SC488 Datasheet | SEMTECH

POWER MANAGEMENT Description The SC488 is a bination switching regulator and linear source/sink regulator intended for DDR1/2 memory systems. The purpose of the switching regulator is to generate the supply voltage, VDDQ, for the memory system. It is a pseudo-fixed frequency constant on-time controller designed for high efficiency, superior DC accuracy, and fast transient response. The purpose of the linear source/sink regulator is to generate the memory termination voltage, VTT, with the ability to source and sink 2.8A peak cur.. rents. For the VDDQ regulator, the switching frequency is constant until a step in load or line voltage occurs at which time the pulse density, i.e., frequency, will increase or decrease to counter the transient change in output or input voltage. After the transient, the frequency will return to steady-state operation. At lighter loads, the selectable Power-Save Mode enables the PWM converter to reduce its switching frequency and improve efficiency. The integrated gate drivers feature adaptive shoot-through protection and softswitching. Additional Features include cycle-by-cycle current limiting, digital soft-start, over-voltage and under-voltage protection and a power good flag. For the VTT regulator, the output voltage tracks REF, which is ½ VDDQ to provide an accurate termination voltage. The VTT output is generated from a 1.2V to VDDQ input by a linear source/sink regulator which is designed for high DC accuracy, fast transient response, and low external ponent count. All three outputs (VDDQ, VTT and REF) are actively discharged when VDDQ is disabled, reducing external ponent count and cost. The SC488 is available in a 24-pin MLPQ (4x4 mm) package. plete DDR1/2/3 Memory Power Supply Features Constant On-Time Controller for Fast Dynamic Response on VDDQ DDR1/DDR2/DDR3 patible VDDQ = Fixed 1.8V or 2.5V, or Adjustable From 1.5V to 3.0V 1.5% Internal Reference (2.5% System Accuracy) Resistor Programmable...