SY8113CADC

Application Notes: AN_SY8113C High Efficiency, 1MHz, 3A, 18V Input Synchronous Step Down Regulator General Description Features The SY8113C is a high efficiency 1MHz synchronous step-down DC-DC converter capable of delivering 3A current. The SY8113C 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. • Temperature Code Package Code Optional Spec Code 翼 r双 fid Co rp .C on Typical Applications Note -- Set Top Box Portable TV Access Point Router DSL Modem LCD TV en Package type TSOT23-6 • • • • • tia l-P re p SY8113 □(□□)□ ar ed Applications Ordering Information Ordering Number SY8113CADC • • • fo Low output voltage ripple and small external inductor and capacitor sizes are achieved with 1MHz switching frequency. It adopts the instant PWM architecture to achieve fast transient responses for high step down applications. • • • • low RDS(ON) for internal switches (top/bottom): 80mΩ/40mΩ 4.5-18V input voltage range 3A output current capability 1MHz switching frequency Instant PWM architecture to achieve fast transient responses. Internal softstart limits the inrush current ±1.5% 0.6V reference TSOT23-6 package Efficiency vs. Load Current 100 80 60 er gy 40 VIN=5V,VOUT=3.3V VIN=12V,VOUT=3.3V VIN=18V,VOUT=3.3V Sil 20 0 0.1 1 10 100 1000 Load Current (mA) Figure 1. Schematic Diagram SY8113C Rev.0.1A Figure2. Efficiency vs. Load Current Silergy Corp. Confidential-prepared for Internal Use Only 1 SY8113C Pinout (top view) BS LX GND IN FB EN TSOT23-6(FC) 翼 Top Mark: WDxyz, (Device code: WD, 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双 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 Recommended Operating Conditions (Note 3) Sil Supply Input Voltage ------------------------------------------------------------------------------------ 4.5V to 18V Junction Temperature Range ----------------------------------------------------------------------- -40°C to 125°C Ambient Temperature Range ------------------------------------------------------------------------ -40°C to 85°C SY8113C Rev.0.1A Silergy Corp. Confidential-prepared for Internal Use Only 2 SY8113C Electrical Characteristics (VIN = 12V, VOUT = 3.3V, 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 Peak Current 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 Typ IOUT=0, VFB=VREF*105% EN=0 100 5 0.6 0.591 IFB RDS(ON)1 RDS(ON)2 ILIM,TOP VFB=3.3V -50 r双 翼 80 40 4 fo ILIM 10 0.609 Unit V µA µA V 50 90 50 6.6 nA mΩ mΩ A 5.2 A 1.5 tia l-P re p ar ed VENH VENL VUVLO VHYS Max 18 tSS TSD 0.3 60 170 1 800 150 90 220 15 V V V V ns ns MHz us °C °C .C on fid en THYS 40 140 0.4 4.5 Co rp 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. Sil Note 3: The device is not guaranteed to function outside its operating conditions AN_SY8113C Rev.0.1A Silergy Corp. Confidential-prepared for Internal Use Only 3 SY8113C Sil er gy Co rp .C on fid en tia l-P re p ar ed fo r双 翼 Block Diagram AN_SY8113C Rev.0.1A Silergy Corp. Confidential-prepared for Internal Use Only 4 SY8113C Typical Performance Characteristics Efficiency vs. Load Current Efficiency vs. Load Current 100 100 90 80 80 70 60 60 50 40 40 VIN=5V,VOUT=1.2V VIN=12V,VOUT=1.2V VIN=18V,VOUT=1.2V 30 20 VIN=5V,VOUT=3.3V VIN=12V,VOUT=3.3V VIN=18V,VOUT=3.3V 20 0 翼 10 1 10 100 1000 0.1 r双 0 0.1 1 100 1000 Load Current (mA) fo Load Current (mA) 10 Efficiency vs. Load Current ar ed 100 90 70 60 50 40 VIN=8V,VOUT=5V VIN=12V,VOUT=5V VIN=18V,VOUT=5V 30 en 20 tia l-P re p 80 0 1 10 100 1000 .C on 0.1 fid 10 Sil er gy Co rp Load Current (mA) AN_SY8113C Rev.0.1A Silergy Corp. Confidential-prepared for Internal Use Only 5 fo r双 翼 SY8113C Short Circuit Protection ar ed Short Circuit Protection (VIN=12V, VOUT=3.3V, 0A to Short) 2V/div 2A/div VOUT IL 2V/div 2A/div .C on fid en IL tia l-P re p VOUT (VIN=12V, VOUT=3.3V, 3A to Short) Time (4ms/div) Sil er gy Co rp Time (4ms/div) AN_SY8113C Rev.0.1A Silergy Corp. Confidential-prepared for Internal Use Only 6 SY8113C SY8113C provides protection functions such as cycle by cycle current limiting and thermal shutdown protection. SY8113C will sense the output voltage conditions for the fault protection. Feedback resistor dividers R1 and R2: ar ed ISAT, MIN > IOUT, MAX + VOUT(1-VOUT/VIN,MAX) 2 ⋅ FSW ⋅ L R1 0.6VFB GND 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 SY8113C 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. VOUT 3) 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: 0.6V R1 . VOUT − 0.6V L= tia l-P re p Because of the high integration in the SY8113C 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. R2 = 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 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. 翼 SY8113C 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. minimize the loop area formed by CIN, and IN/GND pins. In this case, a 10uF low ESR ceramic capacitor is recommended. r双 Operation Input capacitor CIN: Sil 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