BM1410A

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Technical content

www.bookly.com 2.2A Step-Down Converter BM1410A F

FEATURES

 2.2A Output Current  Efficiency up to 92% @+5V output  +5V to +23V Input Range 15µA Shutdown Supply Current 380kHz Switching Frequency  Adjustable Output Voltage from 1.23V to 0.85*VIN Cycle-by-Cycle Current Limit Protection Thermal Shutdown Protection  Frequency Fold Back at Short Circuit Stability with Wide Range of Capacitors, full pin-pin with ACT4060/ TD1410 / MP1410  SOP-8 Package

APPLICATIONS

 TFT LCD Monitors Portable DVDs  NET CARD Telecom Power Supplies  DSL and Cable Modems and Routers LCD TV GENERAL DESCRIPTION The BM1410A is a current-mode step-down DC-DC converter that generates up to 2.2A output current at 380kHz switching frequency. The device utilizes advanced BCD process for operation with input voltage up to +23V c onsuming only 15µA in shutdown mode, the BM1410A is highly efficient with peak efficiency at 92% when in operation. Protection features include cycle-by-cycle current limit, thermal shutdown, and frequency fold back at short circuit. The BM1410A is available in SOP-8 package and requires very few external devices for operation. It can replace ACT4060/MP1410 without change external components and PCB layout. In application , if not use the pin7(en) function , can let the pin7 open , can pull-up to Vin with a pull-up resistor, but can not short to Vin dirrectly. CX4060 G ACT4060 FB COMP SW EN +5V to 20V ENABLE IN BS 2.5V/2A EN BM1410A SW FB COMPGnd Figure 1. Typical Application Circuit

www.bookly.com BM1410A

ORDERING INFORMATION

PART NUMBER TEMPERATURE RANGE PACKAGE BM1410A -10°C to 85°C SOP-8 PIN CONFIGURATION PIN No. PIN NAME PIN DESCRIPTION 1 BS Bootstrap. This pin acts as the positive rail for the high-side switch’s gate driver. Connect a 10nF between this pin and SW. 2 IN Input Supply. Bypass this pin to G with a low ESR capaci tor. See Input Capacitor in Application Information section. 3 SW Switch Output. Connect this pin to the switching end of the inductor. 4 G Ground. 5 FB Feedback Input. The voltage at this pin is regulated to 1.225V. Connect to the resistor divider bet ween output and ground to set output voltage. 6 COMP Compensation Pin. See Compensation Tec hnique in Application Information section. Output voltage is discharged when the IC is off. This pin has a small internal pull up current to a high level voltage when pin is not connected. 8 N/C Not Connected. 81BS IN SW GND Comp EN N/C BM1410A FB

www.bookly.com BM1410A ABSOLUTE MAXIMUM RATINGS (Note: Do not exceed these limits to prevent damage to the device. Exposure to absolute maximum rating conditions for long peri ods may affect device reliability.) PARAMETER VALUE UNIT IN Supply Voltage -0.3 to 23 V SW Voltage -1 to VIN + 1 V BS Voltage VSW - 0.3 to VSW + 6 V EN, FB, COMP Voltage -0.3 to 6 V Continuous SW Current Internally limited A Junction to Ambient Thermal Resistance (θJA) 105 °C/W Operating Junction Temperature -40 to 150 °C Storage Temperature -55 to 150 °C Lead Temperature (Soldering, 10 sec) 300 °C ELECTRICAL CHARCXERISTICS (VIN = 12V, TJ = 25°C unless otherwise specified) PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT Feedback Voltage VFB +5V ≤ VIN ≤ 20V, VCOMP = 1.5V 1.185 1.225 1.26 V High-Side Switch On Resistance RONH 0.20 Ω Low-Side Switch On Resistance RONL 4.7 Ω SW Leakage VEN = 0 0.5 5 µA Current Limit ILIM 2.6 2.9 A COMP to Current Limit Transconductance GCOMP 1.8 A/V Error Amplifier Transconductance GEA ∆ICOMP = ±10µA 550 µA/V Error Amplifier DC Gain AVEA 3200 V/V Switching Frequency fSW 320 380 430 kHz Short Circuit Switching Frequency VFB = 0 50 kHz Maximum Duty Cycle DMAX VFB = 1.1V 90 % Minimum Duty Cycle VFB = 1.4V 0% Enable Threshold Voltage Hysteresis = 0.1V 1.7 1.85 2 V Enable Pull Up Current Pin pulled up to 4.5V typically when left unconnected 2.5 µA Supply Current in Shutdown VEN = 0 20 30 µA IC Supply Current in Operation VEN = 3V, VFB = 1.4V 1 mA Thermal Shutdown Temperature Hysteresis = 10°C 160 °C

