SC424 SEMTECH [Semtech Corporation], SC424 Datasheet
SC424
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SC424 Summary of contents
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... The 5V LDO or an external 3. supply can be used to provide the bias voltage for the SC414/SC424. When the SC414/SC424 is used output switching regula- tor, the 5V LDO can be used as an initial bias supply for the device. Once the switch regulator output is in the switch over range, the LDO will be bypassed by the switcher output for optimum effi ciency ...
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... CBST 1μF CIN CIN 10μF 10μF L1 1.5μH RFB1 10KΩ FB RFB2 30KΩ Key Components Value Manufacturer Murata Panasonic Vishay SC414/SC424 ENABLE PSAVE V5V RILIM 9.09KΩ PAD 1 AGND PGND 18 PGND 17 PGND 16 PGND 15 LX PAD 3 ...
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... AGND 3 PAD 1 LX VOUT 4 PAD 3 VIN 5 VIN VLDO 6 PAD 2 BST SC414 and SC424 MLPQ-28; 4x4, 28 LEAD Marking Information SC414 yyww xxxxx xxxxx yyww = Date Code xxxxx = Semtech Lot Number Ordering Information Device SC414MLTRT SC424MLTRT SC414EVB SC424EVB 20 ...
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... V5V = +5V, Typical Application Circuit J Conditions Sensed at ENL pin, rising edge Sensed at ENL pin, falling edge EN/PSV = High Measured at V5V pin, rising edge Measured at V5V pin, falling edge ENL, EN/PSV = 0V 28V IN Standby mode; ENL=V5V, EN/PSV = 0V SC414/SC424 (2) (°C/W) Min Typ Max Units 2.40 2.60 2.95 V 2.235 2 ...
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... Zero-Crossing Detector Threshold Conditions ENL, EN/PSV = 0V , V5V = 5V ENL, EN/PSV = 0V , V5V = 3V SC414, EN/PSV = V5V, no load (f = 25kHz), SW (2) V > 750mV FB SC424, EN/PSV = V5V, no load, V > 750mV FB V5V = 5V 250kHz, EN/PSV = fl oating, no load SW V5V = 3V 250kHz, EN/PSV = fl oating, no load SW Static V and load +85 °C, V5V = ...
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... FB 8 consecutive clock cycles V with respect to internal 750mV reference FB V with respect to internal 750mV reference FB 10°C hysteresis ENL ENL % of V5V ( V5V EN/PSV= V5V or AGND V = 28V V5V or AGND SC414/SC424 Min Typ Max Units + μs 1 μA 10 Ω 3 ...
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... The LDO drop out voltage is the voltage at which the LDO output drops 2% below the nominal regulation point. Thermal resistance, junction to ambient — guaranteed by design (°C/W) Conditions VLDO load = 10mA Start-up and foldback, V Operating current limit +5V OUT From +5V VLDO VLDO SC414/SC424 Min Typ 4.9 5.0 = 12V 12V 135 200 IN -140 -450 2 = 100mA 1.2 VLDO ...
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... Typical Characteristics Characteristics in this section are based on using the Typical Application Circuit on page 2 (SC414/SC424). Effi ciency vs. Load — Forced Continuous Mode Internally biased 5V 12V, V LDO IN OUT 100 0.001 0.01 0.1 I (A) OUT Effi ciency vs. Load — Powersave Mode (SC414) ...
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... Typical Characteristics (continued) Characteristics in this section are based on using the Typical Application Circuit on page 2 (SC414/SC424). Frequency vs. Load — Forced Continuous Mode Internally biased 5V 12V, V LDO IN OUT 400 350 300 250 200 150 100 0.1 0.001 0.01 I (A) OUT V vs. Load — Powersave Mode (SC414) ...
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... Typical Characteristics (continued) Characteristics in this section are based on using the Typical Application Circuit on page 2 (SC414/SC424). Ultrasonic Powersave Mode — No Load (SC414 12V 1V 0A OUT OUT LDO (50mV/div) (5V/div) Time (10μs/div) Self-Biased Start-Up — Power Good True 12V step, V ...
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... Typical Characteristics (continued) Characteristics in this section are based on using the Typical Application Circuit on page 2 (SC414/SC424). Transient Response — Load Rising (SC414 12V 1V 200mA to 6A OUT OUT (50mV/div) (5A/div) (5V/div) Time (10μs/div) Transient Response — Load Rising (SC424 12V, V ...
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... Enable/power save input for the switching regulator — connect to AGND to disable the switching regula- tor. Float to operate in forced continuous mode (power save disabled). For SC414, connect to V5V to operate 25 EN/PSV with ultrasonic power save mode enabled. For SC424, connect to V5V to operate with power save mode enabled with no minimum frequency. 27 TON On-time programming input — ...
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... Gate Drive On- time - Control Generator Zero Cross Detector Valley Current Limit V IN LDO 28 ENL A = connected to pins 5, 8-11, PAD connected to pins 15, 20, 21, PAD connected to pins 13, 14, 16- connect to pins 3, 26, PAD 1 SC414/SC424 VIN A V V5V IN Bootstrap Switch DL Hi-side MOSFET V5V DL Lo-side MOSFET 7 ...
