SC418ULTRT Semtech, SC418ULTRT Datasheet

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... July 27, 2010 EcoSpeed Description The SC418 is a synchronous EcoSpeed which incorporates Semtech’s advanced, patented adap- tive on-time control architecture to provide excellent light-load efficiency and fast transient response. It fea- tures an integrated bootstrap switch and programmable LDO 3mm package. The device is highly efficient and uses minimal PCB area ...

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... MLPQ-UT20 Marking Information 418 yyww xxxx yyww = Date Code xxxx = Semtech Lot Number Ordering Information Device SC418ULTRT SC418EVB 16 Notes: 1) Available in tape and reel only. A reel contains 3000 devices. PGOOD 15 2) Lead-free packaging only. Device is WEEE and RoHS compliant and halogen-free. ...

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Absolute Maximum Ratings LX to PGND (V -0.3 to +30 LX ...

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Electrical Characteristics (continued) Parameter Input Supplies (continued) VDDA + VDDP Supply Current FB Comparator Threshold Frequency Range Timing On-Time Minimum On-Time (2) Minimum Off-Time (2) Ultrasonic Frequency (2) Soft-Start Soft-Start Ramp Time (2) Analog Inputs/Outputs VOUT Input Resistance Current Sense ...

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Electrical Characteristics (continued) Parameter Power Good On Resistance Fault Protection I Source Current LIM I Source Current Temperature Coefficient LIM I Comparator Offset LIM Output Under-Voltage Threshold Smart Power-Save Protection Threshold (2) Over-Voltage Protection Threshold Over-Voltage Fault Delay (2) Over-Temperature ...

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Electrical Characteristics (continued) Parameter High-Side Driver (DH, BST, LX) Peak Current (2) On Resistance Rise Time (2) Fall Time (2) Propagation Delay (2) Shoot-thru Protection Delay (2) Bootstrap Switch Resistance Low-Side Driver (DL, VDDP, PGND) Peak Current (2) On Resistance ...

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Detailed Application Circuit ENABLE LDO RTON 154kΩ 5V 100nF VIN 100nF VLDO Component CIN1, CIN2 10µF/25V 220µF/15mΩ/6.3V COUT1, COUT2 0.88µH/2.3mΩ L1 (option 1) L1 (option 2) 1.0µH/2.3mΩ Q1 IRF7821 Q2 IRF7832 Note 1 - 5V: Connect VDDA/VDDP to external 3.3V ...

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Typical Characteristics Characteristics in this section are based on using the Detailed Application Circuit. Efficiency vs. Load — Forced Continuous Mode Internally biased 5V 12V, V LDO IN 100 90 85 ...

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Typical Characteristics (continued) Characteristics in this section are based on using the Detailed Application Circuit. Forced Continuous Mode — No Load Internally biased 5V 12V, V LDO IN V OUT (50mV/div) LX (10V/div) DH (10V/div) ...

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Typical Characteristics (continued) Characteristics in this section are based on using the Detailed Application Circuit. Frequency vs. Load — Forced Continuous Mode Internally biased 5V 12V, V LDO IN OUT 320 300 280 260 240 ...

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Pin Descriptions Pin # Pin Name Pin Function Feedback input for switching regulator — connect to an external resistor divider from output — used program the output voltage. Feedback input for the LDO — connect to an ...

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Block Diagram VDDA 3 VDDA VDDA UVLO AGND A Reference Soft Start TON 4 VOUT VLDO Switchover Comparator VLDO 7 VLDO Switchover MUX 2 FBL PSV PGOOD Control & Status VIN ULVO On-time ...

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Applications Information Synchronous Buck Converter The SC418 is a step down synchronous DC-DC buck con- troller with a programmable LDO. It provides high effi- ciency operation in a space saving 3x3 (mm) 20-pin package. The programmable operating frequency range of ...

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Applications Information (continued) comparator and a capacitor. One comparator input is con- nected the other input is connected to the OUT capacitor. When the on-time begins, the internal capaci- tor charges from zero volts through a current ...

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Applications Information (continued) maintain the desired on-time; on-time is calculated according to the voltage at the VOUT pin. V Voltage Selection OUT The switcher output voltage is regulated by comparing V as seen through a resistor divider at the FB ...

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Applications Information (continued) minimum frequency FB Ripple Voltage ( Inductor Current DH On-time is triggered when On-time programmable time-out DL After the programmable time-out, DL drives high if V has not reached ...

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Applications Information (continued) V drifts up to due to leakage OUT current flowing into C OUT Smart Power Save Threshold (550mV) FB threshold DH and DL off High-side Drive (DH) Single DH on-time pulse after DL turn-off Low-side Drive (DL) ...

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Applications Information (continued BST Q1 C BST DH LX ILIM R ILIM DL PGND Q2 Figure 9 — Valley Current Limit Setting the valley current limit to 10A results in a peak inductor current of 10A plus peak ...

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Applications Information (continued) cycle. The switcher will shut off if VDDA falls below 2.7V. VDDP does not have ULVO protection. Note that the VDDA UVLO will not stop MOSFET switching until the VDDA voltage falls to 2.7V. During this time ...

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Applications Information (continued) ENL Logic Control of PWM Operation When the ENL input exceeds the VIN UVLO threshold of 2.6V, internal logic checks the PGOOD signal. If PGOOD is high, the switcher is already running and the LDO will start ...

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Applications Information (continued not recommended to use the switch-over feature for an output voltage of 3.3V or less since this does not provide sufficient voltage for the gate-source drive to the internal p-channel switch-over MOSFET not ...

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Applications Information (continued) load current relates to thermal stresses which drive the selection of the inductor and input capacitors. Peak load current determines instantaneous component stresses and filtering requirements such as inductor saturation, output capacitors, and design of the current ...

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Applications Information (continued) Capacitor Selection The output capacitors are chosen based on required ESR and capacitance. The maximum ESR requirement is con- trolled by the output ripple requirement and the DC toler- ance. The output voltage has a DC value ...

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Applications Information (continued) meet the two design criteria of minimum 379µF and maximum 9mΩ ESR, select two capacitors rated at 220µF and 15mΩ ESR recommended that an additional small capacitor be placed in parallel with C in order ...

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Applications Information (continued) L High- side Low- side FB pin Figure 15 — Virtual ESR Ramp Current This network creates a ramp voltage across C to the ramp voltage generated across the ESR of ...

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Applications Information (continued) tor. For a conventional PWM constant-frequency con- verter, as load increases the duty cycle also increases slightly to compensate for IR and switching losses in the MOSFETs and inductor. A adaptive on-time converter must also compensate for ...

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Applications Information (continued) • All components connected to the FB pin must be located near the pin. The FB traces should be kept small and not routed near any noisy switch- ing connections or power components. • Place the R ...

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Outline Drawing — MLPQ-UT20 3x3 A PIN 1 INDICATOR (LASER MARK) A aaa D/2 NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. COPLANARITY APPLIES TO THE EXPOSED PAD AS WELL ...

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Land Pattern — MLPQ-UT20 3x3 NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. 2. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ARE ...

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... SEMTECH PRODUCTS ARE NOT DESIGNED, INTENDED, AUTHORIZED OR WARRANTED TO BE SUITABLE FOR USE IN LIFE- SUPPORT APPLICATIONS, DEVICES OR SYSTEMS OR OTHER CRITICAL APPLICATIONS. INCLUSION OF SEMTECH PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE UNDERTAKEN SOLELY AT THE CUSTOMER’S OWN RISK. Should a customer ...