AN-1300| Application Note

LP3943 Evaluation Kit

National Semiconductor Application Note 1300 Mary F Kao October 2004

LP3943 Overview
The LP3943 is an integrated device capable of independently driving 16 LEDs. This device also contains an internal oscillator that provides all the necessary timing required for driving LED. Two prescaler registers along with two PWM registers provide a versatile duty cycle control. The LP3943 contains the ability to dim/blink LEDs in SMBUS/I2C applications. For more information, please refer to the LP3943 datasheet.

Install the evaluation software on a PC by copying the "LP3943.exe" from the CD to the LP3943 folder in your computer. There are two ways to launch the software. One way is without the evaluation board. Another way is with the evaluation board connected to the cable. Launching the software without the evaluation board: Start the software by double-clicking on its icon. A message will appear stating that the LP3943 board is not detected, and will ask if the user wants to switch to virtual LED mode. Click "Yes." 2. The default conditions of the virtual LEDs are different than that of the LP3943. Please be aware that the virtual LEDs simulate the functionality of the LP3943, but they do not perform exactly to the specification. To truly evaluate the LP3943, please request for a LP3943 evaluation board. 1.

Evaluation Kit Overview
LP3943 Evaluation Kit contains the evaluation board and PC software, and supports complete functional evaluation of the LP3943. All functions of the chip can be programmed via the use of the I2C interface port. The PC software provided emulates the I2C bus communication protocol. Hand shaking logic to interface to PC's parallel port and all necessary level shifting is provided.

Getting Started
The following instructions show how to use the LP3943 evaluation kit in default conditions. Please use the ESD protection (ground cable) to prevent any unwanted damaging ESD events.

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LP3943 software in virtual LED mode with all LEDs turned on (this is not the default state).

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