SY8366AQQC

Application Notes: AN_SY8366A High Efficiency Fast Response 6A Continuous, 12A Peak, 28V Input Synchronous Step Down Regulator Features The SY8366A develops a high efficiency synchronous step-down DC-DC regulator capable of delivering 6A continuous, 12A peak current. The SY8366A operates over a wide input voltage range from 4V to 28V 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): 40/20 mΩ • Wide input voltage range: 4-28V • Instant PWM architecture to achieve fast transient responses • Internal 600us softstart limits the inrush current • Pseudo-constant frequency: 800kHz. • 6A continuous/12A peak output current capability • ±1.5% 0.6V reference • Programmable peak current limit • Power good indicator • Output discharge function • Hic-cup mode output short circuit protection • Hic-cup mode output over voltage protection • Input UVLO • Over temperature protection • RoHS Compliant and Halogen Free • Compact package: QFN3x3-12 rW fo re d The SY8366A adopts the 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 800kHz under continuous conduction mode to minimize the size of inductor and capacitor. OO KO O General Description pa Ordering Information SY8366 □(□□)□ Note -- -P Package type QFN3x3-12 yC or p. Co nf ide nt ial Ordering Number SY8366AQQC re Temperature Code Packa ge Code Optiona l Spec Code Applications • • • • LCD-TV/Net-TV/3DTV Set Top Box Notebook High Power AP Si le rg Typical Applications Figure 1 Schematic AN_SY8366A Rev. 0.1A Figure 2. Efficiency Silergy Corp. Confidential- Prepared for Customer Use Only 1 AN_SY8366A rW OO KO O Pinout (top view) (QFN3x3-12) 4 VCC BS 5 6 7,9 10,12 8,11 Si le rg IN GND LX d FB re 3 pa ILMT re 2 -P PG Pin Description Enable control. Pull this pin high to turn on the IC. Do not leave this pin floating. Power good Indicator. Open drain output when the output voltage is within 90% to 120% of regulation point. Current limit setting pin. The current limit is set to 6A, 9A or 12A when this pin is pull low, floating or pull high respectively. 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) Internal 3.3V LDO output. Power supply for internal analog circuits and driving circuit. Bypass a capacitor to GND. Boot-Strap Pin. Supply high side gate driver. Decouple this pin to LX pin with 0.1uF ceramic cap. Input pin. Decouple this pin to GND pin with at least 10uF ceramic cap Ground pin Inductor pin. Connect this pin to the switching node of inductor yC or p. Co nf ide nt ial Pin Number 1 fo Top Mark: ATOxyz, (Device code: ATO, x=year code, y=week code, z= lot number code) Pin Name EN AN_SY8366A Rev. 0.1A Silergy Corp. Confidential- Prepared for Customer Use Only 2 AN_SY8366A Absolute Maximum Ratings ko o (Note 1) IN, LX, PG, EN ------------------------------------------------------------------------------------------------------------------ 30V BS-LX, FB, ILMT, VCC -------------------------------------------------------------------------------------------------------- 4V Power Dissipation, PD @ TA = 25°C QFN3x3-12 -----------------------------------------------------------------------3.3W Package Thermal Resistance (Note 2) θ JA -----------------------------------------------------------------------------------------------------------------30°C/W θ JC ---------------------------------------------------------------------------------------------------------------- 4°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 10ns duration --------------------------------------------------------------------- IN+3V to GND-5V oo Recommended Operating Conditions (Note 3) fo rw Supply Input Voltage ---------------------------------------------------------------------------------------------------- 4V to 28V Junction Temperature Range ------------------------------------------------------------------------------------- -40°C to 150°C Ambient Temperature Range -------------------------------------------------------------------------------------- -40°C to 85°C Si le rg yC or p. Co nf ide nt ial -P re pa re d Block Diagram AN_SY8366A Rev. 0.1A Silergy Corp. Confidential- Prepared for Customer Use Only 3 AN_SY8366A Electrical Characteristics IFB Rds(on)1 Rds(on)2 Idis ILIM Typ IOUT=0, VFB=VREF*105% EN=0 Max 28 Unit V µA 10 0.609 µA V nA mΩ mΩ mA 100 3 0.6 0.591 VFB=4V -50 50 40 20 100 ILMT=’0’ ILMT=Floating ILMT=’1’ 6 9 12 Vcc-0.8 KO ISHDN VREF Min 4.0 OO Shutdown Current Feedback Reference Voltage FB Input Current Top FET RON Bottom FET RON Discharge Current Bottom FET Current Limit Test Conditions rW Symbol VIN IQ A fo Parameter Input Voltage Range Quiescent Current O (VIN = 12V, VOUT =5V, COUT = 100uF, TA = 25°C, IOUT = 2A unless otherwise specified) Si le rg yC or p. Co nf ide nt ial -P