SC415 Semtech Corporation, SC415 Datasheet
SC415
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SC415 Summary of contents
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... Embedded Applications Oct 08, 2007 Dual Synchronous Buck Controller Description The SC415 is a versatile, constant on-time, pseudo fi xed- frequency, dual synchronous buck PWM controller intended for notebook computers and other battery operated portable devices. The SC415 contains all the features needed to provide cost-eff ective control of two independent switchmode power supplies ...
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... VOUT1 L1 + COUT1 Q2 1UF EN1 PGD1 RLIM1 100NF 1 LX1 2 BST1 +5V 3 VDD1 4 SC415 DL1 5 EN1 6 SS1 10NF VOUT1 1NF PGD2 Q3 RLIM2 D3 100NF 25 PAD 18 LX2 17 BST2 +5V 16 VDD2 Q4 15 DL2 14 EN2 1UF 13 SS2 10NF EN2 VOUT2 RTON VIN SC415 VIN CIN2 VOUT2 L2 + COUT2 2 ...
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... GND EN1 (PAD) SS1 6 7 MLPQ24: 4x4 24 LEAD Marking Information SC415 yyww xxxxx xxxxx nnnn = Part Number (example: SC415 yyww = Date Code (example: 0652) xxxxx = Semtech Lot No. (example: 09010 xxxxx Ordering Information Device SC415MLTRT SC415EVB 19 LX2 18 Notes: (1) Available in tape and reel only. A reel contains 3,000 devices. ...
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... Min Typ Max Min 3.0 25 4.5 5.5 7 800 0.7425 0.75 0.7388 0.75 1.775 1.8 1.773 1.5 1.4812 1.5 1.4737 SC415 … -40 to +125°C Units Max μA 1200 μA 0.7575 V 0.7612 5.25 V 1.8225 V 1.8315 1.5188 V 1.5263 4 ...
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... ENx = RTN, 16 VOUTx < 300mV EN1 = VDD1 120 EN2 = VDD2 90 10 ILIMx - GND LXx - GND 80 LXx - GND 0 1% Hysteresis Typical, with Respect to -12% Regulation Point 5 SC415 -40° to 85°C Units Max Min Max 1.2343 1.2656 V 1.2281 1.2718 1.0368 1.0631 1.0316 1.0684 V %/V % ...
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... DHx High, BSTx - LXx = 2.5V DHx 25°C -40° to 85°C Min Typ Max Min 4.0 3.7 -30 - +17 5 160 2.0 3.1 1.5 1 0.3 VDDx -0.7 30 0.8 3 1.3 SC415 Units Max 1 μA 4.35 V -25 % clks +23 % μsec °C 1 MΩ MΩ 0.4 V nsec 1.6 Ω Ω Ω 4 Ω ...
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... Open-drain Power Good output for VOUT1 23 ILIM1 Current limit input for VOUT1. Connect through a resistor to the drain of the VOUT1 low-side MOSFET. 24 DH1 Gate drive output for the VOUT1 high-side external MOSFET T PAD Power ground for VOUT1 and VOUT2 gate drivers, and thermal pad for heatsinking SC415 7 ...
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... One-Shot UV- OV Monitor VDD1 Reference REF FB2 Comparator REF FB2 Select SS2 Control TON2 TON2 One-Shot UV- OV Monitor PAD GND SC415 Block Diagram BST1 DH1 S Q DRV LX1 VDD1 DL1 R QB DRV ILIM1 Valley ILIM/ ZCD Detect LX1 BST2 DH2 S Q DRV ...
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... SC415 Synchronous Buck Controller The SC415 is a dual synchronous controller which simplifi es the task of designing a dual-output power supply. VIN and +5V Bias Supplies The SC415 requires an external +5V bias supply in addition to the VIN supply. If stand-alone capability is required, the +5V supply can be generated with an external linear regulator. ...
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... There are fi xed output voltages accessible through each FB pin. If the FB pin is connected to either RTN or +5V, then the IC will ignore the FB pin and instead regulate the output voltage using the VOUT pin which is connected to internal resistor divider. Note that each FB input operates independently of the other. SC415 + 10 ...
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... MOSFET turns off the inductor current falls toward zero. When it reaches zero, the inductance and MOSFET capacitances will tend to ring freely. This is normal PSAVE operation as shown in Figure 3: VIN VOUT L COUT VIN VOUT LX Typical ringing at LX Figure 3 SC415 11 ...
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... VOUT to slowly rise and reach the OVP threshold, causing a hard shutdown; the SC415 uses Smart Power Save to prevent this. When the output voltage exceeds 8% above nominal (810mV at FB), that converter then exits PSAVE (if already active), and DL drives high to energize the low-side MOSFET ...
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... VDD1 exceeds 4.4V, which resets the fault latches and quickly discharges the soft-start capacitors to prepare the PWM for startup switching. At this time the SC415 will exit UVLO and begin the soft-start cycle. Startup Sequence The startup sequence for each output relies on an external ramp at the SS pin ...
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... SmartDrive circuit automatically drives the high-side MOSFET rapid rate. This technique reduces switching less while maintaining high effi ciency, and also avoids the need for snubbers or series resistors in the gate drive. SC415 T = Css × 19 SD_DELAY (T in usec, Css in nF) ...
