BL8076CB5TR

BL8076 2A 3MHz 6V Synchronous Buck Converter DESCRIPTION FEATURES         The BL8076 is a high efficiency synchronous, buck DC/DC converter. Its input voltage range is from 2.6V to 6V and provides an adjustable regulated output voltage from 0.6V to Vin while delivering up to 2A of output current. The internal synchronous switches increase efficiency and eliminate the need for an external Schottky diode. It runs at a fixed 3MHz frequency, which allows the use of small inductor with L2000V Note: Exceed these limits to damage to the device. Exposure to absolute maximum rating conditions may affect device reliability. www.belling.com.cn 2 BL8076 RECOMMENDED WORK CONDITIONS Parameter Value Input Voltage Range Operating Junction Temperature(Tj) Max. 6V -20C –125C ELECTRICAL CHARACTERISTICS (VIN=5V, TA=25C) Symbol Parameter VDD UVLO Vref Ifblk Input Voltage Range Input Under Voltage Lockout Feedback Voltage Feedback Leakage current Iq Conditions Line Regulation Load Regulation Switching Frequency PMOS Rdson RdsonN Ilimit Iswlk Venh, Vmdh Venl, Vmdl Ienlk, Imdlk Rdischarge Typ 2.6 2.1 0.588 Increase Vin Vin=5V, Ven=5V 2.2 0.6 0.01 30 0.1 0.04 0.15 3 100 Active, Vfb=0.65V, No Switching Shutdown Vin=2.7V to 5.5V Iout=0.1 to 2A Quiescent Current LnReg LdReg Fsoc RdsonP Min 2.4 Isw=200mA NMOS Rdson Peak Current Limit SW Leakage Current EN/MODE High Threshold EN/MODE Low Threshold EN/MODE Leakage Current Discharge Resistance Isw=200mA Unit 6.0 V V V uA uA uA %/V %/A MHz mohm 0.612 0.1 1 3.6 120 80 3 2.5 Max 100 Vout=5.5V, EN=GND mohm A uA V V uA Ohm 10 1.5 0.4 EN=MODE=GND EN=GND 180 1 450 300 TYPICAL PERFORMANCE CHARACTERISTICS (Vin=3.6V, L=1uH, Cin=10uF, Cout=10uF, TA=25C, unless otherwise stated) Efficiency at Vout=1.8V 100% 100.00% 90% 90.00% 80% 80.00% 70% 70.00% 60% 60.00% Efficiency Efficiency Efficiency at Vout=3.3V 50% 40% 50.00% 40.00% 30% VIN=3.7V 30.00% VIN=5.0V 20% VIN=4.2V 20.00% VIN=3.0V 10% VIN=5.0V 10.00% VIN=3.6V 0% 0.00% 0.0 0.5 1.0 1.5 2.0 2.5 0.0 www.belling.com.cn 0.5 1.0 1.5 Iout(A) Iout(A) 3 2.0 2.5 BL8076 Efficiency at Vout=1.2V Load Regulation at Vout=1.8V 2 100.00% 1.95 90.00% 1.9 70.00% 1.85 60.00% 1.8 Vout (V) Efficiency 80.00% 50.00% 40.00% 30.00% 1.75 1.7 1.65 VIN=3.0V 20.00% VIN=3.6V 1.6 10.00% VIN=5.0V 1.55 0.00% 0.0 0.5 1.0 1.5 2.0 VIN=3V VIN=3.6V VIN=5V 1.5 2.5 0 Iout(A) Switching waveform Vin=3.6V, Vout=1.2V Iout=0A 0.5 1 1.5 2 2.5 Iout(A) Switching waveform Vin=3.6V, Vout=1.2V Iout=0.7A SW SW VOUT VOUT I_inductor I_inductor Switching waveform Vin=5V, Vout=3.3V, Iout=0A Switching waveform Vin=5V, Vout=3.3V, Iout=0.5A SW SW VOUT VOUT I_inductor I_inductor www.belling.com.cn 4 BL8076 Load Transient Vin=3.6V, Vout=1.2V, Iout=0.2A/1A Load Transient Vin=3.6V, Vout=1.8V, Iout=0.2A/1.5A SW SW VOUT VOUT I_inductor I_inductor FUNCTIONAL DECRIPTIONS The BL8076 high efficiency switching regulator is a small, simple, DC-to-DC step-down converter capable of delivering up to 2A of output current. The device operates in pulse-width modulation (PWM) at 3MHz from a 2.6V to 5.5V input voltage and provides an output voltage from 0.6V to VIN, making the BL8076 ideal for on-board post-regulation applications. An internal synchronous rectifier improves efficiency and eliminates the typical Schottky free-wheeling diode. Using the on resistance of the internal high-side MOSFET to sense switching currents eliminates current-sense resistors, further improving efficiency and cost. Loop Operation BL8076 uses a PWM current-mode control scheme. An open-loop comparator compares the integrated voltage-feedback signal against the sum of the amplified current-sense signal and the slope compensation ramp. At each rising edge of the