SC1486A Semtech Corporation, SC1486A Datasheet
SC1486A
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SC1486A Summary of contents
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... POWER MANAGEMENT Description The SC1486A is a dual output constant on-time synchronous buck PWM controller optimized for cost effective mobile DDR and DDR2 applications. Features include high efficiency, a fast dynamic response with no minimum on time, a REFIN input and a buffered REFOUT pin capable of sourcing 3mA. The excellent transient ...
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... SC1486A ...
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... SC1486A = 2. 1.25 1M VDDQ VTT TON1 TON2 2 ° ° ° µ ...
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... SC1486A = 2. 1.25 1M, R VDDQ VTT TON1 2 ° ° ° ...
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... SC1486A = 2. 1.25 1M, R VDDQ VTT TON1 2 ° ° ° ...
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... SC1486A ...
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... SC1486A . µ ...
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... POR / SS REF BUFFER ON TON OFF CONTROL LOGIC PWM TOFF OC ZERO FAULT UV MONITOR REF + 10% REF - 10% REF - 30% FIGURE 1 - SC1486A Block Diagram 8 SC1486A BST1 (7) DH1 (6) HI LX1 (5) ISENSE ILIM1 (4) VDDP1 (3) DL1 (2) LO PGND1 (1) OT VDDP2 BST2 (21) DH2 (20) HI LX2 (19) ISENSE ILIM2 (18) VDDP2 (17) ...
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... POWER MANAGEMENT Application Information +5V Bias Supplies The SC1486A requires an external +5V bias supply in addition to the battery. If stand-alone capability is required, the +5V supply can be generated with an external linear regulator such as the Semtech LP2951. To minimize channel to channel crosstalk, each controller has 4 supply pins, VDDP, PGND, VCCA and VSSA ...
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... PGND 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 SC1486A monitors the voltage at LX, and greater than a set threshold voltage of 140mV (nom.) the bottom MOSFET is turned off. The device then waits for approximately 2µ ...
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... REFOUT to rise faster, avoiding this issue. REFIN should also be filtered so that VDDQ ripple does not appear at the REFIN pin resistor divider is used to create REFIN from VDDQ, then a 0.1µF capacitor from REFIN to VSSA2 will provide adequate filtering. 11 SC1486A resistor is placed www.semtech.com ...
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... The use of 1% feedback resistors contribute 1%. If tighter DC accuracy is required use 0.1% feedback resistors. The on pulse in the SC1486A 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 regulators regulate to the valley of the output ripple, ½ ...
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... OUT MIN ) RIPPLE _ VIN ( MIN and OUT MAX ) RIPPLE _ VIN ( MAX 13 SC1486A V OUT MIN ) ON _ VIN ( MIN ) V OUT MAX ) ON _ VIN ( MAX ) , converting this to a current. This current is . For our DDR2 VDDQ ...
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... R Ohms V is large enough 100pF. The value of C where R calculating the value term Z OUT TOP . 0 Secondly calculating the value of C this: 14 SC1486A = 36mV, therefore DC = 9.5m for a full 10A load transient maximum for our OUT MAX ...
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... We use the maximum room temperature specification for MOSFET DS(ON VALLEY The ripple at low battery voltage is used because we want to make sure that current limit does not occur under normal operating conditions. 15 SC1486A 2 I RIPPLE _ VIN ( MAX ) I OUT 2 ...
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... 1100 can be seen, the heating effects due to internal power dissipation are practically negligible, thus requiring no special consideration thermally during layout. 2004 Semtech Corp. Ohms 300 SC1486A 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 SC1486A DDR2 reference design used in the Design Procedure section while explaining the layout guidelines in more detail. PWR_SRC ...
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... R11 10R 0402 C18 C19 VCCA2 C22 C23 1u 0u1 0.9V 0603 0402 VSSA2 1u 1n 0603 0402 Figure 6: VTT Side Detail 18 SC1486A 5VSUS VCCA1 R1 10R 0402 U1 SC1486A VDDP1 1M 0402 SOD 1u 1 PGND1 323 0603 6 DH1 7 BST1 5 LX1 4 ILIM1 0402 2 DL1 PGD1 ...
