ETA2842S2G

ETA2842 42V Input Standoff Voltage, 1A Step-Down Converter in SOT23-6 DESCRIPTION FEATURES The ETA2842 is a wide input range, high-efficiency, and high frequency DC-to-DC step-down switching regulator, capable of delivering up to 1A of output current. With a fixed switching frequency of 650KHz, this current mode PWM controlled converter allows the use of small external components, such as ceramic input and output caps, as well as small inductors.ETA2842 also employs a proprietary control scheme that switches the device into a power save mode during light load, thereby extending the range of high efficiency operation. An OVP function protects the IC itself and its downstream system against input voltage surges. With this OVP function, the IC can stand off input voltage as high as 42V, making it an ideal solution for industrial applications such as smart meters as well as automotive applications. In automotive systems, power comes from the battery, with its voltage typically between 9V and 24V. Including cold crank and double battery jump-starts, the minimum input voltage may be as low as 4V and the maximum up to 36V, with even higher transient voltages. With these high input voltages, linear regulators cannot be used for high supply currents without overheating the regulator. Instead, high efficiency switching regulators such as ETA2842 must be used to minimize thermal dissipation. ETA2842 is available SOT23-6 Packages.            Wide Input Operating Range from 4V to 38V Standoff Input Voltage: 42V Output up to 12V High Efficiency at 12V In 5V Out: Up to 91%: High Efficiency PFM mode at light load Capable of Delivering 1A No External Compensation Needed Current Mode control Logic Control Shutdown Thermal shutdown and UVLO Available in SOT23-6 Package APPLICATIONS    Smart Meters Industrial Applications Automotive Applications ORDERING INFORMATION PART # ETA2842S2G PACKAGE PIN SOT23-6 Date Code Product Number TYPICAL APPLICATION VIN Standoff up to 42V 50V 10μF 5 1 10nF BST 10μH 4 SW EN 6 D1 FB GND 2 49.9K 3 16.2K VOUT 3.3V/0.5A ŋ IN 6.3V 22μF TOP MARK EGYW Efficiency Vs IOUT 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% VIN=6V VIN=12V VIN=24V VIN=36V VOUT=5V 0.01 0.1 1 IOUT (A) Outperform with Efficiency www.ETAsolution.com Proprietary Information DO NOT Distribute 1 ETA2842 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.) BST 1 6 SW GND 2 5 IN FB 3 4 IN Voltage...............................................................-0.3V to 42V SW, EN Voltage……………………………………..–0.3V to VIN+0.3V BST Voltage…………………………………………………–0.3V to SW+6V FB Voltage………………………………………………………….–0.3V to 6V SW to ground current ………….…….……….......Internally limited Operating Temperature Range ……................…–40°C to 85°C Storage Temperature Range ………………..….–55°C to 150°C EN SOT23-6 Thermal Resistance θJA θJC SOT23-6……………………………………………..220…….…110 ........oC/W ELECTRICAL CHACRACTERISTICS (VIN = 12V, unless otherwise specified. Typical values are at TA = 25oC.) PARAMETER Input Standoff Voltage Input Voltage Range Input UVLO Input OVP Input Supply Current Input Shutdown Current FB Feedback Voltage FB Input Current Switching Frequency Maximum Duty Cycle FoldBack Frequency High side Switch On Resistance High side Switch Current Limit SW Leakage Current EN Input Current EN Input Low Voltage Thermal Shutdown CONDITIONS MIN 42 4 Rising, Hysteresis=140mV Rising, Hysteresis=1.3V VFB =0.85V TYP MAX 38 3.80 38 0.6 6 0.800 0.01 650 90 VFB = 0V ISW =200mA VIN=12V,VSW =0, EN= GND VIN=12V ,VEN =5V Rising, Hysteresis=100mV Hysteresis=40°C 60 400 1.2 0.8 1 1.1 150 10 5 1.4 UNITS V V V V mA μA V μA KHz % KHz mΩ A μA μA V °C PIN DESCRIPTION PIN # 1 2 3 4 5 6 NAME BST GND FB EN IN SW DESCRIPTION Bootstrap pin. Connect a 10nF capacitor from this pin to SW Ground Feedback Input. Connect an external resistor divider from the output to FB and GND to set VOUT Enable pin for the IC. Drive this pin high to enable the part, low to disable. Supply Voltage. Bypass with a 10μF ceramic capacitor to GND Inductor Connection. Connect an inductor Between SW and the regulator output. Outperform with Efficiency www.ETAsolution.com Proprietary Information DO NOT Distribute 2 ETA2842 TYPICAL CHARACTERISTICS VIN=6V VIN=12V VIN=24V VIN=36V VOUT=5V 0.01 0.1 Efficiency Vs IOUT 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 1 900 800 700 0.01 0.1 0.4 VOUT=3.3V 200 1 0 10 20 0.6 0.8 IOUT (A) VOUT Vs VIN 5.05 5.04 5.03 5.02 5.01 5 4.99 4.98 4.97 4.96 4.95 30 40 VIN (V) VOUT Vs Temperature 3.33 3.32 3.31 VOUT(V) VOUT (V) VOUT (V) VOUT=5V 0.2 400 300 IOUT (A) VOUT Vs IOUT 0 600 500 VIN=5V VIN=12V VIN=24V VIN=36V VOUT=3.3V IOUT (A) 5.05 5.04 5.03 5.02 5.01 5 4.99 4.98 4.97 4.96 4.95 IQ Vs VIN 1000 IQ (μA) Efficiency Vs IOUT 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% ŋ ŋ (Typical values are at TA = 25oC unless otherwise specified.) IOUT=0mA IOUT=500mA 3.3 3.29 3.28 3.27 6 16 26 36 VIN (V) -50 0 50 100 Temperature(OC) Frequency Vs Temperature 800 Frequency(KHz) 750 700 650 600 550 500 -50 0 50 100 Temperature(OC) Outperform with Efficiency www.ETAsolution.com Proprietary Information DO NOT Distribute 3 ETA2842 TYPICAL CHARACTERISTICS (Typical values are at TA = 25oC unless otherwise specified.) Start-up Waveform with EN VIN=12V,VOUT=5V,IOUT=0A Shutdown Waveform with EN VIN=30V,VOUT=5V,IOUT=0.5A Start-up Waveform with EN=VIN VIN=12V,VOUT=5V,IOUT=0A VEN VEN VOUT VIN VOUT VOUT VSW VSW VSW ISW ISW ISW 5ms/div 5ms/div 5ms/div Switching Waveform VIN=12V,VOUT=5V,IOUT=0.1A Switching Waveform VIN=12V,VOUT=5V,IOUT=0.3A Load Transient Response VIN=12V,VOUT=3.3V,IOUT=0 to 0.5A VOUT VOUT VSW VOUT VSW ISW 5ms/div 5ms/div Load Transient Response VIN=12V,VOUT=5V,IOUT=0 to 0.5A Short-Circuit Response VIN=24V,VOUT=5V,IOUT=0A to Short Short-Circuit Recovery VIN=24V,VOUT=5V,IOUT= Short to 0A VOUT VOUT VOUT 5ms/div ISW ISW ISW 5ms/div 5ms/div 5ms/div Outperform with Efficiency www.ETAsolution.com Proprietary Information DO NOT Distribute 4 ETA2842 FUNCTIONAL DESCRIPTIONS Loop Operation The ETA2842 is a wide input range, high-efficiency, DC-to-DC step-down switching regulator, capable of delivering up to 1A of output current, integrated with a 400mΩ high side MOSFET. It uses a PWM current-mode control scheme. An error amplifier integrates error between the FB signal and the internal reference voltage. The output of the integrator is then compared to the sum of a current-sense signal and the slope compensation ramp. This operation generates a PWM signal that modulates the duty cycle of the power MOSFETs to achieve regulation for output voltage. 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 MOSFETs, power is lost due to the finite RDSONs of the MOSFETs and parasitic capacitances. At light load, this loss is prominent and efficiency is therefore very low. ETA2842 employs a proprietary control scheme that improves efficiency in this situation by enabling the device into a power save mode during light load, thereby extending the range of high efficiency operation. BLOCK DIAGRAM EN BST IN UVLO & Thermal shutdown REG &REF Current Sense + - + EA + COMP network Σ - FB PWM Logic DRIVER SW OSC Slope Comp GND Outperform with Efficiency www.ETAsolution.com Proprietary Information DO NOT Distribute 5 ETA2842 APPLICATION INFORMATION Setting Output Voltages Output voltages are set by external resistors. The FB threshold is 0.8V. RTOP = RBOTTOM x [(VOUT / 0.8) - 1] Inductor Selection The peak-to-peak ripple is limited to 30% of the maximum output current. This places the peak current far enough from the minimum overcurrent trip level to ensure reliable operation while providing enough current ripples for the current mode converter to operate stably. In this case, for 1A maximum output current, the maximum inductor ripple current is 300 mA. The inductor size is estimated as following equation: LIDEAL=(VIN(MAX)-VOUT)/IRIPPLE*DMIN*(1/FOSC) Therefore, for VOUT=5V, The inductor values is calculated to be L = 13μH. Chose 10μH or 15μH For VOUT =3.3V, The inductor values is calculated to be L = 9.2μH. Chose 10μH Output Capacitor Selection 1 FC=2∗π√COUT∗L = 8.7Khz For example, for VOUT=5V, L=15μH, COUT=22μF. The output capacitor keeps output ripple small and ensures control-loop stability. The output capacitor must also have low impedance at the switching frequency. Ceramic, polymer, and tantalum capacitors are suitable, with ceramic exhibiting the lowest ESR and high-frequency impedance. Output ripple with a ceramic output capacitor is approximately as follows: VRIPPLE = IL(PEAK)[1 / (2π x fOSC x COUT)] If the capacitor has significant ESR, the output ripple component due to capacitor ESR is as follows: VRIPPLE(ESR) = IL(PEAK) x ESR Input Capacitor Selection The input capacitor in a DC-to-DC converter reduces current peaks drawn from the battery or other input power source and reduces switching noise in the controller. The impedance of the input capacitor at the switching frequency should be less than that of the input source so high-frequency switching currents do not pass through the input source. The output capacitor keeps output ripple small and ensures control-loop stability. Components Selection VOUT (V) 8 5 3.3 COUT (μF) 22 22 22 L (μH) 15 to 22 10 to 15 6.8 to 10 For most applications a nominal 22μF or larger capacitor is suitable. The ETA2842 internal compensation is designed for a fixed corner frequency that is equal to Outperform with Efficiency www.ETAsolution.com Proprietary Information DO NOT Distribute 6 ETA2842 PACKAGE OUTLINE Outperform with Efficiency www.ETAsolution.com Proprietary Information DO NOT Distribute 7