LM5114BSDEVAL/NOPB

User's Guide SNVA625A – January 2012 – Revised May 2013 AN-2206 LM5114 Evaluation Board 1 Introduction The LM5114 is a single low-side gate driver with 7.6A/1.3A peak sink/source drive current capability. It can be used to drive standard Si MOSFETs or enhancement mode GaN FETs in boost type configurations or to drive secondary synchronous FETs in isolated topologies. The LM5114 evaluation board is designed to provide the design engineer with a fully functional boost dc-dc converter to evaluate the LM5114. A 100V enhancement mode GaN FET (EPC2001) is used as the boost power switch. The control circuitry is implemented with the LM5020, a 100V current mode PWM controller. The specifications of the evaluation board are as follows: • Input Operating Voltage: 24V to 66V • Output Voltage: 75V • Output Current: 2A • Measured Efficiency at 48V: 97% @ 2A • Frequency of Operation: 500 kHz • Line UVLO: 23.6V (Rising) /21.6V (Falling) • Board size: 2.99 x 3.26 inches The printed circuit board consists of 2 layers of 2 ounce copper on FR4 material, with a thickness of 0.050 inches. 2 LM5114 Features • • • • • • • • • • • 3 Independent source and sink outputs for controllable rise and fall times +4V to +12.6V single power supply 7.6A/1.3A peak sink/source drive current 0.23Ω open-drain pull-down sink output 2Ω open-drain pull-up source output Power-off pull-down clamping 12ns (Typ) propagation delay Matching delay time between inverting and non-inverting inputs Up to +14V logic inputs (Regardless of VDD voltage) -40°C to +125°C operating temperature range Pin-to-Pin compatible with MAX5048 Package • • SOT-23-6 LLP-6 (3mm x 3mm) All trademarks are the property of their respective owners. SNVA625A – January 2012 – Revised May 2013 Submit Documentation Feedback Copyright © 2012–2013, Texas Instruments Incorporated AN-2206 LM5114 Evaluation Board 1 Powering and Loading Considerations www.ti.com VDD UVLO P_OUT IN DRIVER N_OUT INB UVLO Power-off pull-down clamp VSS Figure 1. Simplified Block Diagram of LM5114 4 Powering and Loading Considerations When applying power to the LM5114 evaluation board, certain precautions need to be followed. A misconnection can damage the assembly. 4.1 Proper Board Connection Figure 2 depicts the typical evaluation setup. The source power is connected to VIN and GND1. The load is connected to VOUT and GND2. Be sure to choose the correct connector and wire size. The input and output voltage must be monitored directly at the terminals of the board. The voltage drop across the connection wires will cause inaccurate measurements. 4.2 Source Power To fully test the LM5114 evaluation board, a DC power supply capable of 66V and 7A is required. When a boost converter is powered up, a high inrush current may be generated due to the charge of the output capacitors. It is desirable to use a source power with a soft start-up to limit the inrush current. 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. This chattering condition is an interaction with the evaluation board under voltage lockout, the cabling impedance and the inrush current. 4.3 Air Flow To ensure a proper and reliable operation, sufficient cooling is required. Insufficient airflow can cause a catastrophic failure. A minimum airflow of 200CFM should always be provided. 4.4 Quick Start-up Pfocedure 1. Connect the source supply to VIN and GND1. Connect the load cable between VOUT and GND2. 2. Set the current limit of the source supply to provide about 1.5 times the anticipated output power. 