LM2841YMK-ADJEV/NOPB

User's Guide SNVA356C – March 2009 – Revised April 2013 AN-1876 LM2841 Evaluation Board 1 Introduction The LM2841 is a PWM DC/DC buck (step-down) regulator. With a wide input range from 4.5V-42V, it is suitable for a wide range of applications from automotive to power conditioning from unregulated sources. The LM2841 evaluation board is designed to provide the design engineer with a fully functional power converter based on the buck topology to evaluate the LM2841 series of buck regulators. The evaluation board comes populated with the LM2841YMK-ADJL but can easily be modified to accommodate any of the LM2841 regulator ICs. 2 Features • • • • • • • 3 4.5V to 42V Input Voltage Range 3.3V Output Voltage Up to 300 mA Output Current 89% Efficiency at 300 mA Switching Frequency of 1.25 MHz Frequency Foldback Current Limit of 550 mA Internal Compensation Shutdown Operation The evaluation board includes a 3 pin header and a jumper to select whether the device is on or off. Placing the jumper in the "ON" position ties SHDN to VIN and enables the device. Placing the jumper in the "OFF" position ties SHDN to GND and disables the device. The jumper may be removed and a logic signal may be applied to the center pin to test startup and shutdown of the device. 4 Adjusting the Output Voltage The output voltage can be changed from 3.3V to another voltage by adjusting the feedback resistors using the following equation: VOUT = VFB(1 + (R1/R2)) (1) Where VFB is 0.76V. All trademarks are the property of their respective owners. SNVA356C – March 2009 – Revised April 2013 Submit Documentation Feedback Copyright © 2009–2013, Texas Instruments Incorporated AN-1876 LM2841 Evaluation Board 1 Evaluation Board Schematic 5 www.ti.com Evaluation Board Schematic VIN ON 1 2 3 SW OFF CBOOT VOUT L1 VIN LM2841 VIN 5 4 2 CIN VIN CB SHDN SW FB GND 1 D1 6 3 R1 U1 CIN2 COUT COUT2 R2 CFB GND1 GND2 Figure 1. LM2841 Evaluation Board Schematic 6 Bill of Materials Table 1. Bill of Materials (BOM) ID Part Number Type Size U1 LM2841 Buck Regulator SOT-6 L1 DO1608C-153MLC Inductor 1608 Qty Vendor 1 Texas Instruments 15 µH, 0.9A 1 Coilcraft D1 MA2YD2600L Diode SOD-123 60V, 800 mA 1 Panasonic CIN GRM31CR71H225KA88 Capacitor 1206 2.2 µF, 50V 1 Murata CIN2 OPEN COUT GRM32ER60J476ME20 Capacitor 1210 47 µF, 6.3V 1 Murata COUT2 OPEN 0.15 µF 1 Vishay/Vitramo n CFB OPEN CBOOT VJ0805Y154KXXA Capacitor 0805 R1 CRCW08053K40FKEA Resistor 0805 3.4 kΩ 1 Vishay R2 CRCW08051K02FKEA Resistor 0805 1.02 kΩ 1 Vishay 1X3 header HDR1X3 0.100 Spacing 1 ON/OFF 2 Parameters ON/OFF 382811-6 Shunt VIN, VOUT, GND1, GND2, SW 1502-2 Test Post AN-1876 LM2841 Evaluation Board TP 1502 1 Tyco/Amp 5 Keystone SNVA356C – March 2009 – Revised April 2013 Submit Documentation Feedback Copyright © 2009–2013, Texas Instruments Incorporated Typical Performance Characteristics www.ti.com 7 Typical Performance Characteristics VIN = 12V, VOUT = 3.3V, IOUT = 200 mA Top Trace: VOUT, 10 mV/div, AC Coupled Bottom Trace: SW, 5V/div, DC Coupled T = 400 ns/div 100 VIN = 12V EFFICIENCY (%) 80 VIN = 36V 60 VIN = 24V 40 20 0 0.0 0.1 0.2 0.3 LOAD CURRENT (A) Figure 2. Efficiency vs. Load Current Figure 3. Switching Node and Output Voltage Waveforms VIN = 12V, VOUT = 3.3V, IOUT = 200 mA to 300 mA Top Trace: VOUT, 20 mV/div, AC Coupled Bottom Trace: IOUT, 100 mA/div, DC Coupled T = 200 µs/div VIN = 12V, VOUT = 3.3V, IOUT = 50 mA Top Trace: VOUT, 1V/div, DC Coupled Bottom Trace: SHDN, 2V/div, DC Coupled T = 40 µs/div Figure 4. Load Transient Waveforms Figure 5. Startup Waveform SNVA356C – March 2009 – Revised April 2013 Submit Documentation Feedback Copyright © 2009–2013, Texas Instruments Incorporated AN-1876 LM2841 Evaluation Board 3 Layout 8 www.ti.com Layout Figure 6. Top Layer and Top Overlay Figure 7. Bottom Layer and Bottom Overlay 4 AN-1876 LM2841 Evaluation Board SNVA356C – March 2009 – Revised April 2013 Submit Documentation Feedback Copyright © 2009–2013, 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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