SY8745AFCC

Application Note: SY8745A High Efficiency 60V, 2.0A, 500KHz Constant Current Step-down Regulator Features SY8745A is a high efficiency, 12V-60V wide input voltage range DC/DC regulator targeting at LED applications. The device integrates the low RDS(ON) MOSFET and internal compensation. Along with the small SO8E package, the device achieves an extremely small solution size for LED driver design. SY8745A also supports PWM dimming and Analog dimming function.         IR IT Low RDS(ON) for internal switches :160mΩ Input range: 12V-60V 500kHz switching frequency PWM/Analog dimming available 2.0A LED current output Compact package: SO8E RoHS Compliant and Halogen Free ±2% 100mV reference or K Ordering Information RO N General Description dF Applications SY8745 □(□□)□  PAR Lamp  Tube Lamp  Bulb Note ---- lP Package type SO8E Typical Applications R3/0.2Ω VIN:50V~60V Efficiency vs. Output current 97.8 VO:40V,IO=1.5A on fi R4/0.2Ω de nti a Ordering Number SY8745AFCC rep are Temperature Code Package Code Optional Spec Code 97.6 D1 SS310 5 6 R2 10K LX SEN EN GND yC 7 NC VIN 8 NC CF GND 3 97.4 97.2 97.0 2 4 Vin=60V Vout=50V 96.8 C4 10nF 96.6 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 Output current(A) Figure 1. Schematic diagram Sil erg U1/SY8745A C3 2.2uF 50V L1/100µH 1 orp R1 100K .C C2 100V 100nF Efficiency(%) R5/0.2Ω C1 63V 10µF AN_SY8745A Rev.0.9 © 2019 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 1 All Rights Reserved. AN_SY8745A Pinout (top view) 1 8 NC CF 2 7 EN LX 3 6 SEN GND 4 5 IN GND RO N NC SO8E 1 CF 2 LX 3 GND 4 IN 5 SEN 6 EN 7 NC 8 dF rep are lP de nti a on fi LX SEN .C IN Pin Description No connection Dimming mode selection: VCF≥1.6V, PWM dimming mode. VCF≤1.4V, analog dimming mode. Inductor node. Connect an inductor from power input to LX pin. Ground pin Input pin. Decouple this pin to GND pin with 1µF ceramic cap. Also used as the positive current sense pin. Negative Current Sense Pin. Analog dimming mode selection: VEN≥8.5V, add 0~1.0V signal to CF PIN, 0~1.0V analog dimming mode.(EN connect to VIN is doable) VEN≤6.5V, add PWM signal to EN, analog dimming with PWM signal input. At analog dimming mode, recommend to connect a 10nF capacitor between CF PIN and GND. No connection or K Pin Name NC IR IT SO8E Top Mark: BUCxyz (device code: BUC, x=year code, y=week code, z= lot number code) orp Current Sense yC PWM Dimming processor Resistor Io reference GND Sil erg EN Driver Control Logic UVLO Dimming mode Thermal Shutdown CF Block Diagram AN_SY8745A Rev.0.9 © 2019 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 2 All Rights Reserved. AN_SY8745A Absolute Maximum Ratings RO N LX, IN, EN, CF------ ------------------------------------------------------------------------------------------------------ -0.3V to 63V SEN ----------------------------------------------------------------------------------------------------------------- -0.3V to VIN  0.6V Power Dissipation, PD @ TA = 25°C SO8E, ----------------------------------------------------------------------------------- 3.3W Package Thermal Resistance (Note 2) θJA ------------------------------------------------------------------------------------------------ 30°C/W θJC -------------------------------------------------------------------------------------------------------------------- 10°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 Sil erg yC orp .C on fi de nti a lP rep are dF or K IR IT IN------------------------------------------------------------------------------------------------------------------------------- 12V to 60V SEN -------------------------------------------------------------------------------------------------- ------------------------- VIN  0.4V Junction Temperature Range ------------------------------------------------------------------------------------------ -40°C to 125°C AN_SY8745A Rev.0.9 © 2019 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 3 All Rights Reserved. AN_SY8745A Electrical Characteristics VIN_ON VIN turn-off threshold VIN_OFF 120 400 98 4.0 1.5 or K Dimming section: Thermal Shutdown Temperature TSD Thermal Hysteresis Hyst 7.5 160 500 100 5.0 Max 60 0.25 Unit V µA mΩ kHz mV mV V V 200 600 102 6.0 9.0 10.0 11.0 V 8.5 9.5 10.5 V 