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SC486 Dataheets PDF



Part Number SC486
Manufacturers Semtech Corporation
Logo Semtech Corporation
Description Complete DDR1/2/3 Memory Power Supply
Datasheet SC486 DatasheetSC486 Datasheet (PDF)

Complete DDR1/2/3 Memory Power Supply POWER MANAGEMENT Description The SC486 is a combination 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 voltag.

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Complete DDR1/2/3 Memory Power Supply POWER MANAGEMENT Description The SC486 is a combination 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. www.DataSheet4U.com 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, 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 component count and cost. The SC486 is available in a 24 pin MLPQ 4mmx4mm Lead-free package. SC486 Features ‹ DDR1, DDR2 and DDR3 compatible ‹ 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 VBAT range = 2.5V to 25V VDDQ DC current sense using low-side RDS(ON) sensing or external RSENSE in series with low-side FET Cycle-by-cycle current limit for VDDQ Digital soft-start for VDDQ Combined EN and PSAVE pin for VDDQ Over-voltage/under-voltage fault protection for both outputs and PGD output (VDDQ only) Separate VCCA and VDDP supplies VTT/REF range = 0.75V – 1.5V VTT source/sink 3A peak Internal resistor divider for VTT/REF VTT is high impedance in S3 VDDQ, VTT and REF are actively discharged in S4/S5 24-pin MLPQ (4 x 4mm) Lead-free package, fully WEEE and RoHS compliant Notebook computers CPU I/O supplies Handheld terminals and PDAs LCD monitors Network power supplies 5VSUS R3 470k R1 R2 10R 11 3 2 6 VBAT Applications ‹ ‹ ‹ ‹ ‹ Typical Application Circuit VBAT 5VSUS 5VRUN U1 VTTEN VDDQS TON FB REF COMP VTTS VCCA VSSA VTT VTT VTTIN VTTIN PGND2 PGND2 PAD SC486 PGD EN/PSV VDDQ C1 no-pop REF R5 .


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