3. Set the load current at 0A. 2 AN-2206 LM5114 Evaluation Board SNVA625A – January 2012 – Revised May 2013 Submit Documentation Feedback Copyright © 2012–2013, Texas Instruments Incorporated Applications Information www.ti.com 4. Set the input voltage at 24V and turn on the power supply. Check that the output voltage is 75V. 5. Slowly increase the input voltage and the load current while monitoring the output voltage. 6. A quick efficiency check is the best way to ensure the evaluation board is working properly. Volt-meter VOUT GND2 LM5114 EVAL + 2A Electronic Load with current meter - GND1 - VIN + 66V, 7A, DC Power Supply Current Meter Figure 2. Typical Evaluation Setup 5 Applications Information 5.1 Operating Description The LM5114 evaluation board operates in both Continuous Conduction Mode (CCM) and Discontinuous Conduction Mode (DCM). For a given input voltage, the operation mode of the evaluation board is determined by the load current. Figure 3 illustrates the operation mode for different input voltages and load currents. The control loop design of a boost converter is usually more challenging than that of a buck converter due to a right half-plane zero (RHZ) in conjunction with quadratic poles. Thanks to the use of a small inductor in DCM operation, RHZ and the pole associated with the inductor move to the higher frequency, which eases the control loop design. Figure 3. CCM and DCM Operation Boundary SNVA625A – January 2012 – Revised May 2013 Submit Documentation Feedback Copyright © 2012–2013, Texas Instruments Incorporated AN-2206 LM5114 Evaluation Board 3 Applications Information 5.2 www.ti.com Gate Drive The enhancement mode GaN FETs have small gate capacitance and low threshold gate voltage. Therefore GaN FETs are prone to gate oscillations induced by PCB parasitic elements. It is necessary to place the driver as close to the GaN FET as possible to minimize the stray inductance. Gate resistors can be used to damp the oscillations and to adjust the switching speed. The LM5114 has split outputs, providing flexibility to adjust the turn-on and turn-off strength independently. In the evaluation board, 1.5Ω and 2.7 Ω gate resistors are used in the turn-on and turn-off path respectively. 5.3 Bias Supply The PWM controller LM5020 contains an internal high voltage startup regulator. When power is applied, the regulator generates 7.7 V output voltage with the output current limited to 15 mA. In addition, an auxiliary bias rail is also generated to reduce the power dissipation of the LM5020. As shown in Figure 17, voltages across the boost inductor during respective turn-on and turn-off periods are sensed by an auxiliary winding, and then are stored in two capacitors. The auxiliary bias voltage is the combination of the two capacitor voltages and is proportional to the output voltage in steady state. The calculation of the auxiliary bias voltage is as follows. (1) Where N is the turns ratio and is equal to 6 in this case. The corresponding bias voltage is around 11 V. Figure 4 compares the efficiency achieved with and without the auxiliary bias winding. As can be seen, with an auxiliary winding, the efficiency is improved by almost 2% at light load. Figure 4. Efficiency Comparison Between With and Without the Auxiliary Bias Winding 4 AN-2206 LM5114 Evaluation Board SNVA625A – January 2012 – Revised May 2013 Submit Documentation Feedback Copyright © 2012–2013, Texas Instruments Incorporated Performance Characteristics www.ti.com 6 Performance Characteristics Conditions: Input Voltage = 48 VDC, Load Current = 