SY8301ABC

Application Note: SY8301 High Efficiency, 1A 40V Input Synchronous Step Down Regulator General Description Features • The SY8301 develops a high efficiency synchronous step-down DC/DC converter capable of delivering 1A load current. The SY8301 operates over a wide input voltage range from 4.5V to 40V and integrates main switch and synchronous switch with low RDS(ON) to minimize the conduction loss. • • • • • • • • • The SY8301 adopts peak current control scheme. The switching frequency is 2MHz. Low output voltage ripple and small external inductor and capacitor sizes are achieved with 2MHz switching frequency. 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. Applications • • • • • • Ordering Information SY8301 □(□□)□ Temperature Code Package Code Optional Spec Code Ordering Number SY8301ABC Package type SOT23-6 Low RDS(ON) for Internal Switches (Top/Bottom):380mΩ/180mΩ 4.5-40V Input Voltage Range 1A Output Current Capability 2MHz Fixed Switching Frequency 0.8V±1.0% Reference Voltage Low Quiescent Current Internal Soft-start Limits the Inrush Current Hic-cup Mode Output Short Circuit Protection Thermal Shutdown and Auto Recovery Compact Package: SOT23-6 LCD-TV SetTop Box Notebook Storage High Power AP Router Networking Note -- Typical Applications Efficiency vs. Load Current 100 95 VIN BS IN L VOUT LX R1 CIN FB ON/OFF CFF (Opt.) R2 EN GND COUT 90 Efficiency (%) CBS 85 80 75 70 VIN=12V, VOUT=5V 65 VIN=24V, VOUT=5V 60 0.001 0.01 0.1 1 Load Current (A) Figure1. Schematic Diagram AN_SY8301 Rev. 0.9A © 2020 Silergy Corp. Figure2. Efficiency Silergy Corp. Confidential- Prepared for Customer Use Only 1 All Rights Reserved. SY8301 Pinout (top view) BS 1 6 LX GND 2 5 IN FB 3 4 EN Top Mark: Iuxyz (Device code: Iu; x=year code, y=week code, z= lot number code) Pin Name Pin Number BS 1 GND 2 FB 3 EN 4 IN LX 5 6 Pin Description Boot-strap pin. Supply high side gate driver. Connect a 0.1μF ceramic capacitor between the BS and the LX pin . 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=0.8× (1+R1/R2) Enable control pin. Pulling this pin high to turn on the IC. Do not leave this pin floating. Input pin. Decouple this pin to the GND pin with at least a 1µF ceramic capacitor. Inductor pin. Connect this pin to the switching node of the inductor. Block Diagram IN HS Current Sense Internal Power VCC Input UVLO BS HSFET VCC EN LX PWM Control & Protection Logic Enable Threshold Internal clock VCC LSFET Slope Compensation HS Current Sense GND Internal SST Comp VREF FB Error Amp Rc Cc SCP OTP Figure3. Block Diagram AN_SY8301 Rev. 0.9A © 2020 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 2 All Rights Reserved. SY8301 Absolute Maximum Ratings (Note 1) Supply Input Voltage -------------------------------------------------------------------------------------------------- -0.3 to 40V LX, FB, EN Voltage --------------------------------------------------------------------------------------------------- -0.3 to 40V BS-LX Voltage-------------------------------------------------------------------------------------------------------- -0.3 to 4V Power Dissipation, PD @ TA = 25°C SOT23-6----------------------------------------------------------------------------- 0.4W Package Thermal Resistance (Note 2) θJA -----------------------------------------------------------------------------------------------------------------------100°C/W θJC ---------------------------------------------------------------------------------------------------------------- 30°C/W Junction Temperature Range ----------------------------------------------------------------------------------- -40°C to 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 Recommended Operating Conditions (Note 3) Supply Input Voltage -------------------------------------------------------------------------------------------------- 4.5V to 40V Junction Temperature Range ------------------------------------------------------------------------------------ -40°C to 125°C Ambient Temperature Range ------------------------------------------------------------------------------------- -40°C to 85°C AN_SY8301 Rev. 0.9A © 2020 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 3 All Rights Reserved. SY8301 Electrical Characteristics (VIN = 12V, TA = 25°C, IOUT=1A, unless otherwise specified) Parameter symbol Test Conditions Min Typ Max Unit Input Voltage Range VIN 4.5 Input UVLO Threshold VUVLO_R 3.6 40 V 4 4.4 V Input UVLO Hysteresis VHYS Quiescent Current IQ IOUT=0,VFB=VREF×105% Shutdown Current ISHDN EN=0 Feedback Reference Voltage VREF FB Input Current IFB Top FET RON RDS(ON),TOP Top FET Peak Current Limit ILIM,TOP Bottom FET RON RDS(ON),BOT EN