Power Electronics

Integrated Power Supply for DDR / DDR2 Memory

Semtech Corp.’s new SC486 is the company’s first switcher/linear combination regulator designed specifically for DDR and DDR2 memory applications. The SC486 integrates a switching regulator for the supply voltage, a linear regulator for the memory termination voltage, and an internal buffered voltage reference into a single device targeted at next-generation notebook computers, PDAs, power supplies and other portable systems.

The SC486 comes in one of the smallest form-factors on the market, a 4-mm × 4-mm MLPQ package, and further reduces board space requirements through the integration of otherwise external circuitry for DDR memories, such as resistor dividers and sense resistors.

The SC486 features an adaptive on-time switching regulator that provides a very accurate supply voltage (VDDQ) to the memory chip with fast dc-dc conversion response and ›90% efficiency. The controller protects the memory from transient changes by monitoring the output voltage and adjusting the frequency to counter the change in load current. The device also features a power-save mode that reduces switching frequency in light load conditions for improved efficiency and lower power consumption.

The low dropout (LDO) regulator creates the memory termination voltage (VTT) and has the capacity to source and sink up to 3 A of peak current. The VTT output tracks an internally generated and buffered reference voltage that is half of VDDQ, providing for a highly accurate termination voltage and contributing to DDR memory reliability. The LDO is designed to operate with ceramic output capacitors for cost/board space savings over switching solutions.

Available immediately, the SC486 is priced at $1.32 each in 1,000-piece lots. The device comes in a 24-pin, lead-free MLPQ package.

For more information, visit www.semtech.com.

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