internal clock, the internal high-side MOSFET turns on until the PWM comparator terminates the on cycle. During this on-time, current ramps up through the inductor, sourcing current to the output and storing energy in the inductor. The current mode feedback system regulates the peak inductor current as a function of the output voltage error signal. During the off cycle, the internal high-side P-channel MOSFET turns off, and the internal low-side N-channel MOSFET turns on. The inductor releases the stored energy as its current ramps down while still providing current to the output. Current Sense An internal current-sense amplifier senses the current through the high-side MOSFET during on time and produces a proportional current signal, which is used to sum with the slope compensation signal. The summed signal then is compared with the error amplifier output by the PWM comparator to terminate the on cycle. Current Limit There is a cycle-by-cycle current limit on the high-side MOSFET. When the current flowing out of SW exceeds this limit, the high-side MOSFET turns off and the synchronous rectifier turns on. BL8076 utilizes a frequency fold-back mode to prevent overheating during short-circuit output conditions. The device enters frequency fold-back mode when the FB voltage drops below 200mV, limiting the current to IPEAK and reducing power dissipation. Normal operation resumes upon removal of the short-circuit condition. Soft Start BL8076 has a internal soft-start circuitry to reduce supply inrush current during startup conditions. When the device exits under-voltage lockout (UVLO), shutdown mode, or restarts following a thermal-overload event, the l soft-start circuitry slowly ramps up current available at SW. www.belling.com.cn 5 BL8076 UVLO and Thermal Shutdown If VIN drops below 2V, the UVLO circuit inhibits switching. Once VIN rises above 2.1V, the UVLO clears, and the soft-start sequence activates. Thermal-overload protection limits total power dissipation in the device. When the junction temperature exceeds TJ= +160°C, a thermal sensor forces the device into shutdown, allowing the die to cool. The thermal sensor turns the device on again after the junction temperature cools by 15°C, resulting in a pulsed output during continuous overload conditions. Following a thermal-shutdown condition, the soft-start sequence begins. DESIGN PROCEDURE 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 2A maximum output current, the maximum inductor ripple current is 667 mA. The inductor size is estimated as following equation: LIDEAL=(VIN(MAX)-VOUT)/IRIPPLE*DMIN*(1/FOSC) Output Capacitor Selection For most applications a nominal 10μF or 22μF capacitor is suitable. The BL8076 internal compensation is designed for a fixed corner frequency that is equal to FC= = 50Khz For example, for VOUT=1.8V, L=1μH, COUT=10μF, for VOUT =1.2V, L=0.47μH, COUT=22μF Setting Output Voltage Output voltages are set by external resistors. The FB_ threshold is 0.6V. RTOP = RBOTTOM x [(VOUT / 0.6) - 1] Therefore, for VOUT=1.8V, The inductor values is calculated to be L = 0.60μH. Choose 1μH Guidelines for Input Capacitor and Output Capacitor 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. 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 And for VOUT =1.2V, The inductor values is calculated to be L = 0.469μH. Choose 0.47μH The resulting ripple is IRIPPLE =(VIN(MAX)-VOUT)/LACTUAL*DMIN*(1/FOSC) When, VOUT=1.8V, IRIPPLE = 403mA VOUT=1.2V, IRIPPLE = 665mA www.belling.com.cn 6 BL8076 PACKAGE OUTLINE Package DFN2x2-8L Package specification： Devices per reel 3000pcs Unit mm Package Devices per reel 3000Pcs Unit mm SOT-23-5 Package specification： www.belling.com.cn 7