SY8089AAAC

Application Note: AN_SY8089/SY8089A High Efficiency 5.5V, 2A continuous, 3A peak, 1MHz Synchronous Step Down Regulator Features The SY8089 and SY8089A are high-efficiency, high frequency synchronous step-down DC-DC regulator IC capable of delivering up to 2A output current. The SY8089 and SY8089A operate over a wide input voltage range from 2.7V 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):110mΩ/80mΩ • 2.7-5.5V input voltage range • 2A continuous, 3A peak load current capability • 1MHz switching frequency minimizes the external components • Internal softstart limits the inrush current • Reliable short circuit protection: SY8089: Latch off protection SY8089A: Hic-cup mode protection • Reliable over-voltage protection: SY8089: Latch off protection SY8089A: No latch off protection • 100% dropout operation • RoHS Compliant and Halogen Free • Compact package: SOT23-5 oc kc hi p General Description fo rR Low output voltage ripple and small external inductor and capacitor sizes are achieved with greater than 1MHz switching frequency. pa re d SY8089 integrates short circuit and over-voltage latch off protection. re Ordering Information Note CIN 22µF VOUT: 1.8V R1 200k FB 1 ON/ OFF 3 L1:2.2µH EN GND 5 R2 100k ww w. 2 Figure 1.Schematic diagram AN_SY8089/A Rev. 0.9A C1 22pF COUT 22µFх2 Efficiency (%) LX SP A IN Ch ip 4 LCD TV Set Top Box Net PC Mini-Notebook PC Access Point Router RK .c on f p. C Sil er gy C or Typical Applications VIN: 2.7-5.5V • • • • • om en tia Applications id Temperature Code Package Code Optional Spec Code Temperature Range: -40°C to 85°C Ordering Number Package type SY8089AAC SOT23-5 SY8089AAAC SOT23-5 l-P SY8089 □(□□)□ Figure 2. Efficiency vs Load Current Silergy Corp. Confidential- Prepared for Customer Use Only 1 SY8089/8089A SOT23-5 re pa re Pin Description Enable control. Pull high to turn on. Do not float. Ground pin. Inductor pin. Connect this pin to the switching node of inductor. Input pin. Decouple this pin to GND pin with at least 10µF ceramic cap. 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). l-P Pin Number 1 2 3 4 5 om en tia Pin Name EN GND LX IN FB d fo rR ① Part Number Package type Top Mark SY8089AAC SOT23-5 JXxyz SY8089AAAC SOT23-5 KVxyz Note① ： x=year code, y=week code, z= lot number code oc kc hi p Pinout (top view) id Absolute Maximum Ratings (Note 1) RK .c Ch ip Sil er gy C or SP A p. C on f Supply Input Voltage ----------------------------------------------------------------------------------------------- -0.3V to 6.0V Enable, FB Voltage------------------------------------------------------------------------------------------ -0.3V to VIN + 0.6V Power Dissipation, PD @ TA = 25°C, SOT23-5 -------------------------------------------------------------------------------------------------------------- 0.6W Package Thermal Resistance (Note 2) θ JA --------------------------------------------------------------------------------------------------------------- 170°C/W θ JC ----------------------------------------------------------------------------------------------------------------130°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 Recommended Operating Conditions (Note 3) ww w. Supply Input Voltage ------------------------------------------------------------------------------------------------ 2.7V to 5.5V Junction Temperature Range ------------------------------------------------------------------------------------ -40°C to 125°C Ambient Temperature Range ------------------------------------------------------------------------------------- -40°C to 85°C AN_SY8089/A Rev. 0.9A Silergy Corp. Confidential- Prepared for Customer Use Only 2 SY8089/8089A l-P re pa re d fo rR oc kc hi p Block Diagram AN_SY8089/A Rev. 0.9A RK .c Ch ip ww w. Sil er gy C or SP A p. C on f id om en tia (SY8089) (SY8089A) Silergy Corp. Confidential- Prepared for Customer Use Only 3 SY8089/8089A Electrical Characteristics (VIN = 5V, VOUT = 2.5V, L = 2.2µH, COUT = 22µF, TA = 25°C, unless otherwise specified) Test Conditions 55 hi 0.1 0.6 1 0.612 50 kc 0.588 -50 VFB=VIN rR oc 110 80 fo 3.5 1.5 IOUT=500mA 75 om id Unit V µA µA V nA mΩ mΩ A V V V V MHz V 1.2 50 ns % ms Ω 160 °C 100 l-P TSD 0.4 2.5 0.2 1 0.25 tia en TSS RDISCH Max 5.5 p IOUT=0, VFB=VREF ⋅ 105% EN=0 d ISHDN VREF IFB RDS(ON),P RDS(ON),N ILIM VENH VENL VUVLO VHYS FOSC VSCP Typ re Shutdown Current Feedback Reference Voltage FB Input Current PFET RON NFET RON PFET Current Limit EN rising threshold EN falling threshold Input UVLO threshold UVLO hysteresis Oscillator Frequency Short Circuit Protection Latch Off Threshold Min ON Time Max Duty Cycle Soft Start Time Output Discharge Switch On Resistance Thermal Shutdown Temperature Min 2.7 pa Symbol VIN IQ re Parameter Input Voltage Range Quiescent Current RK .c p. C on f 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. Sil er gy C or SP A Note 2: 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. ww w. Ch ip Note 3: The device is not guaranteed to function outside its operating conditions. AN_SY8089/A Rev. 0.9A Silergy Corp. Confidential- Prepared for Customer Use Only 4 SY8089/8089A RK .c Ch ip ww w. Sil er gy C or SP A p. C on f id om en tia l-P Efficiency (%) re pa re d fo rR oc kc hi p Efficiency (%) Efficiency (%) Typical Performance Characteristics AN_SY8089/A Rev. 0.9A Silergy Corp. Confidential- Prepared for Customer