BL9341 600mA, 40V Synchronous Step-Down Converter FEATURES DESCRIPTION The BL9341 is a current mode monolithic buck switching regulator. Operating with an input range of 4.7V~40V, the BL9341 delivers 600mA of continuous output current with two integrated N-Channel MOSFETs. The internal synchronous power switches provide high efficiency without the use of an external Schottky diode. At light loads, the regulator operates in low frequency to maintain high efficiency and low output ripple. Current mode control provides tight load transient response and cycle-by-cycle current limit. The BL9341 guarantees robustness with short-circuit protection, thermal protection, current run-away protection, and input under voltage lockout. The BL9341 is available in 6-pin SOT23-6 package, which provides a compact solution with minimal external components. 4.7V to 40V operating input range 600mA output current Up to 93% efficiency High efficiency (>78%) at light load Internal Soft-Start 2MHz switching frequency Input under voltage lockout Available in SOT23-6 package Current run-away protection Short circuit protection Thermal protection APPLICATIONS Distributed Power Systems Automotive Systems High Voltage Power Conversion Industrial Power Systems Battery Powered Systems TYPICAL APPLICATION www.belling.com.cn 1 V1.1 BL9341 ORDER INFORMATION Part Number Package Top Marking Packing BL9341 SOT23-6 BL9341 3000pcs/Tape & Reel PIN CONFIGURATION TOP VIEW BST 1 6 SW GND 2 5 VIN FB 3 4 EN SOT23-6 ABSOLUTE MAXIMUM RATING1) 1) 2) ............... -0.3V to 44V VIN, EN, SW Pin BST Pin Note： .... ............. SW-0.3V to SW+5V All other Pins .................... -0.3V to 6V Junction Temperature 2) 3) .................150ºC ...................260 ºC Lead Temperature Storage Temperature 3) ... ....－65 ºC to +150 ºC Recommended Operating Conditions Input Voltage VIN .................4.7V to 40V Output Voltage Vout............... 0.8V to 37V Operating Junction Temperature...-40ºC to 125ºC 4) ThermaL resistance4) θJA Exceeding these ratings may damage the device. The BL9341 guarantees robust performance from -40°C to 150°C junction temperature. The junction temperature range specification is assured by design, characterization and correlation with statistical process controls. The BL9341 includes thermal protection that is intended to protect the device in overload conditions. Thermal protection is active when junction temperature exceeds the maximum operating junction temperature. Continuous operation over the specified absolute maximum operating junction temperature may damage the device. Measured on JESD51-7, 4-layer PCB. θJc SOT23-6 ........................ 220...130.ºC /W www.belling.com.cn 2 V1.1 BL9341 ELECTRICAL CHARATERISTICS VIN = 24V, TA = 25ºC, unless otherwise stated. Item Symbol Condition VIN_MIN VIN falling 4.2 V VIN_MIN_HYST VIN rising 160 mV Shutdown Supply Current ISD VEN=0V 0.07 Supply Current IQ VEN=5V, VFB=1V 50 VFB 4.7V<VVIN<40V VIN Undervoltage Lockout Thershold VIN Undervoltage Lockout Hysteresis Feedback Voltage Min. 776 Typ. 800 Max. Units 1 μA μA 824 mV Top Switch Resistance RDS(ON)T 500 mΩ Bottom Switch Resistance RDS(ON)B 220 mΩ Top Switch Leakage Current ILEAK_TOP Bottom Switch Leakage Current Top Switch Current Limit VIN=40V, VEN=0V, VSW=0V ILEAK_BOT VIN= VSW = 40V, VEN=0V ILIM_TOP Minimum Duty Cycle 1 uA 1 uA 1 A Switch Frequency fSW 2 MHz Minimum On Time TON_MIN 80 ns Minimum Off Time TOFF_MIN VFB=0V 100 ns VEN_TH VEN falling, FB=0V 1.2 V VEN_HYST VEN rising, FB=0V 40 mV TTSD 135 °C TTSD_HYST 15 °C EN shut down threshold voltage EN shut down hysteresis Thermal Shutdown Thermal Shutdown hysteresis www.belling.com.cn 3 V1.1 BL9341 PIN DESCRIPTION SOT23-6 Pin Name 1 BST 2 GND 3 FB 4 EN 5 VIN 6 SW Description Bootstrap pin for top switch. A 0.1uF or larger capacitor should be connected between this pin and the SW pin to supply current to the top switch and top switch driver. Ground. Output feedback pin. FB senses the output voltage and is regulated by the control loop to 800mV. Connect a resistive divider at FB. Drive EN pin high to turn on the regulator and low to turn off the regulator. Input voltage pin. VIN supplies power to the IC. Connect a 4.7V to 40V supply to VIN and bypass VIN to GND with a suitably large capacitor to eliminate noise on the input to the IC. SW is the switching node that supplies power to the output. Connect the output LC filter from SW to the output load. BLOCK DIAGRAM VIN + Current Ramp Current Sensor + Oscillator - CLK 3.3V BST + 0.8V FB + Current Comparator Error + Amplifier - SW Logic Control - 3.3V LDO Current Sensor + 1.2V + GND EN - www.belling.com.cn 4 V1.1 BL9341 TYPICAL PERFORMANCE CHARACTERISTICS Vin = 12V, Vout = 5V, L = 10μH, Cout = 10μF, TA = +25°C, unless otherwise noted Steady State Test Startup through Enable Shutdown through Enable VIN=12V, Vout=5V Iout=600mA VIN=12V, Vout=5V Iout=600mA(Resistive load) VIN=12V, Vout=5V Iout=600mA(Resistive load) Heavy Load Operation Medium Load Operation Light Load Operation 600mA LOAD 300mA LOAD 0 A LOAD Short Circuit Protection Short Circuit Recovery Load Transient VIN=12V, Vout=5V Iout=600mA- Short VIN=12V, Vout=5V Iout= Short-600mA 300mA LOAD → 600mA LOAD www.belling.com.cn 5 → 300mA LOAD V1.1 BL9341 FUNCTIONAL DESCRIPTION The BL9341 is a synchronous, current-mode, step-down regulator. It regulates input voltages from 4.7V to 40V down to an output voltage as low as 0.8V, and is capable of supplying up to 600mA of load current. low. Vin Under-Voltage Protection A resistive divider can be connected between Vin and ground, with the central tap connected to EN, so that when Vin drops to the pre-set value, EN drops below 1.2V to trigger input under voltage lockout protection. Current-Mode Control The BL9341 utilizes current-mode control to regulate the output voltage. The output voltage is measured at the FB pin through a resistive voltage divider and the error is amplified by the internal transconductance error amplifier. Output of the internal error amplifier is compared with the switch current measured internally to control the output current. Output Current Run-Away Protection At start-up, due to the high voltage at input and low voltage at output, current inertia of the output inductance can be easily built up, resulting in a large start-up output current. A valley current limit is designed in the BL9341 so that only when output current drops below the valley current limit can the top power switch be turned on. By such control mechanism, the output current at start-up is well controlled. PFM Mode The BL9341 operates in PFM mode at light load. In PFM mode, switch frequency decreases when load current drops to boost power efficiency at light load by reducing switch-loss, while switch frequency increases when load current rises, minimizing output voltage ripples. Output Short Protection When output is shorted to ground, output current rapidly reaches its peak current limit and the top power switch is turned off. Right after the top power switch is turned off, the bottom power switch is turned on and stay on until the output current falls below the valley current limit. When output current is below the valley current limit, the top power switch will be turned on again and if the output short is still present, the top power switch is turned off when the peak current limit is reached and the bottom power switch is turned on. This cycle goes on until the output short is removed and the regulator comes into normal operation again. Shut-Down Mode The BL9341 shuts down when voltage at EN pin is below 1.2V. The entire regulator is off and the supply current consumed by the BL9341 drops below 0.1uA when voltage at EN pin is below 0.3V. Power Switch N-Channel MOSFET switches are integrated on the BL9341 to down convert the input voltage to the regulated output voltage. Since the top MOSFET needs a gate voltage great than the input voltage, a boost capacitor connected between BST and SW pins is required to drive the gate of the top switch. The boost capacitor is charged by the internal 3.3V rail when SW is www.belling.com.cn Thermal Protection When the temperature of the BL9341 rises above 135°C, it is forced into thermal shut-down. Only when core temperature drops below 120°C 6 V1.1 BL9341 can the regulator becomes active again. 2. Put the feedback trace as far away from the inductor and noisy power traces as possible. PCB Layout Note 3. The ground plane on the PCB should be as large as possible for better heat dissipation. 1. Place the input decoupling capacitor as close to BL9341 (VIN pin and PGND) as possible to eliminate noise at the input pin. REFERENCE DESIGN Reference 1： VIN : VOUT: IOUT : 5.1V ~ 40 V 3.3V 0~600mA Reference 2： VIN : VOUT: IOUT : 7V ~ 40 V 5V 0~600mA www.belling.com.cn 7 V1.1 BL9341 PACKAGE OUTLINE SOT23-6 UNIT: mm 2.92±0.30 0～10° 0.4±0.20 2.80±0.30 1.60±0.30 0.45±0.15 0.25 0.950BSC 0.15 +0.15 -0.05 www.belling.com.cn 8 1.35MAX 1.10±0.10 0～0.15 1.90±0.20 V1.1