SY8113BADC

Application Note: SY8113B High Efficiency, 500kHz, 3A, 18V Input Synchronous Step Down Regulator General Description Features The SY8113B is a high efficiency 500 kHz synchronous step-down DC-DC converter capable of delivering 3A current. The SY8113B operates over a wide input voltage range from 4.5V to 18V and integrates main switch and synchronous switch with very low RDS(ON) to minimize the conduction loss. • Low output voltage ripple and small external inductor and capacitor sizes are achieved with 500 kHz switching frequency. It adopts the instant PWM architecture to achieve fast transient responses for high step down applications • • • • Ordering Information Applications r fo fid Sil er gy Co rp .C on Typical Applications Note -- Set Top Box Portable TV Access Point Router DSL Modem LCD TV en Package type TSOT23-6 • • • • • ar ed Temperature Code Package Code Optional Spec Code tia l-P re p SY8113 □(□□)□ Ordering Number SY8113BADC • • • • low RDS(ON) for internal switches (top/bottom): 80mΩ/40mΩ 4.5-18V input voltage range 3A output current capability 500 kHz switching frequency Instant PWM architecture to achieve fast transient responses. Cycle-by-cycle peak current limitation Internal softstart limits the inrush current ±1.5% 0.6V reference TSOT23-6 package Figure 1. Schematic Diagram AN_SY8113B Rev.0.1 Figure 2. Efficiency Figure Silergy Corp. Confidential-prepared for Internal Use Only 1 AN_SY8113B Pinout (top view) BS LX GND IN FB EN TSOT23-6(FC) Top Mark: WCxyz, (Device code: WC, x=year code, y=week code, z= lot number code) Pin Number 1 Pin Description Boot-Strap Pin. Supply high side gate driver. Decouple this pin to LX pin with 0.1uF ceramic cap. Ground pin GND 2 FB 3 EN 4 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. IN LX 5 6 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 Absolute Maximum Ratings tia l-P re p ar ed fo r Pin Name BS er gy Co rp .C on fid en (Note 1) Supply Input Voltage ------------------------------------------------------------------------------------------------ 19V Enable Voltage---------------------------------------------------------------------------------------------- VIN + 0.3V FB Voltage ----------------------------------------------------------------------------------------------------------- 4V Power Dissipation, PD @ TA = 25°C, TSOT23-6（FC）----------------------------------------------------- 1W Package Thermal Resistance (Note 2) θ JA ------------------------------------------------------------------------------------------------------ 100°C /W θ JC ----------------------------------------------------------------------------------------------------- 11.2°C /W Junction Temperature Range ----------------------------------------------------------------------------------- 150°C Lead Temperature (Soldering, 10 sec.) ----------------------------------------------------------------------- 260°C Storage Temperature Range ------------------------------------------------------------------------- -65°C to 150°C Sil Recommended Operating Conditions (Note 3) Supply Input Voltage ---------------------------------------------------------------------------------------------- 4.5V to 18V Junction Temperature Range ----------------------------------------------------------------------------------- -40°C to 125°C Ambient Temperature Range ----------------------------------------------------------------------------------- -40°C to 85°C AN_SY8113B Rev.0.1 Silergy Corp. Confidential-prepared for Internal Use Only 2 AN_SY8113B Electrical Characteristics (VIN = 12V, VOUT = 1.2V, L = 2.2uH, 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 Top FET PeakCurrent Limit Bottom FET Valley Current Limit EN Rising Threshold EN Falling Threshold Input UVLO Threshold UVLO Hysteresis Min ON Time Min OFF Time Switching Frequency Soft-start Time Thermal Shutdown Temperature Thermal Shutdown Hysteresis Symbol VIN IQ ISHDN VREF Test Conditions Min 4.5 IOUT=0, VFB=VREF*105% EN=0 0.591 IFB RDS(ON)1 RDS(ON)2 ILIM,TOP VFB=3.3V Typ 100 5 0.6 -50 80 40 3 VENH VENL VUVLO VHYS 1.5 10 0.609 Unit V µA µA V 50 90 50 6 nA mΩ mΩ A 4.25 A tia l-P re p ar ed fo r ILIM Max 18 tSS TSD 0.3 80 170 500 800 150 120 220 15 V V V V ns ns kHz uS °C °C fid en THYS 50 140 0.4 4.5 Co rp .C on 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. er gy Note 2: θ JA is measured in the natural convection at TA = 25°C on a low effective 4-layer thermal conductivity test board of JEDEC 51-3 thermal measurement standard. Pin2 of TSOT23-6 packages is the case position for θ JC measurement. Sil Note 3: The device is not guaranteed to function outside its operating conditions AN_SY8113B Rev.0.1 Silergy Corp. Confidential-prepared for Internal Use Only 3 AN_SY8113B Sil er gy Co rp .C on fid en tia l-P re p ar ed fo r Block Diagram AN_SY8113B Rev.0.1 Silergy Corp. Confidential-prepared for Internal Use Only 4 AN_SY8113B Typical Performance Characteristics Efficiency vs. Load Current 100 95 90 85 80 VIN=6V,VOUT=5V VIN=12V,VOUT=5V VIN=16V,VOUT=5V 75 70 0.01 0.10 1.00 10.00 fo r Load Current (A) ar ed Efficiency vs. Load Current 95 tia l-P re p 90 85 80 VIN=5V,VOUT=1.2V VIN=12V,VOUT=1.2V VIN=16V,VOUT=1.2V 70 65 0.10 1.00 10.00 .C on 0.01 fid 60 en 75 Sil er gy Co rp Load Current (A) AN_SY8113B Rev.0.1 Silergy Corp. Confidential-prepared for Internal Use Only 5 fo r AN_SY8113B Short Circuit Protection ar ed Short Circuit Protection (VIN=12V, VOUT=3.3V, Open to Short) 2V/div 1A/div VOUT 2V/div IL 1A/div .C on fid en IL tia l-P re p VOUT (VIN=12V, VOUT=3.3V, 3A to Short) Time (2ms/div) Sil er gy Co rp Time (2ms/div) AN_SY8113B Rev.0.1 Silergy Corp. Confidential-prepared for Internal Use Only 6 AN_SY8113B Operation SY8113B 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. Feedback resistor dividers R1 and R2: ar ed VOUT (1 − VOUT /VIN, MAX ) FSW × I OUT, MAX × 40% where Fsw is the switching frequency and IOUT,MAX is the maximum load current. The SY8113B 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 + VOUT(1-VOUT/VIN,MAX) 2 ⋅ FSW ⋅ L VOUT 3) R1 R2 er gy Co rp .C on fid en 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: GND L= tia l-P re p Because of the high integration in the SY8113B 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. 0.6VFB 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 Applications Information 0.6V R2 = R1 . VOUT − 0.6V 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 22uF capacitance. r SY8113B provides protection functions such as cycle by cycle current limiting and thermal shutdown protection. SY8113B will sense the output voltage conditions for the fault protection. minimize the loop area formed by CIN, and IN/GND pins. In this case, a 10uF low ESR ceramic capacitor is recommended. Sil Input capacitor CIN: The ripple current through input capacitor is calculated as： I CIN _ RMS = I OUT ⋅ D(1 − D) . 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