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... Applications Information Synchronous Buck Converter The SC414/SC424 is a step down synchronous DC-DC buck converter with integrated power MOSFETs and a 5V LDO. The device is capable of 6A operation at very high effi - ciency. A space saving 4x4 (mm) 28-pin package is used. The programmable operating frequency range of 200kHz to 1MHz enables optimizing the configuration for PCB area and effi ciency ...
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... OUT The SC414/SC424 uses an external resistor to set the on- time which indirectly sets the frequency. The on-time can be programmed to provide an operating frequency from 200kHz to 1MHz using a resistor between the TON pin and ground. The resistor value is selected by the following equation. ...
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... When EN/PSV is high (above 45% of the voltage at V5V) for SC424, the switching regulator turns on with power- save enabled. The SC424 power-save operation is designed to maximize effi ciency at light loads with no minimum frequency limits. This makes the SC424 an excellent choice for portable and battery-operated systems ...
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... FB threshold. Figure 5 — Ultrasonic Power-save Operation Power-save Mode Operation (SC424) The SC424 provides power-save operation at light loads with no minimum operating frequency. With power-save enabled, the internal zero crossing comparator monitors the inductor current via the voltage across the low-side MOSFET during the off -time ...
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... During soft-start the output voltage tracks the internal ramp, which limits the start-up inrush current and provides a controlled soft-start profi le for a wide range of applications. Typical soft-start ramp time is 1.7ms. SC414/SC424 Time Figure 8 — Valley Current Limit value is calculated by the following equation. = 1250 ...
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... DH/DL drivers until V5V rises above 2.9V. An internal Power-On Reset (POR) occurs when V5V exceeds 2.9V, which resets the fault latch and soft-start counter to begin the soft-start cycle. The SC414/SC424 then begins a soft-start cycle. The PWM will shut off if V5V falls below 2.7V. ...
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... V5V ≥ V • V5V ≥ either V diode will turn on and the SC414/SC424 operating current will flow through this diode. This has the potential of damaging the device. ENL pin and V The ENL pin also acts as the switcher under-voltage lockout for the V grammable via a resistor divider at the VIN, ENL, and AGND pins ...
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... If PGOOD is low, then the LDO will not allow any PWM switching until the LDO output has reached 90% of it’s fi nal value. Using the On-chip LDO to Bias the SC414/SC424 Switcher status The following steps must be followed when using the off internal LDO to bias the device ...
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... A slightly larger value of 1.5μH is selected. This will decrease the maximum I , 250kHz Note that the inductor must be rated for the maximum DC load current plus 1/2 of the ripple current. The ripple current under minimum V checked using the following equations SC414/SC424 ). The equation for determining inductance is OUT ( ...
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... The following can be used to calculate the needed capaci- tance for a given dI by the next equation. I LPK I LPK Rate I MAX C OUT Example dl LOAD SC414/SC424 of 1.150 (100mV rise upon PEAK MIN ...
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... SP or POSCAP devices. For stability the ESR zero of the output capacitor should be lower than approximately one-third the switching fre- quency. The formula for minimum ESR is shown by the following equation SC414/SC424 C TOP To FB pin V R1 OUT R2 Figure 13 — ...
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... The error comparator off set is trimmed so that under static condi- tions it trips when the feedback pin is 750mV, 1%. The on-time pulse from the SC414/SC424 in the design example is calculated to give a pseudo-fi xed frequency of 250kHz. Some frequency variation with line and load is expected ...
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... The net eff ect is that switching frequency increases slightly with increasing load. PCB Layout Guidelines The optimum layout for the SC414/SC424 is shown in Figure 15. This layout shows an integrated FET buck regu- AGND plane on inner layer ...
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... IC, the inductor, and the output capacitors must be as close as possible to each other to power to the reduce IR drop across the copper. OUT • All bypass and output capacitors must be con- nected as close as possible to the respective pin on the IC. SC414/SC424 should be close to the IC and connected to 27 ...
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... MARK aaa C 0.73±0.10 1.45±0. 0.20 PIN 1 IDENTIFICATION NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL AS THE TERMINALS 2.58 1.29 D1 LxN e 1. bxN D1 bbb D/2 SC414/SC424 DIMENSIONS MILLIMETERS DIM MIN NOM MAX - 1. 0.00 0.05 - (0.20 0.17 0.23 0.29 D 3.90 4.00 4.10 D1 0.96 1.06 1.16 E 3.90 4.00 4. ...
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... COMPANY'S MANUFACTURING GUIDELINES ARE MET. 3. SQUARE PACKAGE-DIMENSIONS APPLY IN BOTH X AND Y DIRECTIONS. Contact Information 1. 2.58 Semtech Corporation Power Management Products Division 200 Flynn Road, Camarillo, CA 93012 Phone: (805) 498-2111 Fax: (805) 498-3804 www.semtech.com SC414/SC424 DIMENSIONS DIM MILLIMETERS (3.95 3.20 H 2.58 H1 0.73 H2 1.45 K 1.06 P 0.45 X ...