SC486 is a power management chip for DDR1/2/3 memory systems from Semtech. It integrates switching power supply and linear source/sink regulator functions. The switching regulator is used to provide the supply voltage VDDQ for the memory system. It is a pseudo-fixed frequency constant on-time controller designed for high efficiency, high accuracy DC voltage 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 component count. Additional features include cycle-by-cycle current limiting.
The SC486 is a combination switching regulator and linear source/sink regulator designed for DDR1, DDR2 and DDR3 memory systems. It provides a programmable VDDQ output (1.5 V‑3 V) and a VTT termination voltage with up to 3 A peak source/sink capability, while maintaining high efficiency and fast transient response.
The document includes functional features, absolute‑maximum ratings, detailed electrical characteristics, pin configuration and descriptions, a block diagram, mechanical dimensions, land‑pattern data, and contact information for Semtech’s Power Management Products Division.
| VDDQ programmable range | 1.5 V to 3 V |
|---|---|
| VCCA / VDDP supply range | 4.5 V to 5.5 V |
| VBAT input range | 2.5 V to 25 V |
| VIT/REF reference range | 0.75 V to 1.5 V |
| Package type | 24‑pin MLPQ 4 mm × 4 mm lead‑free |
| VIT source/sink peak current | 3 A |
The VDDQ output can be programmed from 1.5 V to 3 V.
The SC486 is supplied in a 24‑pin MLPQ package.
VBAT can accept voltages from 2.5 V up to 25 V.
The VIT/REF reference is adjustable between 0.75 V and 1.5 V.