CYT9174 Features Description The CYT9174 regulator is designed to convert ¾ Support Both DDR 1 (1.25VTT) and DDR 2 (0.9VTT) Requirements voltage supplies ranging from 1.6V to 6V into a desired output voltage, which is adjusted by two ¾ SOP-8 Packages external voltage divider resistors. The regulator is ¾ Capable of Sourcing and Sinking Current 2.0A capable of sourcing or sinking up to 2.0A of current ¾ Current-limiting Protection while regulating an output voltage to within 2% ¾ Thermal Protection (DDR 1 or DDR 2) or less. ¾ Current-shoot-through protection The CYT9174, used in conjunction with series ¾ Integrated Power MOSFETs termination resistors, provides an excellent voltage ¾ Generates Termination Voltages for SSTL-2 source for active termination schemes of high ¾ High Accuracy Output Voltage at Full-Load speed transmission lines as those seen in high ¾ Adjustable Vout by External Resistors speed memory buses and distributed back-plane ¾ Minimum External Components designs. The voltage output of the regulator can be ¾ Shutdown for Standby or Suspend Mode Operation with High-impedance Output used as a termination voltage for DDR SDRAM. Current limits in both sourcing and sinking mode, plus on-chip thermal shutdown make the circuit tolerant of the output fault conditions. Pin Configuration Application ¾ DDR Memory Termination ¾ Active Termination Buses ¾ Supply Splitter Pin Description Pin Name U Pin function VIN Power Input GND Ground VCNTL Gate Drive Voltage REFEN Reference Voltage input and Chip Enable VOUT Output Voltage Block Diagram VCNTL Current Limiting Sensor REFEN Thermal CNTL VIN VOUT GND All contents are subject to change without prior notice 1 CYT9174 Absolute Maximum Rating (1) Parameter Symbol Value Unit Input Voltage VIN 6 V Power Dissipation PD Internally Limited -- ESD Rating -- 3 KV TS -65 to 150 °C TLEAD 260 °C ΘJC 15.7 ºC/W Storage Temperature Range Lead Temperature (Soldering, 5 sec.) Package Thermal Resistance Electrical Characteristics VIN=2.5V, VCNTL=3.3V, VREFEN=1.25V, COUT=10µF (Ceramic)), TA=25ºC, unless otherwise specified Parameter Symbol Test Conditions Min Typ Max Units Output Offset Voltage (2) VOS IOUT = 0A -20 -5 20 mV IL : 0A→2.0A -- 0.5 2 IL : 0A→-2.0A -- 0.5 2 Keep VCNTL≥VIN on 1.6 2.5/1.8 -- -- 3.3 6 -- 1 90 µA -- 2.5 -- A -- 1.4 3 mA -- 100 -- Load Regulation (DDR 1/2) Input Voltage Range (DDR 1/2) Current In Shutdown Mode |∆VLOAD| VIN VCNTL ISHDN operation power on and power off sequences VREFEN ＜0.2V, RL = 180Ω % V Short Circuit Protection Current limit ILIMIT Quiescent Current IQ IL=2.0A Over Temperature Protection Thermal Shutdown Temperature Thermal Shutdown Hysterresis TCASE 3.3V ≤ VCNTL ≤5 V ºC Guaranteed by design -- 30 -- Shutdown Function Shutdown Threshold Output=High 0.8 -- -- Trigger Output=Low -- -- 0.2 Note 1: Exceeding the absolute maximum rating may damage the device. Note 2: VOS offset is the voltage measurement defined as VOUT subtracted from VREFEN All contents are subject to change without prior notice 2 V CYT9174 Application Information Layout Consideration The Internal parasitic diode CYT9174 regulator is packaged in Avoid forward-bias internal parasitic diode, thermally enhanced plastic SOP-8 package. This VOUT to VCNTL, and VOUT to VIN, the VOUT should not small footprint package is unable to convectively be forced same voltage respect to ground on this dissipate the heat generated when the regulator is pin while the VCNTL or VIN is disappeared. operating at high current levels. In order to control Consideration while designs the resistance of die operating temperatures, the PC board layout voltage divider should allow for maximum possible copper area at Make sure the sinking current capability of pull-down NMOS if the lower resistance was chosen the VCNTL pins of the CYT9174. The multiple VCNTL pins on the SOP-8 package so that the voltage on VREFEN is below 0.2V. are internally connected, but lowest thermal In addition to item1, the capacitor and voltage resistance will result if these pins are tightly divider form the low-pass filter. There are two connected on the PC board. This will also aid heat reasons doing this design; one is for output voltage dissipation at high power levels. soft-start while another is for noise immunity. If the large copper around the IC is unavailable, a buried layer may be used as a heat Thermal Consideration CYT9174 regulators have internal thermal limiting circuitry designed to protect the device during overload conditions. For continuous normal load conditions however, the maximum junction spreader, Use via to conduct the heat into the buried or backside of PCB layer. The via should be small enough to retain solder when the board is wave-soldered. temperature rating of 150°C must not be exceeded. Terminator Resis Higher continuous currents or ambient temperature R0 require additional heatsinking. Heat sinking to the CYT9174 IC package must consider the worst case power dissipation which may occur. VOUT R2 R3 R4 REFEN It should also be noted that with the VCNTL equal to 5V, the point of thermal shutdown will be degraded by approx. 20°C compared to the VCNTL R1 R5 CYT9174 VOUT equipped with 3.3V. It is highly recommended that R6 R7 R8 R9 to use the 3.3V rail acting as the VCNTL so as to minimize the thermal concern of the CYT9174 in the SOP-8 package. All contents are subject to change without prior notice 3 RN RN1 BUS(0) BUS(1) BUS(2) BUS(3) BUS(4) BUS(5) BUS(6) BUS(7) BUS(8) BUS(9) BUS(N+1) BUS(N) CYT9174 Application Diagram R1 = R2 = 100KΩ, RTT = 50Ω/33Ω/25Ω COUT, min = 10µF(Ceramic) + 1000µF under the worst case testing condition RDUMMY = 1KΩ as for VOUT discharge when VIN is not present but VCNTL is present CSS = 1µF, CIN = 470µF(Low ESR), CCNTL = 47µF All contents are subject to change without prior notice 4 CYT9174 Outline Drawing SOP-8 1 8 2 7 3 6 D B B1 5 4 A1 E H C A DIMN A A1 B B1 C D H E DIMENSIONS INCHES MM MIN MAX MIN MAX 0.0532 0.0688 0.0040 0.0098 0.0130 0.0200 0.050 BSC 0.0075 0.0098 0.1890 0.1968 0.2284 0.2440 0.1497 0.1574 All contents are subject to change without prior notice 5 1.35 1.75 0.10 0.25 0.33 0.51 1.27 BSC 0.19 0.25 4.80 5.00 5.80 6.20 3.80 4.00