SY8303AAIC

Applications Note: SY8303A High Efficiency Fast Response, 3A, 40V Input Synchronous Step Down Regulator Features The SY8303A develops a high efficiency synchronous step-down DC/DC converter capable of delivering 3A load current. The SY8303A operates over a wide input voltage range from 4.5V to 40V 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): 110/70 mΩ  4.5-40V Input Voltage Range  Internal Compensation  Internal 1ms Soft-start Limits the Inrush Current  Adjustable Switching Frequency Range: 500kHz to 2.5MHz  3A Output Current Capability  1.5% 0.6V Reference  Low Quiescent Current  Cycle-by-cycle Peak Current Limitation  Short Circuit Protection  Thermal Shutdown and Auto Recovery  RoHS Compliant and Halogen Free  Compact Package: TSOT23-8 fo r ry e General Description re pa re d The SY8303A adopts peak current control scheme. The switching frequency is adjustable from 500 kHz to 2.5MHz using an external resistor. The device also features ultra low quiescent operating to achieve high efficiency under light load. And the internal soft-start limits inrush current during power on. l-P SY8303A is available in TSOT23-8 package. Ordering Information ia Applications id en t SY8303 □(□□)□ Temperature Code Package Code Optional Spec Code Package type TSOT23-8 Note -- LCD-TV SetTop Box Notebook Storage High Power AP Router Networking .C on f Ordering Number SY8303AAIC       y VIN Efficiency vs. Load Current 100 CBS BS IN le rg LX Si CIN ON/ OFF R1 FB R2 EN 80 VOUT L C1(opt.) COUT Efficiency (%) Co rp Typical Applications 60 40 VIN=9V, VOUT=5V VIN=12V, VOUT=5V VIN=24V, VOUT=5V VIN=40V, VOUT=5V FS GND RFS 20 0 1 10 100 1000 10000 Load Current (mA) Figure 1. Schematic Diagram AN_SY8303A Rev. 0.9A © 2018 Silergy Corp. Figure 2. Efficiency vs. Load Current Silergy Corp. Confidential- Prepared for Customer Use Only 1 All Rights Reserved. SY8303A Pinout (top view) 2 EN 8 GND 3,4 IN LX BS 5 6 7 EN FS 2 7 BS GND 3 6 LX GND 4 5 IN bQxyz (Device code: bQ, x=year code, y=week code, z= lot number code) Pin Description 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: V OUT=0.6*(1+R1/R2) Frequency programming pin. Connect a resistor to ground to program a switching frequency between 500kHz to 2.5MHz. The switching frequency equals to: Fsw(kHz) =105/RFS(kΩ) . Enable control. Pull high to turn on. Do not float. fo r FS 8 re pa re d Pin Number 1 1 ry e Top Mark: Pin Name FB FB Ground pin. id en t ia l-P Input pin. Decouple this pin to GND pin with at least 4.7uF ceramic cap. Inductor pin. Connect this pin to the switching node of inductor. Boot-strap pin. Supply high side gate driver. Decouple this pin to LX pin with 100nF ceramic cap. .C on f Block Diagram HS Current Sense Comp Internal Power Co rp IN Input UVLO HS current Limitation VCC BS HSFET VCC le rg y EN Si FS LX Enable Threshold PWM Control & Protect Logic Internal clock LS Current Sense VCC LSFET Slope Compensation HS Current Sense GND Internal SST Comp Comp VREF FB LS current Limitation Error Amp Rc SCP OTP Cc AN_SY8303A Rev. 0.9A © 2018 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 2 All Rights Reserved. SY8303A Absolute Maximum Ratings (Note 1) fo r ry e IN to GND ------------------------------------------------------------------------------- ---------------- -0.3V to 40V LX, FB, EN, FS to GND------------------------------------------------------------------------------------------ -0.3V to 40V BS-LX ------------------------------------------------------------------------------ ------------- 4V Power Dissipation, PD @ T A = 25°C TSOT23-8 ------------------------------------------------------------ 2W Package Thermal Resistance (Note 2) θ JA -------------------------------------------------------------------------------------------------------------- 60.2°C/W θ JC --------------------------------------------------------------------------------------------------------------- 11.2°C/W Junction Temperature Range ------------------------------------------------------------------------------------------------ 150°C Ambient Temperature Range ------------------------------------------------------------------------------------- -40°C to 105°C Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------------ 260°C Storage Temperature Range -------------------------------------------------------------------------------------- -65°C to 150°C Recommended Operating Conditions (Note 3) Si le rg y Co rp .C on f id en t ia l-P re pa re d Supply Input Voltage -------------------------------------------------------------------------------------------------- 