SC486 Semtech Corporation, SC486 Datasheet
SC486
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SC486 Summary of contents
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... 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 pseudo-fixed frequency constant on-time controller designed for high efficiency, superior DC accuracy, and fast transient response ...
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... ° SC486 ° ° C ° C ° ° ...
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... SC486 ° µ ...
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... SC486 ° µ µ µ µ ...
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... (typ.) until LX = 1.5V (typ.). This negates the tplhDH SC486 ° www.semtech.com ...
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... SC486 ...
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... SC486 www.semtech.com ...
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... POWER MANAGEMENT Block Diagram www.DataSheet4U.com 2006 Semtech Corp. Figure 1 - SC486 Block Diagram 8 SC486 www.semtech.com ...
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... SC486 www.semtech.com ...
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... POWER MANAGEMENT Application Information +5V Bias Supply The SC486 requires an external +5V bias supply in addition to the battery. This is connected to VDDP for the VDDQ switching drive power and via an RC filter to VCCA for the chip supply. If stand-alone capability is required, the +5V supply can be generated with an external linear regulator ...
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... VTT VDDQ 2006 Semtech Corp. VDDQ Current Limit Circuit Current limiting of the SC486 can be accomplished in two ways. The on-state resistance of the low-side MOSFETs can be used as the current sensing element or sense resistors in series with the low-side sources can be used if greater accuracy is desired. R sensing is more efficient and less expensive ...
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... PGND1 through the inductor and bottom MOSFET). In this case, when the bottom MOSFET is turned on, the phase node, LX, will be higher than PGND initially. The SC486 monitors the voltage at LX, and greater than a set threshold voltage of 125mV (nom.) the bottom MOSFET is turned off. The device then waits for approximately 2.5µ ...
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... RC filter (with R from VTT to VTTS less than 100 from VTTS to VSSA, R8 and C7 in Figure 2) may be used to compensate any zeroes created by less than optimal ESR at the output. With the recommended output capacitors they are not necessary so R should be 0 and C should be no-pop. 13 SC486 should and C www.semtech.com ...
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... DC accuracy. The use of 1% feedback resistors contribute 1%. If tighter DC accuracy is required use 0.1% feedback resistors. The on-pulse in the SC486 is calculated to give a pseudo fixed frequency. Nevertheless, some frequency variation with line and load can be expected. This variation changes the output ripple voltage. Because constant on-time regulators regulate to the valley of the output ripple, ½ ...
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... BAT ( MAX ) OUT OUT = 0.8µH and L = 1.0µH VBAT(MAX VBAT ( MIN ) BAT ( MIN ) OUT VBAT ( MAX ) BAT ( MAX ) OUT SC486 Hz . The OUT . For our DDR2 MAX ) H VBAT ( MIN ) VBAT ( MAX ) www.semtech.com ...
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... TOP , in order to ensure that V TOP should not be greater than 100pF. The value TOP can be calculated as follows, where R TOP required: R BOT 015 RIPPLE _ VBAT ( MIN ) . 0 015 SC486 20mV P-P at minimum P P-P is large FB is the BOT Ohms www.semtech.com ...
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... V V OUT ) OUT BAT ( MIN ) OUT V BAT RMS . Refer to manufacturer’s data RMS 4.5V for purposes of this calculation RIPPLE _ VBAT ( MIN ) I A OUT Ohms VALLEY DS(ON) = 8.69A and R = 13.1k ILIM SC486 OUT A RMS MIN www.semtech.com ...
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... VBAT +VDDP = 13V (MIN) (MIN) = 1.8/8 = 0.225 2500 e 5 150 366 225 206 206 29 120 C SC486 condition (since www.semtech.com ...
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... Current sense connections must always be made using Kelvin connections to ensure an accurate signal. We will examine the SC486 DDR2 reference design used in the Design Procedure section while explaining the layout guidelines in more detail. ...
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... Figure 8: Example VSSA 0.020” Trace 20 5VRUN U1 SC486 11 7 VTTEN PGD 3 VDDQS 1 EN/PSV 2 TON REF 9 24 COMP BST 10 VTTS VCCA C11 C12 21 ILIM VSSA LX 14 VTT 15 VTT VTTIN 13 20 VTTIN VDDP 16 PGND2 17 18 PAD PGND2 PGND1 SC486 C18 1u www.semtech.com ...
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... SC486 11 7 VTTEN PGD 10R 3 VDDQS C2 1 EN/PSV 2 TON REF 9 24 COMP BST 10 VTTS VCCA 21 ILIM 4 22 VSSA LX 14 VTT 15 VTT VTTIN 13 20 VTTIN VDDP 16 PGND2 17 18 PGND2 PAD PGND1 21 SC486 VDDQ + + C13 C14 220u/15m 220u/15m www.semtech.com ...
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... 2n2/50V 0u1/25V L1 1u5 FDS6676S Figure 10: VDDQ Power Section and Input Loop Figure 11: Example VDDQ Power Section Layout 22 SC486 C7 C8 10u/25V 10u/25V VDDQ C13 C14 + 220u/15m 220u/15m www.semtech.com ...
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... DL the most critical. Use multiple vias when switching between layers. Locate the current limit resistor (R10) at the chip with a kelvin connection to the phase node. 2006 Semtech Corp. SC486 7 PGD 1 EN/PSV 24 BST 23 DH R10 13k0 21 ILIM VDDP 18 PGND1 PAD 23 SC486 Q1 IRF7811AV L1 1u5 Q2 FDS6676S www.semtech.com ...
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... C15 C16 C17 10u 10u 1u Figure 13: VTT Output 24 U1 SC486 11 7 VTTEN PGD 3 VDDQS 1 EN/PSV 2 TON REF 9 24 COMP BST 10 VTTS VCCA 21 ILIM 4 22 VSSA LX 14 VTT 15 VTT VTTIN 13 20 VTTIN VDDP 16 PGND2 17 18 PGND2 PGND1 SC486 www.semtech.com ...
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... NOM A .031 .035 .039 0.80 0.90 0.02 A1 .000 .001 .002 0. (.008) A2 (0.20) b .007 0.25 .010 .012 0.18 D .152 .157 .163 3.85 4.00 D1 2.70 .100 .106 .110 2.55 E 3.85 4.00 4.15 .152 .157 .163 E1 .100 .106 .110 2.55 2.70 2.80 e .020 BSC 0.50 BSC L .012 .016 .020 0.30 0. aaa .004 0.10 bbb .004 0.10 SEATING PLANE SC486 MAX 1.00 0.05 - 0.30 4.15 2.80 0.50 www.semtech.com ...
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... FAILURE MAY COMPROMISE THE THERMAL AND/OR FUNCTIONAL PERFORMANCE OF THE DEVICE. Contact Information 2006 Semtech Corp. K DIM Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805)498-2111 FAX (805)498-3804 26 SC486 DIMENSIONS INCHES MILLIMETERS (.156) (3.95 .122 3.10 H .106 2.70 K ...