SC427MLTRT Semtech, SC427MLTRT Datasheet

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... DC power supply applications. EN/PSV LXS ILIM ENL PGOOD TON VOUT LX V5V SC417/SC427 FB BST VIN LXBST AGND PGND CBST © 2010 Semtech Corporation SC417/SC427 Integrated FET TM buck regulator which incorporates Semtech’s RILIM PGOOD VOUT L1 RFB1 COUT + RFB2 US Patent: 7,714,547 B2 1 ...

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... SC417 and SC427 MLPQ-32; 5x5, 32 LEAD Marking Information SC417 yyww xxxxxx xxxxxx yyww = Date Code xxxxxx = Semtech Lot Number xxxxxx = Semtech Lot Number Ordering Information Device SC417MLTRT SC427MLTRT 26 25 SC417EVB SC427EVB PGND 22 Notes: 1) Available in tape and reel only. A reel contains 3000 devices. ...

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Absolute Maximum Ratings LX to PGND (V -0 ...

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Electrical Characteristics (continued) Parameter Input Supplies (continued) V5V Supply Current FB On-Time Threshold Frequency Range Bootstrap Switch Resistance Timing On-Time Minimum On-Time (2) Minimum Off-Time (2) Soft-Start Soft-Start Ramp Time (2) Analog Inputs/Outputs VOUT Input Resistance Current Sense Zero-Crossing Detector ...

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Electrical Characteristics (continued) Parameter Fault Protection Valley Current Limit I Source Current LIM I Comparator Offset LIM Output Under-Voltage Fault Smart Power-save Protection Threshold (2) Over-Voltage Protection Threshold Over-Voltage Fault Delay (2) Over-Temperature Shutdown (2) Logic Inputs/Outputs Logic Input High ...

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Electrical Characteristics (continued) Parameter Linear Regulator (LDO) FBL Accuracy LDO Current Limit VLDO to VOUT Switch-over Threshold (3) VLDO to VOUT Non-switch-over Threshold VLDO to VOUT Switch-over Resistance LDO Drop Out Voltage (4) Notes: (1) V UVLO is programmable using ...

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Detailed Application Circuit ENABLE LDO RTON 154KΩ Note: V5V is tied to VLDO RLDO1 57.6KΩ RLDO2 1µF 1µF 10KΩ VIN +12V Component CIN 4 x 10µF/25V COUT1,2 (option 220µF/15mΩ COUT1,2 (option 2) L1 (option 1) 0.88µH/2.3mΩ L1 ...

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Typical Characteristics Characteristics in this section are based on using the Detailed Application Circuit on page 7 (SC417/SC427). SC417 Efficiency/Power Loss vs. Load — PSAVE Mode Internal biased: VLDO = 5V 1.05V OUT 100 95 12V IN 6V ...

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Typical Characteristics (continued) Characteristics in this section are based on using the Detailed Application Circuit on page 7 (SC417/SC427). SC427 Efficiency/Power Loss vs. Load — PSAVE Mode External biased: V5V = 5V 1.05V OUT 100 12V IN 95 ...

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Typical Characteristics (continued) Characteristics in this section are based on using the Detailed Application Circuit on page 7 (SC417/SC427). SC417 Load Regulation —FCM External biased; V5V = 5V 1.05V OUT 1.08 1.07 19V 12V 1.06 6V 1.05 1.04 ...

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Typical Characteristics (continued) Characteristics in this section are based on using the Detailed Application Circuit on page 7 (SC417/SC427). Ultrasonic Powersave Mode — No Load (SC417 12V 1.05V 0A OUT OUT 1.073V ...

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Typical Characteristics (continued) Characteristics in this section are based on using the Detailed Application Circuit on page 7 (SC417/SC427). Transient Response — Load Rising (SC417 12V 1.05V 10A OUT OUT ...

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Typical Characteristics (continued) Characteristics in this section are based on using the Detailed Application Circuit on page 7 (SC417/SC427). Shorted Output Response — Normal Operation V = 12V 1.05V 0A OUT OUT LDO 1.05V ...

