BL8091 18V (30V spike) 2A Synchronous PFM/PWM Buck Converter DESCRIPTION FEATURES The BL8091 is a high efficiency current-mode synchronous, 18V/2A buck converter. Its input voltage ranges from 4.5V to 18V and it provides an adjustable regulated output voltage from 0.923V to 15V while delivering up to 2A of output current. The internal synchronous switches increase efficiency and eliminate the need for an external Schottky diode. The switching frequency is set to 340KHz. And the BL8091 will automatically switch between PFM and PWM mode based on the load current, thus to enhance the converter efficiency at light load. Adjustable Output Voltage, Vfb=0.923V Maximum output current is 2A Range of operation input voltage: Max 18V Withstand input voltage spike >30V Standby current: 1mA (typ.) Operating current at zero load: 1.2mA (typ.) Line regulation: 0.1%/V (typ.) Load regulation: 10mV (typ.) High efficiency, up to 95% Environment Temperature: -20C~85C APPLICATIONS BL8091 consists of many protection block such as UVLO, input voltage over voltage protection to stand much higher input voltage spike, thermal protection and output short circuit protection. The BL8091 is available in the SOP8 and ESOP8 (with exposed pad for heat dissipation) package TYPICAL APPLICATION Set-top-box Consumer Electronic Device for automobile LCD Monitor and LCD TV Portable DVD ADSL Modem, WLAN router Other 12V or double cell Li-ion battery powered device PIN OUT 10uH 0.1uF BST SS VIN EN VOUT 3.3V/2A 10nF 100K VIN LC2321 BL8091 10uF SW 3.3nF 10K 22uF x2 LC2321 BL8091 SW COMP GND FB PFM at Light Load 26.1K * When Vin is as low as 5V, Cc is recommended to be 100pf, but not needed when Vin larger than 5V. www.belling.com.cn EN SOP8 and ESOP8 COMP FB SS VIN 5.6K *Cc optional GND BST 1 BL8091 MARK and ORDERING INFORMATION Mark Explanation Ordering Information HH|: Product Code LL: Lot No. U: Fab code YW: Date code HH | LLUYW SOP8 2500pcs/reel BL8091CD8TR ESOP8 2500pcs/reel BL8091CS8TR PINOUT DESCRIPTION PIN # 1 2 3 4 5 NAME BST VIN SW GND FB 6 COMP 7 EN 8 SS DESCRIPTION High side power transistor gate drive boost input Power input, the input capacitor should be placed as close to VIN and GND pin as possible Power switching node to connect inductor Ground. Feedback input with reference voltage set to 0.923 Compensation node. A serial RC connected to this pin is required to maintain the Buck converter control loop stable. Enable input. Setting it to high level or connecting to Vin via a resistor may turn on the chip, while setting it to ground level will turn off the chip. Soft-start node. Connecting a 0.1uF capacitor to ground make the Buck converter output rise smoothly. BLOCK DIAGRAM SS VIN UVLO & Thermal shutdown 0.923V Ref + ISense 5V BST - + + - Σ Comp Network - EA EN PWM Logic Anti-ShootThrough Driver SW Slope Comp + OSC Vcomp - FB COMP www.belling.com.cn 2 GND BL8091 ABSOLUTE MAXIMUM RATING Parameter Value Max Input Voltage Max Operating Junction Temperature(Tj) Ambient Temperature(Ta) SOP-8L Package Thermal Resistance (jc) ESOP-8L Storage Temperature(Ts) Lead Temperature & Time ESD (HBM) 30V 125C -20C – 85C 45C / W 10C / W -40C - 150C 260C, 10S >2000V Note: Exceed these limits to damage to the device. Exposure to absolute maximum rating conditions may affect device reliability. RECOMMENDED WORK CONDITIONS Parameter Value Input Voltage Range Operating Junction Temperature(Tj) Max. 18V -20C –125C ELECTRICAL CHARACTERISTICS (VIN=12V, TA=25C) Symbol Parameter VDD Input Voltage Range UVLO_UP UVLO,IN UVLO Rising Vref Feedback Voltage Ifb Feedback Leakage current Iq Quiescent Current Conditions Min Typ 4.5 Record VIN pin voltage as V(UVLO) when measure I(IN)> 500uA Vin=12V, Ven=5V 