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1
Introduction
The LM25119EVAL evaluation board provides the design engineer with a fully functional dual output buck
converter, employing the LM25119 Dual Emulated Current Mode Synchronous Buck Controller. The
evaluation board is designed to provide both 3.3V and 1.8V outputs over an input range of 6.0V to 36V.
Also the evaluation board can be easily configured for a single 3.3V, 16A regulator.
2
Performance of the Evaluation Board
Input Voltage Range: 6.0V to 36V
Output Voltage: 3.3V (CH1), 1.8V (CH2)
Output Current: 8A (CH1), 8A (CH2)
Nominal Switching Frequency: 230 KHz
Synchronous Buck Operation: Yes
Diode Emulation Mode: Yes
Hiccup Mode Overload Protection: Yes
External VCC Sourcing: No
3
Powering and Loading Consideration
When applying power to the LM25119 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 0.5V. 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 LM25119. For complete design information, see the
LM25119/LM25119Q Wide Input Range Dual Synchronous Buck Controller Data Sheet (SNVS680).
All trademarks are the property of their respective owners.
SNVA445B – August 2010 – Revised April 2013
Submit Documentation Feedback
AN-2066 LM25119 Evaluation Board
Copyright © 2010–2013, Texas Instruments Incorporated
User's Guide
SNVA445B – August 2010 – Revised April 2013
AN-2066 LM25119 Evaluation Board
1

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Summary of Contents for Texas Instruments LM25119EVAL

  • Page 1 AN-2066 LM25119 Evaluation Board Introduction The LM25119EVAL evaluation board provides the design engineer with a fully functional dual output buck converter, employing the LM25119 Dual Emulated Current Mode Synchronous Buck Controller. The evaluation board is designed to provide both 3.3V and 1.8V outputs over an input range of 6.0V to 36V.
  • Page 2: Quick Start-Up Procedure

    6. Slowly sweep the input voltage from 6.0V to 36V while monitoring the output voltages. The outputs should remain in regulation. AN-2066 LM25119 Evaluation Board SNVA445B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated...
  • Page 3: Soft Start

    Bottom Trace: 1.8V Output Voltage, Volt/div = 1V Horizontal Resolution = 1 ms/div Figure 2. Start-up with Resistive Load SNVA445B – August 2010 – Revised April 2013 AN-2066 LM25119 Evaluation Board Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated...
  • Page 4: Load Transient

    Top Trace: SW voltage on CH1, Volt/div = 10V Bottom Trace: Inductor Current Amp/div = 10A Horizontal Resolution = 20 ms/div Figure 4. Short Circuit AN-2066 LM25119 Evaluation Board SNVA445B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated...
  • Page 5: External Clock Synchronization

    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 SNVA445B – August 2010 – Revised April 2013 AN-2066 LM25119 Evaluation Board Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated...
  • Page 6: Performance Characteristics

    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 AN-2066 LM25119 Evaluation Board SNVA445B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated...
  • Page 7 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. SNVA445B – August 2010 – Revised April 2013 AN-2066 LM25119 Evaluation Board Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated...
  • Page 8: Loop Response

    (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 9. Loop Response Measurement Setup AN-2066 LM25119 Evaluation Board SNVA445B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated...
  • Page 9: Evaluation Board Schematic

    Evaluation Board Schematic www.ti.com Evaluation Board Schematic SNVA445B – August 2010 – Revised April 2013 AN-2066 LM25119 Evaluation Board Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated...
  • Page 10 Q1,Q2,Q3,Q4 40V, 58A PowerPAK SO-8 SI7884BDP Vishay WQFN32 LM25119 J1,J2,J3,J4,J5,J6 7693 Keystone TP1,TP2,TP3 Φ10 5002 Keystone TP5,TP6,TP7,TP8 1040 Keystone AN-2066 LM25119 Evaluation Board SNVA445B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated...
  • Page 11: Pcb Layout

    PCB Layout www.ti.com PCB Layout SNVA445B – August 2010 – Revised April 2013 AN-2066 LM25119 Evaluation Board Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated...
  • Page 12 PCB Layout www.ti.com AN-2066 LM25119 Evaluation Board SNVA445B – August 2010 – Revised April 2013 Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated...
  • Page 13 PCB Layout www.ti.com SNVA445B – August 2010 – Revised April 2013 AN-2066 LM25119 Evaluation Board Submit Documentation Feedback Copyright © 2010–2013, Texas Instruments Incorporated...
  • Page 14: Important Notice

    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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