation Terminal equivalent circuit diagram GND (connected 0V) VIN 2 FB Output voltage detection terminal 2 SGND 3 PDET Off latch signal output terminal VIN 4,7,8 SW Output terminal 4 5 7 6 8 7 PGND 5,6 PGND Power GND (Same voltage as SGND) 9,10,11 VIN Power supply input terminal www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 4/11 2009.05 - Rev.A BD8629FS No. Symbol Explanation Technical Note Terminal equivalent circuit diagram 12 REG Internal regulator output terminal 13 EN Enable terminal www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 5/11 2009.05 - Rev.A BD8629FS No. Symbol Explanation Technical Note Terminal equivalent circuit diagram 14 SS Soft start time adjustment terminal 15 FC Error amplifier compensation terminal 16 RT Oscillator frequency adjustment terminal www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 6/11 2009.05 - Rev.A BD8629FS ● Operation description Enable control The device can be controlled ON/OFF by EN terminal (13 pin) voltage. An internal circuit starts when VEN reaches 1.4V. VEN Technical Note EN terminal voltage VENTH 0 VSSCLM VSS SS terminal voltage VSSTH 0 VO Output setting voltage 0 tSS VPDET PDET 0 Fig. 3 ON/OFF transition wave form in EN controlling Soft start time set function As for BD8629FS, 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. www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 7/11 2009.05 - Rev.A BD8629FS Technical Note OSC oscillation frequency setting function The output oscillation frequency can be set by connecting resistance between terminal RT (16 pins) and SGND (range = 250kHz - 1MHz) The relation between RT terminal resistance and the oscillation frequency follows Fig.4. 10000 Frequency [kHz] 1000 100 10 10 100 1000 10000 RT terminal resistance [kΩ] Fig. 4 RT resistance-oscillation frequency www.rohm.com © 2009 ROHM Co., Ltd. All rights reserved. 8/11 2009.05 - Rev.A BD8629FS Technical Note ● 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 operation 1.4V(typ) Effective >VIHEN >VLVP OFF 1.4V(typ) Effective >VIHEN