LM2852X-3.3EVAL

User's Guide SNVA124A – September 2005 – Revised April 2013 AN-1397 LM2852X Demonstration Board 1 Introduction This document describes the demonstration board for the LM2852X. The LM2852 is a 2A buck regulator belonging to Texas Instruments Simple Synchronous™ family. The LM2852 input voltage can range from 2.85 V to 5.5 V. Output voltages are factory set from 0.8 V to 3.3 V in 100mV increments. On-chip typethree compensation facilitates simple, low component count power supply design. Two frequency versions of the LM2852 are available: 500 kHz (LM2852Y) and 1500 kHz (LM2852X). The demonstration board for the LM2852X (1500 kHz version) is described in this document. A separate application note describes the LM2852Y. For detailed information regarding component selection, consult the device-specific data sheet. 2 VIN, GND and VOUT Three solder terminals are provided for connections to VIN, GND and VOUT. The input voltage to the LM2852 is connected to two PVIN pins and an AVIN pin. PVIN is the supply connected to the output power switches; AVIN powers the controller logic of the regulator. The demonstration board includes filtering of the AVIN voltage using components RF and CF. The back side plane of the board is connected to ground through the solder terminal via as well as vias underneath the exposed DAP of the LM2852. 3 Enable (EN) The LM2852 enable pin is internally pulled up through a large resistance. The demonstration board includes a via connected to the EN line to facilitate soldering a jumper wire if application of an enable signal is desired. 4 CIN and CINX The demonstration board provides two capacitor footprints for the input capacitance. The larger footprint holds the bulk of the capacitance, for example 47 µF. Additional high frequency filtering may also be accomplished by adding a smaller capacitor – CINX. A 1 µF or 100 nF capacitor is commonly used for high frequency filtering. 5 CSS The soft-start capacitor is used to control the startup behavior of the switching regulator. A 2.7 nF capacitor yields approximately a 3 ms startup time. 6 Output Filter - L, and CO Since the LM2852 uses on-chip compensation, the output filter component values must be restricted to a certain range. The LM2852X is designed for ceramic output capacitors with ESR values below 10 mΩ. The recommended inductance and capacitance for standard input and output voltages are 1 µH and 10 µF. Simple Synchronous is a trademark of Texas Instruments. All other trademarks are the property of their respective owners. SNVA124A – September 2005 – Revised April 2013 Submit Documentation Feedback AN-1397 LM2852X Demonstration Board Copyright © 2005–2013, Texas Instruments Incorporated 1 Board Schematic 7 www.ti.com Board Schematic U1 CF RF 1 2 EN 3 4 CSS 5 6 VIN CIN 7 CINX 14 AVIN SNS 13 EN NC SGND NC 12 11 SS PGND NC PGND 10 9 PVIN SW PVIN SW L VOUT 8 CO GND 8 Bill of Materials (BOM) for 1500 kHz Solution (LM2852X) Table 1. Bill of Materials 2 ID Part Number Type Size U1 LM2852XMXA-x.x 2A Buck ETSSOP-14 Parameters Qty Vendor 1 NSC L DO1608C-102 Inductor 1 µH 1 Coilcraft CO GRM31MR61A106KE19 Capacitor 1206 10 µF/X5R/10 V 1 Murata CIN GRM31CR60J476M Capacitor 1206 47 µF/X5R/6.3 V 1 Murata CINX GRM188R61A105K Capacitor 0603 1 µF/X5R/10 V 1 Murata CSS VJ0603Y272KXXA Capacitor 0603 2.7 nF ± 10% 1 Vishay-Vitramon RF CRCW060310R0F Resistor 0603 10 Ω ±10% 1 Vishay-Dale CF GRM188R61A105K Capacitor 0603 1 µF/X5R/10 V 1 Murata 160-1026-02-05-00 Solder Terminals Terminals for VIN, GND and VOUT 3 Wearnes AN-1397 LM2852X Demonstration Board SNVA124A – September 2005 – Revised April 2013 Submit Documentation Feedback Copyright © 2005–2013, Texas Instruments Incorporated PCB Layouts: 835 (mil) X 850 (mil) www.ti.com 9 PCB Layouts: 835 (mil) X 850 (mil) Figure 1. Top Layer 10 Figure 2. Bottom Layer Efficiency Plot 100 PVIN = 3.3V EFFICIENCY (%) 90 80 PVIN = 5.0V 70 60 50 40 0.1 1.0 10 ILOAD (A) Figure 3. LM2852X Typical Efficiency for 2.5 V Output SNVA124A – September 2005 – Revised April 2013 Submit Documentation Feedback AN-1397 LM2852X Demonstration Board Copyright © 2005–2013, Texas Instruments Incorporated 3 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All semiconductor products (also referred to herein as “components”) are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its components to the specifications applicable at the time of sale, in accordance with the warranty in TI’s terms and conditions of sale of semiconductor products. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by applicable law, testing of all parameters of each component is not necessarily performed. TI assumes no liability for applications assistance or the design of Buyers’ products. Buyers are responsible for their products and applications using TI components. To minimize the risks associated with Buyers’ products and applications, Buyers should provide adequate design and operating safeguards. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right relating to any combination, machine, or process in which TI components or services are used. Information published by TI 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 TI under the patents or other intellectual property of TI. Reproduction of significant portions of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations, and notices. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional restrictions. Resale of TI components or services with statements different from or beyond the parameters stated by TI for that component or service voids all express and any implied warranties for the associated TI component or service and is an unfair and deceptive business practice. TI is not responsible or liable for any such statements. Buyer 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 TI components in its applications, notwithstanding any applications-related information or support that may be provided by TI. Buyer 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. Buyer will fully indemnify TI and its representatives against any damages arising out of the use of any TI components in safety-critical applications. In some cases, TI components may be promoted specifically to facilitate safety-related applications. With such components, TI’s goal is to help enable customers to design and create their own end-product solutions that meet applicable functional safety standards and requirements. Nonetheless, such components are subject to these terms. No TI components are authorized for use in FDA Class III (or similar life-critical medical equipment) unless authorized officers of the parties have executed a special agreement specifically governing such use. Only those TI components which TI has specifically designated as military grade or “enhanced plastic” are designed and intended for use in military/aerospace applications or environments. Buyer acknowledges and agrees that any military or aerospace use of TI components which have not been so designated is solely at the Buyer's risk, and that Buyer is solely responsible for compliance with all legal and regulatory requirements in connection with such use. TI has specifically designated certain components as meeting ISO/TS16949 requirements, mainly for automotive use. In any case of use of non-designated products, TI will not be responsible for any failure to meet ISO/TS16949. Products Applications Audio www.ti.com/audio Automotive and Transportation www.ti.com/automotive Amplifiers amplifier.ti.com Communications and Telecom www.ti.com/communications Data Converters dataconverter.ti.com Computers and Peripherals www.ti.com/computers DLP® Products www.dlp.com Consumer Electronics www.ti.com/consumer-apps DSP dsp.ti.com Energy and Lighting www.ti.com/energy Clocks and Timers www.ti.com/clocks Industrial www.ti.com/industrial Interface interface.ti.com Medical www.ti.com/medical Logic logic.ti.com Security www.ti.com/security Power Mgmt power.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense Microcontrollers microcontroller.ti.com Video and Imaging www.ti.com/video RFID www.ti-rfid.com OMAP Applications Processors www.ti.com/omap TI E2E Community e2e.ti.com Wireless Connectivity www.ti.com/wirelessconnectivity Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265 Copyright © 2013, Texas Instruments Incorporated