LM5088MH-2EVAL/NOPB

User's Guide SNVA379E – November 2008 – Revised April 2013 AN-1913 LM5088 Evaluation Board 1 Introduction The LM5088 evaluation board is designed to provide the design engineer with a fully functional power converter based on Emulated Current Mode Control to evaluate the LM5088 controller IC. The LM5088 evaluation board is available in two versions (like the LM5088 controller): the LM5088-1 evaluation board provides ±5% oscillator frequency dithering to reduce EMI and the LM5088-2 evaluation board provides hiccup mode restart to reduce over load stress. Both the evaluation boards share the same layout except for silkscreen. The printed circuit board consists of 2 layers, 2 ounce of copper top and bottom and the board size is 2.55 × 1.5 × 0.5 inches. Specification LM5088-1 LM5088-2 Input Voltage Range 5.5V to 55V 5.5V to 55V Output Voltage 5.0V 5.0V Max. Average Load Current 7A 7A Load Regulation 2% 2% Current Limit Type Cycle-by-cycle current limit Hiccup Mode Restart Frequency 250 kHz (±5% Oscillator Dithering) 250 kHz Figure 1. Typical Efficiency Curves of LM5088-1 and LM5088-2 Evaluation Boards All trademarks are the property of their respective owners. SNVA379E – November 2008 – Revised April 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated AN-1913 LM5088 Evaluation Board 1 Powering and Loading Considerations 2 www.ti.com Powering and Loading Considerations Read this entire section prior to attempting to power the evaluation board. 2.1 Quick Setup Procedure Step 1: Set the power supply current limit to 10A. Turn off the power supply. Connect the power supply to the VIN terminals. Step 2: Connect the load, with a 7A capability, to the VOUT terminals. Step 3: Slowly increase the load while monitoring the output, VOUT should be in regulation with a nominal 5V output. Step 4: Slowly sweep the input voltage from 5.5V to 55V, VOUT should remain in regulation with a nominal 5V output. Step 5: Temporarily short the EN pin to check the shutdown function, Also, EN pin can be set between 0.4V and 1.2V, for example, by shorting EN pin to ground with a diode, to check the standby function. Step 6: Increase the load beyond the rated current to check the current limiting. The output current should limit at approximately 10A. The LM5088-1 board will enter cycle-by-cycle current limiting, while LM5088-2 is configured for a hiccup mode restart. Cooling is critical in this step. 2.2 Air Flow Prolonged operation with high input voltage (>36V) at full load will cause the LM5088 and MOSFETs to overheat and could potentially result in thermal shutdown. A fan with a minimum of 100LFM should always be used to cool the LM5088 evaluation board. Figure 2. Typical Thermal Profile at 48VIN 2.3 Powering Up It is suggested that the load be kept low during the first power up. Set the current limit of the source supply to provide about 1.5 times the anticipated wattage of the load. A quick efficiency check is the best way to confirm that everything is operating properly. If something is amiss one can be reasonably sure that it will affect the efficiency adversely. Few parameters can be correct in a switching power supply without creating losses and potentially damaging heat. 2 AN-1913 LM5088 Evaluation Board SNVA379E – November 2008 – Revised April 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Typical Performance Waveforms of LM5088-1 and LM5088-2 Evaluation Boards www.ti.com 2.4 Over Current Protection The LM5088-1 and LM5088-2 evaluation boards are both configured with over-current protection schemes. The LM5088-1 employs a cycle-by-cycle current limiting, while the LM5088-2 is configured for a hiccup mode restart. For more information on RES pin, see LM5088/LM5088Q Wide Input Range NonSynchronous Buck Controller (SNVS600). 2.5 Synchronization A Sync pin has been provided on the evaluation board. This pin can be used to synchronize the LM5088 to an external clock. For more information on Sync pin, see LM5088/LM5088Q Wide Input Range NonSynchronous Buck Controller (SNVS600). 2.6 Active Loads When using electronic load, it is strongly recommended to power up the evaluation board at light load and then slowly increase the load. This is necessary as most of the electronic loads do not draw any current till the output reaches an internally set point; this can result in soft-start function to not work as desired and can trip the current sense comparator. Electronic loads, in general, are best suited for monitoring steady state waveforms. If it is desired to power up the evaluation board at maximum load, resistor banks can be used. This will ensure a soft-start and evaluation board will perform as desired. Ensure that there is sufficient cooling for both the resistor banks and the LM5088 evaluation board, while running