BL9641B 42V Input Standoff Voltage, 0.4A Step-Down Converter FEATURES DESCRIPTION • • • • • • • • • • The BL9641B is a wide input range, highefficiency, and high frequency DC-to-DC stepdown switching regulator, capable of delivering up to 0.4A of output current. With a fixed switching frequency of 750KHz, 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.BL9641B 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 BL9641B must be used to minimize thermal dissipation. BL9641B is available SOT23-6 Packages. APPLICATIONS • • • Smart Meters Industrial Applications Automotive Applications PIN OUT TYPICAL APPLICATION www.belling.com.cn Wide Input Operating Range from 4V to 38V Standoff Input Voltage: 42V High Efficiency at 20V In 12V Out: Up to 95%: High Efficiency PFM mode at light load Capable of Delivering 0.4A No External Compensation Needed Current Mode control Logic Control Shutdown Thermal shutdown and UVLO Available in SOT23-6 Package 1 BL9641B MARK and ORDERING INFORMATION Mark Explanation X2: Type Y: Year W: Week PINOUT 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. BLOCK DIAGRAM EN BST IN + UVLO & Thermal shutdown REG &REF Current Sense - + EA + COMP network Σ - FB PWM Logic DRIVER OSC Slope Comp GND www.belling.com.cn 2 SW BL9641B ABSOLUTE MAXIMUM RATING Parameter Value Input Voltage Range Max Operating Junction Temperature(Tj) SW, EN Voltage BST Voltage FB Voltage SW to ground curren Operating Temperature(To) SOT23-6 Package Thermal Resistance (θjc) Storage Temperature(Ts) -0.3V-42V 150°C –0.3V to VIN+0.3V –0.3V to SW+6V –0.3V to 6V Internally limited -40°C –85°C 110°C / W -55°C - 150°C Note: Exceed these limits to damage to the device. Exposure to absolute maximum rating conditions may affect device reliability. ELECTRICAL CHARACTERISTICS (VIN = 12V, unless otherwise specified. Typical values are at TA = 25°C .) 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 www.belling.com.cn CONDITIONS MIN TYP 42 4 Rising, Hysteresis=140mV Rising, Hysteresis=1.3V VFB =0.85V 0.780 MAX 38 3.80 38 0.6 6 0.800 0.01 750 0.820 90 VFB = 0V ISW =200mA 95 550 0.7 VIN=12V,VSW=0, EN= GND VIN=12V ,VEN =5V Rising, Hysteresis=100mV Hysteresis=40°C 0.8 3 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 BL9641B TYPICAL PERFORMANCE CHARACTERISTICS (Typical values are at TA = 25°C unless otherwise specified.) www.belling.com.cn 4 BL9641B TYPICAL CHARACTERISTICS (Typical values are at TA = 25°C unless otherwise specified.) www.belling.com.cn 5 BL9641B FUNCTIONAL DECRIPTIONS Loop Operation The BL9641B is a wide input range, high-efficiency, DC-to-DC step-down switching regulator, capable of delivering up to 0.4A of output current, integrated with a 550mΩ 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. BL9641B 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. www.belling.com.cn 6 BL9641B PACKAGE OUTLINE www.belling.com.cn 7