LM25117EVAL/NOPB

User's Guide SNVA469B – May 2011 – Revised April 2013 AN-2112 LM25117 Evaluation Board 1 Introduction The LM25117 evaluation board provides the design engineer with a fully functional synchronous buck converter based on Emulated Current Mode Control to evaluate the LM25117 controller IC. The evaluation board provides 3.3V output with a 9A current capability in addition with average output current information. The input voltage ranges from 6V to 36V. 2 Performance of the Evaluation Board • • • • • • • • • Input Voltage Range: 6V to 36V Output Voltage: 3.3V Output Current: 9A Nominal Switching Frequency: 230 kHz Synchronous Buck Operation: Yes Diode Emulation Mode: Yes Hiccup Mode Overload Protection: Yes External VCC Sourcing: No Current Monitor Output: Yes 3 Powering and Loading Consideration 3.1 Proper Board Connection When applying power to the LM25117 evaluation board certain precautions need to be followed. A misconnection can damage the assembly. The input connection is made to the J1 (VIN+) and J2 (VIN-) connectors. The load is connected to the J3 (VOUT+) and J4 (VOUT-). Be sure to choose the correct connector and wire size when attaching the source power supply and the load. The average output current can be monitored at J5. Use RCA jack to remotely sense the current monitor output. TP5 is directly connected to UVLO and can be used as an input of the remote shutdown signal. 3.2 Source Power The power supply and cabling must present low impedance to the evaluation board. Insufficient cabling or a high impedance power supply will droop during power supply application with the evaluation board inrush current. If large enough, this droop will cause a chattering condition upon power up. During power down, this insufficient cabling or a high impedance power supply will overshoot, results in a nonmonotonic decay on the output. An additional external bulk input capacitor may be required unless the output voltage droop/overshoot of the source power supply is less than 0.5V. All trademarks are the property of their respective owners. SNVA469B – May 2011 – Revised April 2013 Submit Documentation Feedback AN-2112 LM25117 Evaluation Board Copyright © 2011–2013, Texas Instruments Incorporated 1 Powering and Loading Consideration 3.3 www.ti.com Loading When using an electronic load, it is strongly recommended to power up the evaluation board at light load and then slowly increase the load. If it is desired to power up the evaluation board at maximum load, resistor bank must be used. In general, electronic load is best suited for monitoring steady state waveforms. 3.4 Air Flow Prolonged operation with high input voltage at full power will cause the MOSFETs to overheat. A fan with a minimum of 200LFM should be always provided. 3.4.1 1. 2. 3. 4. 5. 6. Quick Start-up Procedure Set the power supply current limit to at least 11A. Connect the power supply to J1 and J2. Connect the load with a 9A capacity between J3 and J4. Set input voltage to 6V and turn it on. Measure the output voltage. The output should be regulated at 3.3V. Slowly increase the load current while monitoring the output voltage. The output should remain in regulation up to full load current. Slowly sweep the input voltage from 6V to 36V while monitoring the output voltage. The output should remain in regulation. Current-meter 0-36V, 11A DC Power Supply J1 VIN+ VOUT+ J3 LM25117 BUCK J2 VIN- VOUT- J4 + Electronic Load With Current Meter - 0A-9A Scope J5 Volt-meter Volt-meter Figure 1. Typical Evaluation Setup 3.5 3.5.1 Waveforms Soft Start When applying power to the LM25117 evaluation board a certain sequence of events occurs. Soft-start capacitor and other components allow for a linear increase in output voltage. Figure 2 shows the output voltage during a typical start-up with a load of 0.5Ω 2 AN-2112 LM25117 Evaluation Board SNVA469B – May 2011 – Revised April 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Powering and Loading Consideration www.ti.com Conditions: Input Voltage = 24VDC 0.5Ω Load on the output Traces: Top Trace: Output Voltage, Volt/div = 1V Bottom Trace: Inductor Current, Amp/div=2A Horizontal Resolution = 1ms/div Figure 2. Start-Up with Resistive Load 3.5.2 Load Transient Figure 3 shows the transient response for a load of change from 2A to 6.5A. The upper waveform shows output voltage droop and overshoot during the sudden change in output current shown by the lower waveform. Conditions: Input Voltage = 24VDC Output Current 2A to 6.5A Traces: Top Trace: Output Voltage Volt/div = 100mV, AC coupled Bottom Trace: Load Current, Amp/div = 2A Horizontal Resolution = 0.5ms/div Figure 3. Load Transient Response SNVA469B – May 2011 – Revised April 2013 Submit Documentation Feedback AN-2112 LM25117 Evaluation Board Copyright © 2011–2013, Texas Instruments Incorporated 3 Powering and Loading Consideration 3.5.3 www.ti.com Overload Protection The evaluation board is configured with hiccup mode overload protection. The restart time can be programmed by C20 restart capacitor. Figure 4 shows hiccup mode