100 900 mV mV 155 °C 20 °C rep are VCF dF At Minimum ILED At Maximum ILED Analog dimming range on CF Typ RO N VIN turn-on threshold Min 12 IR IT (VIN =24V, VOUT=12V, IOUT=100mA, TA = 25°C unless otherwise specified) Parameter Symbol Test Conditions Input Voltage Range VIN Shutdown Current ISHDN EN=0 Low Side Main FET RON RDS(ON) Switching Frequency FSW Internal Current Sense Reference VIN-SEN Min current sense reference VIN-SEN_MIN EN Rising Threshold VENH EN Falling Threshold VENL de nti a lP 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: θ JA is measured in the natural convection at T A = 25°C on a low effective single layer thermal conductivity test board of JEDEC 51-3 thermal measurement standard. Sil erg yC orp .C on fi Note 3. The device is not guaranteed to function outside its operating conditions AN_SY8745A Rev.0.9 © 2019 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 4 All Rights Reserved. AN_SY8745A Typical Performance Characteristics Analog dimming with PWM signal input 1.6 1.4 1.4 1.2 1.2 LED Current(A) 0.8 0.6 1.0 0.8 RO N 1.0 0.6 0.4 0.4 0.2 0.2 0.0 0.0 0 0.2 0.4 0.6 0.8 1 1.2 0 20 40 IR IT LED Current(A) 0-1.0V Analog Dimming 1.6 VCF(V) 60 80 100 120 Dimming Duty(%) PWM Dimming or K 1.60 1.40 dF 1.00 0.80 0.60 0.40 0.20 0.00 20 40 60 lP 0 rep are LED Current (A) 1.20 80 100 120 PWM Dimming (VIN=60V, VO=40V,IO=1.5A,90% Duty) 0.5A/div PWM Dimming (VIN=60V, VO=40V,IO=1.5A,50% Duty) Iout IL 0.5A/div 0.5A/div 20V/div VLX 20V/div erg yC VLX orp .C IL 0.5A/div on fi Iout de nti a Duty (%) Time (400µs/div) Sil Time (400µs/div) AN_SY8745A Rev.0.9 © 2019 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 5 All Rights Reserved. AN_SY8745A PWM Dimming PWM Dimming (VIN=60V, VO=40V,IO=1.5A,10% Duty) (VIN=60V, VO=40V,IO=1.5A,1% Duty) Iout 0.5A/div IL IL 0.5A/div VLX VLX Time (400µs/div) or K Time (400µs/div) Startup rep are 0.5A/div VLX Iout IL lP 0.5A/div 20V/div de nti a IL Shutdown (VIN=60V,VO=50V,IO=1.5A) dF (VIN=60V,VO=50V,IO=1.5A) Iout 20V/div IR IT 20V/div 0.5A/div 0.5A/div RO N Iout Time (20ms/div) 1.0A/div IL 1.0A/div VLX 20V/div Time (20ms/div) orp .C Iout 0.5A/div on fi Short LED (VIN=60V,VO=50V,IO=1.5A) 0.5A/div VLX Sil erg yC 20V/div Time (200µs/div) AN_SY8745A Rev.0.9 © 2019 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 6 All Rights Reserved. AN_SY8745A Operation The SY8745A 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. SY8745A is a grounding switch buck regulator IC that integrates the PWM control, power MOSFET on the same die to minimize the switching transition loss and conduction loss. With ultra low RDS(ON) power MOSFET and proprietary PWM control, this regulator IC can achieve the high efficiency and Along with the small SO8E package, the device achieves an extremely small solution size for LED driver design. SY8745A also supports PWM/Analog dimming function. RO N 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 Applications Information IR IT Dimming Operation: Dimming mode: 1: 0~1.0V analog dimming. Set VEN≥8.5V, and add 0~1.0V dimming signal to CF PIN. 2: Analog dimming with PWM signal input. Recommend to connect a capacitor to CF PIN, and add PWM signal to EN (VEN_HIGH≤6.5V) 3: PWM dimming. Set VCF≥1.6V, and add PWM signal to EN PIN. dF or K Because of the high integration in the SY8745A IC, the application circuit based on this regulator IC is rather simple. Only input capacitor CIN, output capacitor COUT, output inductor L and current sense resistor RSEN need to be selected for the targeted applications specifications. ILED(A)  0.1(V) R SEN () rep are Current sense resistor RSEN: Choose RSEN to program the proper output Current: PWM -PWM≥8.5V Input capacitor CIN: Dimming mode PWM dimming 0~1.0V analog dimming Analog dimming with PWM PWM≤6.5V ≤1.4V signal input At PWM dimming mode, the minimum TPWM_ON time is suggest setting bigger than 20µs. on fi de nti a lP The ripple current through input capacitor is calculated as: ICIN_RMS  IOUT  D(1 - D) A typical X7R or better grade ceramic capacitor with suitable capacitance should be chosen to 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. CF ≥1.6V ≤1.4V yC orp .C Output capacitor COUT: The output capacitor is selected to handle the output current