MP1482M/TR

MP1482 2A 27V Synchronous Buck Converter Description Features The MP1482 is a monolithic synchronous buck regulator. The device integrates 95 mΩ MOSFETS that provide 2A continuous load current over a wide operating input voltage of 4.5V to 27V. Current mode control provides fast transient response and cycle-by-cycle current limit. An adjustable soft-start prevents inrush current at turn on.            2A Output Current Wide 4.5V to 27V Operating Input Range Integrated Power MOSFET switches Output Adjustable from 0.925V to 0.8Vin Up to 96% Efficiency Programmable Soft-Start Stable with Low ESR Ceramic Output Capacitors Fixed 340KHZ Frequency Cycle-by-Cycle Over Current Protection Short Circuit Protection Input Under Voltage Lockout Package： SOP-8L Applications      Distributed Power Systems Networking Systems FPGA, DSP, ASIC Power Supplies Green Electronics/ Appliances Notebook Computers Typical Application Circuit http://www.hgsemi.com.cn 1 2018 AUG MP1482 Pin Assignments Pin Descriptions Pin Number Name 1 BS Bootstrap. This pin acts as the positive rail for the high-side switch’s gate driver. Connect a 0.01uF capacitor between BS and SW. 2 VIN Input Supply. Bypass this pin to GND with a low ESR capacitor. See Input Capacitor in the Application Information section. 3 SW Switch Output. Connect this pin to the switching end of the inductor. 4 GND 5 FB Feedback Input. The voltage at this pin is regulated to 0.925V. Connect to the resistor divider between output and ground to set output voltage. 6 COMP Compensation Pin. See Stability Compensation in the Application Information section. EN Enable Input. When higher than 2.7V, this pin turns the IC on. When lower than 1.1V, this pin turns the IC off. Output voltage is discharged when the IC is off. This pin should not be left open. Recommend to put a 100KΩ pull up resistor to Vin for startup. SS Soft-Start Control Input. SS controls the soft-start period. Connect a capacitor from SS to GND to set the soft-start period. A 0.1uF capacitor sets the soft-start period to 15ms. To disable the soft-start feature, leave SS unconnected. 7 8 http://www.hgsemi.com.cn Description Ground. 2 2018 AUG MP1482 Block Diagram Absolute Maximum Ratings Parameter Value Unit Input Supply Voltage -0.3 to 30 V SW Voltage -0.3 to VIN + 0.3 V BS Voltage VSW – 0.3 to VSW + 6 V EN, FB, COMP Voltage -0.3 to 5. V Continuous SW Current Internally limited A Junction to Ambient Thermal Resistance (θJA) (Test on Approximately 3 in2 Copper Area 1oz copper FR4 board) 87 °C/W SOP-8L Power Dissipation Internal limit W Maximum Junction Temperature 150 °C Storage Temperature Range -65 to 150 °C Moisture Sensitivity (MSL) Please refer the MSL Label on the IC package bag/carton for detail (Note: Exceeding these limits may damage the device., Even the duration of exceeding is very short. Exposure to absolute maximum rating conditions for long periods may affect device reliability.) http://www.hgsemi.com.cn 3 2018 AUG MP1482 Recommended Operating Conditions Parameter Min Max Input Supply Voltage 4.5 27 Operating Junction Temperature Unit (1) V (2) -20 +125 °C (Note (1): Operating the IC over this voltage is very easy to cause over voltage condition to VIN pin, SW pin, BS pin & EN pin) (Note (2): If the IC experienced OTP, then the temperature may need to drop to 15V, pure ceramic Cin (* no EC cap) is not recommended. This is because the ESR of a http://www.hgsemi.com.cn 6 2018 AUG MP1482 ceramic cap is often too small, Pure ceramic Cin will work with the parasite inductance of the input trace and forms a Vin resonant tank. When Vin is hot plug in/out, this resonant tank will boost the Vin spike to a very high voltage and damage the IC. Output Capacitor The output capacitor also needs to have low ESR to keep low output voltage ripple. In the case of ceramic output capacitors, RESR is very small and does not contribute to the ripple. Therefore, a lower capacitance value can be used for ceramic