2 A Traces: Top Trace: Switch-node voltage, Volt/div = 50 V Bottom Trace: Gate-Source Voltage of GaN FET, Volt/div = 2 V Bandwidth Limit = 600 MHz Horizontal Resolution = 500 ns/div Figure 5. Evaluation Board Efficiency Figure 6. Gate-Source Voltage Conditions: Input Voltage = 24 VDC, Load Current = 2 A Traces: Top Trace: Inductor Current, Amp/div = 5 A Bottom Trace: Switch-Node Voltage, Volt/div = 20 V Bandwidth Limit = 600 MHz Horizontal Resolution = 1 us/div Figure 7. Close Loop Gain Measurement, VIN = 48 V, Load Current = 2 A Figure 8. Switching Node Voltage VIN = 24 V, Load Current = 2 A SNVA625A – January 2012 – Revised May 2013 Submit Documentation Feedback Copyright © 2012–2013, Texas Instruments Incorporated AN-2206 LM5114 Evaluation Board 5 Performance Characteristics www.ti.com Conditions: Input Voltage = 48 VDC Load Current = 2 A Traces: Top Trace: Inductor Current, Amps/div = 5 A Bottom Trace: Switch-Node Voltage, Volt/div = 20 V Bandwidth Limit = 600 MHz Horizontal Resolution = 1 us/div Figure 9. Switching Node Voltage VIN = 48 V, Load Current = 2 A Conditions: Input Voltage = 24 VDC Load Current = 2 A Traces: Trace: Output voltage ripple, Volt/div = 500 mV, AC coupled Bandwidth Limit = 20 MHz Horizontal Resolution = 1 us/div Conditions: Input Voltage = 66 VDC Load Current = 2 A Traces: Top Trace: Inductor Current, Amp/div = 5 A Bottom Trace: Switch-Node Voltage, Volt/div = 20 V Bandwidth Limit = 600 MHz Horizontal Resolution = 1 us/div Figure 10. Switching Node Voltage VIN = 66 V, Load Current = 2 A Conditions: Input Voltage = 48 VDC Load Current = 2 A Traces: Trace: Output voltage ripple, Volt/div = 500 mV, AC coupled Bandwidth Limit = 20 MHz Horizontal Resolution = 1 us/div Figure 11. Output Ripple VIN = 24 V, Load Current = 2 A Figure 12. Output Ripple, VIN= 48 V, Load Current = 2 A 6 AN-2206 LM5114 Evaluation Board SNVA625A – January 2012 – Revised May 2013 Submit Documentation Feedback Copyright © 2012–2013, Texas Instruments Incorporated Performance Characteristics www.ti.com Conditions: Input Voltage = 66 VDC, Load Current = 2 A Traces: Trace: Output voltage ripple, Volt/div = 500 mV, AC coupled Bandwidth Limit = 20 MHz Horizontal Resolution = 1 us/div Figure 13. Output Ripple, VIN = 66 V, Load Current = 2 A Conditions: Input Voltage = 48 VDC Load Current = 0A Traces: Top Trace: Inductor Current, Amp/div = 5 A Bottom Trace: Output Voltage, Volt/div = 20 V Bandwidth Limit = 600 MHz Horizontal Resolution = 5 ms/div Figure 15. Start-Up at No Load Conditions: Input Voltage = 48 VDC Load Current = 0.1 A to 2 A Traces: Top Trace: Load Current, Amp/div = 1 A Bottom Trace: Output Voltage Volt/div = 2 V, AC coupled Bandwidth Limit = 20 MHz Horizontal Resolution = 5 ms/div Figure 14. Step Load Response Conditions: Input Voltage = 48 VDC, Load Current = 2 A Traces: Top Trace: Inductor Current, Amp/div = 5 A Bottom Trace: Output Voltage, Volt/div = 20 V Bandwidth Limit = 600 MHz Horizontal Resolution = 5 ms/div Figure 16. Start-Up at Full Load SNVA625A – January 2012 – Revised May 2013 Submit Documentation Feedback Copyright © 2012–2013, Texas Instruments Incorporated AN-2206 LM5114 Evaluation Board 7 Evaluation Board Schematic 7 www.ti.com Evaluation Board Schematic Figure 17. Application Circuit: Input 24 V to 66 V, Output 75 V, 2 A, 500 kHz 8 AN-2206 LM5114 Evaluation Board SNVA625A – January 2012 – Revised May 2013 Submit Documentation Feedback Copyright © 2012–2013, Texas Instruments Incorporated Bill of Materials www.ti.com 8 Bill of Materials Part Value C1, C2, C3, C20, CAP, CERM, 