operation in the event of an output short. Conditions: Input Voltage = 24VDC Output Short Traces: Top Trace: SW Voltage Volt/div = 10V Bottom Trace: Inductor Current, Amp/div = 5A Horizontal Resolution = 20ms/div Figure 4. Short Circuit 3.5.4 External Clock Synchronization A TP3 (SYNC) test point has been provided on the evaluation board in order to synchronize the internal oscillator to the external clock. Figure 5 shows the synchronized switching operation. Conditions: Input Voltage = 24VDC Load Current = 9A Traces: Top Trace: SYNC pulse, 20% duty cycle, Volt/div = 5V Middle Trace: SW voltage, Volt/div = 20V Bottom Trace: Inductor Current, Amp/div = 5A Horizontal Resolution = 2µs/div Figure 5. Clock Synchronization 4 AN-2112 LM25117 Evaluation Board SNVA469B – May 2011 – Revised April 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Powering and Loading Consideration www.ti.com 3.5.5 Shutdown Figure 6 shows the shutdown procedure by powering off the source power. When UVLO pin voltage is less than 1.26V, the switching stops and soft-start capacitor is discharged by internal switches. Conditions: Input Voltage = 24VDC 0.5Ω Load on the Output Traces: Top Trace: Output Voltage, Volt/div = 1V Bottom Trace: Inductor Current, Amp/div = 2A Horizontal Resolution = 1ms/div Figure 6. Shutdown 3.6 Performance Characteristics Figure 7 shows the efficiency curves. During the efficiency measurement, monitor the current into and out of the evaluation board and monitor the voltage directly at the input and output terminals of the evaluation board. Figure 7. Typical Efficiency vs Load Current SNVA469B – May 2011 – Revised April 2013 Submit Documentation Feedback AN-2112 LM25117 Evaluation Board Copyright © 2011–2013, Texas Instruments Incorporated 5 Powering and Loading Consideration 3.7 3.7.1 www.ti.com Board Configuration Loop Response TP6 and TP7 have been provided in order to measure the loop transfer function. Refer to AN1889(SNVA364) for detail information about the loop transfer function measurement. VOUT+ Probe Signal Generator TP6 5~50: TP7 Isolation transformer RFB2 FB Probe RFB1 Figure 8. Loop Response Measurement Setup 6 AN-2112 LM25117 Evaluation Board SNVA469B – May 2011 – Revised April 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Powering and Loading Consideration www.ti.com 3.8 Evaluation Board Schematic SNVA469B – May 2011 – Revised April 2013 Submit Documentation Feedback AN-2112 LM25117 Evaluation Board Copyright © 2011–2013, Texas Instruments Incorporated 7 Powering and Loading Consideration 3.9 www.ti.com Bill of Materials Part Value Package Part Number Manufacturer C1 470pF, 100V, C0G 0805 C2012C0G2A471J TDK C2 820pF, 50V, C0G 0603 C1608C0G1H821J TDK C1608C0G1H101J TDK C3, C5 100pF, 50V, C0G 0603 C4, C23 NU 0603 C6, C9, C10, C11, C12, C13, C14 2.2µF,50V, X7R 1210 C3225X7R1H225K TDK C7 0.047µF, 16V, X7R 0603 C1608X7R1C473K TDK C8 0.01µF, 25V, C0G 0603 C1608C0G1E103J TDK C15 680µF, 6.3V, 10mΩ Φ10 APXA6R3ARA681MJC0 G UNITED CHEMICON C16, C17 22µF, 16V, X7R 2220 C5750X7R1C226M TDK C18, C21 1µF, 16V, X7R 0603 C1608X7R1C105K TDK C19 150pF, 50V, C0G 0603 C1608C0G1H151J TDK C20, C22 0.47µF, 25V, X7R 0603 GRM188R71E474KA12 MURATA C24, C27, C28, C29, C30, C31 NU 2220 C25 1000pF, 50V, X7R 0603 C1608X7R1H102K TDK C26 0.47µF, 50V, X7R 0805 GRM21BR71H474KA88L MURATA R1 0 ohm 0805 MCR10EZPJ000 ROHM R2 105k, 1% 0805 CRCW0805105KFKEA VISHAY R3 49.9k, 1% 0805 CRCW080549K9FKEA VISHAY R4 14k, 1% 0603 CRCW060314K0FKEA VISHAY R5, R6, R7, R12 NU 0603 R11, R14, R15 0 ohm 0603 MCR03EZPJ000 ROHM R8 22.1k, 1% 0603 CRCW060322K1FKEA VISHAY VISHAY R9 27.4k, 1% 0603 CRCW060327K4FKEA R10 2.49 ohm, 1% 0603 CRCW06032R49FKEA VISHAY R13 0.008 ohm, 1W, 1% 0815 RL3720WT-R008-F SUSUMU R16 1.05k ohm, 1% 0603 CRCW06031K05FKEA VISHAY R17 3.24k, 1% 0603 CRCW06033K24FKEA VISHAY R18 41.2 ohm, 1% 0805 CRCW080541R2FKEA VISHAY R19 5.1k, 5% 0603 CRCW06035K10JNEA VISHAY R21 10 ohm, 1% 2010 CRCW201010R0FKEF VISHAY R22 NU 1206 D1 NU PowerDI323 D2 60V, 1A SOD123F PMEG6010CEH NXP Z1 NU SOT89 L1 6.8µH, 18.5A / 27A 18.2x18.3 7443556680 WE Q1, Q2 40V, 58A PowerPAK SO-8 SI7884BDP VISHAY HTSSOP-20 U1 8 LM25117 Texas Instruments J1, J2, J3, J4 Terminal-Turret 1509 KEYSTONE J5 RCA Jack, Blue RCJ-025 CUI TP2, TP3, TP4, TP5, TP6, TP7 Test Point 1040 KEYSTONE AN-2112 LM25117 Evaluation Board SNVA469B – May 2011 – Revised April 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Powering and Loading Consideration www.ti.com 3.10 PC Board Layout SNVA469B – May 2011 – Revised April 2013 Submit Documentation Feedback AN-2112 LM25117 Evaluation Board Copyright © 2011–2013, Texas Instruments Incorporated 9 Powering and Loading Consideration 10 www.ti.com AN-2112 LM25117 Evaluation Board SNVA469B – May 2011 – Revised April 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Powering and Loading Consideration www.ti.com SNVA469B – May 2011 – Revised April 2013 Submit Documentation Feedback AN-2112 LM25117 Evaluation Board Copyright © 2011–2013, Texas Instruments Incorporated 11 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