re pa re d ILMT Rising Threshold VILMTH VCC V ILMT Falling Threshold VILMTL 0.8 V ILMT Floating Threshold VILMIF 1.3 2 V Soft Start Time TSS 600 us EN Rising Threshold VENH 0.8 V EN Falling Threshold VENL 0.4 V EN Leakage Current IEN -1 1 uA Input UVLO Threshold 3.9 V VUVLO UVLO hysteresis VHYS 0.3 V Oscillator Frequency FOSC Vo=5V 0.68 0.8 0.92 MHz Min ON Time TON,MIN VIN=VINMAX 50 ns Min OFF Time TOFF,MIN 180 ns VCC Output VCC VIN=4V 3.2 3.3 3.4 V Output Over Voltage VFB Rising 115 120 125 %VREF Threshold Output Over Voltage 2 %VREF Hysteresis Output Over Voltage 20 us Delay Time Power Good Threshold VFB Rising 88 90 92 %VREF Power Good Hysteresis 2 %VREF Power Good Delay Time 10 us Thermal Shutdown TSD 150 °C Temperature Thermal Shutdown THYS 15 °C hysteresis 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 four-layer Silergy Evaluation Board.. Note 3: The device is not guaranteed to function outside its operating conditions. AN_SY8366A Rev. 0.1A Silergy Corp. Confidential- Prepared for Customer Use Only 4 AN_SY8366A Typical Performance Characteristics Efficiency vs. Load Current Efficiency vs. Load Current 100 100 90 90 80 80 70 70 60 60 50 50 40 VIN=5V,VOUT=1.2V VIN=12V,VOUT=1.2V VIN=19V,VOUT=1.2V VIN=28V,VOUT=1.2V 10 0.001 0.01 0.10 1.00 O KO 20 VIN=5.0V,VOUT=1.8V VIN=12V,VOUT=1.8V VIN=19V,VOUT=1.8V VIN=28V,VOUT=1.8V 40 30 20 0.001 10.00 OO 30 0.01 1.00 10.00 Load Current (A) fo rW Load Current (A) 0.10 Efficiency vs. Load Current 90 90 pa re 100 d Efficiency vs. Load Current 100 80 re 80 -P 70 50 40 30 yC or p. Co nf ide nt ial 60 VIN=5.0V,VOUT=3.3V VIN=12V,VOUT=3.3V VIN=19V,VOUT=3.3V VIN=28V,VOUT=3.3V 0.001 0.01 0.10 1.00 Load Current (A) rg 60 VIN=7.4V,VOUT=5V VIN=12V,VOUT=5V VIN=19V,VOUT=5V VIN=28V,VOUT=5V 50 40 0.001 0.01 0.10 1.00 Load Transient Output Ripple (VIN=12V, VOUT=5V, ILOAD=6A) VOUT(AC) 10V/div 5A/div Si IL Time (100µs/div) AN_SY8366A Rev. 0.1A 10mV/div 50mV/div VLX IL 10.00 Load Current (A) (VIN=12V, VOUT=5V, ILOAD=0.6-6A) VOUT(AC) le 10.00 70 5A/div Time (1µs/div) Silergy Corp. Confidential- Prepared for Customer Use Only 5 AN_SY8366A Short Circuit Protection Short Circuit Protection (VIN=12V, VOUT=5V, ILIMIT= Floating, ILOAD=0 to Short) (VIN=12V, VOUT=5V, ILIMIT= Floating, ILOAD=6A to Short) VOUT 5V/div VOUT 20V/div VLX 20V/div VLX 10A/div IL 10A/div OO KO O IL 5V/div Time (4ms/div) fo rW Time (4ms/div) Startup from VIN Shutdown from VIN (VIN=12V, VOUT=5V, ILOAD=6A) VOUT 5V/div VIN pa 10V/div 10V/div VOUT 5V/div VLX 10V/div IL 5A/div 10V/div yC or p. Co nf ide nt ial VLX -P re VIN re d (VIN=12V, VOUT=5V, ILOAD=6A) IL 5A/div Time (2ms/div) Time (10ms/div) Startup from Enable Shutdown from Enable (VIN=12V, VOUT=5V, ILOAD=6A) (VIN=12V, VOUT=5V, ILOAD=6A) 5V/div VOUT 5V/div EN VOUT 5V/div 5V/div VLX 10V/div VLX 10V/div IL 5A/div IL 5A/div Si le rg EN Time (400µs/div) AN_SY8366A Rev. 0.1A Time (400µs/div) Silergy Corp. Confidential- Prepared for Customer Use Only 6 Si le rg yC or p. Co nf ide nt ial -P re pa re d fo rW OO KO O Frequency(kHz) AN_SY8366A AN_SY8366A Rev. 0.1A Silergy Corp. Confidential- Prepared for Customer Use Only 7 AN_SY8366A O 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: VOUT (1 − VOUT /VIN, MAX ) FSW × I OUT, MAX × 40% re d L= pa where Fsw is the switching frequency and IOUT,MAX is the maximum load current. The SY8366A 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. -P Because of the high integration in the SY8366A 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. re Applications Information fo rW The SY8366A adopts the 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 800kHz under continuous conduction mode to minimize the size of inductor and capacitor. KO The SY8366A develops a high efficiency synchronous step-down DC-DC regulator capable of delivering 6A continuous, 12A peak current. The SY8366A operates over a wide input voltage range from 4V to 28V and integrates main switch and synchronous switch with very low RDS(ON) to minimize the conduction loss. 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 most applications, an X5R or better grade ceramic capacitor greater than 66uF capacitance can work well. The capacitance derating with DC voltage must be considered. OO Operation yC or p. Co nf ide nt ial 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: ISAT, MIN > IOUT, MAX + VOUT(1-VOUT/VIN,MAX) 2 ⋅ FSW ⋅ L VOUT 0.6V R2 = R1 . VOUT − 0.6V 0.6VFB GND R1 R2 Si le rg Input capacitor CIN: The ripple current through input capacitor is calculated as： I = I ⋅ D(1 − D) . CIN _ RMS OUT 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 10uF low ESR ceramic capacitor is recommended. AN_SY8366A Rev. 0.1A 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