4.5V to 40V AN_SY8303A Rev. 0.9A © 2018 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 3 All Rights Reserved. SY8303A Electrical Characteristics (VIN = 12V, VOUT = 5V, COUT = 47uF, TA = 25°C, IOUT = 1A unless otherwise specified) Test Conditions IFB RDS(ON)1 RDS(ON)2 ILIM,TOP VENL VENH VUVLO VHYS FOSC VFB=VCC Min 4.5 IOUT=0, VFB=VREF×105% EN=0 1 0.6 0.591 -50 110 70 ia l-P tSS 425 id en t TSD Max 40 19 2 0.609 Unit V µA µA V 50 2.5 nA mΩ mΩ A V V V V MHz 575 kHz 6.8 1.5 4.35 0.3 0.5 re pa RFS=40k~200k re d fo r 4 0.5 RFS=200k TSD,HYS Typ ry e Symbol VIN IQ ISHDN VREF 500 1 80 120 150 ms ns ns °C 15 °C on f Parameter Input Voltage Range Quiescent Current Shutdown Current Feedback Reference Voltage FB Input Current Top FET RON Bottom FET RON Top FET Current Limit EN Low Threshold EN High Threshold Input UVLO Threshold UVLO Hysteresis Oscillator Frequency Program Range Oscillator Frequency Accuracy Soft-start Time Min ON Time Min OFF Time Thermal Shutdown Temperature Thermal Shutdown Hysteresis Co rp .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. le rg y Note 2: θ JA is measured in the natural convection at T A = 25°C on a low effective 4-layer thermal conductivity test board of JEDEC 51-3 thermal measurement standard. Pin 2 of TSOT-23-8 packages is the case position for θ JC measurement. Si Note 3: The device is not guaranteed to function outside its operating conditions. AN_SY8303A Rev. 0.9A © 2018 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 4 All Rights Reserved. SY8303A Typical Performance Characteristics Load Transient Efficiency vs. Load Current (VIN=12V, VOUT=5V, IOUT=0.3A ~ 3A) 100 ΔVOUT 0.5V/div 40 IL VIN=9V, VOUT=5V VIN=12V, VOUT=5V VIN=24V, VOUT=5V VIN=40V, VOUT=5V 20 0 10 100 1000 10000 Time (40μs/div) re pa re Load Current (mA) Startup from VIN 10V/div 2V/div 2A/div .C IL 10V/div VLX 10V/div VOUT 2V/div IL 2A/div on f VOUT VIN ia VLX id en t 10V/div Shutdown from VIN (VIN=12V, VOUT=5V, IOUT=3A) l-P (VIN=12V, VOUT=5V, IOUT=3A) VIN 2A/div d 1 ry e 60 fo r Efficiency (%) 80 Co rp Time (4ms/div) Time (20ms/div) Shutdown from Enable (VIN=12V, VOUT=5V, IOUT=3A) le rg y Startup from Enable (VIN=12V, VOUT=5V, IOUT=3A) 5V/div EN 5V/div VLX 10V/div VLX 10V/div 2V/div VOUT 2V/div 2A/div IL 2A/div Si EN VOUT IL Time (4ms/div) AN_SY8303A Rev. 0.9A © 2018 Silergy Corp. Time (100μs/div) Silergy Corp. Confidential- Prepared for Customer Use Only 5 All Rights Reserved. SY8303A Short Circuit Protection Short Circuit Protection (VIN=12V, VOUT=5V, 0A to Short) (VIN=12V, VOUT=5V, 3A to Short) VOUT 5V/div VOUT IL 2A/div 2A/div fo r ry e IL 5V/div Time (10ms/div) re d Time (10ms/div) Output Ripple 10mV/div VLX 10V/div 2A/div Si le rg y Co rp .C Time (2μs/div) on f IL id en t ia l-P ΔVOUT re pa (VIN=12V, VOUT=5V, IOUT= 3A) AN_SY8303A Rev. 0.9A © 2018 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 6 All Rights Reserved. SY8303A Operation 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. The SY8303A develops a high efficiency synchronous step-down DC/DC converter capable of delivering 3A load current. The SY8303A operates over a wide input voltage range from 4.5V to 40V and integrates main switch and synchronous switch with very low RDS(ON) to minimize the conduction loss. 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: Applications Information l-P where Fsw is the switching frequency and I OUT,MAX is the maximum load current. The SY8303A regulator 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. id en t ia Because of the high integration in the SY8303A IC, the application circuit based on this regulator 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. VOUT (1  VOUT /VIN, MAX ) FSW  IOUT, MAX  40% re pa L re d fo r ry e The SY8303A adopts peak current control scheme. The switching frequency is adjustable from 500kHz to 2.5MHz using an external resistor. The device also features ultra low quiescent operating to achieve high efficiency under light load. And the internal soft-start limits inrush current during power on. Co rp .C on f 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: 0.6VFB GND ISAT, MIN  IOUT, MAX  VOUT(1-VOUT/VIN,MAX) 2  FSW  L VOUT R1 R2 le rg y 0.6V R2  R1 . VOUT  0.6V 2) The saturation current rating of the inductor must be selected to be greater than the peak inductor current under full load conditions. Si Input Capacitor CIN: The ripple current through input capacitor is calculated as： I CIN _ RMS  I OUT  D(1  D) . 3) 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