2.2 uF, 100 C25, C26, C27, V, +/-10%, X7R C28, C29 C4, C5, C6 C7, C13 Package Part Number Manufacturer 1210 GRM32ER72A225KA35L MuRata 0805 C0805C104K1RACTU Kemet NU CAP, CERM, 0.1 uF, 100 V, +/-10%, X7R C8 CAP, CERM, 1000 pF, 100 0603 V, +/-5%, C0G/NP0 GRM1885C2A102JA01D MuRata C9 CAP, CERM, 0.1 uF, 16 V, +/-10%, X7R 0603 C0603C104K4RACTU Kemet C10 CAP, CERM, 0.047 uF, 50 V, +/-10%, X7R 0603 GRM188R71H473KA61D MuRata C11 CAP, CERM, 220 pF, 50 V, 0603 +/-5%, C0G/NP0 C0603C221K5GACTU Kemet C12, C17 CAP, CERM, 1 uF, 16 V, +/-10%, X5R 0603 C0603C105K4PACTU Kemet C15, C16 CAP, CERM, 2.2 uF, 25 V, +/-10%, X7R 0805 GRM21BR71E225KA73L MuRata C18, C31 CAP, CERM, 100 pF, 50 V, 0603 +/-5%, C0G/NP0 C1608C0G1H101J TDK C19 CAP, CERM, 2.2 uF, 10 V, +/-10%, X7R 0603 GRM188R71A225KE15D MuRata C21 CAP, CERM, 1 uF, 6.3 V, +/-20%, X5R 0402 C1005X5R0J105M TDK C22 CAP, CERM, 680 pF, 100 V, +/-10%, X7R 0805 08051C681KAT2A AVX C23, C24 CAP, AL, 22 uF, 100 V, +/20%, 0.55 ohm SMD VEJ-220M2ATR-0810 Lelon C30 NU D1, D2 Diode, Schottky, 30 V, 1 A SOD-123 MBR130T1G ON Semiconductor D3 Diode Schottky 8 A 100 V TO-277 V8P10-M3/86A Vishay D4 Diode SW 100 V 250 MA SOD323 BAS316 NXP Semiconductors D5 NU Q1 eGaN FET, 100 V, 25 A, 7 mΩ 4105um X 1632 um EPC2001 EPC R1 RES, 49.9 ohm, 1%, 0.1 W 0603 CRCW060349R9FKEA Vishay-Dale R2 RES, 100 k ohm, 1%, 0.1 W 0603 CRCW0603100KFKEA Vishay-Dale R3 RES, 5.62 k ohm, 1%, 0.1 W 0603 CRCW06035K62FKEA Vishay-Dale R4 RES, 12.7 k ohm, 1%, 0.1 W 0603 RC0603FR-0712K7L Yageo America R5 RES, 43.2 k ohm, 1%, 0.1 W 0603 RC0603FR-0743K2L Yageo America R6, R7 RES, 0 ohm, 5%, 0.1 W 0603 MCR03EZPJ000 Rohm R10 RES, 10.0 k ohm, 1%, 0.1 W 0603 RC0603FR-0710KL Yageo America R11 NU R12 RES, 1.5 ohm, 5%, 0.063 W 0402 CRCW04021R50JNED Vishay-Dale R13 RES, 2.7 ohm, 5%, 0.063 W 0402 CRCW04022R70JNED Vishay-Dale R14 RES, 10.0 ohm, 1%, 3 W 2512 SCW-SC3LF-10R0-F TT Electronics R15 RES, 10 ohm, 5%, 0.1 W 0603 CRCW060310R0JNEA Vishay-Dale SNVA625A – January 2012 – Revised May 2013 Submit Documentation Feedback Copyright © 2012–2013, Texas Instruments Incorporated AN-2206 LM5114 Evaluation Board 9 Bill of Materials 10 www.ti.com Part Value Package Part Number Manufacturer R16 RES, 147 k ohm, 1%, 0.1 W 0603 CRCW0603147KFKEA Vishay-Dale R17, R19 RES, 2.49 k ohm, 1%, 0.1 W 0603 CRCW06032K49FKEA Vishay-Dale R18 RES, 3.40 ohm, 1%, 0.1 W 0603 CRCW06033R40FKEA Vishay-Dale R20 RES, 0 ohm, 5%, 0.1W 0603 ERJ-3GEY0R00V Panasonic T1 Inductor, 4.7 uH, with a single aux winding SMD 12.6mmX12.7mm MA5639–AE Coilcraft T2 Current Sensing Transformer 100:1 SMT PA1005.100NL Pulse Engineering U1 100 V Current Mode PWM Controller VSSOP-10 LM5020 Texas Instruments U2 Micropower 50 mA Ultra Low-Dropout Regulator 5-pin SOT-23 LP2982 Texas Instruments U3 7.6A Single Low-Side Driver WQFN-6 LM5114 Texas Instruments AN-2206 LM5114 Evaluation Board SNVA625A – January 2012 – Revised May 2013 Submit Documentation Feedback Copyright © 2012–2013, Texas Instruments Incorporated PCB Layouts www.ti.com 9 PCB Layouts Figure 18. Top Layer Component View Figure 19. Bottom Layer Component View SNVA625A – January 2012 – Revised May 2013 Submit Documentation Feedback Copyright © 2012–2013, Texas Instruments Incorporated AN-2206 LM5114 Evaluation Board 11 PCB Layouts www.ti.com Figure 20. Top Layer Figure 21. Bottom Layer 12 AN-2206 LM5114 Evaluation Board SNVA625A – January 2012 – Revised May 2013 Submit Documentation Feedback Copyright © 2012–2013, 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. 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