SC411 Semtech Corporation, SC411 Datasheet
SC411
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SC411 Summary of contents
Page 1
... After the transient event, the controller frequency will return to steady-state operation. At light loads, Powersave Mode enables the SC411 to skip PWM pulses for better effi ciency. The output voltage can be adjusted from 0.5V to VCCA. A frequency setting resistor sets the on-time for the controller ...
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... J T STG T PKG =1.25V 1MΩ. OUT TON Conditions Min Off-time > 800ns 1.8 FB > regulation point LOAD FB > regulation point LOAD 2 SC411 Maximum -0.3 to +25.0 -0.3 to +30.0 -2.0 to +25.0 -0.3 to +0.3 -0.3 to +6.0 0.3 to +6.0 - -0.3 to +6.0 -0.3 to +6.0 31 -40 to +125 -65 to +150 260 25°C -40°C to 125°C Typ Max Min Max 5.0 4 ...
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... VCCA VDDP, TON VCCA = 4.5V to 5.5V Includes variations of internal x3 gain stage, com- parator, and 1.5V REF R = 1MΩ TON R = 500kΩ TON EN/PSV = GND DL high PGND - ILIM (PGND - LX), EN/PSV = 5V 3 SC411 25°C -40°C to 125°C Typ Max Min Max 0.500 -1.2% +1.2% 0.5 ...
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... FB in regulation, PGD = 5V With respect to internal ref. FB forced outside PGD window Falling (100mV Hysteresis) 10°C Hysteresis EN/PSV Low EN High, PSV Low (Floating) EN/PSV High R Pullup to VCCA R Pulldown to VSSA 4 SC411 25°C -40°C to 125°C Typ Max Min Max 100 80 120 200 170 ...
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... This negates the need for an external gate or boost resistor. © 2007 Semtech Corp. Conditions Min EN/PSV High to PGD High EN/PSV High to UV High Rising DL Low DL = 2.5V DL High DL = 2.5V 5 SC411 25°C -40°C to 125°C Typ Max Min Max 440 440 30 0.80 1.75 3 ...
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... REF = +/- 1.0% © 2007 Semtech Corp. POR / TON OFF PWM TOFF 1.5V REF + - X3 Error Comparator OV FAULT UV MONITOR REF + 16% REF - 10% REF - 30 CONTROL LOGIC OC ISENSE ZERO LO SC411 BST (13) DH (12) LX (11) ILIM (10) VDDP (9) DL (8) PGND (7) NC (5) NC (14) www.semtech.com ...
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... PGND. Current limit input. Connect to drain of low-side MOSFET for RDS(on) sensing or the source for resistor sensing through a threshold sensing resistor. Phase node (junction of top and bottom MOSFETs and the output inductor) connection. 7 Device Package SC411MLTRT MLPQ-16 (2) SC411EVB Evaluation Board www.semtech.com SC411 (1) ...
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... This pin is used to sense VBAT through a pullup resistor, RTON, and to set the top MOSFET on-time. Bypass this pin with a 1nF ceramic capacitor to VSSA. Pad for heatsinking purposes. Connect to ground plane using multiple vias. Not connected internally SC411 tplhDH www.semtech.com ...
Page 9
... POWER MANAGEMENT Application Information +5V Bias Supplies The SC411 requires an external +5V bias supply in addi- tion 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. For optimal operation, the controller has its own ground reference, VSSA, which should be tied along with PGND directly to the thermal pad under the part, which in turn www ...
Page 10
... Figure 2: Setting The Output Voltage Current Limit Circuit Current limiting of the SC411 can be accomplished in two ways. The on-state resistance of the low-side MOSFET can be used as the current sensing element or sense resistors in series with the low-side source can be used if greater accuracy is desired. R fi ...
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... MOSFET is turned on, the phase node, LX, will be higher than PGND initially. The SC411 monitors the voltage at LX, and greater than a set threshold voltage of 125mV (nom) the bottom MOS- FET is turned off. The device then waits for approximately 2.5μ ...
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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 SC411 is calculated to give a pseu- do- fi xed frequency. Nevertheless, some frequency varia- tion 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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... 19.8mΩ ( − ERR ERR = ESR MAX ) ⎛ I ⎜ ⎜ + RIPPLE _ VBAT ( MAX I OUT 2 ⎝ is the transient output tolerance. Note that TR SC411 A P 2.18A P-P ( MAX ) A ( MIN ) 2 Ohms Ohms ⎞ ⎟ ⎟ ) ⎠ term OUT www.semtech.com ...
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... R ⎝ 14.8mV - good P-P OUT_ST_POS = + V V ERR OUT POS OUT DC = 1.226V = • V TOL OUT T R SC411 ) 015 Ohms required to achieve = BOT : TOP ⎞ ⎟ ⎟ ⎟ V ⎟ − ⎟ ⎟ • • ⎟ VBAT ( MIN ...
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... ambient temperature (° power dissipation in (W) D θ = thermal impedance junction to ambient JA from absolute maximum ratings (°C/W) = • + • P VCCA I VDDP I D VCCA VDDP + • • + • • VBST chip supply voltage (V) = operating current (A) SC411 DS(ON) A Ohms W www.semtech.com ...