www.bookly.com BM1410A Figure 2 . Functional Block Diagram FUNCTIONAL DESCRIPTION As seen in Figure 2, Functional Block Diagram, the BM1410A is a current mode pulse width modulation (PWM) converter. The converter operates as follows: A switching cycle starts when the rising edge of the Oscillator clock output causes the High-Side Power Switch to turn on and the Low-Side Power Switch to turn off. With the SW side of the inductor now connected to IN, the inductor current ramps up to store energy in the its magnetic field. The inductor current level is measured by the Current Sense Amplifier and added to the Oscillator ramp signal. If the resulting summation is higher than the COMP voltage, the output of the PWM Comparator goes high. When this happens or when Oscillator clock output goes low, the High-Side Power Switch turns off and the Low-Side Power Switch turns on. At this point, the SW side of the inductor swings to a diode voltage below ground, causing the inductor current to decrease and magnetic energy to be transferred to output. This state continues until the cycle starts again. The High-Side Power Switch is driven by logic using BS bootstrap pin as the positive rail. This pin is charged to V SW + 6V when the Low-Side Power Switch turns on. The COMP voltage is the integration of the error between FB input and the internal 1.28V reference. If FB is lower than the reference voltage, COMP tends to go higher to increase current to the output. Current limit happens when COMP reaches its maximum clam value of 2.55V. The Oscillator normally swit ches at 380kHz. However, if FB voltage is less than 0.7V, then the switching frequency decreases until it reaches a minimum of 50kHz at V FB = 0.5V. SHUTDOWN CONTROL The BM1410A has an enable input EN for turning the IC on or off. When EN is less than 1.8V, the IC is in 8µA low current shutdown mode and output is discharged through the Low-Side Power Switch. When EN is higher than 1.85V, the IC is in normal operation mode. EN is internally pulled up with a 2.5µA current source and can be left unconnected for always-on operation. Note that EN is a low voltage input with a maximum voltage of 6V; it should never be directly connected to Vin THERMAL SHUTDOWN The BM1410A automatically turns off when its junction temperature exceeds 160°C.

www.bookly.com BM1410A 220uF/35V 22nF 4.75V to +20V ACT4060 IN EN 3.3V/2A BS FB COMP SW ENABLE G 15K 10K D1 SK34 16.9K IC1 BM1410A 10nF L1 22uH/3A 470 uF/ 10V ceramic,or 47uF/6 .3 SP cap (optional) IN Figure5: BM1410A 2.5V/2A Output Application TYPECIAL PERFORMANCE AND CHARACTERISTICS:

www.bookly.com BM1410A PACKAGE OUTLINE SOP-8 PACKAGE OUTLINE AND DIMENSIONS DIMENSION IN MILIMETERS DIMENSION IN INCHES SYMBOL MIN MAX MIN MAX A 1.350 1.750 0.053 0.069 A1 0.100 0.250 0.004 0.010 A2 1.350 1.550 0.053 0.061 B 0.330 0.510 0.013 0.020 C 0.190 0.250 0.007 0.010 D 4.780 5.000 0.188 0.197 E 3.800 4.000 0.150 0.157 E1 5.800 6.300 0.228 0.248 e 1.270 TYP 0.050 TYP L 0.400 1.270 0.016 0.050 θ 0° 8° 0° 8° Figure10: Figure11: