SP1471SRL

SP1471SRL 3A Wide Input 500kHz Synchronous Step-Down Converter FEATURES GENERAL DESCRIPTION • • • • • • • • The SP1471 is a fully integrated, high efficiency 3A synchronous rectified step-down converter. The SP1471 operates at high efficiency over a wide output current load range. This device offers two operation modes, PWM control and PFM Mode switching control, which allows a high efficiency over the wider range of the load. The SP1471requires a minimum number of readily available standard external components and is available in an 6-pin SOT23 ROHS compliant package. 4.5V to 16V Wide Input Voltage Range Max 3A Output Current,Up to 96% Efficiency Excellent Line and Load Transient Response Over Current Protection with Hiccup-Mode Inrush Current Limit and Soft Start circuit 0.8V Reference Voltage -40°C to +85°C Temperature Range Available in SOT23-6 Package TYPICAL APPLICATION CIRCUIT C2 1uF L VIN BS VIN SW SP1471 CIN 22μF EN R1 C1 100k 22pF 1% opt. FB R2 GND 19k 1% 1 V01 VOUT 6.8μH www.sourcechips.com COUT 22μF*3 SP1471SRL FUNCTIONAL BLOCK DIAGRAM VIN + ∑ VCC REGULATOR RSEN - VCC CURRENT SENSE AMPLIFIER BOOST REGULATOR BS OSCILLATOR HS DRIVER + EN COMPARATOR - REFERENCE CURRENT LIMIT COMPARATOR 1pF 1M 56pF VCC LOGIC CONTROL 400k + + - FB PIN CONFIGURATION Order Part Number Package SP1471SRL SOT23-6 TOP VIEW 6 BS SW 2 5 EN VIN 3 4 FB 6-LEAD PLASTIC SOT-23 TJMAX = 150°C, θJA = 170°C/ W, θJC = 130°C/W V01 LS DRIVER GND ERROR AMPLIFIER GND 1 SW ON TIME CONTROL 2 www.sourcechips.com SP1471SRL PIN DESCRIPTIONS Pin Name Pin Number Description GND 1 Analog ground pin. SW 2 Switching Pin. VIN 3 Power supply Pin FB 4 Adjustable version feedback input. Connect FB to the center point of the external resistor divider EN 5 Drive this pin to a logic-high to enable the IC. Drive to a logic-low to disable the IC and enter micro-power shutdown mode. For automatic start-up, connect EN to VIN using a 200kΩ resistor. BS 6 Bootstrap. A capacitor connected between SW and BS pins is required to form a floating supply across the high-side switch driver. ABSOLUTE MAXIMUM RATINGS Input Supply Voltage…….…….…-0.3V to 17V V01 EN Voltages…………………………-0.3V to 6V Thermal Resistance θJA……….…..….....….170°C /W Junction Temperature(Note2)…….…............150°C FB Voltages…………………………-0.3V to 6V Operating Temperature Range….….-40°C to 85°C SW Voltage………………...-0.3V to (VIN+0.5V) Lead Temperature(Soldering,10s)……...…...300°C BS Voltage…………..(VSW-0.3V) to (VSW+5V) Storage Temperature Range……....-65°C to 150°C Power Dissipation…………………...……...0.6W ESD HBM(Human Body Mode)…………..…...2kV Thermal Resistance θJC…………...….130°C /W ESD MM(Machine Mode)……………......…….200V 3 www.sourcechips.com SP1471SRL ELECTRICAL CHARACTERISTICS (VIN=12V, VOUT=5V, TA = 25°C) PARAMETER CONDITIONS MIN Input Voltage Range 4.5 Supply Current in Operation VEN=3.0V, VFB=2V Supply Current in Shutdown VEN =0 or EN = GND Regulated Feedback Voltage TA = 25°C, 4.5V≤ VIN ≤16V 0.6 MAX UNIT 16 V 0.8 mA 1 780 800 µA 820 mV High-Side Switch On-Resistance 90 mΩ Low-Side Switch On-Resistance 70 mΩ High-Side Switch Leakage Current VEN=0V, VSW=0V 1 µA Low-Side Switch Leakage Current VEN=0V, VSW=12V 1 µA Upper Switch Current Limit Minimum Duty Cycle Maximum Duty Cycle 400 VFB=0.8V Minimum On-Time Soft-start Time A 4.5 Oscillation Frequency Tss Thermal Shutdown 4 