RT9205ACS

Preliminary RT9205/A Dual Regulators - Synchronous Buck PWM DC-DC and Linear Controller General Description The RT9205/A is a dual-output power controllers designed for high performance graphics cards and personal computers. The IC integrates a synchronous buck controller, a linear controller and protection functions into a small 14-pin package. The RT9205/A uses an internal compensated voltage mode PWM control for simplying design. An internal 0.8V reference allows the output voltage to be precisely regulated to meet low output voltage requirement. A fixed 300kHz oscillation frequency reduces the component size for saving board area. The RT9205/A also features over voltage protection (OVP) and under voltage lock-out (UVLO). Features Operates at 5V 0.8V Internal Reference Drives Two N-channel MOSFET Voltage Mode PWM Control Fast Transient Response Fixed 300kHz Oscillator Frequency Dynamic 0~100% Duty Cycle Internal PWM Loop Compensation Internal Soft-Start Adaptive Non-overlapping Gate Driver Over-voltage Protection Uses Lower MOSFET Pin Configurations Part Number RT9205/ACS (Plastic SOP-14) Pin Configurations TOP VIEW LGATE 1 PGND 2 GND 3 VCC 4 DRV 5 FBL 6 NC 7 14 13 12 11 10 9 8 Applications PC Motherboard Cable Modems, Set-Top-Box, and XDSL Modems DSP and Core Communications Processor Supplies Memory Power Supplies Personal Computer Peripherals Industrial Power Supplies 5V Input DC-DC Regulators Low Voltage Distributed Power Supplies Graphic Cards UGATE BOOT NC NC NC FB NC Ordering Information RT9205/A Package Type S : SOP-14 Operating Temperature Range C : Commercial Standard UVP : Hiccup Mode UVP : Latch Mode DS9205/A-03 May 2003 www.richtek.com 1 2 5V 5V L1 1µ H Be Careful during La you t pha se C1 1µ F www.richtek.com 4 VCC 5 DRV UGATE 0.8V D1 1N5819 RT9205/A Typical Application Circuit 5V + CE1 100 µF Q1 2SD180 2 BOOT 14 G1 S2 G2 R3 200 R4 200 C7 10n F VOUT1 = 0.8V*(1+R3/R4) 13 2 D1 D2 D2 5 pha se C3 0.1µF 1 S1 7 6 C2 1µ F PHKD6N02LT D1 8 + R1 390 CE2 680 µF L2 5µ H VOUT1 1.6V Preliminary 6 FBL LGATE 1 4 9 VOUT2 3.4V VOUT2 = 0.8*(1+R1/R2) R2 120 3 Fig.1 RT9205/A powered form 5V RT9205/A FB PGND GND 3 2 R2 < 1K R4 < 1K C5 1µ F C6 1µ F + CE5 470 µF C4 10n F + CE3 680 µF LE SR + CE4 680 µF LE SR Pull FB tra ce out after C OUT DS9205/A-03 May 2003 DS9205/A-03 May 2003 5V 12V 5V R5 2.2 R6 10 L1 1uH Be Careful dur ing Layout 3.3V + CE 1 100uF 4 VCC 13 BOOT C1 1uF C2 0.1uF + + Q1 2SD5706 5 DRV UGATE 14 PHB66NQ03LT C3 1uF CE2 1000uF CE3 L2 1000uF 5uH C5 1uF CE5 1000uF LESR VOU T1 1.7V Suggest use Transistor + CE4 + + R1 0.8V 6 430 FB RT9205/A C4 10nF R3 200 R4 200 C7 10nF VO UT 1 = 0 .8V*(1+R3/R4) Preliminary V OUT2 = 0.8V*(1+R1/R2) VOUT2 2.5V 9 GND 3 FBL LGATE 1 PHB108NQ03LT Phase + C6 1uF CE7 CE5 CE4 1000uF LESR 1000uF LESR Pull FB tr ace out after COUT Fig.2 RT9205/A powered from 12V PGND R2 200 R2