ETA3521FSG

ETA3521 2MHz, 4A, COT Synchronous Step-down Converter in SOT563 DESCRIPTION FEATURES The ETA3521 is a high-efficiency, DC-to-DC step-down switching regulator, capable of delivering up to 4A of output current. The devices operate from an input voltage range of 2.5V to 6.0V and provide output voltages from 0.6V to VIN, making the ETA3521 ideal for low voltage power conversions. ETA3521 adopts an adaptive COT control scheme that enables very fast transient response and provides a very smooth transition when the output varies from light load to heavy load. During light load, ETA3521 goes into a PFM mode that saves switching loss to achieve a high efficiency. The adaptive COT control also maintains a constant switching frequency across line and load. Running at a fixed frequency of 2MHz allows the use of small inductance value and low DCR inductors, thereby achieving a higher efficiency. Other external components, such as ceramic input and output caps, can also be small due to higher switching frequency, while maintaining exceptional low-noise output voltages. Internal soft-start control circuitry reduces inrush current. Short-circuit and thermal-overload protection improves design reliability ETA3521 is available in a tiny SOT563 package.              Up to 95% Efficiency Up to 4A Max Output Current Adaptive COT Control Ultra-fast Load Transient Response 2MHz Frequency High Efficiency PFM Mode at Light Load 50uA Quiescent Current 1% Feedback Accuracy Adjustable Output Voltage from 0.6V Cycle-by-cycle Over Current Protection Short Circuit Protection with Hiccup Mode Stable with Low-ESR Output Ceramic Capacitors Available in SOT563 Package APPLICATIONS    LCD TV Set Top Box IP CAM TYPICAL APPLICATION 6 VIN 3 VIN SW 2 1uH ETA3521 22 uF EN OUT 4 EN GND VOUT R1 47pF optional FB 5 R2 1 Vout= ORDERING INFORMATION www.etasolution.com 22uF R1+R2 x 0.6(V) R2 PART No. PACKAGE TOP MARK Pcs/Reel ETA3521FSG SOT563 CBYW 5000 1 Empower Thinkers ETA3521 PIN CONFIGURATION ABSOLUTE MAXIMUM RATINGS (Note: Exceeding these limits may damage the device. Exposure to absolute maximum rating conditions for long periods may affect device reliability.) Top View GND 1 SW 2 ETA3521 VIN 3 6 OUT 5 FB 4 EN VIN, FB, EN, OUT, SW Voltage ..............–0.3V to 6.5V Operating Temperature Range ............–40°C to 85°C Storage Temperature Range .............–55°C to 150°C Thermal Resistance ΘJA ΘJC SOT563..............................80.............50.......... °C/W Lead Temperature (Soldering 10sec) ................260°C ESD HBM (Human Body Mode) ..........................4KV ESD CDM (Charged Device Mode) .....................1KV SOT563 ELECTRICAL CHARACTERISTICS (VIN = 5.0V, unless otherwise specified. Typical values are at TA = 25°C.) PARAMETER CONDITIONS Input Voltage Range MIN TYP 2.5 MAX UNIT 6.0 V Input UVLO Rising, Hysteresis=300mV 2.3 2.4 2.5 V Input OVP Rising, Hysteresis=0.25V 6.0 6.35 6.7 V Input Supply Current VFB=0.65V, no switching 50 100 µA 0 1 µA 0.6 0.606 V 0 1 µA VIN V Input Shutdown Current FB Voltage 2.5V≤VIN≤6.0V 0.594 FB Input Current Output Voltage Range 0.6 Load Regulation Line Regulation VIN=2.7V to 5.5V Switching Frequency Soft Start Time 1.5 0.7 %/A 0.2 %/V 2 2.5 MHz VOUT Rising from 10% to 90% 0.5 mS On Time 0.5 mS Off Time 3.5 mS FB Hiccup Threshold 0.2 V High Side Switch On Resistance 53 74 mΩ Low Side Switch On Resistance 31 50 mΩ Short Circuit Hiccup Time