V01 TYP www.sourcechips.com 500 92 580 KHz % 60 nS 1 mS 180 ℃ SP1471SRL TYPICAL PERFORMANCE CHARACTERISTICS 100 100 95 95 90 90 85 85 80 80 75 75 70 65 70 60 65 60 0.01 55 0.1 1 50 0.01 10 0.1 1 10 100 100 95 90 90 85 80 80 75 70 70 60 65 60 50 55 40 0.01 0.1 1 50 0.01 10 5 V01 www.sourcechips.com 0.1 1 10 SP1471SRL OPERATION Internal Regulator The SP1471 is a current mode step down DC/DC converter that provides excellent transient response with no extra external compensation components. This device contains an internal, low resistance, high voltage power MOSFET, and operates at a high 500K operating frequency to ensure a compact, high efficiency design with excellent AC and DC performance. Over-Current-Protection and Hiccup The The SP1471 has cycle-by-cycle over current limit when the inductor current peak value exceeds the set current limit threshold. Meanwhile, output voltage starts to drop until FB is below the Under-Voltage (UV) threshold, typically 30% below the reference. Once a UV is triggered, the The SP1471 enters hiccup mode to periodically restart the part. This protection mode is especially useful when the output is deadshort to ground. The average short circuit current is greatly reduced to alleviate the thermal issue and to protect the regulator. The SP1471 exits the hiccup mode once the over current condition is removed. Error Amplifier The error amplifier compares the FB pin voltage with the internal FB reference (VFB) and outputs a current proportional to the difference between the two. This output current is then used to charge or discharge the internal compensation network to form the COMP voltage, which is used to control the power MOSFET current. The optimized internal compensation network minimizes the external component counts and simplifies the control loop design. Startup and Shutdown If both VIN and EN are higher than their appropriate thresholds, the chip starts. The reference block starts first, generating stable reference voltage and currents, and then the internal regulator is enabled. The regulator provides stable supply for the remaining circuitries. Three events can shut down the chip: EN low, VIN low and thermal shutdown. In the shutdown procedure, the signaling path is first blocked to avoid any fault triggering. The COMP voltage and the internal supply rail are then pulled down. The floating driver is not subject to this shutdown command. Internal Soft-Start The soft-start is implemented to prevent the converter output voltage from overshooting during startup. When the chip starts, the internal circuitry generates a soft-start voltage (SS) ramping up from 0V to 0.8V. When it is lower than the internal reference (REF), SS overrides REF so the error amplifier uses SS as the reference. When SS is higher than REF, REF regains control. The SS time is internally fixed to 1ms. 6 V01 www.sourcechips.com SP1471SRL PACKAGE OUTLINE SOT23-6 PACKAGE OUTLINE AND DIMENSIONS D θ 0.2 SYMBOL E E1 c e A A1 A2 e1 DIMENSION IN INCHES MIN MAX A - 1.450 - 0.057 A1 0.000 0.150 0.000 0.006 A2 0.900 1.300 0.035 0.051 b 0.300 0.500 0.012 0.020 c 0.080 0.220 0.003 0.009 D 2.900 BSC 0.114 BSC E 1.600 BSC 0.063 BSC E1 2.800 BSC 0.110 BSC e 0.950 BSC 0.037 BSC e1 1.900 BSC 0.075 BSC L 0.300 θ 0°° 7 V01 DIMENSION IN MILLIMETERS MIN L b www.sourcechips.com 0.600 0.012 0.024 8°