ripple noise requirements. For the best performance, it is recommended to use X7R or better grade ceramic capacitor greater than 1µF capacitance. Sil erg 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: VOUT (1  VOUT /VIN,MAX ) L FSW  I OUT, MAX  40% where Fsw is the switching frequency and I OUT,MAX is the LED current. AN_SY8745A Rev.0.9 © 2019 Silergy Corp. Soft Start: Add a ceramic capacitor CCF on CF to achieve soft start, the soft start time can be adjusted by C CF. SCP: If VVIN-VSEN>=0.2V, PWM is disabled, When VVIN-VSEN =0.15V, IC will recover work. EN OFF: IC shut down after EN OFF with 15ms. Layout Design: The layout design of SY8745A regulator is relatively simple. For the best efficiency and minimum noise problems, we should place the following components close to the IC: CIN, L, COUT, CF and RSEN. 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. Silergy Corp. Confidential- Prepared for Customer Use Only 7 All Rights Reserved. AN_SY8745A 3) The PCB copper area associated with LX pin must be minimized to avoid the potential noise problem. PCB Layout Suggestion CF NC 3 2 1 COUT 8 EN NC or K 7 SEN LED+ Top Layer Bottom Layer Sil erg yC orp .C on fi de nti a lP rep are 6 IN RSEN dF CIN GND 5 VIN LED- IR IT LX 4 EN CF GND GND RO N D1 L1 AN_SY8745A Rev.0.9 © 2019 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 8 All Rights Reserved. AN_SY8745A dF or K IR IT RO N SO8E Package Outline & PCB layout Side view erg yC orp .C on fi de nti a lP rep are Top view Sil Front view Recommended PCB Layout (Reference Only) Notes: All dimension in millimeter and exclude mold flash & metal burr. AN_SY8745A Rev.0.9 © 2019 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 9 All Rights Reserved. AN_SY8745A Taping & Reel Specification or K IR IT RO N 1. Taping orientation SO8E Feeding direction lP rep are dF 2. Carrier Tape & Reel specification for packages Pocket Reel size Trailer * Leader * Qty per reel pitch(mm) (Inch) length(mm) length (mm) (pcs) 8 13" 400 400 2500 orp Tape width .C on fi de nti a Reel Size Package types yC (mm) 12 erg SO8E Sil 3. Others: NA AN_SY8745A Rev.0.9 © 2019 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 10 All Rights Reserved. AN_SY8745A Revision History Sil erg yC orp .C on fi de nti a lP rep are dF or K IR IT RO N The revision history provided is for informational purpose only and is believed to be accurate, however, not warranted. Please make sure that you have the latest revision. Date Revision Change September 19,2019 Revision 0.9 Initial Release AN_SY8745A Rev.0.9 © 2019 Silergy Corp. Silergy Corp. Confidential- Prepared for Customer Use Only 11 All Rights Reserved. AN_SY8745A IMPORTANT NOTICE 1. Right to make changes. Silergy and its subsidiaries (hereafter Silergy) reserve the right to change any information published in this document, including but not limited to circuitry, specification and/or product design, manufacturing or descriptions, at any time and without notice. This document supersedes and replaces all information supplied prior to the publication hereof. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All semiconductor products are sold subject to Silergy’s standard terms and conditions of sale. or K IR IT RO N 2. Applications. Application examples that are described herein for any of these products are for illustrative purposes only. Silergy makes no representation or warranty that such applications will be suitable for the specified use without further testing or modification. Buyers are responsible for the design and operation of their applications and products using Silergy products. Silergy or its subsidiaries assume no liability for any application assistance or designs of customer products. It is customer’s sole responsibility to determine whether the Silergy product is suitable and fit for the customer’s applications and products planned. To minimize the risks associated with customer’s products and applications, customer should provide adequate design and operating safeguards. Customer represents and agrees that it has all the necessary expertise to create and implement safeguards which anticipate dangerous consequences of failures, monitor failures and their consequences, lessen the