Description: ADC0808 8-Bit A/D Converter
ADC0808 Analog To Digital Converter IC 8-Bit A/D Converter With 8-Channel Multiplexer Integrated Circuit DIP-28 Dual In Line Package IC Electrical Circuitry & Parts
ADC0808 is an 8 bit analog to digital converter with eight input analog channels, it can take eight different analog inputs. The input which is to be converted to digital form can be selected by using three address lines. The voltage reference can be set using the Vref+ and Vref- pins. The step size is decided based on set reference value. Step size is the change in analog input to cause a unit change in the output of ADC. The default step size is 19.53mV corresponding to 5V reference voltage. ADC0808 needs an external clock to operate unlike ADC0804 which has an internal clock. The ADC needs some specific control signals for its operations like start conversion and bring data to output pins. When the conversion is complete the EOC pins goes low to indicate the end of conversion and data ready to be picked up.
- Resolution: 8 Bits
- 8-channel multiplexer with address logic
- Total Unadjusted Error ±1/2LSB and ±1LSB
- 0V to 5V input range with single 5V power supply
- Low Power 15 mW
- Conversion Time 100 us
- Operates ratiometrically or with 5 VDC or analog span adjusted voltage reference
- No zero or full-scale adjust required
- Easy to interface with all Microprocessors or works standalone.
- Can measure up to 8 Analog values seamlessly
- On-chip Clock not available, external Oscillator is needed (Clock)
- Digital output various from 0 to 255, Operating power is 15mW, conversion time 100us
- When Vref = 5V, for every 19.53mV of analog value there will be rise of one bit on digital side (Step size)
- Available in 28-pin PDIP, SOIC packages
- Outputs meet TTL voltage level specifications
- ADC0808 is equivalent to MM74C949
Where to use a ADC0808
The ADC0808 IC is a commonly used ADC module for projects were an external ADC is required. It is a 28-pin Eight channel 8-bit ADC module. Meaning it can measure up to eight ADC value from 0V to 5V and the precision when voltage reference (Vref –pin 9) is +5V is 19.53mV (Step size). That is for every increase of 19.53mV on input side there will be an increase of 1 bit at the output side.
This IC is very Ideal to use with Microprocessors like Raspberry Pi, Beagle bone etc.. Or even to use as a standalone ADC module. Every ADC module requires a clock to function; this IC requires an external clock pulse to work. Hence, if you are looking for a ADC module with a decent resolution of 8-bit that could measure up to 8 channels then this IC is for you.
How to use ADC0808
Since the ADC0808 IC can measure up to eight Analog voltage and also does not have an internal clock slightly requires more components to make it work compared to its predecessor ADC0804. The IC can be powered by +5V. The Vref + and the Output enable should also be supplied +5V to obtained the output. Powering the V ref + with +5V will make the IC operate with a step size of 19.53mV. The external clock should be connected to clock pin, this can either be a oscillator circuit or can just be an pulse generated from a MCU/MPU.
The right input analog voltage can be given to pins from IN1 to IN7, but the IC can read the voltage of only one channel at a time. This channel selection can be done with the pins ADD A, ADD B and ADD C. These three bits have to be set as shown in the table below to access the respective analog channel. Once the channel is set it should be enabled by making the Address latch enabled (ALE) pin to go high momentarily.
The digital output will be obtained from the pins 2-1 (OUT 1) to 2-8 (OUT 8) and the analog voltage should be connected to V in(+) pin as shown in the circuit. Also note that another end of the voltage source (sensor/module) should also be grounded to the circuit for the ADC conversion to work. Now, for the ADC Conversion to start we have o make the START pin to go high as soon as the EOC pin goes high. This can either be done through program or we can simple connect the EOC pin with START pin as shown in the circuit below.
- Operates With Any 8-Bit (uP) Processors or as a Stand-Alone Device
- Can measure up to eight channel hence can be used for complex projects
- Available in smaller packages for its performance, hence used in portable electronics.
- Widely used with Raspberry Pi, Beagle Bone, and other MPU development platforms
- Interface to Temp Sensors, Voltage Sources, and Transducers
- 1 x ADC0808 Analog To Digital Converter IC 8-Bit A/D Converter With 8-Channel Multiplexer Integrated Circuit DIP-28 Dual In Line Package IC