capacitors. In the case of tantalum or electrolytic capacitors, the ripple is dominated by RESR multiplied by the ripple current. In that case, the output capacitor is chosen to have sufficiently low ESR. For ceramic output capacitors, typically choose of about 22uF. For tantalum or electrolytic capacitors, choose a capacitor with less than 50mΩ ESR. Optional Schottky Diode During the transition between high-side switch and low-side switch, the body diode of the low side power MOSFET conducts the inductor current. The forward voltage of this body diode is high. An optional Schottky diode may be paralleled between the SW pin and GND pin to improve overall efficiency. Table 3 lists example Schottky diodes and their Manufacturers. Table 3－Diode Selection Guide Vin max Part Number Voltage/Current Rating 20V SK14 40V, 1A Vendor Stability Compensation CCOMP2 is needed only for high ESR output capacitor Figure2. Stability Compensation The feedback loop of the IC is stabilized by the components at the COMP pin, as shown in Figure 2. The DC loop gain of the system is determined by the following equation: http://www.hgsemi.com.cn 7 2018 AUG MP1482 The dominant pole P1 is due to CCOMP1: The second pole P2 is the output pole: The first zero Z1 is due to RCOMP and CCOMP: And finally, the third pole is due to RCOMP and CCOMP2 (if CCOMP2 is used): The following steps should be used to compensate the IC: STEP1. Set the crossover frequency at 1/10 of the switching frequency via RCOMP: But limit RCOMP to 10KΩ maximum. More than 10 KΩ is easy to cause overshoot at power on. STEP2. Set the zero fZ1 at 1/4 of the crossover frequency. If RCOMP is less than 10KΩ, the equation for CCOMP is: STEP3. If the output capacitor’s ESR is high enough to cause a zero at lower than 4 times the crossover frequency, an additional compensation capacitor CCOMP2 is required. The condition for using CCOMP2 is: And the proper value for CCOMP2 is: Though CCOMP2 is unnecessary when the output capacitor has sufficiently low ESR, a small value CCOMP2 such as 100pF may improve stability against PCB layout parasitic effects http://www.hgsemi.com.cn 8 2018 AUG MP1482 Table 4－ Component Selection Guide for Stability Compensation Rcomp (R3) (kΩ) Ccomp (C4) (nF) Ccomp2 (C5) (pF) Inductor (uH) 1.0 3.3 5.6 none 4.7 5 - 15 1.2 3.9 4.7 none 4.7 5 - 15 1.8 5.6 3.3 none 10 5 - 15 2.5 8.2 2.2 none 10 5 - 15 3.3 10 2 none 10 7 - 15 5 10 3.3 none 10 5 - 12 1.0 5 - 15 1.2 5 - 23 1.8 5 - 27 2.5 5 -27 3.3 7 -27 5 Vin Rang(V) Vout (V) 5 – 12 Cout 22uF x2 Ceramic 4.7 470uF/6.3V/ 120mΩ 10 6.8 680 10 Figure3. Load Transient Testing vs Compensation Value Typical Performance Characteristics (VIN=12V, Io=0 mA, Temperature = 25 degree C, unless otherwise specified) Light Load Operation (No load) Heavy Load Operation (2A Load) VIN=12V, Iin=8.2 mA, Vout=3,3V VIN=12V, Vout=3,3V http://www.hgsemi.com.cn 9 2018 AUG MP1482 Startup Vin=12V, Vout=3.3V, Iout=1A through Vin. through Enable. Short Circuit Protection Vin=12V http://www.hgsemi.com.cn 10 2018 AUG MP1482 http://www.hgsemi.com.cn 11 2018 AUG MP1482 Important statement: Huaguan Semiconductor Co,Ltd. reserves the right to change the products and services provided without notice. Customers should obtain the latest relevant information before ordering, and verify the timeliness and accuracy of this information. Customers are responsible for complying with safety standards and taking safety measures when using our products for system design and machine manufacturing to avoid potential risks that may result in personal injury or property damage. Our products are not licensed for applications in life support, military, aerospace, etc., so we do not bear the consequences of the application of these products in these fields. Our documentation is only permitted to be copied without any tampering with the content, so we do not accept any responsibility or liability for the altered documents. http://www.hgsemi.com.cn 12 2018 AUG