likelihood of failures that might cause harm and take appropriate remedial actions. Silergy assumes no liability related to any default, damage, costs or problem in the customer’s applications or products, or the application or use by customer’s third-party buyers. Customer will fully indemnify Silergy, its subsidiaries, and their representatives against any damages arising out of the use of any Silergy components in safetycritical applications. It is also buyers’ sole responsibility to warrant and guarantee that any intellectual property rights of a third party are not infringed upon when integrating Silergy products into any application. Silergy assumes no responsibility for any said applications or for any use of any circuitry other than circuitry entirely embodied in a Silergy product. lP rep are dF 3. Limited warranty and liability. Information furnished by Silergy in this document is believed to be accurate and reliable. However, Silergy makes no representation or warranty, expressed or implied, as to the accuracy or completeness of such information and shall have no liability for the consequences of use of such information. In no event shall Silergy be liable for any indirect, incidental, punitive, special or consequential damages, including but not limited to lost profits, lost savings, business interruption, costs related to the removal or replacement of any products or rework charges, whether or not such damages are based on tort or negligence, warranty, breach of contract or any other legal theory. Notwithstanding any damages that customer might incur for any reason whatsoever, Silergy’ aggregate and cumulative liability towards customer for the products described herein shall be limited in accordance with the Standard Terms and Conditions of Sale of Silergy. on fi de nti a 4. Suitability for use. Customer acknowledges and agrees that it is solely responsible for compliance with all legal, regulatory and safety-related requirements concerning its products, and any use of Silergy components in its applications, notwithstanding any applications-related information or support that may be provided by Silergy. Silergy products are not designed, authorized or warranted to be suitable for use in life support, life-critical or safety-critical systems or equipment, nor in applications where failure or malfunction of an Silergy product can reasonably be expected to result in personal injury, death or severe property or environmental damage. Silergy assumes no liability for inclusion and/or use of Silergy products in such equipment or applications and therefore such inclusion and/or use is at the customer’s own risk. orp .C 5. Terms and conditions of commercial sale. Silergy products are sold subject to the standard terms and conditions of commercial sale, as published at http://www.silergy.com/stdterms, unless otherwise agreed in a valid written individual agreement specifically agreed to in writing by an authorized officer of Silergy. In case an individual agreement is concluded only the terms and conditions of the respective agreement shall apply. Silergy hereby expressly objects to and denies the application of any customer’s general terms and conditions with regard to the purchase of Silergy products by the customer. erg yC 6. No offer to sell or license. Nothing in this document may be interpreted or construed as an offer to sell products that is open for acceptance or the grant, conveyance or implication of any license under any copyrights, patents or other industrial or intellectual property rights. Silergy makes no representation or warranty that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right. Information published by Silergy regarding third-party products or services does not constitute a license to use such products or services or a warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the third party, or a license from Silergy under the patents or other intellectual property of Silergy. Sil For more information, please visit: www.silergy.com © 2019 Silergy Corp. AN_SY8745A Rev.0.9 © 2019 Silergy Corp. Powered by TCPDF (www.tcpdf.org) All Rights Reserved. Silergy Corp. Confidential- Prepared for Customer Use Only 12 All Rights Reserved.