LM2733XEVAL/NOPB

User's Guide SNVA066B – April 2003 – Revised April 2013 AN-1280 LM2731/LM2733 Evaluation Board 1 Introduction The LM2731 and LM2733 are high frequency switching boost regulators that offer small size and high power conversion efficiency. The "X" version of the part operates at 1.6MHz switching frequency and the "Y" version at 600kHz. The primary difference between the LM2731 and LM2733 is that the LM2731 has a higher current internal switch FET (with lower breakdown voltage), while the LM2733 has a higher voltage FET that handles less current. The LM2733 targets applications with higher output voltages, while the LM2731 is intended for applications requiring higher load currents at lower output voltages. This user's guide will describe the evaluation board supplied to demonstrate the operation of these parts and give information on its usage. 2 Basic Application Circuit The basic application circuit shown in Figure 1 provides the component designators used on the evaluation board. L1 D1 U1 VIN VIN LM273X R1 VOUT SW R2 FB SHDN SHDN GND C1 C3 R3 C2 Figure 1. Evaluation Board Basic Application Circuit All trademarks are the property of their respective owners. SNVA066B – April 2003 – Revised April 2013 Submit Documentation Feedback AN-1280 LM2731/LM2733 Evaluation Board Copyright © 2003–2013, Texas Instruments Incorporated 1 Component Layout 3 www.ti.com Component Layout OUT C2 D1 R2 C3 R3 GND U1 L1 R1 C1 S/D IN Figure 2. Evaluation Board Component Layout 2 AN-1280 LM2731/LM2733 Evaluation Board Copyright © 2003–2013, Texas Instruments Incorporated SNVA066B – April 2003 – Revised April 2013 Submit Documentation Feedback Basic Application Circuit - LM2733Y www.ti.com 4 Basic Application Circuit - LM2733Y Table 1. LM2733Y Bill of Materials (VIN = 5V, VOUT = 12V, IOUT = 250mA) Designation Description Size Manufacturer Part # Vendor C1 Cap 2.2µF 16V 1206 EMK316BJ225ML Taiyo Yuden C2 Cap 4.7µF 16V 1812 EMK432BJ475ML Taiyo Yuden C3 Cap 220pF 50V 0805 VJ0805A221JXACW1BC Vishay R1 RES, 51k Ohm, 5%, 0.1W 0805 CRCW080551K0JNEA Vishay R2 RES, 118k Ohm, 1%, 0.1W 0805 CRCW0805118KFKEA Vishay R3 RES, 13.3k Ohm, 1%, 0.1W 0805 CRCW080513K3FKEA Vishay L1 Shielded Inductor 10µH 4A CDRH125-100MC Sumida D1 Diode 20V 0.5A MBR0520 International Rectifier U1 IC LM2733YMF VOUT 5V/Div SOT23 Texas Instruments VOUT ripple 100 mV/Div VIN 2V/Div VSW 5V/Div IO 100 mA/Div TIME (10 ms/DIV) Figure 3. Start Up VIN = 5V, VOUT = 12V, IOUT = 250mA TIME (1 µs/DIV) Figure 4. Switching Waveform and Output Voltage Ripple VIN = 5V, VOUT = 12V, IOUT = 250mA 100 VOUT ripple 100 mV/Div IO 100 mA/Div EFFICIENCY [%] 90 80 70 60 50 TIME (1 µs/DIV) 0 25 50 75 100 125 150 175 200 225 250 IOUT[mA] Figure 5. Load Transient VIN = 5V, VOUT = 12V, IOUT = 50mA to 200mA SNVA066B – April 2003 – Revised April 2013 Submit Documentation Feedback Figure 6. Efficiency VIN = 5V, VOUT = 12V AN-1280 LM2731/LM2733 Evaluation Board Copyright © 2003–2013, Texas Instruments Incorporated 3 Basic Application Circuit - LM2733X 5 www.ti.com Basic Application Circuit - LM2733X Table 2. LM2733X Bill of Materials (VIN = 5V, VOUT = 12V, IOUT = 250mA) Designation Description Size Manufacturer Part # Vendor C1 Cap 2.2µF 16V 1206 EMK316BJ225ML Taiyo Yuden C2 Cap 4.7µF 16V 1812 EMK432BJ475ML Taiyo Yuden C3 Cap 220pF 50V 0805 VJ0805A221JXACW1BC Vishay R1 RES, 51k Ohm, 5%, 0.1W 0805 CRCW080551K0JNEA Vishay R2 RES, 118k Ohm, 1%, 0.1W 0805 CRCW0805118KFKEA Vishay R3 RES, 13.3k Ohm, 1%, 0.1W 0805 CRCW080513K3FKEA Vishay L1 Shielded Inductor 10µH 4A CDRH125-100MC Sumida D1 Diode 20V 0.5A MBR0520 International Rectifier U1 IC LM2733XMF SOT23 Texas Instruments VOUT ripple VOUT 5V/Div 20 mV/Div VIN 2V/Div VSW 5V/Div IO 50 mA/Div TIME (5 ms/DIV) TIME (200 ns/DIV) Figure 7. Start Up VIN = 5V, VOUT = 12V, IOUT = 250mA Figure 8. Switching Waveform and Output Voltage Ripple VIN = 5V, VOUT = 12V, IOUT = 250mA 100 VOUT ripple 100 mV/Div EFFICIENCY [%] 90 IO 100 mA/Div 80 70 60 50 TIME (200 µs/DIV) 0 25 50 75 100 125 150 175 200 225 250 IOUT[mA] Figure 9. Load Transient VIN = 5V, VOUT = 12V, IOUT = 50mA to 200mA 4 AN-1280 LM2731/LM2733 Evaluation Board Copyright © 2003–2013, Texas Instruments Incorporated Figure 10. Efficiency VIN = 5V, VOUT = 12V SNVA066B – April 2003 – Revised April 2013 Submit Documentation Feedback Basic Application Circuit - LM2731Y www.ti.com 6 Basic Application Circuit - LM2731Y Table 3. LM2731Y Bill of Materials (VIN = 3.3V, VOUT = 5V, IOUT = 500mA Designation Description Size Manufacturer Part # Vendor C1 Cap 2.2µF 16V 1206 EMK316BJ225ML Taiyo Yuden C2 Cap 22µF 16V 1812 EMK432BJ226ML Taiyo Yuden C3 Cap 470pF 50V 0805 VJ0805A471JXAMX Vishay R1 RES, 51k Ohm, 5%, 0.1W 0805 CRCW080551K0JNEA Vishay R2 RES, 40.2k Ohm, 1%, 0.1W 0805 CRCW08054022F Vishay R3 RES, 13.3k Ohm, 1%, 0.1W 0805 CRCW080513K3FKEA Vishay L1 Shielded Inductor 4.7µH 1.68A NRS6012T6R8MMGJ Taiyo Yuden D1 Diode 20V 0.5A MBR0520 International Rectifier U1 IC LM2731YMF SOT23 Texas Instruments VOUT ripple 50 mV/Div VOUT 2V/Div VIN 1V/Div VSW 2V/Div IO 200 mA/Div TIME (2 ms/DIV) TIME (500 ns/DIV) Figure 11. Start Up VIN = 3.3V, VOUT = 5V, IOUT = 500mA Figure 12. Switching Waveform and Output Voltage Ripple VIN = 3.3V, VOUT = 5V, IOUT = 500mA 100 VOUT ripple 100 mV/Div EFFICIENCY [%] 90 IO 100 mA/Div 80 70 60 50 TIME (200 µs/DIV) 0 50 100 150 200 250 300 350 400 450 500 IOUT[mA] Figure 13. Load Transient VIN = 3.3V, VOUT = 5V, IOUT = 200mA to 400mA SNVA066B – April 2003 – Revised April 2013 Submit Documentation Feedback Figure 14. Efficiency VIN = 3.3V, VOUT = 5V AN-1280 LM2731/LM2733 Evaluation Board Copyright © 2003–2013, Texas Instruments Incorporated 5 Basic Application Circuit - LM2731X 7 www.ti.com Basic Application Circuit - LM2731X Table 4. LM2731XBill of Materials (VIN = 5V, VOUT = 12V, IOUT = 500mA Designation Description Size Manufacturer Part # Vendor C1 Cap 2.2µF 16V 1206 EMK316BJ225ML Taiyo Yuden C2 Cap 4.7µF 16V 1812 EMK432BJ475ML Taiyo Yuden C3 Cap 220pF 50V 0805 VJ0805A221JXACW1BC Vishay R1 RES, 51k Ohm, 5%, 0.1W 0805 CRCW080551K0JNEA Vishay R2 RES, 118k Ohm, 1%, 0.1W 0805 CRCW0805118KFKEA Vishay R3 RES, 13.3k Ohm, 1%, 0.1W 0805 CRCW080513K3FKEA Vishay L1 Shielded Inductor 10µH 4A CDH53-4R7MC Sumida D1 Diode 20V 0.5A MBR0520 International Rectifier U1 IC LM2731XMF SOT23 Texas Instruments VOUT ripple 100 mV/Div VOUT 5V/Div VIN 2V/Div VSW 5V/Div IO 200 mA/Div TIME (5 ms/DIV) TIME (200 ns/DIV) Figure 15. Start Up VIN=5V, VOUT=12V, IOUT=500mA Figure 16. Switching Waveform and Output Voltage Ripple VIN=5V, VOUT=12V, IOUT=500mA 100 VOUT ripple 200 mV/Div IO 200 mA/Div EFFICIENCY [%] 90 80 70 60 50 TIME (200 µs/DIV) 0 50 100 150 200 250 300 350 400 450 500 IOUT[mA] Figure 17. Load Transient VIN=5V, VOUT=12V, IOUT= 200mA to 400mA 6 AN-1280 LM2731/LM2733 Evaluation Board Copyright © 2003–2013, Texas Instruments Incorporated Figure 18. Efficiency VIN=5V, VOUT=12V SNVA066B – April 2003 – Revised April 2013 Submit Documentation Feedback Adjusting the Output Voltage www.ti.com 8 Adjusting the Output Voltage The output voltage is set using R2 and R3 as given by the formula: VOUT = 1.23 (R2/R3) + 1.23 (1) Solved for R2: R2 = (VOUT - 1.23) / 1.23 × R3 (2) The evaluation board as shipped has a 13.3k resistor installed at R3. The appropriate value for R2 for any output may be calculated from the above formula. 