LM5119EVAL/NOPB

User's Guide SNVA444B – August 2010 – Revised April 2013 AN-2065 LM5119 Evaluation Board 1 Introduction The LM5119EVAL evaluation board provides the design engineer with a fully functional dual output buck converter, employing the LM5119 Dual Emulated Current Mode Synchronous Buck Controller. The evaluation board is designed to provide both 10V and 5V outputs over an input range of 14V to 55V. Also the evaluation board can be easily configured for a single 10V, 8A regulator. 2 Performance of the Evaluation Board • • • • • • • • 3 Input Voltage Range: 14V to 55V Output Voltage: 10V (CH1), 5V (CH2) Output Current: 4A (CH1), 8A (CH2) Nominal Switching Frequency: 230 KHz Synchronous Buck Operation: Yes Diode Emulation Mode: Yes Hiccup Mode Overload Protection: Yes External VCC Sourcing: Yes Powering and Loading Consideration When applying power to the LM5119 evaluation board, certain precautions need to be followed. A misconnection can damage the assembly. 3.1 Proper Board Connection The input connections are made to the J1 (VIN) and J2 (RTN/GND) connectors. The CH1 load is connected to the J3 (OUT1+) and J4 (OUT1-/GND) and the CH2 load is connected to the J6 (OUT2+) and J5 (OUT2-/GND). Be sure to choose the correct connector and wire size when attaching the source power supply and the load. 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 during power up. During power down, insufficient cabling or a high impedance power supply will overshoot. This overshoot will cause a non-monotonic decay on the output. An additional external bulk input capacitor may be required unless the output voltage droop/overshoot of the source power is less than 0.7V. In this board design, UVLO setting is conservative while UVLO hysteresis setting is aggressive. Minimum input voltage can goes down with an aggressive design. Minimum operating input voltage depends on the output voltage droop/overshoot of the source power supply and the forced off-time of the LM5119. For complete design information, see the LM5119/LM5119Q Wide Input Range Dual Synchronous Buck Controller Data Sheet (SNVS676). All trademarks are the property of their respective owners. SNVA444B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated AN-2065 LM5119 Evaluation Board 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 banks must be used. In general, electronic loads are 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. Figure 1. Typical Evaluation Setup 3.5 Quick Start-Up Procedure 1. Set the power supply current limit to at least 16A. Connect the power supply to J1 and J2. 2. Connect one load with a 4A capacity between J3 and J4. Connect another load with an 8A capacity between J6 and J5. 3. Set input voltage to 24V and turn it on. 4. Measure the output voltages. CH1 should regulate at 10V and CH2 should regulate at 5V. 5. Slowly increase the load current while monitoring the output voltages. The outputs should remain in regulation up to full load current. 6. Slowly sweep the input voltage from 14V to 55V while monitoring the output voltages. The outputs should remain in regulation. 2 AN-2065 LM5119 Evaluation Board SNVA444B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated Waveforms www.ti.com 4 Waveforms 4.1 Soft Start When applying power to the LM5119 evaluation board a certain sequence of events occurs. Soft-start capacitors and other components allow for a linear increase in output voltages. The soft-start time of each output can be controlled independently. Figure 2 shows the output voltage during a typical start-up with a load of 3Ω on the 10V output, and 1Ω on the 5V output, respectively. Conditions: Input Voltage = 24VDC 3Ω Load on 10V output 1Ω Load on 5V output Traces: Top Trace: 10V Output Voltage, Volt/div = 5V Bottom Trace: 5V Output Voltage, Volt/div = 5V Horizontal Resolution = 1 ms/div Figure 2. Start-Up With Resistive Load SNVA444B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated AN-2065 LM5119 Evaluation Board 3 Waveforms 4.2 www.ti.com Load Transient Figure 3 shows the transient response for a load of change from 2A to 6A on 5V output. 