SY8201CABC

Applications Note: SY8201C High Efficiency Fast Response, 1A, 27V Input Synchronous Step Down Regulator Features SY8201C develops high efficiency synchronous stepdown DC-DC converter capable of delivering 1A load current. SY8201C operates over a wide input voltage range from 4.5V to 27V and integrates main switch and synchronous switch with very low RDS(ON) to minimize the conduction loss. • Low RDS(ON) for internal switches (top/bottom):350/150 mΩ • 4.5-27V input voltage range • Instant PWM architecture to achieve fast transient responses • Internal softstart limits the inrush current • 2% 0.6V reference • RoHS Compliant and Halogen Free • Compact package: SOT23-6 fo Ordering Information Temperature Code Package Code Optional Spec Code Note -- en Typical Applications C1 fid .C on VIN Set Top Box Portable TV Access Point Router DSL Modem LCD TV tia l-P re p Package type SOT23-6 • • • • • ar ed Applications SY8201□(□□)□ Ordering Number SY8201CABC rr SY8201C always operates under continuous condition mode, low output ripple and small inductor and capacitor size are achieved with 1.15MHz switching frequency. ye General Description 5 BS IN LX 6 L1 VOUT ON/ OFF R1 SY8201C 4 EN FB C4 COUT 3 GND R2 Sil er gy Co rp CIN AN_SY8201C Rev. 0.9 Figure 1. Schematic Diagram Silergy Corp. Confidential- Prepared for Customer Use Only 1 SY8201C Pinout (top view) (SOT23-6) Top Mark: YUxyz, (Device code: YU, x=year code, y=week code, z= lot number code) BS 1 GND 2 FB 3 EN IN LX 4 5 6 Pin Description Boot-Strap Pin. Supply high side gate driver. Decouple this pin to LX pin with 0.1uF ceramic cap. Ground pin 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) Enable control. Pull high to turn on. Do not float. Input pin. Decouple this pin to GND pin with at least 1uF ceramic cap Inductor pin. Connect this pin to the switching node of inductor ye Pin Number tia l-P re p ar ed fo rr Pin Name Absolute Maximum Ratings (Note 1) er gy Co rp .C on fid en Supply Input Voltage --------------------------------------------------------------------------------------------------------- 30V LX, EN Voltage-------------------------------------------------------------------------------------------------------- VIN + 0.3V FB, BS-LX Voltage------------------------------------------------------------------------------------------------------------- 4V Power Dissipation, PD @ TA = 25°C SOT23-6, ------------------------------------------------------------------------- 0.6W Package Thermal Resistance (Note 2) θ JA ------------------------------------------------------------------------------------------------------------- 250°C/W θ JC ------------------------------------------------------------------------------------------------------------- 130°C/W Junction Temperature Range --------------------------------------------------------------------------------------------- 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) Sil Supply Input Voltage ---------------------------------------------------------------------------------------------- 4.5V to 27V Junction Temperature Range --------------------------------------------------------------------------------- -40°C to 125°C Ambient Temperature Range ---------------------------------------------------------------------------------- -40°C to 85°C AN_SY8201C Rev. 0.9 Silergy Corp. Confidential- Prepared for Customer Use Only 2 SY8201C Sil er gy Co rp .C on fid en tia l-P re p ar ed fo rr ye Block Diagram AN_SY8201C Rev. 0.9 Silergy Corp. Confidential- Prepared for Customer Use Only 3 SY8201C Electrical Characteristics (VIN = 12V, VOUT = 1.2V, L = 2.2uH, COUT = 10uF, 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 Valley Current Limit EN Rising Threshold EN Falling Threshold Input UVLO Threshold Switching Frequency Min ON Time Min Off Time Thermal Shutdown Temperature Thermal Shutdown Hysteresis Symbol VIN IQ ISHDN Test Conditions Min 4.5 IOUT=0, VFB=VREF×105% EN=0 0.588 VREF IFB RDS(ON)1 RDS(ON)2 VFB=VIN Typ 400 5 0.6 -50 Max 27 10 0.612 50 0.35 0.15 1.5 VENH VENL VUVLO FSW tON,MIN tOFF,MIN 1.5 1.15 50 100 150 V V V MHz ns ns °C 15 °C rr fo ar ed tia l-P re p TSD THYS nA Ω Ω A ye ILIM Unit V µA µA V 0.4 4.5 .C on fid en Note 1: Stresses beyond “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 may affect device reliability. Co rp 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. Pin 2 of SOT23-6 packages is the case position for θ JC measurement. Sil er gy Note 3: The device is not guaranteed to function outside its operating conditions. AN_SY8201C Rev. 0.9 Silergy Corp. Confidential- Prepared for Customer Use Only 4 SY8201C Sil er gy Co rp .C on fid en Efficiency (%) tia l-P re p ar ed fo rr ye Efficiency (%) Efficiency (%) Typical Performance Characteristics AN_SY8201C Rev. 0.9 Silergy Corp. Confidential- Prepared for Customer Use Only 5 SY8201C Shutdown Short Circuit Protection (EN=10Hz,VIN=24V, VOUT=3.3V, ILOAD=1A) (VIN=24V, VOUT=3.3V, Null load to Short) VOUT EN 2V/div VOUT 2V/div VOUT 20V/div IL 0.5A/div Time (100us/div) fo rr Time (2ms/div) ar ed Short Circuit Protection (VIN=24V, VOUT=3.3V, Full load to Short) 2V/div 0.5A/div .C on fid IL en tia l-P re p VOUT 0.5A/div ye IOUT 2V/div Sil er gy Co rp Time (2ms/div) AN_SY8201C Rev. 0.9 Silergy Corp. Confidential- Prepared for Customer Use Only 6 SY8201C VOUT (1 − VOUT /VIN, MAX ) FSW × IOUT, MAX × 40% where Fsw is the switching frequency and IOUT,MAX is the maximum load current. The SY8201 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. tia l-P re p 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: L= en ISAT, MIN > IOUT, MAX + R1 GND R2 .C on 0.6VFB Co rp 0.6V R1 . VOUT − 0.6V fid VOUT R2 = er gy Input capacitor CIN: The ripple current through input capacitor is calculated as： I CIN _ RMS = I OUT ⋅ D(1 − D) . Sil 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. In this case, a 4.7uF low ESR ceramic capacitor is recommended. ye Because of the high integration in the SY8201C 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. rr Applications Information 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: fo SY8201C 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. 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 22uF capacitance. ar ed Operation 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 desirable to choose an inductor with DCR