LM5117EVAL/NOPB

User's Guide SNVA466B – May 2011 – Revised April 2013 AN-2103 LM25117 Evaluation Board 1 Introduction The LM5117 evaluation board provides the design engineer with a fully functional synchronous buck converter based on Emulated Current Mode Control to evaluate the LM5117 controller IC. The evaluation board provides 12V output with a 9A current capability in addition with average output current information. The input voltage ranges from 15V to 55V. 2 Performance of the Evaluation Board • • • • • • • • • Input Voltage Range: 15V to 55V Output Voltage: 12V Output Current: 9A Nominal Switching Frequency: 230 kHz Synchronous Buck Operation: Yes Diode Emulation Mode: Yes Hiccup Mode Overload Protection: Yes External VCC Sourcing: Yes Current Monitor Output: Yes 3 Powering and Loading Consideration 3.1 Proper Board Connection When applying power to the LM5117 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 1V. All trademarks are the property of their respective owners. SNVA466B – May 2011 – Revised April 2013 Submit Documentation Feedback AN-2103 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 16A. Connect the power supply to J1 and J2. Connect the load with a 9A capacity between J3 and J4. Set input voltage to 15V and turn it on. Measure the output voltage. The output should be regulated at 12V. 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 15V to 55V while monitoring the output voltage. The output should remain in regulation. Current-meter 0-55V, 16A DC Power Supply J1 VIN+ VOUT+ J3 LM5117 BUCK J2 VIN- VOUT- J4 + Electronic Load With Current Meter - 0A-9A Scope J5 Volt-meter Volt-meter Figure 1. Typical Evaluation Setup 2 AN-2103 LM25117 Evaluation Board SNVA466B – May 2011 – Revised April 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Powering and Loading Consideration www.ti.com 3.5 3.5.1 Waveforms Soft Start When applying power to the LM5117 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 1.5Ω Conditions: Input Voltage = 48VDC 1.5Ω Load on the output Traces: Top Trace: Output Voltage, Volt/div = 5V Bottom Trace: Inductor Current, Amp/div=5A Horizontal Resolution = 2ms/div Figure 2. Start-Up With Resistive Load SNVA466B – May 2011 – Revised April 2013 Submit Documentation Feedback AN-2103 LM25117 Evaluation Board Copyright © 2011–2013, Texas Instruments Incorporated 3 Powering and Loading Consideration 3.5.2 www.ti.com 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 = 48VDC Output Current 2A to 6.5A Traces: Top Trace: Output Voltage Volt/div = 100mV, AC coupled Bottom Trace: Load Current, Amp/div = 5A Horizontal Resolution = 0.5ms/div Figure 3. Load Transient Response 4 AN-2103 LM25117 Evaluation Board SNVA466B – May 2011 – Revised April 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Powering and Loading Consideration www.ti.com 3.5.3 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 = 48VDC Output Short Traces: Top Trace: SW Voltage Volt/div = 20V Bottom Trace: Inductor Current, Amp/div = 5A Horizontal Resolution = 20ms/div Figure 4. Short Circuit SNVA466B – May 2011 – Revised April 2013 Submit Documentation Feedback AN-2103 LM25117 Evaluation Board Copyright © 2011–2013, Texas Instruments Incorporated 5 Powering and Loading Consideration 3.5.4 www.ti.com 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 = 48VDC Load Current = 9A Traces: Top Trace: SYNC pulse, 20% duty cycle, Volt/div = 5V Middle Trace: SW voltage, Volt/div = 50V Bottom Trace: Inductor Current, Amp/div = 5A Horizontal Resolution = 2µs/div Figure 5. Clock Synchronization 6 AN-2103 LM25117 Evaluation Board SNVA466B – 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 = 48VDC 1.5Ω Load on the Output Traces: Top Trace: Output Voltage, Volt/div = 5V Bottom Trace: Inductor Current, Amp/div = 5A Horizontal Resolution = 2ms/div Figure 