SY8088AAC

Application Notes: AN_SY8088 High Efficiency 1.5MHz, 1A Synchronous Step Down Regulator General Description Features SY8088 is a high efficiency 1.5MHz synchronous step down DC/DC regulator IC capable of delivering up to 1A output current. It can operate over a wide input voltage range from 2.5V to 5.5V and integrate main switch and synchronous switch with very low RDS (ON) to minimize the conduction loss. Low RDS(ON) for internal switches (top/bottom) 260m /170m 2.5~5.5V input voltage range 40 A typical quiescent current High light load efficiency Ordering Information High switching frequency 1.5MHz minimizes the external components SY8088 Internal soft-start limits the inrush current ( ) Temperature Code Package Code Optional Spec Code Temperature Range: -40°C to 85°C Ordering Number SY8088AAC Package Type SOT23-5 Note 1A 100% dropout operation RoHS Compliant and Halogen Free Compact package: SOT23-5 Applications ortable Navigation Device Set Top Box USB Dongle Media Player Smart phone Typical Application Figure1. Schematic Diagram AN_SY8088 Rev. 0.1 Figure2. Efficiency Silergy Corp. Confidential- Prepared for Customer Use Only 1 AN_SY8088 Pinout (Top View) (SOT23-5) Top Mark: LD Pin Name EN GND LX IN Pin Number 1 2 3 4 FB 5 (device code: LD, Pin Description Enable control. Pull high to turn on. Do not float. Ground pin. Inductor pin. Connect this pin to the switching node of the inductor. Input pin. Decouple this pin to the GND pin with at least 4.7uF ceramic capacitor. 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).Add optional C1 (10pF~47pF) to speed up the transient response. Absolute Maximum Ratings (Note 1) Supply Input Voltage -------------------------------------------------------------------------------------------------------- 6.0V Enable, FB Voltage---------------------------------------------------------------------------------------------------- VIN + 0.6V Power Dissipation, PD @ TA = 25°C, SOT23-5--------------------------------------------------------------------------- 0.6W Package Thermal Resistance (Note 2) JA -------------------------------------------------------------------------------------------------------------- 170°C/W JC ---------------------------------------------------------------------------------------------------------- ----130°C/W Junction Temperature Range ----------------------------------------------------------------------------------------------125°C Lead Temperature (Soldering, 10 sec.) ---------------------------------------------------------------------------------- 260°C Storage Temperature Range ----------------------------------------------------------------------------------- -65°C to 150°C Recommended Operating Conditions (Note 3) Supply Input Voltage ----------------------------------------------------------------------------------------------- 2.5V to 5.5V Junction Temperature Range ----------------------------------------------------------------------------------- -40°C to 125°C Ambient Temperature Range ------------------------------------------------------------------------------------ -40°C to 85°C AN_SY8088 Rev. 0.1 Silergy Corp. Confidential- Prepared for Customer Use Only 2 AN_SY8088 Electrical Characteristics (V IN = 5V, VOUT = 2.5V, L = 2.2uH, COUT = 10uF, TA = 25°C, unless otherwise specified) Parameter Input Voltage Range Quiescent Current Shutdown Current Feedback Reference Voltage PFET RON Symbol VIN IQ ISHDN VREF RDS(ON),P NFET RON PFET Current Limit EN rising threshold EN falling threshold Input UVLO threshold UVLO hysteresis Oscillator Frequency Min ON Time Max Duty Cycle Soft Start Time Thermal Shutdown Temperature Thermal Shutdown Hysteresis RDS(ON),N ILIM VENH VENL VUVLO VHYS FOSC Test Conditions Min 2.5 IOUT=0, VFB=VREF 105% EN=0 0.588 Typ 40 0.1 0.6 260 1 0.612 170 1.3 1.5 0.4 2.5 0.1 1.5 80 100 TSS TSD THYS Max 5.5 1 160 15 Unit V µA µA V m m A V V V V MHz ns % ms °C °C Note 1: Stresses beyond the “Absolute Maximum Ratings” may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note 2: JA is measured in the natural convection at TA = 25°C on a low effective single layer thermal conductivity test board of JEDEC 51-3 thermal measurement standard. Exposed Paddle of DFN package is the case position for JC measurement. Note 3: The device is not guaranteed to function outside its operating conditions. AN_SY8088 Rev. 0.1 Silergy Corp. Confidential- Prepared for Customer Use Only 3 AN_SY8088 Typical Performance Characteristics AN_SY8088 Rev. 0.1 Silergy Corp. Confidential- Prepared for Customer Use Only 4 AN_SY8088 AN_SY8088 Rev. 0.1 Silergy Corp. Confidential- Prepared for Customer Use Only 5 AN_SY8088 Operation The SY8088 is a high-efficiency 1.5MHz synchronous step-down DC-DC converters capable of delivering up to 1A output current. It operates over a wide input voltage range from 2.5V to 5.5V and integrates main switch and synchronous switch with very low RDS(ON) to minimize the conduction loss. Applications Information Because of the high integration in the SY8088 IC, the application circuit based on this regulator IC is rather simple. Only input capacitor C IN, output capacitor COUT, output inductor L and 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 100k and 1M is highly recommended for both resistors. If R2=120k is chosen, then R1 can be calculated to be: R1 (VOUT 0.6V) R2 0.6V where Fsw is the switching frequency and Iout,max is the maximum load current. The SY8088 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 (1-VOUT/VIN,MAX) ISAT, MIN IOUT, MAX 2 FSW L 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