SY8213FCC

Application Notes: AN_SY8213 High Efficiency Fast Response, 3A, 30V Input Synchronous Step Down Regulator General Description Features SY8213 develops a high efficiency synchronous stepdown DC-DC converter capable of delivering 3A output current. SY8213 operates over a wide input voltage range from 4.5V to 30V and integrates main switch and synchronous switch with very low RDS(ON) to minimize the conduction loss.  SY8213 adopts the proprietary instant PWM architecture to achieve fast transient responses for high step down applications and high efficiency at light loads. In addition, it operates at pseudo-constant frequency of 500kHz under continuous conduction mode to minimize the size of inductor and capacitor. Ordering Information SY8213 □(□□)□ Temperature Code Package Code Optional Spec Code Temperature Range: -40°C to 85°C Ordering Number Package type Note SY8213FCC SO8E --    Low RDS(ON) for internal switches (top/bottom): 90/60 mΩ 4.5-30V input voltage range Instant PWM architecture to achieve fast transient responses External softstart limits the inrush current Pseudo-constant frequency: 500kHz 3A continuous load current capability 1.5% 0.6V reference Output over current limit Output short circuit protection with current fold back Thermal shutdown and auto recovery RoHS Compliant and Halogen Free Compact package: SO8E   LCD-TV SetTop Box      Notebook High power AP router LCD Monitor DVR/NVR NAS         Applications Typical Applications Figure 1. Schematic Diagram AN_SY8213 Rev. 0.9 Silergy Corp. Confidential- Prepared for Customer Use Only 1 AN_SY8213 Pinout (top view) Top Mark: AJYxyz (device code: AJY, x=year code, y=week code, z= lot number code) Pin Name EN BS Pin Number 3 1 LX VCC 2 6 SVIN 7 PVIN 8 FB 5 GND Exposed Paddle SS 4 Pin Description Enable control. Boot-Strap Pin. Supply high side gate driver. Decouple this pin to LX pin with 0.1uF ceramic cap. Inductor pin. Connect this pin to the switching node of inductor Internal 3.3V LDO output. Power supply for internal analog circuits and driving circuit. Add a 1uF bypass capacitor between this pin and GND. Analog supply input. Bypass a 1uF capacitor to ground. Power supply input. Decouple this pin to GND pin with at least 10uF ceramic cap Output Feedback Pin. Connect this pin to the center point of the output resistor divider (as shown in Figure 1) to program the output voltage: Vout=0.6*(1+R1/R2) Ground pin. Softstart programming pin. Connect a capacitor from this pin to ground to program the softstart time. Tss(ms)=Css(nF)*0.6(V)/10(uA) Absolute Maximum Ratings (Note 1) PVIN, SVIN, LX, BS, EN------------------------------------------------------------------------------------------------------------ V VCC, FB, SS, BS-LX----------------------------------------------------------------------------------------------------------------- V Power Dissipation, PD @ TA = 25°C SO8E------------------------------------------------------------------------------------- 3.3W Package Thermal Resistance (Note 2) θ JA-------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 30°C/W θ JC-------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 10°C/W Junction Temperature Range------------------------------------------------------------------------------------------40°C to 150°C Lead Temperature (Soldering, 10 sec.)---------------------------------------------------------------------------------------- 260°C Storage Temperature Range-------------------------------------------------------------------------------------------65°C to 150°C Recommended Operating Conditions (Note 3) Supply Input Voltage----------------------------------------------------------------------------------------------------- -- 4.5V to 30V Junction Temperature Range--------------------------------------------------------------------------------------------40°C to 125°C Ambient Temperature Range---------------------------------------------------------------------------------------------40°C to 85°C SY8213 Rev0.1 Silergy Corp. Confidential-prepared for Customer Use Only 2 AN_SY8213 Electrical Characteristics (VIN = 12V, VOUT = 5V, COUT = 47uF, TA = 25°C, IOUT = 1A unless otherwise specified) Parameter Input Voltage Range Quiescent Current Shutdown Current Feedback Reference Voltage FB Input Current Top FET RON Bottom FET RON Bottom FET Current Limit EN falling threshold EN threshold hysteresis Input UVLO threshold UVLO hysteresis Oscillator Frequency Min ON Time Min OFF Time Internal LDO Output Thermal Shutdown Temperature Thermal Shutdown