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

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Block Diagram V5V 3 V5V AGND D Reference Soft Start Comparator TON 31 5 VOUT Bypass Comparator Bypass Comparator A VLDO VLDO Switchover MUX 2 FBL PGOOD EN/PSV 26 29 Control & Status Gate ...

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Applications Information Synchronous Buck Converter The SC417/SC427 is a step down synchronous DC-DC buck converter with integrated power MOSFETs and a program- mable LDO. The device is capable of 10A operation at very high efficiency. A space saving 5x5 (mm) ...

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Applications Information (continued) internal 500mV reference. This feeds into the gate drive and turns on the high-side MOSFET, and also starts the one-shot timer. The one-shot timer uses an internal com- parator and a capacitor. One comparator input is con- ...

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Applications Information (continued) the output of the switching regulator soft-discharges the output into a 15Ω internal resistor via the V EN/PSV is allowed to float, the pin voltage will float to 33% of the voltage at V5V. The switching regulator ...

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Applications Information (continued) minimum f ~ 25kHz SW FB Ripple Voltage ( Inductor Current DH On-time is triggered when On-time 40µs time-out DL After the 40µsec time-out, DL drives high if V ...

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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) Power Good Output The power good (PGOOD) output is an open-drain output which requires a pull-up resistor. When the output voltage is 10% below the nominal voltage, PGOOD is pulled low held low until the ...

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Applications Information (continued) nal bias voltage at V5V and the ENL pin is used to program the VIN UVLO feature, the voltage at FBL needs to be higher than 750mV to force the LDO off. Timing is important when driving ...

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Applications Information (continued) grammed to 3.3V. After start-up, the device would connect VOUT to VLDO and disable the LDO, since the two volt- ages are within the ±300mV switch-over window. To avoid unwanted switch-over, the minimum difference between the voltages ...

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Applications Information (continued) The desired switching frequency is 250kHz which results from using components selected for optimum size and cost. A resistor ( used to program the on-time (indirectly TON setting the frequency) using the following equation. T ...

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Applications Information (continued) Since this 2% error comes from 1/2 of the ripple voltage, the allowable ripple is 4%, or 42mV for a 1.05V output. The maximum ripple current of 4.4A creates a ripple voltage across the ESR. The maximum ...

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Applications Information (continued) Double-pulsing occurs due to switching noise seen at the FB input or because the FB ripple voltage is too low. This causes the FB comparator to trigger prematurely after the 250ns minimum off-time has expired. In extreme ...

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Applications Information (continued) The component values used in this circuit are calculated using the following procedure. Select C (100nF) and R to provide a 25mV ripple across OUT L ...

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Applications Information (continued) To compensate for valley regulation, it may be desirable to use passive droop. Take the feedback directly from the output side of the inductor and place a small amount of trace resistance between the inductor and output ...

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Applications Information (continued) PCB Layout Guidelines The optimum layout for the SC417/SC427 is shown in Figure 15. This layout shows an integrated FET buck regu- lator with a maximum current of 10A. The total PCB area is approximately 20 x ...

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Applications Information (continued) to AGND are done by wide copper traces or vias down to AGND. • Connect PGND to AGND with a short trace or 0Ω resistor. This connection should be as close to the IC as possible. FB, ...

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Outline Drawing — MLPQ-5x5-32 A PIN 1 INDICATOR (LASER MARK) A aaa C A1 1.05 1.49 3.61 1. R0.20 PIN 1 IDENTIFICATION e NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. COPLANARITY APPLIES TO ...

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Land Pattern — MLPQ-5x5-32 3. (C) 3. NOTES: 1. CONTROLLING DIMENSIONS ARE IN MILLIMETERS (ANGLES IN DEGREES). 2. THIS LAND PATTERN IS FOR REFERENCE PURPOSES ONLY. CONSULT YOUR MANUFACTURING GROUP TO ENSURE YOUR COMPANY'S MANUFACTURING GUIDELINES ...

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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 ...