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 6A Traces: Top Trace: 5V Output Voltage, Volt/div = 100mV, AC coupled Bottom Trace: Output Current, Amp/div = 2A Horizontal Resolution = 0.5 ms/div Figure 3. Load Transient Response 4.3 Overload Protection The evaluation board is configured with hiccup mode overload protection. The restart time can be programmed by C11. Figure 4 shows hiccup mode operation in the event of an output short on CH2 output. One channel may operate in the normal mode while the other is in hiccup mode overload protection. Conditions: Input Voltage = 24VDC Output Short on 5V Traces: Top Trace: SW Voltage on CH2, Volt/div = 20V Bottom Trace: Inductor Current, Amp/div = 10A Horizontal Resolution = 20 ms/div Figure 4. Short Circuit 4 AN-2065 LM5119 Evaluation Board SNVA444B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated Waveforms www.ti.com 4.4 External Clock Synchronization A TP1 (SYNC) test point has been provided on the evaluation board in order to synchronize the internal oscillator to an external clock.Figure 5 shows the synchronized switching operation. Each channel operates 180° out of phase from the other. Conditions: Input Voltage = 24VDC 4A on 10V Output 8A on 5V Output Traces: Top Trace: SYNC pulse, Volt/div = 5V Middle Trace: SW voltage on CH1, Volt/div = 10V Bottom Trace: SW voltage on CH2, Volt/div = 10V Horizontal Resolution = 1 µs/div Figure 5. Clock Synchronization SNVA444B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated AN-2065 LM5119 Evaluation Board 5 Performance Characteristics 4.5 www.ti.com 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 capacitors are discharged by internal switches. Conditions: Input Voltage = 24VDC 1Ω Load on 5V Output Traces: Top Trace: Input Voltage, Volt/div = 20V Middle Trace1: 5V Output, Volt/div = 2V Middle Trace2: VCC, Volt/div = 5V Bottom Trace: SS Voltage, Volt/div = 5V Horizontal Resolution = 20 ms/div Figure 6. Shutdown 5 Performance Characteristics Figure 7 shows the efficiency curves. The efficiency of the power converter is 96% at 24V with full load current. Monitor the current into and out of the evaluation board. Monitor the voltage directly at the input and output terminals of the evaluation board. Figure 7. Typical Efficiency vs Load Current 6 AN-2065 LM5119 Evaluation Board SNVA444B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated Board Configuration www.ti.com 6 Board Configuration 6.1 Interleaved Buck Operation for Single 10V 8A Output The evaluation board is designed to be easily converted to a 10V, 8A single output regulator with the interleaved operation. Proper electronic load connection is shown in Figure 8. Connecting the electronic load at the center of shorting bar is recommended to prevent a voltage difference between CH1 and CH2 output. In order to produce a single 10V output with 8A maximum output current, populate R21 and R22 with 0Ω resistor and open R6, C15 and C14. The electronic load should have over 8A capability to test the interleaved operation. Figure 8. Load Connection for Single Output 6.2 External VCC Supply and VCC Disable External VCC supply helps to reduce the temperature and the power loss of the LM5119 at high input voltage. By populating D3 and D4, VCC can be