Hysteresis Symbol VIN IQ ISHDN VREF Test Conditions IFB RDS(ON)1 RDS(ON)2 ILIM VFB =VCC VENL VEN,HYS VUVLO VHYS FOSC VVCC TSD IOUT=0, VFB =V REF *105% EN=0 Min 4.5 0.591 -50 4 1.1 IOUT=200mA VIN=4V 3.2 TSD,HYS Typ 200 5 0.6 90 60 1.2 0.1 0.2 0.5 80 120 3.3 160 Max 30 10 0.609 Unit V µA µA V 50 nA mΩ mΩ A 1.3 V V V V MHz ns ns V °C 4 3.4 20 °C Note 1: Stresses beyond the “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specification is not implied. Exposure to absolute maximum rating conditions for extended periods may 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. Paddle of SO8E packages is the case position for θ JC measurement. Note 3: The device is not guaranteed to function outside its operating conditions. SY8213 Rev0.1 Silergy Corp. Confidential-prepared for Customer Use Only 3 AN_SY8213 Function Block SY8213 Rev0.1 Silergy Corp. Confidential-prepared for Customer Use Only 4 AN_SY8213 Efficiency (%) Efficiency (%) Efficiency (%) Typical Performance Characteristics SY8213 Rev0.1 Silergy Corp. Confidential-prepared for Customer Use Only 5 AN_SY8213 Short Circuit Protection Short Circuit Protection (VIN=12V, VOUT=1.8V, 3A to Short) (VIN=12V, VOUT=1.8V, 0A to Short) VOUT 1V/div IL 2A/div Time (2ms/div) SY8213 Rev0.1 VOUT 1V/div IL 2A/div Time (2ms/div) Silergy Corp. Confidential-prepared for Customer Use Only 6 AN_SY8213 Operation PVIN/GND pins. In this case, a 10uF low ESR ceramic capacitor is recommended. SY8213 is a synchronous buck regulator IC that integrates the PWM control, top and bottom switches on the same die to minimize the switching transition loss and conduction loss. With ultra low Rds(on) power switches and proprietary PWM control, this regulator IC can achieve the highest efficiency and the highest switch frequency simultaneously to minimize the external inductor and capacitor size, and thus achieving the minimum solution footprint. SY8213 provides protection functions such as cycle by cycle current limiting and thermal shutdown protection. SY8213 will sense the output voltage conditions for the fault protection. Applications Information Because of the high integration in the SY8213 IC, the application circuit based on this regulator IC is rather simple. Only input capacitor CIN, output capacitor COUT, output inductor L and feedback resistors (R1 and R2) need to be selected for the targeted applications specifications. Feedback resistor dividers R1 and R2: Choose R1 and R2 to program the proper output voltage. To minimize the power consumption under light loads, it is desirable to choose large resistance values for both R1 and R2. A value of between 10kΩ and 1MΩ is highly recommended for both resistors. If Vout is 3.3V, R1=100k is chosen, then using following equation, R2 can be calculated to be 22.1k: VOUT R2  0.6V V  0.6V R1 . 0.6VFB R1 OUT GND R2 Input capacitor CIN: The ripple current through input capacitor is calculated as：  I  D(1 D) . I CIN _ RMS The internal analog circuit is powered from SVIN. To avoid the noise issue, a 1uF ceramic capacitor connected closely from SVIN to GND is recommended. An RC filter can also be added from power input to SVIN. 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 consideration when selecting this capacitor. For the best performance, it is recommended to use X5R or better grade ceramic capacitor greater than 47uF capacitance. Output inductor L: There are several considerations in choosing this inductor. 1) Choose the inductance to provide the desired ripple current. It is suggested to choose the ripple current to be about 40% of the maximum output current. The inductance is calculated as: L AN_SY8213 Rev. 0.9 FSW  IOUT,MAX  40% where Fsw is the switching frequency and IOUT,MAX is the maximum load current. The SY8213 regulator IC is quite tolerant of different ripple current amplitude. Consequently, the final choice of inductance can be slightly off the calculation value without significantly impacting the performance. 2) The saturation current rating of the inductor must be selected to be greater than the peak inductor current under full load conditions. ISAT, MIN  IOUT, MAX  OUT To minimize the potential noise problem, place a typical X5R or better grade ceramic capacitor really close to the PVIN and GND pins. Care should be taken to minimize the loop area formed by CIN, and VOUT (1  VOUT /VIN, MAX ) 3) VOUT(1-VOUT/VIN,MAX) 2 FSW L 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 Silergy Corp. Confidential- Prepared for Customer Use Only 7 AN_SY8213 desirable to choose an inductor with DCR