LM2733

SNVS209F – NOVEMBER 2002 – REVISED DECEMBER 2014

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8 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

8.1 Application Information

The LM2733 device is a high frequency switching boost regulator that offers small size and high power

conversion efficiency. The "X" version of the part operates at 1.6 MHz switching frequency and the "Y" version at

600 kHz.

The LM2733 device targets applications with high output voltages and uses a high voltage FET allowing switch

currents up to 1 A. The LM2731 device is similar to the LM2733 device but has a lower voltage FET allowing

switch currents up to 1.8 A.

8.2 Typical Application

Figure 24. Basic Application Circuit

8.2.1 Design Requirements

Table 1. Circuit Configurations

LM2733-X

LM2733-X

LM2733-Y

Component

Low Voltage 5-12V 330mA typ

High Voltage 20V 170mA typ.

High Voltage 30V 110mA typ

R1

117K

205K

309K

R2

13.3K

13.3K

13.3K

Cf

220pF

120pF

82pF

D1

MBR0520

MBR0530

MBR0540

8.2.2 Detailed Design Procedure

8.2.2.1 Selecting the External Capacitors

The best capacitors for use with the LM2733 device are multi-layer ceramic capacitors. They have the lowest

ESR (equivalent series resistance) and highest resonance frequency which makes them optimum for use with

high frequency switching converters.

When selecting a ceramic capacitor, only X5R and X7R dielectric types should be used. Other types such as

Z5U and Y5F have such severe loss of capacitance due to effects of temperature variation and applied voltage,

they may provide as little as 20% of rated capacitance in many typical applications. Always consult capacitor

manufacturer’s data curves before selecting a capacitor. High-quality ceramic capacitors can be obtained from

Taiyo-Yuden, AVX, and Murata.

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