SY7304DBC

Applications Note:SY7304 High Efficiency 33V, 4A, 1MHz Step Up Regulator General Description Features The SY7304 is a high efficiency, current-mode control Boost regulator. The device integrates a 120mΩ low RDS(ON) N-channel MOSFET for high efficiency. The fixed 1MHz switching frequency and internal compensation reduce external components size and count. The build-in internal soft start circuitry minimizes the inrush current at start-up. The SY7304 is available in compact DFN3×3-10 package.     Ordering Information SY7304□(□□)□ Ordering Number SY7304DBC Temperature Code Package Code Optional Spec Code Package type DFN3×3-10       Wide input range: 3-33V Maximum output voltage: 33V 1MHz switching frequency Integrated 120 mΩ RDS(ON) switch with 4A peak current capability Internal soft-start 0.6V±2% reference voltage Cycle by cycle peak current limit Over temperature protection RoHS Compliant and Halogen Free Compact package: DFN3×3-10 Applications Note 4A    Portable Device Battery Powered System Networking cards powered from PCI or PCIexpress slots Typical Applications Figure 1. Schematic Diagram AN_SY7304 Rev. 0.9 Figure 2. Efficiency vs. Load Current Silergy Corp. Confidential- Prepared for Customer Use Only 1 SY7304 Pinout (top view) NC 1 FB 2 NC 3 LX 4 LX 5 10 NC 11 GND 9 EN 8 NC 7 IN 6 NC （DFN3×3-10） Top Mark: VIxyz (Device code: VI, x=year code, y=week code, z= lot number code) Pin Name IN GND LX FB Pin Number 7 11 4,5 2 EN 9 NC 1,3,6,8,10 Pin Description Input pin. Decouple this pin to GND pin with 1uF ceramic cap. Ground pin Inductor node. Connect an inductor between IN pin and LX pin. Feedback pin. Connect a resistor R1 between VOUT and FB, and a resistor R2 between FB and GND to program the output voltage: VOUT=0.6V*(R1/R2+1). Enable control. High to turn on the part. Don’t leave it floated. No connection. Absolute Maximum Ratings (Note 1) LX, IN, EN------------------------------------------------------------------------------------------------------------ - -0.3V to 36V FB------------------------------------------------------------------------------------------------------------------------ - -0.3V to 4V Power Dissipation, PD @ TA = 25°C DFN3×3-10---------------------------------------------------------------------- --2.6W Package Thermal Resistance (Note 2) θ JA--------------------------------------------------------------------------------------------------------------------------------------------------------------------- 38°C/W θ JC---------------------------------------------------------------------------------------------------------------------------------------------------------------------- 8°C/W Junction Temperature Range----------------------------------------------------------------------------------------- 40 to 150°C Lead Temperature (Soldering, 10 sec.)------------------------------------------------------------------------------------ 260°C Storage Temperature Range---------------------------------------------------------------------------------------65°C to 150°C Dynamic LX voltage in 50ns duration--------------------------------------------------------------------- IN+3V to GND-4V Recommended Operating Conditions (Note 3) IN------------------------------------------------------------------------------------------------------------------------------- V to 33V Junction Temperature Range---------------------------------------------------------------------------------------- 40°C to 125°C Ambient Temperature Range------------------------------------------------------------------------------------------40°C to 85°C AN_SY7304 Rev0.9 Silergy Corp. Confidential- Prepared for Internal Use Only 2 SY7304 Block Diagram AN_SY7304 Rev0.9 Silergy Corp. Confidential- Prepared for Internal Use Only 3 SY7304 Electrical Characteristics (VIN = 5V, VOUT =12V, IOUT =100mA, TA = 25°C unless otherwise specified) Parameter Input Voltage Range Quiescent Current Shutdown Current Low Side Main FET RON Main FET Current Limit Switching Frequency Feedback Reference Voltage FB Pin Input Current IN UVLO Rising Threshold UVLO Hysteresis EN Rising Threshold EN Falling Threshold Max Duty Cycle Thermal Shutdown Temperature Thermal Recovery Hysteresis Symbol VIN IQ ISHDN RDS(ON) Test Conditions ILIM Duty