6. Shutdown SNVA466B – May 2011 – Revised April 2013 Submit Documentation Feedback AN-2103 LM25117 Evaluation Board Copyright © 2011–2013, Texas Instruments Incorporated 7 Powering and Loading Consideration 3.6 www.ti.com 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 3.7 3.7.1 Board Configuration Loop Response TP6 and TP7 have been provided in order to measure the loop transfer function. For detail information about the loop transfer function measurement, see AN-1889 How to Measure the Loop Transfer Function of Power Supplies (SNVA364). VOUT+ Probe Signal Generator TP6 5~50: TP7 Isolation transformer RFB2 FB Probe RFB1 Figure 8. Loop Response Measurement Setup 8 AN-2103 LM25117 Evaluation Board SNVA466B – May 2011 – Revised April 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Powering and Loading Consideration www.ti.com 3.7.2 External VCC Supply External VCC supply helps to reduce the temperature and the power loss of the LM5117 at high input voltage. By populating D1 and R7, VCC can be supplied from the output. In this evaluation board, VCC is supplied from 12V output to achieve high efficiency. Figure 9. Loss Comparison at 48V; With External VCC vs Without External VCC SNVA466B – May 2011 – Revised April 2013 Submit Documentation Feedback AN-2103 LM25117 Evaluation Board Copyright © 2011–2013, Texas Instruments Incorporated 9 Powering and Loading Consideration www.ti.com 3.8 Evaluation Board Schematic 10 AN-2103 LM25117 Evaluation Board SNVA466B – May 2011 – Revised April 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Powering and Loading Consideration www.ti.com 3.9 Bill of Materials (BOM) Part Value Package Part Number Manufacturer C1 470pF, 100V, C0G 0805 C2012C0G2A471J TDK C2 820pF, 50V, C0G 0603 C1608C0G1H821J TDK C1608C0G1H470J TDK C3 47p, 50V, C0G 0603 C4, C23 NU 0603 C5 100pF, 50V, C0G 0603 C1608C0G1H101J TDK C6, C9, C10, C11, C12, C13, C14 3.3µF, 100V, X7S 1210 C3225X7S2A335K TDK C7 0.1µF, 25V, X7R 0603 C1608X7R1E104K TDK C8 0.022µF, 50V, X7R 0603 06035C223JAT2A AVX C15 470µF, 16V, 20mΩ Φ10 PCG1C471MCL1GS NICHICON C16, C17 22µF, 16V, X7R 2220 C5750X7R1C226M TDK C18, C21 1µF, 16V, X7R 0603 C1608X7R1C105K TDK C19 180pF, 50V, C0G 0603 C1608C0G1H181J 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, 100V, X7R 0805 GRM21BR72A474KA73 MURATA R1 3.9 ohm, 5% 0805 CRCW08053R90JNEA VISHAY R2 165k, 1% 0805 MCR10EZPF1653 ROHM R3 100k, 1% 0805 CRCW0805100KFKEA VISHAY R4 9.76k, 1% 0603 CRCW06039K76FKEA VISHAY R5, R6, R12 NU 0603 R7, 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 357 ohm, 1% 0603 CRCW0603357RFKEA VISHAY R17 4.99k, 1% 0603 CRCW06034K99FKEA VISHAY R18 8.06 ohm, 1% 0805 CRCW08058R06FKEA VISHAY R19 5.1k, 5% 0603 CRCW06035K10JNEA VISHAY R21 10 ohm, 1% 2010 CRCW201010R0FKEF VISHAY R22 0.1 ohm, 1% 1206 MCR18EZHFLR100 ROHM D1 20V, 1A PowerDI323 PD3S120L DIODES D2 60V, 1A SOD123F PMEG6010CEH NXP Z1 NU SOT89 L1 10µH, 15A / 21.5A 18.2x18.3 74435561100 WE Q1, Q2 60V, 100A LFPAK SO-8 PSMN5R5-60YS NXP HTSSOP-20 LM5117 TI J1, J2, J3, J4 U1 Terminal-Turret 1509 KEYSTONE J5 RCA Jack, Blue RCJ-025 CUI TP2, TP3, TP4, TP5, TP6, TP7 Test Point 1040 KEYSTONE SNVA466B – May 2011 – Revised April 2013 Submit Documentation Feedback AN-2103 LM25117 Evaluation Board Copyright © 2011–2013, Texas Instruments Incorporated 11 Powering and Loading Consideration www.ti.com 3.10 PC Board Layout 12 AN-2103 LM25117 Evaluation Board SNVA466B – May 2011 – Revised April 2013 Submit Documentation Feedback Copyright © 2011–2013, Texas Instruments Incorporated Powering and Loading Consideration www.ti.com SNVA466B – May 2011 – Revised April 2013 Submit Documentation Feedback AN-2103 LM25117 Evaluation Board Copyright © 2011–2013, Texas Instruments Incorporated 13 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. 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