High Side Current Limit 5.5 6 A Low Side Current Limit 4.4 5 A SW Leakage Current VOUT=5.5V, VSW=0 or 5.5V, EN= GND EN Logic High Threshold Rising EN Logic Low Threshold Falling 0.4 V EN Input Current VEN=2V 1 uA Thermal Shutdown Rising, Hysteresis =34°C www.etasolution.com 10 1.2 2 µA V 150 °C Empower Thinkers ETA3521 PIN DESCRIPTION PIN # 1 2 3 NAME GND SW VIN 4 EN 5 FB 6 OUT DESCRIPTION Ground Inductor Connection. Connect an inductor Between SW and the regulator output. Supply Voltage. Bypass with a 22μF ceramic capacitor to GND Enable pin. EN is high voltage level to enable. For automatic start-up, connect EN pin to VIN pin with a pull-up resistor. Feedback Input. Connect an external resistor divider from the output to FB and GND to set VOUT Output pin. Bypass with a 22uF or larger ceramic capacitor closely between this pin and GND TYPICAL CHARACTERISTICS (Typical values are with Cff=47pF, at TA = 25°C unless otherwise specified.) VOUT Vs. IOUT Eff. Vs. IOUT 4 100% VOUT=3.3V 3.5 90% 80% 3 Efficiency VOUT(V) 2.5 2 1.5 Vin=3.6V Vin=4V Vin=4.5V Vin=5V Vin=5.5V 1 0.5 0 VOUT=3.3V 70% 0 1 2 IOUT(A) 3 60% 50% 40% Vin=3.6V Vin=4V Vin=4.5V Vin=5V Vin=5.5V 30% 20% 10% 0% 0.001 4 0.01 VOUT Vs. IOUT 0.1 IOUT(A) Eff. Vs. IOUT 100% 2.5 90% VOUT=1.8V 2 80% VOUT=1.8V 1.5 1 Efficiency VOUT(V) 70% Vin=3V Vin=3.6V Vin=4V Vin=5V Vin=5.5V 0.5 0 1 0 1 2 3 50% 40% Vin=3V Vin=3.6V Vin=4V Vin=5V Vin=5.5V 30% 20% 10% 4 IOUT(A) www.etasolution.com 60% 0% 0.001 0.01 0.1 1 IOUT(A) 3 Empower Thinkers ETA3521 TYPICAL CHARACTERISTICS (cont’) (Typical values are with Cff=47pF, at TA = 25°C unless otherwise specified.) VOUT Vs. IOUT Eff. Vs. IOUT 100% 1.6 90% VOUT=1.2V 1.4 80% 70% 1 Efficiency VOUT(V) 1.2 0.8 Vin=2.5V Vin=3V Vin=3.6V Vin=4V Vin=5V Vin=5.5V 0.6 0.4 0.2 0 0 1 2 3 Vin=2.5V Vin=3V Vin=3.6V Vin=4V Vin=5V Vin=5.5V 40% 20% 10% 0% 0.001 4 0.01 IOUT(A) VOUT Vs. IOUT Eff. Vs. IOUT 90% 80% 70% Efficiency 0.5 0.4 Vin=2.5V Vin=3.0V Vin=3.6V Vin=4V Vin=5V Vin=5.5V 0.3 0.2 0.1 0 1 2 3 60% VOUT=0.6V 50% 40% Vin=2.5V Vin=3.0V Vin=3.6V Vin=4V Vin=5V Vin=5.5V 30% 20% 10% 0% 0.001 4 0.01 VIN UVLO 1.6 0.1 1 IOUT(A) IOUT(A) IQ Vs. VIN 80 VOUT=1.2V 1.4 75 1.2 70 1 65 IQ(uA) VOUT(V) 1 100% VOUT=0.6V 0.6 0.8 VOUT=1.2V,IOUT=0A 60 55 0.6 0.4 Rising 50 0.2 Falling 45 0 0.1 IOUT(A) 0.7 VOUT(V) VOUT=1.2V 50% 30% 0.8 0 60% 1 2 3 www.etasolution.com VIN(V) 4 5 6 40 2 3 4 5 6 VIN(V) 4 Empower Thinkers ETA3521 TYPICAL CHARACTERISTICS (cont’) (Typical values are with Cff=47pF, at TA = 25°C unless otherwise specified.) VOUT Vs. Temp. VOUT Vs. VIN 1.3 1.3 VOUT=1.2V 1.25 1.2 VOUT(V) VOUT(V) 1.2 1.15 Iout=0A Iout=0.5A Iout=1A Iout=2A Iout=3A 1.1 1.05 1 VOUT=1.2V,IOUT=0.5A 1.25 1.15 1.1 1.05 1 2 3 4 5 VIN(V) Vin=2.5V Vin=3.6V Vin=5V 6 -40 -20 0 20 40 60 80 Temperature(℃) 100 120 140 Load Transient VIN=3.3V, VOUT=1.2V,IOUT=0.1A-4A Max IOUT Vs. Temp. 6 VOUT=1.2V 5 VOUT IOUT(A) 4 3 2 Vin=3.6V 1 0 Vin=5V ISW -40 -20 0 20 40 60 80 Temperature(℃) 100 120 140 Start Up from EN VIN=3.3V, VOUT=1.2V,IOUT=4A Shut Down from EN VIN=3.3V, VOUT=1.2V,IOUT=4A VEN VEN VOUT VOUT SW SW ISW ISW www.etasolution.com 5 Empower Thinkers ETA3521 TYPICAL CHARACTERISTICS (cont’) (Typical values are with Cff=47pF, at TA = 25°C unless otherwise specified.) Start Up from VIN VIN=3.3V, VOUT=1.2V,IOUT=4A Shut Down from VIN VIN=3.3V, VOUT=1.2V,IOUT=4A VIN VIN VOUT VOUT SW SW ISW ISW Short Circuit Protection Short Circuit Recovery VOUT VOUT ISW