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User's Guide

SNVA012B–May 1999–Revised April 2013

AN–1133 LM2653EVAL 1.5A Synchronous Switching

Regulator Evaluation Board

1 Introduction

The LM2653 switching regulator provides high efficiency power conversion over a 100:1 load range (1.5A

to 15 mA). This feature makes the LM2653 an ideal fit in battery-powered applications.

Synchronous rectification and 75 mΩ internal switches provide up to 97% efficiency. At light loads, the

LM2653 enters a low power hysteretic or “sleep” mode to keep the efficiency high. In many applications,

the efficiency still exceeds 80% at 15 mA load. A shutdown pin is available to disable the LM2653 and

reduce the supply current to 7 µA.

The IC contains patented current sensing circuitry for current mode control. This feature eliminates the

external current sensing required by other current-mode DC-DC converters.

The IC has a 300kHz fixed frequency internal oscillator. The high oscillator frequency allows the use of

extremely small, low profile components.

The evaluation board can be obtained by ordering part number LM2653EVAL from your local Texas

Instruments sales office, or TI's website at http://www.ti.com.

2 Evaluation Board Design

The evaluation board is designed to supply 2.5 V at up to 1.5A. The input voltage range is 4 V to 14 V.

Components were selected based on the design procedure in the LM2653 1.5A High Efficiency

Synchronous Switching Regulator Data Sheet (SNVS050). The feedback resistors can be adjusted to

achieve a different output voltage:

OUT

= 1.238 V x [1+ (R

)] (1)

Choose 1% resistors between 10 kΩ to 100 kΩ for R1 and R2.

PCB layout is critical to reduce noises and ensure specified performance. For layout guidelines, see the

LM2653 1.5A High Efficiency Synchronous Switching Regulator Data Sheet (SNVS050). The artwork for

the evaluation board is shown at the end of this application report.

The schematic for the evaluation board is shown in Figure 1, and the parts list is given in Table 1.

When the undervoltage protection occurs, the output voltage can be pulled below ground as the inductor

current is reversed through the synchronous FET. For applications that need to be protected from a

negative voltage, a clamping diode D2 is recommended.

The PGOOD flag goes low whenever the overvoltage or undervoltage latch protection is enabled. The

overvoltage protection will be enabled immediately when the output voltage exceeds 110% of its nominal.

While the undervoltage latch protection will wait for a period of time set by the LDELAY capacitor. If the

output voltage is still below 80% of its nominal after this waiting period, the latch protection will be

enabled.

All trademarks are the property of their respective owners.

SNVA012B–May 1999–Revised April 2013 AN–1133 LM2653EVAL 1.5A Synchronous Switching Regulator Evaluation

Board

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Summary of content (5 pages)

PAGE 1
User's Guide SNVA012B – May 1999 – Revised April 2013 AN–1133 LM2653EVAL 1.5A Synchronous Switching Regulator Evaluation Board 1 Introduction The LM2653 switching regulator provides high efficiency power conversion over a 100:1 load range (1.5A to 15 mA). This feature makes the LM2653 an ideal fit in battery-powered applications. Synchronous rectification and 75 mΩ internal switches provide up to 97% efficiency.
PAGE 2
Evaluation Board Design www.ti.com Figure 1. LM2653 EVAL Schematic Table 1. Parts List (Bill Of Materials) Designation 2 Description L1 22 µH, Coilcraft DO3316P-223 CIN (input capacitor) 100 µF, 16 V, Sprague 594D107X0016D2T CIN2 (input capacitor) 0.1 µF ceramic capacitor CB (bootstrap capacitor) 0.1 µF ceramic capacitor CSS (softstart capacitor) 4.7 nF ceramic capacitor COUT (output capacitor) 120 µF, 6.3 V, Sprague 594D127X06R3C2T CC1 (compensation) 2.
PAGE 3
Typical PC Board Layout: (2X Size) www.ti.com 3 Typical PC Board Layout: (2X Size) Figure 2. Component Placement Guide Figure 3. Component Side PC Board Layout SNVA012B – May 1999 – Revised April 2013 Submit Documentation Feedback AN–1133 LM2653EVAL 1.
PAGE 4
References www.ti.com Figure 4. Solder Side PC Board Layout 4 References LM2653 1.5A High Efficiency Synchronous Switching Regulator Data Sheet (SNVS050) 4 AN–1133 LM2653EVAL 1.
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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.