3.8 0.900 Active, Vfb=1V, No Switching Shutdown, Vin=8V 4.1 0.923 Max Unit 18 V 4.4 V 0.946 V 0.1 0.4 uA 1.1 1.5 mA 6 10 uA LnReg Line Regulation Vin=5V to 12V 0.1 %/V LdReg Load Regulation Iout=0.1 to 2A 0.02 %/A Switching Frequency Ven=2V, Vin=12V 340 KHz RdsonP Fsoc PMOS Rdson 130 mohm RdsonN NMOS Rdson 110 mohm Ilimit Peak Current Limit Venh EN High Threshold Venl EN Low Threshold Vovp Input Over-Voltage Protection TSD Over Temperature Proection www.belling.com.cn 2.5 1 Ven=2V 1.5 18 V 0.5 V V 160 3 A 2 C BL8091 TYPICAL PERFORMANCE CHARACTERISTICS (Vin=12V, Vout=3.3V, L=10uH, Cin=10uF, Cout=22uF, TA=25C, unless otherwise stated) Efficiency (Vout=3.3V) Vout Vs. Iout 100 3.5 3 80 Vout (V) Eff. (%) 2.5 60 40 Vin=5V Vin=12V Vin=4.5V 20 2 1.5 1 Vin=4.5V Vin=5V Vin=12V 0.5 0 0 1 10 100 1,000 0 Iout (mA) 1 1.5 2 Iout (A) Vout Vs. Vin Zero Load Operating Current Vs. Vin 4 1.4 3.5 1.2 3 1 2.5 Iq (mA) Vout (V) 0.5 2 1.5 0.8 0.6 0.4 1 IOUT=300mA 0.5 0.2 0 Iq (mA) 0 4 6 8 10 12 14 16 18 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 Vin (V) Vin (V) Switching waveform Vin=18V, Iout=0 Switching waveform Vin=18V, Iout=2A VIN VIN VOUT VOUT I_L SW SW I_L www.belling.com.cn 4 BL8091 Switching waveform Vin=5V, Iout=0 Switching waveform Vin=5V, Iout=2A VOUT VOUT VIN VIN SW SW I_L I_L FUNCTIONAL DECRIPTIONS Loop Operation The BL8091 is a wide input range, high-efficiency, DC-to-DC step-down switching regulator, capable of delivering up to 2A of output current, integrated with a 110m synchronous MOSFET, eliminating the need for external diode. 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. Current Limit There is a cycle-by-cycle current limit on the high-side MOSFET of 3A(typ). When the current flowing out of SW exceeds this limit, the high-side MOSFET turns off and the synchronous rectifier turns on. Unlike the traditional method of current limiting by limiting the voltage at the compensation pin, which usually has large variation due to duty cycle variance, this type of peak current limiting scheme provides a relatively more accurate limit for output current, thereby lowering the requirements for system design. Light Load Operation Traditionally, a fixed current mode 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. BL8091 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. Faster Transient Response Normally, people use 3.3nF and 5.6Kohm RC for compensation to keep the loop stable. However, if one needs to have faster load transient response, 3.3nF and 8.5Kohm is recommended. www.belling.com.cn 5 BL8091 COMPONENT SELECTRION When setting up the BL8091 for different output voltage, please use following recommended component value for the best performance. VOUT (V) 8 5 3.3 2.5 1.8 1.2 COUT (F) 22x2 22x2 22x2 22x2 22x2 22x2 L (H) 22 15 10 6.8 4.7 3.3 THERMAL CONSIDERATION BL8091 is high efficiency Buck converter, which means it consumes very few power when converting the high voltage to low voltage. However, when output power is very large, like 5V/2A, the output power is as high as 10W, a heat dissipation path is strongly recommended to be routed on PCB. BL8091 has two different SOP8 package. For the normal SOP8, the heat is conducted out via Pin 4 (GND), so the heat dissipation route on PCB should be connected to the Pin 4 of the chip. If ESOP8 is selected, the heat dissipation copper area should be exposed and connected to the exposed pad underneath the chip body. When output power is larger than 10W, the ESOP8 package is recommended. www.belling.com.cn 6 BL8091 PACKAGE OUTLINE Package SOP8 Devices per reel 2500 Unit mm Devices per reel 2500 Unit mm Package specification： Package ESOP8 Package specification： www.belling.com.cn 7