at full load. 3 Typical Performance Waveforms of LM5088-1 and LM5088-2 Evaluation Boards Conditions: Input Voltage = 48VDC Output Current = 4A to 7A Bandwidth Limit = 20 MHz Traces: Bottom Trace: Output Current Amps/div = 2A Top Trace: Output Voltage response Volts/div = 100 mV Horizontal Resolution = 500 µs/div Figure 3. Transient Response SNVA379E – November 2008 – Revised April 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated AN-1913 LM5088 Evaluation Board 3 Typical Performance Waveforms of LM5088-1 and LM5088-2 Evaluation Boards www.ti.com Conditions: Input Voltage = 48VDC Output Current = 7A Trace: Output Voltage Volts/div = 1V Figure 4. Soft-Start Conditions: Input Voltage = 48VDC Output Current = 7A Bandwidth Limit = 20 MHz Trace: Output Ripple Volts/div = 50 mV Horizontal Resolution = 5.0 µs/div Figure 5. Output Voltage Ripple 4 AN-1913 LM5088 Evaluation Board SNVA379E – November 2008 – Revised April 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Typical Performance Waveforms of LM5088-1 and LM5088-2 Evaluation Boards www.ti.com Figure 6. Conducted Emissions Measured at the Input of a LM5088-1 Evaluation Board SNVA379E – November 2008 – Revised April 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated AN-1913 LM5088 Evaluation Board 5 Bill of Materials for LM5088-1 and LM5088-2 Evaluation Boards 4 6 www.ti.com Bill of Materials for LM5088-1 and LM5088-2 Evaluation Boards Part Value Package Manufacturer Manufacturer Part Number Description C1,C2,C3, C4,C5 2.2 µF C1210 Murata GRM32ER72A225KA35L CAP CER 2.2 µF 100V X7R 1210 C6,C19 0.1 µF C0805 TDK Corporation C2012X7R2A104K CAP CER .10 µF 100V X7R 10% 0805 C7 1 µF C0603 Murata GRM188R71C105KA12D CAP CER 1 µF 16V X7R 0603 C8,C11 100 pF C0603 AVX Corporation 06031A101FAT2A CAP CERM 100 pF 1% 100V NP0 0603 C9 270 pF C0603 Murata GRM1885C2A271JA01D CAP CER 270 pF 100V 5% C0G 0603 C13 0.1 µF C0603 Murata GRM188R72A104KA35D CAP CER .1 µF 100V X7R 0603 C10 0.022 µF C0603 Murata GRM188R71C223KA01D CAP CER 22000 pF 16V 10% X7R 0603 C12 0.015 µF C0603 Murata GRM188R71H153KA01D CAP CER 15000 pF 50V 10% X7R 0603 C15 470 µF 0.327 × 0.327 × 0.303 Nippon-Chemicon APXF6R3ARA471MH80G CAP 470 µF 6.3V ELECT POLY SMD C17,C18 47 µF C1210 Murata GRM32ER61A476KE20L CAP CER 47 µF 10V X5R 1210 C20 1000 pF C0805 Murata GRM2195C2A102JA01D CAP CER 1000 pF 100V 5% C0G 0805 C16 NU 0.327 × 0.327 × 0.303 NU NU NU C21 NU C0603 NU NU NU C14 (LM50881) 0.1 µF C0603 Murata GRM188R72A104KA35D CAP CER .1 µF 100V X7R 0603 C14 (LM50882) 0.022 µF C0603 Murata GRM188R71C223KA01D CAP CER 22000 pF 16V 10% X7R 0603 D1 Schottky Diode D2PAK On Semi MBRB2060CT Schottky Rectifiers 20 Amp 60 Volt D2 NU SOD123 NU NU NU L1 6.8 µH HC9 series Coiltronics HC9-6R8-R INDUCTOR HIGH CURRENT 6.8 µH Q1 MOSFET SO-8 Vishay IR SI7148DP-T1-E3 MOSFET N-CH 75V 28A PWR PAK SO8 R1 54.9 kΩ R0805 Rohm MCR10EZHF5492 RES 54.9 kΩ 1/8W 1% 0805 SMD R2 16.2 kΩ R0603 Rohm MCR03EZPFX1622 RES 16.2 kΩ 1/10W 1% 0603 SMD R3 24.9 kΩ R0603 Rohm MCR03EZPFX2492 RES 24.9 kΩ 1/10W 1% 0603 SMD R4 18.2 kΩ R0603 Rohm MCR03EZPFX1822 RES 18.2 kΩ 1/10W 1% 0603 SMD R5 10 mΩ R0815 Susumu Co Ltd RL3720WT-R010-F RES .01Ω 1W 1% 0815 SMD R6 5.1Ω R2512 Panasonic - ECG ERJ-1TRQF5R1U RES 5.1Ω 1W 1% 2512 SMD R7 10Ω R0805 Rohm MCR10EZHF10R0 RES 10.0Ω 1/8W 1% 0805 SMD R8 5.11 kΩ R0603 Rohm MCR03EZPFX5111 RES 5.11 kΩ 1/10W 1% 0603 SMD R9 1.62 kΩ R0603 Rohm MCR03EZPFX1621 RES 1.62 kΩ 1/10W 1% 0603 SMD R10 NU R0603 NU NU NU J1,J2,J3, J4 Terminal_ Turret Keystone 1509 Terminal, Turret TP1,TP2 Slotted test point Keystone 1040 Terminal test point slotted U1 PWM IC Texas Instruments LM5088-1/LM5088-2 ECM Buck Controller HTSSOP-16 AN-1913 LM5088 Evaluation Board SNVA379E – November 2008 – Revised April 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated PCB Layout www.ti.com 5 PCB Layout Figure 7. LM5088-1 and LM5088-2 Top Layer Figure 8. LM5088-1 and LM5088-2 Bottom Layer SNVA379E – November 2008 – Revised April 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated AN-1913 LM5088 Evaluation Board 7 PCB Layout www.ti.com Figure 9. LM5088-2 Silk Screen Figure 10. LM5088-1 Silk Screen 8 AN-1913 LM5088 Evaluation Board SNVA379E – November 2008 – Revised April 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Schematics www.ti.com 6 Schematics Figure 11. LM5088-1 W/Dithering Schematic SNVA379E – November 2008 – Revised April 2013 Submit Documentation Feedback AN-1913 LM5088 Evaluation Board Copyright © 2008–2013, Texas Instruments Incorporated 9 Schematics www.ti.com Figure 12. LM5088-2 W/Restart Schematic 10 AN-1913 LM5088 Evaluation Board SNVA379E – November 2008 – Revised April 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated 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. 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