Use Only 5 RK .c Ch ip ww w. Sil er gy C or SP A p. C on f id om en tia l-P re pa re d fo rR oc kc hi p SY8089/8089A AN_SY8089/A Rev. 0.9A Silergy Corp. Confidential- Prepared for Customer Use Only 6 SY8089/8089A VOUT Operation Principle kc ICIN_RMS =IOUT × D(1-D) hi p Input capacitor CIN: This ripple current through input capacitor is calculated as: rR oc This formula has a maximum at VIN=2VOUT condition, where ICIN_RMS=IOUT/2. This simple worst-case condition is commonly used for DC/DC design. re d fo With the maximum load current at 2.0A. A typical X5R or better grade ceramic capacitor with 6.3V rating and more than 1 pcs 22µ F capacitor can handle this ripple current well. To minimize the potential noise problem, ceramic capacitor should really be placed close to the IN and GND pins. Care should be taken to minimize the loop area formed by CIN, and IN/GND pins or Sil er gy C ww w. Ch ip 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 10k and 1M is highly recommended for both resistors. If Vout is 1.8V, R1=100k is chosen, then R2 can be calculated to be 50k.: 0.6V R2 = R 1 (Ω) . VOUT -0.6V AN_SY8089/A Rev. 0.9A 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: SP A p. C Because of the high integration in the SY8089 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. om on f Applications Information 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 with 6.3V rating and greater than 22µF capacitance. RK .c id en tia l-P (SY8089A) The frequency is folded back to about 30% of the nominal frequency and the current limit is folded back to 3.0A to prevent the inductor current from runaway and to reduce the power dissipation of the IC under short circuit conditions. Over-voltage Protection If the output voltage exceeds 120% of the regulation level for more than 20µs, IC will turn off both power switches and turn on the discharge switch, entering over-voltage protection. It will remain in this state until IN or EN voltage is recycled. R2 GND pa Short Circuit Protection （SY8089）After the soft start is over, if the output voltage falls below 40% of the regulation level, IC will turn off both power switches, entering short circuit protection. It will remain in this state until the IN or EN voltage is recycled. R1 FB re SY8089 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. 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 SY8089 regulator IC is quite tolerant of different ripple current amplitude. Consequently, the final choice Silergy Corp. Confidential- Prepared for Customer Use Only 7 SY8089/8089A 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. 1) It is desirable to maximize the PCB copper area connecting to GND pin to achieve the best thermal and noise performance. If the board space allowed, a ground plane is highly desirable. 2) CIN must be close to Pins IN and GND. The loop area formed by CIN and GND must be minimized. kc oc rR fo d 5) If the system chip interfacing with the EN pin has a high impedance state at shutdown mode and the IN pin is connected directly to a power source such as a LiIon battery, it is desirable to add a pull down 1MΩ resistor between the EN and GND pins to prevent the noise from falsely turning on the regulator at shutdown mode. RK .c Ch ip ww w. Sil er gy C or SP A p. C on f id om en tia l-P Load Transient Considerations: The SY8089 regulator IC integrates the compensation components to achieve good stability and fast transient responses. In some applications, adding a 22pF ceramic cap in parallel with R1 may further speed up the load transient responses and is thus recommended for applications with large load transient step requirements. 4) The components R1, R2, and the trace connecting to the FB pin must NOT be adjacent to the LX net on the PCB layout to avoid the noise problem. re Enable Operation Pulling the EN pin low (1.5V) will turn on the IC again. 3) The PCB copper area associated with LX pin must be minimized to avoid the potential noise problem. pa 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 IOUT, MAX + Layout Design: The layout design of SY8089 regulator is relatively simple. For the best efficiency and minimum noise problems, we should place the following components close to the IC: CIN, L, R1 and R2. AN_SY8089/A Rev. 0.9A Silergy Corp. Confidential- Prepared for Customer Use Only 8 SY8089/8089A SOT23-5 Package outline & PCB layout design 0.55 1.50 - 1.70 kc re d 0.80 fo rR oc 2.70 - 3.00 2.40 hi p 2.80 - 3.10 0.30 - 0.50 pa 0.95 TYP RK .c on f 0.95 TYP 1.90 TYP SP A Sil er gy C or p. C 0.3 - 0.6 0.01 - 0.1 om 1.0 - 1.3 id en 0.1 - 0.15 0.25 REF tia l-P re Recommended Pad Layout ww w. Ch ip Notes: All dimensions are in millimeters. All dimensions don’t include mold flash & metal burr. AN_SY8089/A Rev. 0.9A Silergy Corp. Confidential- Prepared for Customer Use Only 9 SY8089/8089A Taping & Reel Specification 1. Taping orientation SOT23-5 3.9/4.1 d fo rR oc 7.7/8.3 kc hi p 1.45/1.55 re Feeding direction Reel Width id RK .c Tape width (mm) Pocket pitch(mm) Reel size (Inch) Reel width(mm) Trailer length(mm) Leader length (mm) Qty per reel 8 4 7" 8.4 280 160 3000 ww w. 3. Others: NA Ch ip SOT23-5 SP A Sil er gy C or p. C on f Reel Size Package types om en tia l-P re pa 2. Carrier Tape & Reel specification for packages AN_SY8089/A Rev. 0.9A Silergy Corp. Confidential- Prepared for Customer Use Only 10