SC486 Datasheet | SEMTECH

Description The SC486 is a bination switching regulator and linear source/sink regulator intended for DDR1/2/3 memory systems. The switching regulator is used 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 linear source/sink regulator is used to generate the memory termination voltage, VTT, with the ability to source and sink a 3A peak current. .. 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 soft-switching. For the VTT regulator, the output voltage tracks VREF, 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. Additional Features include cycle-by-cycle current limiting, digital soft-start, power good (all VDDQ only) and over-voltage and under-voltage protection (VDDQ and VTT). All 3 outputs (VDDQ, VTT and REF) are actively discharged when VDDQ is disabled, reducing external ponent count and cost. The SC486 is available in a 24 pin MLPQ 4mmx4mm Lead-free package. Features ‹ DDR1, DDR2 and DDR3 patible ‹ Constant on-time controller for fast dynamic ‹ ‹ ‹ ‹ ‹ ‹ ‹ ‹ ‹ ‹ ‹ ‹ ‹ ‹ ‹ ‹ ‹ response on VDDQ Programmable VDDQ range - 1.5V to 3V 1% Internal Reference (2% System Accuracy) Resistor programmable on time for VDDQ VCCA/VDDP range = 4.5V to 5.5V...