1. LM35 is linear temperature sensor, by linear it means you do not need any special type of circuitry and the out put is exactly proportional with input i.e Temperature in this case.

2.If you are using 8051(P89V51,AT89S51,DS5000) you need a ADC 0808/0809

3. As the output is 10mV/C so you need a simple conversion here just apply the output of LM35 directly to ADC 0804 and give the reference voltage as 0.64V so that it will give you some around sensitivity for 20mV change!!

4. Best you may refer the PAGE no 8, of LM35 datasheet!!

5. IF you are using PIC or AVR, then no prob at all !! since they have inbuilt ADC just configure it no amplifier is needed then as such!!

6. Again , If you want to display it on LCD 16x2, simple it is, I have given the code next, just compile it in keil, or ASM51(freeware small cross assembler best!!!)

PROGRAM
TO DISPLAY ADC READOUT ON LCD FOR 8051, and 16x2 LCD, ADC 0809

ORG 000H
INTR BIT P3.7
lPORT EQU P2
EN BIT P0.0
RW BIT P0.1
RS BIT P0.2
MYDATA EQU P1
MOV P1,#0FFH
SETB INTR
BACK: CLR WR
SETB WR ; TO START CONVERSION
HERE: JB INTR,HERE
CLR RD
MOV A,MYDATA
ACALL CONVERSION
ACALL DATA_DISPLAY
SETB RD ; FOR NEXT ROUND
SJMP BACK
CONVERSION:
MOV B,#10
DIV AB
MOV R7,B
MOV B,#10
DIV AB
MOV R6,B
MOV R5,A
RET
DATA_DISPLAY:
MOV lPORT,R5
ACALL DISPLAY
MOV lPORT,R6
ACALL DISPLAY
MOV lPORT,R7
ACALL DISPLAY
RET
DISPLAY: ACALL DELAY
SETB RS
CLR RW
SETB EN
ACALL DELAY
CLR EN
RET
COMNWRT: MOV lPORT,A
CLR RS
CLR RW
SETB EN
ACALL DELAY
CLR EN
RET
DELAY: MOV R3,#250
D1: MOV R4,#20
D2: NOP
NOP
DJNZ R4,D2
DJNZ R3,D1
RET
END