AN-1274| Application Note

LM2623 Evaluation Board

National Semiconductor Application Note 1274 September 2005

The LM2623 is a general purpose, gated oscillator based, DC/DC boost converter that can run from low input voltage and produce a regulated output voltage with low ripple. The LM2623 evaluation board is programmed for a 5V output running off a two-cell power supply. For more information

regarding the LM2623, please refer to the data sheet, Application Note AN-1258, as well as the cookbook (AN-1221) for more application configurations. A bill of material and a schematic follow:

TABLE 1. Bill of Materials Designator U1 L1 C1 C2 D1 RF2 RF1 R3 R5 C3 Description LM2623 DC-DC Converter MSOP-8 Inductor (4.7uH 20% 2A) Manufacturer National Semiconductor Coilcraft Model Number LM2623 DO1813P-472HC 595D227X06R3C2 293D107X96R3C2T MBRS340T3 CRCW06031003F CRCW06033003F CRCW06031503F CRCW0603000F C1608C0G1H4R7C

Input Capacitor (220uF Tantalum Vishay - Sprague Capacitor ( 20% 6.3V )) Output Capacitor (100uF Vishay - Sprague Tantalum Capacitor (10%, 6.3V)) Output Diode (40V 3A Schottky) 100 k Feedback Resistor 300 k Feedback Resistor 150 k Frequency Set Resistor 0 Resistor 4.7pF Ceramic Capacitor OnSemi Vishay - Dale Vishay - Dale Vishay - Dale Vishay - Dale TDK

20065204

Evaluation Board Application Circuit

Within the Application Board Circuit Diagram there are many components shown that are not populated on the 5V output evaluation board. These component footprints are used in

numerous other applications found in application note AN1221. In addition, jumpers J1, J2, and J4 are closed on the two-cell input to 5V output application board.

AN-1274

2005 National Semiconductor Corporation

AN200652

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