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An analog-to-digital converter (abbreviated ADC, A/D or A to D) is a device that converts a continuous physical quantity (usually voltage) to a digital number that represents the quantity’s amplitude.

Most real world data is in analog form. Whether it be temperature, pressure, voltage, etc, their variation is always analog in nature..so we have to convert this analog data into digital format so that computer or microcontroller can understand it and process on it. Sensor gives analog data in form of variation in current and voltage, ADC read this variation and process a digital data according to analog input and send to microcontroller to process it further.

Resolution – The resolution of the converter indicates the number of discrete values it can produce over the range of analog values. A computer is a digital machine that stores a number in binary. If you are storing a digital 2-bit number you can store 4 different values: 00, 01, 10, or 11. Now, you can say ADC have 2-bit resolution and you have a device which converts an analog voltage between 0 and 10 volts into a 2-bit digital value for storage in a computer. This device will give digital values as follows :

 Voltage 2-Bit Digital Representation 0 to 2.5 00 2.5 to 5 01 5 to 7.5 10 7.5 to 10 11

Higher the resolution smaller the step size
Smaller the step size better accuracy

• Step size – small amount of change in analog input that can understand
for example 8-bit ADC, step size=Vref/2^8 = Vref/256
Vref – used to detect step size
• Conversion –
Dout=Vinput/(step size)
Dout – decimal output digital data
For example – for 8 bit ADC, Vref = 2.56 V, calculate digital output for 1.7 V input.
step size=(2.56 V)/256=10 mV
Dout=(1.7 V)/(10 mV)=170=10101010

• 7 differential channel input
• 2 different input channel with gain of 10X and 200X
• 3 option of Vref
1). internal 2.56 V

2). AVcc (pin 30)
3). AREFF (pin 32) Applications

### 1. CIRCUIT DIAGRAM OF ADC OF ARM7 (LPC2148)

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### In this program TEMPERATURE data is appeared on the LCD connected to the controller using ADC

#### PROTEUS File for SIMULATION(Password Of RAR file is :-firmcodes.com) _______________________________________________________________________________________________________

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