9 Feedforward Compensation The feedforward capacitor C3 should be selected to set the compensation zero at approximately 8 kHz. The value of C3 is calculated using: C3 = 1 / (2 × π × 8k × R2) (3) The value of C3 is calculated after R2 is selected for the output voltage needed for the specific application. 10 Guidelines for Component Selection Since it is assumed that some of the eval boards will be modified to be used in different voltage and current configurations, some guidelines are given to help select components which are likely to be changed. INDUCTOR L1: The amount of inductance required depends on switching frequency, duty cycle and amount of allowable ripple current. 10 µH is a good choice for most applications. At low boost ratios such as 3.3V to 5V, the LM2731 loop stability requires that the inductance not exceed 6.8 µH. Smaller inductors may be used in applications with less output current. Higher ripple current resulting from a smaller inductor means the maximum average current (and power) will be less. Duty cycle also affects ripple current, since the time the switch is ON determines the length of time that the current has to ramp up. Any design must be verified for maximum load current over the full temperature range of the application to make sure the inductance is sufficient. Smaller inductors can be used (and make more sense economically) if the load current is fairly light. The part may operate in discontinuous mode (where inductor current drops to zero during each switching cycle) using less inductance, but this is harmless and actually increases stability (phase margin) compared to continuous operation. DIODE D1: Because of the fast switching speeds, a Schottky diode must be used for D1. The voltage rating (minimum) should be at least 5V higher than the output voltage for safe design margin. The average current rating of the diode should be at least 50% more than the maximum output load current of the application. OUTPUT CAPACITOR C2: The output capacitor(s) used on the LM273X must be good quality ceramics of the X7R or X5R type. Z5U or Z5F types will not give sufficient capacitance because of the applied voltage reducing effective capacitance. The output capacitor is also critical for stability. As a basic guideline, it is recommended for the LM2733: 4.7 µF minimum, at output voltages of 10V or above. At lower output voltages, use 10-22 µF. In general, the higher the load current, the more output capacitance is required for stability. For the LM2731: use at least 10 µF in 5V to 12V applications, and use 22 µF at lower boost ratios (such as 3.3 to 5V). Stability of the specific application should be verified over the full operating temperature range by load step testing, where the load current is increased from no load to full load abruptly. This can be done simply by tapping the lead from the load box onto the output terminal. The amount of ringing seen on the output voltage waveform will define the stability of the design. SNVA066B – April 2003 – Revised April 2013 Submit Documentation Feedback AN-1280 LM2731/LM2733 Evaluation Board Copyright © 2003–2013, Texas Instruments Incorporated 7 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. 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