RT9173BGL5 Richtek

RT9173B 2A Bus Termination Regulator General Description Features The RT9173B regulator is designed to convert voltage zz z zz Support Both DDR I (1.25V ) and DDR II (0.9V ) TT TT supplies ranging from 1.7V to 6V into a desired output Requirements voltage of which adjusted by two external voltage divider zz z zz SOP-8 and TO-252-5 Packages resistors. The regulator is capable of sourcing or sinking zz z zz Capable of Sourcing and Sinking Current up to 2A of current while regulating an output voltage to zz z zz Current-limiting Protection within 40mV. zz z zz Thermal Protection zz z zz Integrated Power MOSFETs The RT9173B, used in conjunction with series termination zz z zz Generates Termination Voltages for SSTL-2 resistors, provides an excellent voltage source for active zz z zz High Accuracy Output Voltage at Full-Load termination schemes of high speed transmission lines as zz z zz Adjustable V by External Resistors OUT those seen in high speed memory buses and distributed zz z zz Minimum External Components backplane designs. The voltage output of the regulator can zz z zz Shutdown for Standby or Suspend Mode Operation be used as a termination voltage for DDR SDRAM. with High-impedance Output Current limits in both sourcing and sinking mode, plus on- zz z zz RoHS Compliant and 100% Lead (Pb)-Free chip thermal shutdown make the circuit tolerant of the output fault conditions. Applications The RT9173B are available in the popular 5-lead TO-252 z DDR Memory Termination Supply and fused SOP-8 (the multiple V pins on the SOP-8 CNTL z Active Termination Buses package are internally connected but lowest thermal z Desktop PC/AGP Graphics resistance) surface mount packages. z Set Top Box/IPC z Supply Splitter Ordering Information Pin Configurations RT9173B (TOP VIEW) Package Type S : SOP-8 VIN 8 VCNTL L5 : TO-252-5 GND 2 7 VCNTL Lead Plating System REFEN 3 6 VCNTL P : Pb Free VOUT 4 5 VCNTL G : Green (Halogen Free and Pb Free) Note : SOP-8 Richtek products are : RoHS compliant and compatible with the current require- 5 VOUT ments of IPC/JEDEC J-STD-020. 4 REFEN Suitable for use in SnPb or Pb-free soldering processes. 3 VCNTL (TAB) 2 GND 1 VIN TO-252-5 DS9173B-10 April 2011 www.richtek.com 1RT9173B Typical Application Circuit V = 3.3V CNTL V = 2.5V IN R C TT CNTL C R VCNTL IN 1 VIN RT9173B REFEN VOUT 2N7002 EN GND R 2 C OUT R DUMMY R = R = 100k, R = 50 / 33 / 25 1 2 TT C = 10F (Ceramic) + 1000F under the worst case testing condition OUT(MIN) R = 1k as for VOUT discharge when VIN is not present but VCNTL is present DUMMY C = 470F (Low ESR), C = 47F IN CNTL Test Circuit 3.3V 2.5V VCNTL VIN RT9173B V OUT 1.25V REFEN VOUT V GND C OUT I L Figure 1. Output Voltage Tolerance, V OUT 3.3V 2.5V A VCNTL VIN 1.25V RT9173B V OUT 1.25V REFEN VOUT 0V GND C OUT R L 0.2V V R and C L OUT Time deleay Figure 2. Current in Shutdown Mode, SHDN www.richtek.com DS9173B-10 April 2011 2