Rising Threshold VENH EN Falling Threshold VENL Soft-start Time tSS Switching Frequency fSW Output UVP Threshold VUVP 50 %VREF Output UVP Wait Time tWAIT 60 µs Min ON Time tON 80 ns Min OFF Time tOFF 100 ns Thermal Shutdown Temperature TSD 150 °C Thermal Shutdown Hysteresis THYS 15 °C 0.6 12 0.792 VFB=3.3V V 22 28 µA 1 2 µA 0.8 0.808 V 50 nA -50 mΩ 380 1.6 2.5 mΩ 180 1.4 V 1 1 1.6 A 2 V ms 2.4 MHz 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: Package thermal resistance is measured in the natural convection at TA = 25°C on a two-layer Silergy Evaluation Board. Note 3: The device is not guaranteed to function outside its operating conditions. AN_SY8301 Rev. 0.9A © 2020 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 4 All Rights Reserved. SY8301 Typical Performance Characteristics Efficiency vs. Load Current Efficiency vs. Load Current 100 100 95 95 Efficiency (%) Efficiency (%) 90 85 80 75 90 85 80 VIN=12V, VOUT=5V 70 VIN=24V, VOUT=12V 75 VIN=24V, VOUT=5V 65 VIN=36V, VOUT=12V 70 60 0.001 0.01 0.1 Load Current (A) 1 0.001 0.01 0.1 Load Current (A) Startup from VIN Shutdown from VIN (VIN=12V, VOUT=5V, IOUT=0A) (VIN=12V, VOUT=5V, IOUT=0A) VIN VIN 1 10V/div 10V/div VOUT 5V/div VOUT VLX VLX IL 10V/div 10/div IL 500mA/div Time (2ms/div) 500mA/div Time (100ms/div) Startup from VIN Shutdown from VIN (VIN=12V, VOUT=5V, IOUT=1A) (VIN=12V, VOUT=5V, IOUT=1A) VIN VIN 5V/div 10V/div 10V/div VOUT VLX IL 5V/div VOUT 5V/div 10V/div VLX 10V/div IL 1A/div Time (2ms/div) AN_SY8301 Rev. 0.9A © 2020 Silergy Corp. 1A/div Time (2ms/div) Silergy Corp. Confidential- Prepared for Customer Use Only 5 All Rights Reserved. SY8301 Startup from Enable Shutdown from Enable (VIN=12V, VOUT=5V, IOUT=0A) (VIN=12V, VOUT=5V, IOUT=0A) EN EN 5V/div VOUT 5V/div VLX 10V/div VOUT IL 5V/div 5V/div VLX 10V/div IL 0.5A/div 0.5A/div Time (800µs/div) Time (100ms/div) Startup from Enable Shutdown from Enable (VIN=12V, VOUT=5V, IOUT=1A) (VIN=12V, VOUT=5V, IOUT=1A) EN 5V/div VOUT 5V/div EN 5V/div VOUT VLX 10V/div IL 1A/div Time (800µs/div) 5V/div VLX 10V/div IL 1A/div Time (800µs/div) Short Circuit Protection Short Circuit Protection (VIN=12V, VOUT=5V, 0A to Short) (VIN=12V, VOUT=5V, 1A to Short) VOUT IL 5V/div 1A/div Time (4ms/div) AN_SY8301 Rev. 0.9A © 2020 Silergy Corp. VOUT IL 5V/div 1A/div Time (4ms/div) Silergy Corp. Confidential- Prepared for Customer Use Only 6 All Rights Reserved. SY8301 Load Transient Load Transient (VIN=12V, VOUT=5V, 0A to 0.5A) (VIN=12V, VOUT=5V, 0.1A to 1A) ΔVOUT IL 0.1V/div 0.5A/div Time (200µs/div) ΔVOUT IL Output Ripple Output Ripple (VIN=12V, VOUT=5V, IOUT=0A) (VIN=12V, VOUT=5V, IOUT= 1A) IL 20mV/div 20mV/div VLX VLX 1A/div Time (200µs/div) ΔVOUT ΔVOUT 0.2V/div 5V/div 5V/div IL 1A/div Time (2μs/div) AN_SY8301 Rev. 0.9A © 2020 Silergy Corp. 1A/div Time (400ns/div) Silergy Corp. Confidential- Prepared for Customer Use Only 7 All Rights Reserved. SY8301 Operation ICIN_RMS =IOUT  D(1-D) . The SY8301 develops a high efficiency synchronous step-down DC/DC converter capable of delivering 1A load current. The SY8301 operates over a wide input voltage range from 4V to 40V and integrates main switch and synchronous switch with low RDS(ON) to minimize the conduction loss. To minimize the potential noise problem, a typical X5R or a better grade ceramic capacitor should be placed 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 4.7µF low ESR ceramic capacitor is recommended. The SY8301 adopts peak current control scheme. The switching frequency is 2MHz. Low output voltage ripple and small external inductor and capacitor sizes are achieved with 2MHz switching frequency. 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 an X5R or a better grade ceramic capacitor greater than 22µF capacitance. 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. Applications Information Because of the high integration in the SY8301, the application circuit based on this regulator is rather simple. Only the input capacitor CIN, the output capacitor COUT, the output inductor L and the feedback resistors (R1 and R2) need to be selected for the targeted applications specifications. 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 32k: 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: L= VOUT (1 − VOUT /VIN,MAX ) fSW  IOUT,MAX  40% Where fSW is the switching frequency and IOUT,MAX is the maximum load current. The SY8301 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. 0.8V R1 . VOUT -0.8V VOUT ISAT, MIN  IOUT, MAX + R1 0.8VFB GND 3) R2 Input Capacitor CIN The ripple current through input capacitor is calculated as： AN_SY8301 Rev. 0.9A © 2020 Silergy Corp. 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