supplied from an external power supply. Use TP3 as an input of the external VCC supply with 0.1A current limit. R36, R35 and C45 should be populated with proper value when the voltage of the external VCC is smaller than 7V. The voltage at the VCCDIS pin can be monitored at TP2. To prevent a reverse current flow from VCC to VIN through the internal diode, the external VCC voltage should always be lower than VIN. In this LM5119 evaluation board, VCC1 and VCC2 are supplied from the 10V output to achieve high efficiency. Figure 9. Efficiency Comparison at 48V With External VCC vs Without External VCC SNVA444B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated AN-2065 LM5119 Evaluation Board 7 Board Configuration 6.3 www.ti.com Loop Response TP5 and TP6 (TP7 and TP8) have been provided in order to measure the loop transfer function of CH1 (CH2). For detail information about the loop transfer function measurement, see AN-1889 How to Measure the Loop Transfer Function of Power Supplies (SNVA364). Figure 10. Loop Response Measurement Setup 8 AN-2065 LM5119 Evaluation Board SNVA444B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated Evaluation Board Schematic www.ti.com 7 Evaluation Board Schematic SNVA444B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated AN-2065 LM5119 Evaluation Board 9 Bill of Materials (BOM) 8 www.ti.com Bill of Materials (BOM) Table 1. Bill of Materials (BOM) Part Value Package Part Number Manufacturer C1, C2, C3, C4,C5, C32, C35,C36, C37, C38, C39, C40, C41, C42 2.2µF, 100V, X7R 1210 C3225X7R2A225K TDK TDK C6, C7, C25,C29 1µF, 16V, X7R 0603 C1608X7R1C105K C8, C10, C14, C16 100pF, 50V, C0G 0603 C1608C0G1H101J TDK C9 0.47µF, 100V, X7R 0805 GRM21BR72A474KA73 Murata C11, C18, C19 0.47µF, 25V, X7R 0603 GRM188R71E474KA12 Murata C12,C13 0.047µF, 16V, X7R 0603 C1608X7R1C473K TDK C15,C17 6800pF, 25V, C0G 0603 C1608C0G1E682J TDK C20,C21 820pF, 50V, C0G 0603 C1608C0G1H821J TDK C22,C26 470µF, 16V Φ10 PCG1C471MCL1GS Nichicon C23,C24,C27,C28 22µF,16V, X7R 1210 C3225X7R1C226K TDK C30,C31 1000pF, 50V, X7R 0603 C1608X7R1H102K TDK C33,C34 1000pF,100V, C0G 0805 C2012C0G2A102J TDK C43,C44,C45,C46,C47 NU R1 3.9 ohm, 5% 0805 CRCW08053R90JNEA Vishay R2 60.4k, 1% 0805 CRCW080560K4FKEA Vishay R3 6.19k, 1% 0603 CRCW06036K19FKEA Vishay R4 22.1k, 1% 0603 CRCW060322K1FKEA Vishay R5,R16,R21,R22,R35,R 36 NU R6,R7 36.5k, 1% 0603 CRCW060336K5FKEA Vishay R8,R9,R23,R24,R31, R32 10 ohm, 5% 0805 CRCW080510R0JNEA Vishay R10,R12 6.98k, 1% 0805 CRCW08056K98FKEA Vishay R11 604 ohm, 1% 0805 MCR10EZHF6040 Rohm R13 1.33k, 1% 0805 MCR10EZHF1331 Rohm R14,R15 73.2k, 1% 0603 CRCW060373K2FKEA Vishay R17,R37 0 ohm 0603 MCR03EZPJ000 Rohm R18,R20 0.01 ohm, 1W, 1% 0815 RL3720WT-R010-F Susumu R25,R26 5.1 ohm, 1W, 1% 2512 ERJ-1TRQF5R1U Panasonic — ECG R27,R28,R29,R30 0 ohm 0805 MCR10EZPJ000 Rohm D1,D2 60V, 1A SOD123F PMEG6010CEH NXP D3,D4 20V, 1A PowerDI323 PD3S120L Diodes L1,L2 15µH, 14A 18.2x18.3 74435571500 WE Q1,Q3, Q2,Q4 60V, 100A LFPAK SO-8 PSMN5R5-60YS NXP WQFN32 LM5119 TI 7693 Keystone 5002 Keystone 1040 Keystone U1 J1,J2,J3,J4,J5,J6 15A TP1,TP2,TP3 Φ0.1 TP5,TP6,TP7,TP8 10 AN-2065 LM5119 Evaluation Board SNVA444B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated PCB Layout www.ti.com 9 PCB Layout SNVA444B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated AN-2065 LM5119 Evaluation Board 11 PCB Layout 12 AN-2065 LM5119 Evaluation Board www.ti.com SNVA444B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated PCB Layout www.ti.com SNVA444B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated AN-2065 LM5119 Evaluation Board 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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