SY8008BAAC

Applications Note: AN_SY8008A/B/C tu nt ec h High Efficiency 1.5MHz, 0.6A/1A/1.2A Synchronous Step Down Regulator Features The SY8008A, SY8008B and SY8008C are highefficiency 1.5MHz synchronous step-down DC-DC regulator ICs capable of delivering up to 1.2A output currents. The SY8008 family 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) ο SY8008A: 300m Ω /250m Ω, 0.6A ο SY8008B: 250m Ω /200m Ω, 1A ο SY8008C: 200m Ω /150m Ω, 1.2A • 2.5-5.5V input voltage range • 1.5MHz switching frequency minimizes the external components • Internal softstart limits the inrush current • 100% dropout operation • RoHS Compliant and Halogen Free • Compact package: SOT23-5/ TSOT23-5 pin fo rF or General Description l-P re pa re d Low output voltage ripple and small external inductor and capacitor sizes are achieved with 1.5MHz switching frequency. This along with small SOT23/TSOT-23 footprint provides small PCB area application. Applications Ordering Information en nf id Temperature Code Package Code Optional Spec Code tia SY8008□(□□)□ Portable Navigation Device Smart phone USB Dongle Set Top Box Media Player Note 0.6A 1A 1.2A 0.6A 1A gy Co rp . Co Temperature Range: -40°C to 85°C Ordering Number Package type SY8008AAAC SOT23-5 SY8008BAAC SOT23-5 SY8008CAAC SOT23-5 SY8008AACC TSOT23-5 SY8008BACC TSOT23-5 • • • • • EN IN L VOUT LX C1(opt.) R1 CIN COUT FB GND Efficiency (%) VIN Sil er Typical Applications R2 Figure 1. Schematic Diagram AN_SY8008 Rev. 1.0B Figure 2. Efficiency vs Load Current (SY8008B) Silergy Corp. Confidential- Prepared for Customer Use Only 1 AN_SY8008A/B/C Pinout (top view) (SOT23-5, TSOT23-5) ① Part Number Package type Top Mark SY8008AAAC SOT23-5 AAxyz SY8008BAAC SOT23-5 ABxyz SY8008CAAC SOT23-5 ACxyz SY8008AACC TSOT23-5 BIxyz SY8008BACC TSOT23-5 BGxyz Note① ： x=year code, y=week code, z= lot number code. Pin Name EN GND LX IN Pin Number 1 2 3 4 FB 5 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 1uF 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, LX Voltage---------------------------------------------------------------------------------------0.3V to VIN + 0.6V Power Dissipation, PD @ TA = 25°C, SOT23-5, TSOT23-5 ------------------------------------------------------------- 0.6W Package Thermal Resistance (Note 2) SOT23-5, TSOT23-5, θ JA ------------------------------------------------------------------------------------- 170°C/W SOT23-5, TSOT23-5, θ JC ------------------------------------------------------------------------------------- 130°C/W Junction Temperature Range ----------------------------------------------------------------------------------------------- 125°C Lead Temperature (Soldering, 10 sec.) ----------------------------------------------------------------------------------- 260°C Storage Temperature Range ------------------------------------------------------------------------------------- -65°C to 150°C ESD Susceptibility (Note 2) HBM (Human Body Mode) ---------------------------------------------------------------------------------------------------- 2kV MM (Machine Mode) ---------------------------------------------------------------------------------------------------------- 200V 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_SY8008 Rev. 1.0B Silergy Corp. Confidential- Prepared for Customer Use Only 2 AN_SY8008A/B/C Electrical Characteristics (VIN = 5V, VOUT = 2.5V, L = 2.2uH, COUT = 10uF, TA = 25°C, IMAX = 1A unless otherwise specified) Parameter Input Voltage Range Shutdown Current Feedback Reference Voltage FB Input Current PFET RON Symbol VIN ISHDN VREF IFB RDS(ON),P NFET RON RDS(ON),N PFET Current Limit ILIM EN Rising Threshold EN Falling Threshold Input UVLO Threshold UVLO Hysteresis Oscillator Frequency Min ON Time Max Duty Cycle Thermal Shutdown Temperature VENH VENL VUVLO VHYS FOSC Test Conditions Min 2.5 EN=0 0.588 VFB=VIN SY8008A SY8008B SY8008C SY8008A SY8008B SY8008C SY8008A SY8008B SY8008C Typ 0.1 0.6 -50 Max 5.5 1 0.612 Unit V µA V 50 nA mΩ mΩ mΩ mΩ mΩ mΩ A A A V V V V MHz ns % °C 300 250 200 250 200 150 0.8 1.2 1.5 1.5 0.4 2.5 0.1 1.5 50 IOUT=100mA 100 TSD 160 Note 1: Stresses listed as the above “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: θ 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. Pin 2 of SOT23-5/TSOT23-5 packages is the case position for θ JC measurement. Test condition: Device mounted on 2” x 2” FR-4 substrate PCB, 2oz copper, with minimum recommended pad on top layer and thermal vias to bottom layer ground plane Note 3: The device is not guaranteed to function outside its operating conditions. AN_SY8008 Rev. 1.0B Silergy Corp. Confidential- Prepared for Customer Use Only 3 AN_SY8008A/B/C Typical Performance Characteristics (SY8008B) Efficiency vs Load Current Efficiency vs Load Current 88% 92% 86% 84% 82% 78% Vin=5.0V Vin=3.6V Vin=2.7V 96% 94% 88% 86% 82% Vout=3.3V Vout=1.8V 90% 84% 76% 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Load C urrent (A ) 98% E fficiency a 94% E fficien cy a E fficien cy a Vout=1.2V 90% 80% Efficiency vs Load Current 96% 92% Vin=5.0V Vin=3.6V Vin=2.7V 80% 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Load C urrent (A ) 92% 90% 88% 86% 84% Vin=5.0V Vin=4.2V Vin=3.6V 82% 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Load C urrent (A ) Oscillator Frequency vs Vin 1.70 F requncy(M H z) a 1.65 1.60 1.55 1.50 1.45 1.40 1.35 1.30 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Input V oltage (V ) AN_SY8008 Rev. 1.0B Silergy Corp. Confidential- Prepared for Customer Use Only 4 AN_SY8008A/B/C Operation SY8008A/B/C 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. The internal softstart time is about 1ms. Applications Information Because of the high integration in the SY8008 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. 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 − 0.6 V) ⋅ (R2) 0.6V Input capacitor CIN: With the maximum load current at 1.2A (SY8008C), the maximum ripple current through the input capacitor is about 0.6Arms. A typical X7R or better grade ceramic capacitor with 6V rating and greater than 4.7uF capacitance can handle this ripple current well. To minimize the potential noise problem, place this 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. 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 X7R or better grade ceramic capacitor with >6V rating and greater than 4.7uF capacitance. 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: V (1 − VOUT /VIN, MAX ) L = OUT FSW × IOUT, MAX × 40% where Fsw is the switching frequency and IOUT,MAX is the maximum load current. The SY8008 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