cycle=80% VFB=0.66V EN=0 Min 3 Typ 100 Max 33 15 120 Fsw VREF 4 0.8 0.588 IFB VIN,UVLO UVLO,HYS VENH VENL Dmax TSD THYS 1 0.6 -50 2 6 A 1.2 0.612 MHz V 50 2.7 nA V 0.4 V V V % °C 0.1 90 150 Unit V µA µA mΩ 15 °C Note 1: Stresses listed as the above “Absolute Maximum Ratings” may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note 2: θ JA is measured in the natural convection at TA = 25°C on a low effective single layer thermal conductivity test board of JEDEC 51-3 thermal measurement standard. Test condition: Device mounted on 2” x 2” FR-4 substrate PCB, 2oz copper, with minimum recommended pad on top layer and thermal vias to bottom layer ground plane. Note 3: The device is not guaranteed to function outside its operating conditions. AN_SY7304 Rev0.9 Silergy Corp. Confidential- Prepared for Internal Use Only 4 SY7304 Typical Performance Characteristics Load Transient Efficiency vs. Load Current (V IN =5.0V, V OUT=12V, IO=0.12 ~ 1.2A) 100 95 ∆V OUT 90 0.5V/div 85 80 75 IL 70 2A/div V IN =3.3V,V OUT =12V V IN =5.0V,V OUT =12V V IN =9.0V,V OUT =12V 65 60 55 50 1 10 100 1000 Load Current (mA) 10000 Time (100µs/div) Shutdown from VIN (V IN =5.0V, V OUT=12V, IO=1.2A) V IN 2V/div V OUT 5V/div V LX 10V/div Io 1A/div Time (800µs/div) Shutdown from Enable (V IN =5.0V, V OUT=12V, IO =1.2A) EN 5V/div V OUT 5V/div V LX 10V/div IO 1A/div Time (200µs/div) AN_SY7304 Rev0.9 Silergy Corp. Confidential- Prepared for Internal Use Only 5 SY7304 Output Ripple Output Ripple (V IN =5.0V, V OUT=12V, IO=1.2A) (V IN =5.0V, V OUT =12V, IO=0.6A) ∆V OUT 100mV/div V LX 10V/div IL ∆V OUT 20mV/div V LX 10V/div IL 2A/div 2A/div Time (1µs/div) Time (1µs/div) Output Ripple (V IN =5.0V, V OUT=12V, IO=0.06A) ∆V OUT 10mV/div V LX 10V/div IL 0.5A/div Time (1µs/div) AN_SY7304 Rev0.9 Silergy Corp. Confidential- Prepared for Customer Use Only 6 SY7304 Applications Information 1) Because of the high integration in SY7304, the application circuit based on this regulator IC is rather simple. Only input capacitor C ,INoutput capacitor C , OUT inductor L and feedback resistors (R1 and R2) need to be selected for the targeted applications. Feedback resistor divider R1 and R2 Choose R1 and R2 to program the proper output voltage. To minimize the power consumption under light load, it is desirable to choose large resistance values for both R1 and R2. A value between 10k and 1M is recommended for both resistors. If R1=200k is chosen, then R2 can be calculated to be: R 2 (VOUT VIN)  VIN  (H) L  F SW  I OUT_MAX  40% V OUT   where FSW is the switching frequency and the maximum load current. VOUT 2 R1 R2 3) Input capacitor CIN The ripple current through input capacitor is calculated as: ICIN_RMS  The saturation current rating of an inductor must be selected to guarantee an adequate margin to the peak inductor current under full load conditions.  VOUT   VIN  (VOUT VIN) ISAT_MIN     IOUT_MAX     VIN   VOUT  2  FSW  L FB GND IOUT_MAX is SY7304 regulator IC is less sensitive to the ripple current variations. Consequently, the final choice of inductance can be slightly off the calculation value without significantly impacting the performance. 2) 0.6R1 () VOUT  0.6 Choose the inductance to provide the desired ripple current. It is suggested to choose the ripple current to be about 40% of the maximum average input current. 2The inductance is calculated as: VIN  (VOUT  VIN) 2 3 L FSW VOUT (A) To minimize the potential noise problem, place a typical X5R or better grade ceramic capacitor really close to the IN and GND pins. Care should be taken to minimize the loop area formed by CIN, and IN/GND pins. A low ESR ceramic capacitor with greater than 10uF capacitance is recommended. Output capacitor COUT The output capacitor is selected to handle the output ripple noise requirements. Both steady state ripple and transient requirements must be taken into account when selecting this capacitor. For the best performance, it is recommended to use X5R or better grade ceramic capacitor with greater than 22uF capacitance. Boost inductor L There are several considerations in choosing this inductor. AN_SY7304 Rev0.9 The DCR of the inductor and the core loss at the switching frequency must be low enough to achieve the desired efficiency requirement. It is desirable to choose an inductor with DCR