AN-1407| Application Note

LM3502/03 Evaluation Board

AN-1407 LM3502/03 Evaluation Board
General Description
The LM3502/03 evaluation board is a working demonstration of a step up DC-DC converter. The LM3502/03 is a white LED driver for lighting applications. The LM3502/03 contains two LED strings designed for dual displays with independence EN pins. The LM3502 LED current can be adjusted with PWM signal while the LM3503 LED current can be adjusted with a DC voltage or RC filtered PWM (pulse-widthmodulated) signal at the Cntrl pin. The LM3502/03 can drive up to 10 white LEDs. Both devices feature internal over voltage protection (OVP) and under voltage protection (UVP). For evaluation purpose, the evaluation board is assembled in micro SMD package for 25V version (LM3503ITL) and 44V version (LM3502ITL). The LM3502/03

National Semiconductor Application Note 1407 Anne Lu July 2006

are also available in 16-LLP package (see ordering information). For further information on boost converter topology, device electrical characteristics, and component selection, please refer to the LM3502 and LM3503 datasheets.

Operating Conditions

VIN range: 2.5V VIN 5.5V OVP options: 16V, 25V, 35V & 44V (see ordering information) 10 Bump MicroSMD or 16 Pin LLP package Ambient temperature (TA) range: -30C to +85C Junction temperature (TJ) range: -30C to +125C

Typical Application

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FIGURE 1. Typical Application Circuit LM3502

AN-1407

2006 National Semiconductor Corporation

AN201689

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