SY8823QUC

Application Note: SY8823 Ultra Low Quiescent Current, 2.0MHz, 3.5A Synchronous Step Down Regulator • • • Ordering Information Tempera ture Code Packa ge Code Optiona l Spec Code • • • • fid Set Top Box Net PC Mini-Notebook PC Access Point Router on Co rp .C Typical Applications io nc l-P Note 3.5A tia Package Type QFN2x1.5-8 Applications en Ordering Number SY8823QUC fo rZ re SY8823 □(□□)□ Input voltage range: 2.5V to 5.5V 2.0 MHz switching frequency 3.5A maximum output current Peak current mode control for the fast transient speed 100% drop out function Typical 18uA quiescent current Low RDS(ON) for internal switches (PFET/NFET): 55mΩ/35mΩ Hic-cup mode protection for hard short condition RoHS Compliant and Halogen Free Compact package: QFN2x1.5-8 d SY8823 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. • • • • • • • re SY8823 is a high efficiency ultra low quiescent current, 2.0MHz synchronous step-down DC-DC regulator IC capable of delivering up to 3.5A output current. om Features pa General Description Efficiency vs. Load Current 100 95 90 rg y 85 80 VIN=3.3V,VOUT=1.8V VIN=4.2V,VOUT=1.8V VIN=5.0V,VOUT=1.8V le 75 Si 70 1 10 100 1000 10000 Load Current (mA) Figure 1. Schematic Diagram AN_SY8823 Rev.0.9C Figure 2. Efficiency Figure Silergy Corp. Confidential-Prepared for Customer Use Only 1 SY8823 Pin Number PVIN 1 PGND LX 2 3 PG 4 FB 5 SGND 6 SVIN 7 EN 8 Pin Description Supply voltage for power circuit. Decouple this pin to ground with at least 22uF ceramic cap. Power ground pin. Inductor pin. Connect this pin to the switching node of inductor Power good indicator (Open drain output). Low if the output < 90% of regulation voltage; High otherwise. Connect a pull-up resistor to the input. 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=0.6V*(1+RH/RL). Signal ground pin. Supply voltage for control circuit. Decouple this pin to ground with at least 1uF ceramic cap. Enable input pin. Integrated 4MΩ pull down resistor. id en tia l-P re pa re d Pin Name fo rZ Part Number Package type Top Mark① SY8823QUC QFN2x1.5-8 VPxyz Note① ： x=year code, y=week code, z= lot number code. io nc om Pinout (top view) Absolute Maximum Ratings rg y Co rp .C on f (Note 1) All pins --------------------------------------------------------------------------------------------------------------------------- 6V Power Dissipation, PD @ TA = 25°C QFN2x1.5-8---------------------------------------------------------------------------1W Package Thermal Resistance (Note 2) θ JA ------------------------------------------------------------------------------------------------------------- 100°C/W θ JC --------------------------------------------------------------------------------------------------------------- 15°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 --------------------------------------------------------------------- -4V to +7V le Recommended Operating Conditions (Note 3) Si 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_SY8823 Rev. 0.9C Silergy Corp. Confidential- Prepared for Customer Use Only 2 SY8823 Electrical Characteristics (VIN = 5V, VOUT = 2.5V, L = 0.47uH, COUT = 22uF, TA = 25°C, unless otherwise specified) Test Conditions Peak Current Limit ILIM 4.5 EN rising threshold EN falling threshold Input UVLO threshold UVLO hysteresis Oscillator Frequency PGOOD Under-voltage Threshold Short Circuit Protection Threshold Min ON Time Soft Start time Output Discharge Switch On Resistance Thermal Shutdown Temperature Thermal Shutdown Hysteresis VENH VENL VUVLO VHYS FOSC VFB,LV VSCP 1.5 IOUT=0, VFB=VREF ⋅ 105% EN=0 18 0.1 0.6 55 35 Max 5.5 1 0.609 80 55 7.5 d pa re IOUT=500mA re l-P Unit V µA µA V mΩ mΩ A 0.15 2 0.55 0.26 80 1 V V V V MHz V V ns ms 50 Ω 150 15 °C °C 0.4 2.5 id en tia TSD THYS Typ fo rZ 0.591 30 15 TSS RDSC Min 2.5 om Symbol VIN IQ ISHDN VREF RDS(ON),P RDS(ON),N io nc Parameter Input Voltage Range Quiescent Current Shutdown Current Feedback Reference Voltage PFET RON NFET RON 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. .C 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. Si le rg y Co rp Note 3: The device is not guaranteed to function outside its operating conditions. AN_SY8823 Rev. 0.9C Silergy Corp. Confidential- Prepared for Customer Use Only 3 SY8823 + l-P re pa re d fo rZ io nc om Block Diagram Si le rg y Co rp .C on f id en tia - AN_SY8823 Rev. 0.9C Silergy Corp. Confidential- Prepared for Customer Use Only 4 SY8823 Si le rg y Co rp .C on f id en tia l-P re pa re d fo rZ io nc om Typical Performance Characteristics AN_SY8823 Rev. 0.9C Silergy Corp. Confidential- Prepared for Customer Use Only 5 SY8823 Output Ripple (VIN=5.0V, VOUT=1.8V, IO=3.5A) 20mV/div VLX 2V/div IL 2A/div fo rZ io nc om ∆VOUT d Time (400ns/div) Shutdown from Enable (VIN=5.0V, VOUT=1.8V, IO=3.5A) VLX 5V/div IL 2A/div pa re 2V/div l-P VOUT id en tia 5V/div on f EN re Startup from Enable (VIN=5.0V, VOUT=1.8V, IO=3.5A) 5V/div VOUT 2V/div VLX 5V/div IL 2A/div Time (200µs/div) Si le rg y Co rp .C Time (800µs/div) EN AN_SY8823 Rev. 0.9C Silergy Corp. Confidential- Prepared for Customer Use Only 6 Si le rg y Co rp .C on f id en tia l-P re pa re d fo rZ io nc om SY8823 AN_SY8823 Rev. 0.9C Silergy Corp. Confidential- Prepared for Customer Use Only 7 SY8823 Applications Information .C on f Because of the high integration in SY8823, the application circuit based on this regulator