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... For 15V input and 1.8V output, the typical on-time is: TONtyp = VOUT/VIN/Freq TONtyp = 444nsec. The timing resistor RTON must be selected to provide TONtyp: RTON = (TONtyp – 35) × (VIN/(3.3 × VOUT) – 37 RTON = 976k. We will use RTON = 1Meg. Note that side2 will run typically 20% faster than side1, in this case 320kHz. SC415 15 ...
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... This will cause a peak voltage on the capacitor according to the equation: ESRMAX = 36mV / 4.2A RIPPLE RIPPLEMAX ESRMAX = 8.6 mΩ × (IOUT + 1/2 × OUTMIN RIPPLEMAX _______________________ PEAK OUT SC415 16 ...
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... Over one cycle of ringing after the initial step is a sign that the ESR should be increased. SC415 ESR Requirements The on-time control used in the SC415 regulates the valley of the output ripple voltage. This ripple voltage consists of a term generated by the ESR of the output capacitor and a term based on the capacitance charging and discharging during the switching cycle ...
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... The idealized circuit has an inductor, a capacitor COUT with series ESR. The charging and discharging of COUT is generally much smaller than the ripple voltage due to ESR, so the resulting ripple waveform is generally determined by ESR only. VOUT C R1 COUT Figure 10 SC415 18 ...
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... DH pulse is fi nished, there is the potential ESL for double-pulsing. ESR COUT Ripple Current VOUT ripple from ESR VOUT ripple from ESL VOUT ripple from ESL FB ripple VOUT LX (to MOSFETs) ESL ESR R2 COUT Figure 13 SC415 750 mV LOAD CB 19 ...
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... The IC duty-factor limitation is given by: Actual ripple with DUTY = TONMIN/(TONMIN + TOFFMAX (~2.2 – 10 uF) Be sure to include inductor resistance and MOSFET on- Ripple from ESL state voltage drops when performing worst-case dropout duty-factor calculations. FB trip point VOUT VOUT ripple FB ripple Figure 16 SC415 ...
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... Applications Information (continued) SC415 System DC Accuracy (VOUT Controller) Three factors aff ect VOUT accuracy: the trip point of the FB error comparator, the switching frequency variation with line and load, and the external resistor tolerance. The error comparator off set is trimmed to trip when the feedback pin is 750mV, +/-1% over the range 85° ...
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... Note that grounds (1) and (2) are high-current and contain high noise. These grounds carry the DL gate drive current as well as the high switching current through the MOSFETs and low-side diode important to note that the SC415 Side 2 Power/Gate has only one power ground pin (PAD, pin 25), which must ...
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... ILIM resistor on another layer if needed. Route the VOUT/FB feedback traces in a “quiet” layer, away from noise sources. Avoid routing near any of the high- noise switching signals or other noise sources. SC415 Side 2 Power Components Side 2 Analog ...
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... VIN(V) VOUT2 Load Regulation 1.5V PSAVE Enabled 1.53 1.52 20V 1.51 1.50 15V 1.49 10V 1.48 1. LOAD (A) Frequency vs. Load, VOUT2 at 1.5V 430 420 410 10V 400 390 380 370 15V 20V 360 350 340 LOAD (A) SC415 10A ...
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... VOUT2 Effi ciency, 1.5V PSave Enabled 10V 15V 20V LOAD (A) VOUT2 Effi ciency, 1.5V PSave Disabled 15V 20V LOAD (A) Load Step VOUT2, 1.5V SC415 10V ...
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... Typical Characteristics (continued) Load Release VOUT1, 1.8V PSAVE Enabled www.DataSheet4U.com Load Release VOUT1, 1.8V PSAVE Disabled Load Release VOUT2, 1.5V PSAVE Enabled Load Release VOUT2, 1.5V PSAVE Disabled SC415 26 ...
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... Typical Characteristics (continued) Startup VOUT1 1.8V www.DataSheet4U.com Shutdown VOUT1, 1.8V No Load Shutdown VOUT1, 1.8V 2A Load SC415 Startup VOUT2 1.5V Shutdown VOUT2, 1.5V No Load Shutdown VOUT2, 1.5V 2A Load 27 ...
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... C20 R6 R6 10K 10K C22 C22 100NF 100NF R9 R9 10K 10K Part Number www.murata.com EEFSX0D331XR www.panasonic.com BAT54A www.onsemi.com MBSR140LT3 www.onsemi.com IRF7821 IRF7832 SC415 VIN 10UF 10UF 10UF 10UF 1.5V at 10A VOUT2 + + C11 C11 C12 C12 100NF 100NF 330UF 330UF Web www ...
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... NOM MAX MIN NOM MAX A .031 .040 0.90 1.00 .035 0.80 A1 .000 .001 .002 0.00 0.02 0.05 - (.008 (0.20) 0.25 b .007 .010 .012 0.18 0.30 D .151 .157 .163 3.85 4.00 4.15 D1 2.70 .100 .106 .110 2.55 2.80 E .151 .157 .163 3.85 4.00 4.15 E1 .100 .106 .110 2.55 2.70 2.80 e .020 BSC 0.50 BSC L .011 .016 .020 0.30 0.40 0. aaa .004 0.10 bbb .004 0. SC415 29 ...
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... COMPANY'S MANUFACTURING GUIDELINES ARE MET. Contact Information Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805) 498-2111 Fax: (805) 498-3804 www.semtech.com DIMENSIONS DIM INCHES MILLIMETERS (.155) (3.95 .122 3.10 H .106 2.70 K .106 2.70 P .021 0.50 X .010 0.25 Y .033 0.85 .189 4.80 Z SC415 30 ...