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... VOUT1 REFIN REFOUT 26 10 FB1 REFOUT 23 9 TON2 TON1 TON2 VCCA2 25 11 VCCA1 VCCA2 C22 28 14 VSSA1 VSSA2 1u 0603 19 SC1486A PWR_SRC R4 649k 0402 1.8V R9 10k0 0402 R11 10R R12 0402 C18 C19 10k0 0402 C23 1u 0u1 0.9V 0603 0402 1n VSSA2 0402 www.semtech.com ...
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... FB2 24 8 VOUT1 REFIN 26 10 FB1 REFOUT 23 9 TON1 TON2 VCCA2 25 11 VCCA1 VCCA2 C22 28 14 VSSA1 VSSA2 1u 0603 20 SC1486A U1 SC1486A 3 17 VDDP1 VDDP2 1 15 PGND1 PGND2 6 20 DH1 DH2 7 21 BST1 BST2 5 19 LX1 LX2 4 18 ILIM1 ILIM2 2 16 DL1 ...
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... FDS6982S FDS6676S Figure 15: VTT Power Component Placement 21 SC1486A 2n2/50V 0u1/25V 10u/25V 0402 0603 1210 0.9V, 1.5A L2 3u9 7 C15 C16 + 0u1 220u/25m 0402 7343 0402 Figure 11: VTT Power Section ...
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... LX1 LX2 ILIM1 ILIM2 DL1 DL2 27 13 PGD1 PGD2 22 12 EN/PSV1 FB2 24 8 VOUT1 REFIN 26 10 FB1 REFOUT 23 9 TON1 TON2 25 11 VCCA1 VCCA2 28 14 VSSA1 VSSA2 22 SC1486A FDS6982S 3u9 www.semtech.com ...
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... SC1486A vs. Output Current vs. Input Voltage V = 20V BAT BAT (A) OUT vs. Output Current vs. Input Voltage V BAT V BAT ...
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... Please refer to Figure 4 on Page 17 for test schematic 2004 Semtech Corp. VTT Switching Frequency (Continuous Conduction Mode) vs. Output Current vs. Input Voltage 450 REFIN = 0.9V 425 BAT 400 375 350 V = 20V 325 BAT 300 275 250 0 SC1486A BAT V = 20V BAT 0.2 0.4 0.6 0.8 1.0 1.2 I (A) OUT www.semtech.com 1.4 1.6 ...
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... Trace 4: load current, 10A/div Timebase: 40µs/div. Trace 1: VDDQ, 20mV/div., AC coupled Trace 2: LX, 10V/div Trace 3: not connected Trace 4: load current, 10A/div Timebase: 10µs/div. Trace 1: VDDQ, 50mV/div., AC coupled Trace 2: LX, 10V/div Trace 3: not connected Trace 4: load current, 10A/div Timebase: 10µs/div. 25 SC1486A www.semtech.com ...
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... Trace 4: load current, 10A/div Timebase: 40µs/div. Trace 1: VDDQ, 20mV/div., AC coupled Trace 2: LX, 10V/div Trace 3: not connected Trace 4: load current, 10A/div Timebase: 10µs/div. Trace 1: VDDQ, 50mV/div., AC coupled Trace 2: LX, 10V/div Trace 3: not connected Trace 4: load current, 10A/div Timebase: 10µs/div. 26 SC1486A www.semtech.com ...
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... Trace 4: load current, 1A/div Timebase: 40µs/div. Trace 1: VTT, 20mV/div., AC coupled Trace 2: LX, 10V/div Trace 3: not connected Trace 4: load current, 1A/div Timebase: 10µs/div. Trace 1: VTT, 20mV/div., AC coupled Trace 2: LX, 10V/div Trace 3: not connected Trace 4: load current, 1A/div Timebase: 10µs/div. 27 SC1486A www.semtech.com ...
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... Please refer to Figure 4 on Page 17 for test schematic 2004 Semtech Corp. Trace 1: VDDQ, 1V/div. Trace 2: VTT, 0.5V/div Trace 3: REFOUT, 0.5V/div Trace 4: En/PSV1, 2V/div. Timebase: 2ms/div. Trace 1: VDDQ, 1V/div. Trace 2: VTT, 0.5V/div. Trace 3: PGD1, 5V/div. Trace 4: PGD2, 5V/div Timebase: 2ms/div. 28 SC1486A www.semtech.com ...
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... POWER MANAGEMENT Outline Drawing - TSSOP-28 Land Pattern - TSSOP-28 Contact Information Phone: (805)498-2111 FAX (805)498-3804 2004 Semtech Corp. Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 29 SC1486A www.semtech.com ...