IC is rather simple. Only input capacitor CIN, output capacitor COUT, inductor L and feedback resistors (R1 and R2) need to be selected for the targeted applications. rg y Co rp Feedback resistor divider R1 and R2 Choose R1 and R2 to program the proper output voltage. To minimize the power consumption under light load, it is desirable to choose large resistance values for both R1 and R2. A value between 10k and 1M is recommended for both resistors. If R1=100k is chosen, then R2 can be calculated to be: 0.6 R1 (Ω) VOUT - 0.6 Si le R2 = VOUT R1 FB GND R2 AN_SY8823 Rev. 0.9C om D (1 -D ) (A) io nc This formula has a maximum at VIN=2×VOUT condition, where ICIN_RMS=IOUT/2. re d fo rZ With the maximum load current at 3.5A, a typical X5R or better grade ceramic capacitor with 6.3V rating and greater than 22uF capacitance can handle this ripple current well. To minimize the potential noise problem, place this ceramic capacitor really close to the PVIN and GND pins. Care should be taken to minimize the loop area formed by CIN, PVIN and GND pins. pa A 1µF ceramic capacitor needs to be added across SVIN and GND. Output capacitor COUT Both steady state ripple and transient requirements must be taken into account when selecting this capacitor. For the best performance, it is recommended to use X5R or better grade ceramic capacitor with 6.3V rating and more than two pcs 22µF capacitors. id en tia SY8823 senses the output voltage conditions for the fault protection. If the DC output voltage is about 3% over the regulation level, both switches turn off and remain in the off state. If the DC output voltage is below 42% of the regulation level, the IC will enter hic-up short protection mode. When the output voltage is below 42% of the regulation, the frequency is folded back to 25% of the normal frequency and the current limit is decreased to 55% of the normal current limit to prevent the inductor current runaway and to reduce the power dissipation within the IC under true short circuit conditions. I C IN _R M S = I O U T × re SY8823 is an ultra low quiescent current synchronous buck regulator IC that integrates the PWM control, top and bottom switches on the same die to minimize the switching losses and conduction losses. With low RDS(ON) power switches and proprietary PWM control, this regulator IC achieves a higher efficiency with high switching frequency to minimize the external inductor and capacitor size, and thus achieving the minimum solution footprint. Input capacitor CIN This ripple current through input capacitor is calculated as: l-P Operation 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 average input current. The inductance is calculated as: L= VOUT (1 − VOUT /VIN_MAX ) FSW × IOUT_MAX × 40% (H) Where FSW is the switching frequency and the maximum load current. IOUT_MAX is SY8823 is less sensitive to the ripple current variations. Consequently, the final choice of inductance can be slightly off the calculation value without significantly impacting the performance. 2) The saturation current rating of an inductor must be selected to guarantee an adequate margin to the peak inductor current under full load conditions. Silergy Corp. Confidential- Prepared for Customer Use Only 8 SY8823 om io nc fo rZ 4) The components RL, RH and the trace connecting to the FB pin must NOT be adjacent to the LX node on the PCB layout to minimize the noise coupling to FB pin. Si le rg y Co rp .C on f id en tia Load Transient Considerations: SY8823 integrates the compensation components to achieve good stability and fast transient responses. Adding a 10pF~22pF ceramic capacitor in parallel with R1 may further speed up the load transient responses. 3) The PCB copper area associated with LX pin must be minimized to improve the noise immunity. d Power Good Indication PG is an open-drain output pin. Connect an above 100k pull-up resistor to VIN. PG pin will output high after the output voltage exceeds 90% of normal output voltage. 2) The decoupling capacitor of PVIN and SVIN must be placed as close as possible to the pins. The loop area formed by the capacitors and GND must be minimized. re Enable Operation Pulling the EN pin low (1.5V) will turn on the IC again. 1) It is desirable to maximize the PCB copper area connecting to GND pin to achieve the best thermal and noise performance. Reasonable vias are suggested to be placed underneath the ground pad to enhance the soldering quality and thermal performance 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 + AN_SY8823 Rev. 0.9C Silergy Corp. Confidential- Prepared for Customer Use Only 9 SY8823 re pa re d fo rZ io nc om QFN2x1.5-8 Package Outline Drawing Bottom View Si le rg y Co rp .C on f id en tia l-P Top View Side View Notes: Recommended PCB layout (Reference only) All dimension in millimeter and exclude mold flash & metal burr AN_SY8823Rev. 0.9C Silergy Corp. Confidential- Prepared for Customer Use Only 10 SY8823 Taping & Reel Specification re pa re d fo rZ io nc om 1. QFN2x1.5 taping orientation l-P Feeding direction .C on f id en tia 2. Carrier Tape & Reel specification for packages Si le rg y Co rp Reel Size Package types Tape width (mm) Pocket pitch(mm) Reel size (Inch) Trailer length(mm) Leader length (mm) Qty per reel QFN2x1.5 8 4 7 400 160 3000 3. Others: NA AN_SY8823Rev. 0.9C Silergy Corp. Confidential- Prepared for Customer Use Only 11