ISW FUNCTIONAL BLOCK DIAGRAM VIN EN Band gap&UVLO ILIM OTP OUT Soft start COT FBCOMP SW LOGIC FB COMP Ramp Generator HICCUP GND www.etasolution.com 6 Empower Thinkers ETA3521 FUNCTIONAL DESCRIPTION The ETA3521 is a synchronous buck regulator that integrates the adaptive COT control, top and bottom switches on the same die to minimize the switching transition loss and conduction loss. ETA3521 is a high-efficiency and high-frequency DC-to-DC step-down switching regulator, capable of delivering up to 4A of output current. It adopts an adaptive COT control scheme that enables very fast transient response and provides a very smooth transition when the output varies from light load to heavy load. It compares the sum of the FB voltage and a ripple voltage that mimics the voltage due to the output ESR and capacitance. The constant-on-time timer varies with line to achieve relative constant switching frequency across line. Light Load Operation Traditionally, a fixed constant frequency PWM DC-DC regulator always switches even when the output load is small. When energy is shuffling back and forth through the power MOSFET, power is lost due to the finite Rdson of the MOSFET and parasitic capacitances. At light load, this loss is prominent and efficiency is therefore very low. ETA3521 goes into a power save mode during light load, thereby extending the range of high efficiency operation. Over Current Protection and Hiccup ETA3521 has a cycle-by-cycle over current limit for when the inductor current peak value is over the set current limit threshold. When the output voltage drop until FB falls below UV threshold (0.2V), the ETA3521 will enter hiccup mode. It will turn off the chip immediately for 3.5mS. After that, it will try to re-starts as normal for 0.5mS. After 0.5mS, if FB is still below UV threshold, then the chip enters hiccup mode again. If FB is higher than UV threshold, it will enter the normal mode. Over-Temperature Protection Thermal protection disables the output when the junction temperature rises to approximately 150°C, allowing the device to cool down. When the junction temperature cools to approximately 115°C, the output circuitry is again enabled. Depending on power dissipation, thermal resistance, and ambient temperature, the thermal protection circuit may cycle on and off. This cycling limits regulator dissipation, protecting the device from damage as a result of overheating. APPLICATION INFORMATION External Output Voltage Setting In external Output Voltage Setting Version selected, the ETA3521 regulator is programmed using an external resistor divider. The output voltage is calculated using below equation. VOUT =VREF × (1+ R1 ) R2 Where: VREF =0.6V typically (the internal reference voltage) Resistors R2 has to be between 1KOhm to 70KOhm and thus R1 is calculated by following equation. www.etasolution.com R1 = � 7 VOUT -1� ×R2 VREF Empower Thinkers ETA3521 PCB LAYOUT GUIDE Keep the power devices as close to the chip as possible to achieve the smallest power loop area, which leads to the best EMI performance; Cin is always placed nearest to Vin and GND Via Top Layer VOUT Bottom Layer GND 22uF 1uH GND 1 22uF VIN SW 2 VIN 3 6 ETA3521 OUT 5 FB 4 EN 47pF R1 R2 EN GND www.etasolution.com 8 Empower Thinkers ETA3521 PACKAGE OUTLINE Package: SOT563 www.etasolution.com 9 Empower Thinkers ETA3521 TAPE AND REEL INFORMATION www.etasolution.com 10 Empower Thinkers