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... The Reference Design is shown in Figure on Page 17. An additional design optimized for effi ciency and capable of a higher load current of 10A is shown in Figure 11 on Page 21. © 2007 Semtech Corp. (V) ON condition (since (MIN) − 6 • − • SC411 www.semtech.com ...
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... VOUT VCCA LX SC411 ILIM 4 9 PGD VDDP C9 1uF 0603 Figure 4: Reference Design 17 5VSUS VBAT D1 SOD323 C1 0u1 0603 Q1 IRF7811AV 2n2/50V 0u1/25V 10u/25V 0402 0603 1210 L1 2u2 R4 7k87 C6 0402 + Q2 FDS6676S 220u/25m 7343 C10 1uF 0603 SC411 VOUT C7 + 220u/25m 7343 www.semtech.com ...
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... R1 1M 0402 R2 10R U1 0402 VOUT 1 VOUT C5 R3 20k0 2 VCCA 56p 0402 0402 SC411 PGD VDDP R5 C8 14k3 C9 0402 1nF 1uF 0402 0603 Figure 5: Components Connected to VSSA Figure 6: Control Section Example 18 5VSUS ILIM 9 C10 1uF 0603 www.semtech.com SC411 ...
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... Figure 8: Power Section and Input Loop VOUT 220u/25m 220u/25m 7343 7343 SC411 www.semtech.com ...
Page 20
... BST is also a noisy node and should be kept as short as possible. 4) Connect PGND and VSSA directly to the thermal pad, and connect the thermal pad to the ground plane using mul- tiple vias. © 2007 Semtech Corp. Figure 9: Power Component Placement and Copper Pours 20 SC411 www.semtech.com ...
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... R4 7k15 0402 1u5 1u5 + + Q2 Q2 IRF7832 IRF7832 470u/15m 470u/15m 7343 L1 = 1.5uH Vishay IHLP 5050CE C10 C10 C6 470uF / 15milli ohm 1uF 1uF Sanyo POS Cap 2R5TPE470MF 0603 SC411 2u2 C4 C4 10u/25V 10u/25V 1210 VOUT 470u/15m 470u/15m 7343 www.semtech.com ...
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... BAT 1.204 1.200 1.196 BAT 1.192 1.188 1.184 1.180 (A) OUT Mode) vs. Output Current vs. Input Voltage 400 BAT 350 300 250 V = 20V BAT 200 150 100 (A) OUT SC411 www.semtech.com ...
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... Trace 1: 1.2V, 20mV/div., AC coupled Trace 2: LX, 10V/div Trace 3: not connected Trace 4: load current, 5A/div Timebase: 10μs/div. Trace 1: 1.2V, 50mV/div., AC coupled Trace 2: LX, 10V/div Trace 3: not connected Trace 4: load current, 5A/div Timebase: 10μs/div. Please refer to Figure 4 on Page 17 for test schematic 23 SC411 www.semtech.com ...
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... Trace 1: 1.2V, 20mV/div., AC coupled Trace 2: LX, 10V/div Trace 3: not connected Trace 4: load current, 5A/div Timebase: 10μs/div. Trace 1: 1.2V, 50mV/div., AC coupled Trace 2: LX, 10V/div Trace 3: not connected Trace 4: load current, 5A/div Timebase: 10μs/div. Please refer to Figure 4 on Page 17 for test schematic 24 SC411 www.semtech.com ...
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... Startup (CCM), EN/PSV 0V to Floating © 2007 Semtech Corp. Trace 1: 1.2V, 0.5V/div. Trace 2: LX, 10V/div Trace 3: EN/PSV, 5V/div Trace 4: PGD, 5V/div. Timebase: 1ms/div. Trace 1: 1.2V, 0.5V/div. Trace 2: LX, 10V/div Trace 3: EN/PSV, 5V/div Trace 4: PGD, 5V/div. Timebase: 1ms/div. Please refer to Figure 4 on Page 17 for test schematic 25 SC411 www.semtech.com ...
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... MAX MIN NOM MAX - - A .031 .040 0.80 1. .000 .002 0.00 0.05 (.008) (0.20 .010 .012 .014 0.25 0.30 0.35 D .153 .157 .161 3.90 4.00 4.10 D1 .079 .085 .089 2.00 2.15 2.25 E .153 .157 .161 3.90 4.00 4.10 E1 .079 .085 .089 2.00 2.15 2.25 e .026 BSC 0.65 BSC L .012 .016 .020 0.30 0.40 0. aaa .003 0.08 bbb .004 0.10 SEATING PLANE E SC411 www.semtech.com ...
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... Semtech Corp. K DIM Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805) 498-2111 Fax: (805) 498-3804 27 SC411 DIMENSIONS INCHES MILLIMETERS (.152) (3.85) .114 2.90 .091 2.30 .091 2.30 .026 0.65 .016 0.40 .037 0.95 .189 4.80 ...