National LM95235 manual Introduction, 1.1Block Diagram

1.0 Introduction

The LM95235 Evaluation Board is used together with the National Semiconductor SensorEval software (provided in the kit), and with a USB cable (not provided in the kit), and with an external personal computer (PC). Power to the LM95235 Evaluation Board is provided by the +5 VDC line of the USB connection. No external power supply or signal sources are required for operation of the LM95235 evaluation board.

Before connecting the PC to the LM95235 evaluation board through the USB cable, the PC is first turned on and allowed to go through its boot-up procedure. The user installs and initiates the SensorEval software. See Section 4.0 for details.

After the SensorEval software is running, the user can connect the USB cable first to the computer and then to the LM95235 Evaluation Board.

The PC should be able to recognize the board and the user simply selects the LM95235 Eval Board radio button.

1.1Block Diagram

The block diagram below describes the LM95235 Evaluation Board itself. The USB input provides the +5.0 VDC power to the board, which is regulated down to 3.3 VDC to power the IC’s. The EEPROM is programmed at the factory with a unique ID code for this particular board. When the USB cable is plugged in, the PC interrogates the USB devices and can identify this device as the LM95235 Evaluation Board.

The microcontroller on the board provides the serial SMBus clock (SMBCLK), provides the SMBus data (SMBDAT) signal, and relays the information from the LM95235 to the PC via the USB lines.

The block in the lower right of the Block Diagram shows the signals that are available to probe by the user for the LM95235 device on the board.

USB	USB D+
	USB D-
Input
			SMBCLK	EEPROM
		Microcontroller
GND	+5.0 VDC		SMBDAT	Circuit
		Circuitry
				GND
	+3.3 VDC
Voltage
Regulator
Circuit
				VDD
				SMBCLK
		U2		SMBDAT
		LM95235		T_Crit
				OS/A0
			GND	GND

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