ICL7107 CPL (ADC with Display Driver)

Description.

The circuit given here is of a very useful and accurate digital voltmeter with LED display using the ICL7107 from Intersil. The ICL7107 is a high performance, low power, 3.5 digit analog to digital converter.

The IC includes internal circuitry for seven segment decoders, display drivers, reference voltage source and a clock. The power dissipation is less than 10mW and the display stability is very high.

The working of this electronic circuit is very simple.

The voltage to be measured is converted into a digital equivalent by the ADC inside the IC and then this digital equivalent is decoded to the seven segment format and then displayed.

The ADC used in ICL7107 is dual slope type ADC. The process taking place inside our ADC can be stated as follows.

For a fixed period of time the voltage to be measured is integrated to obtain a ramp at the output of the integrator.

Then a known reference voltage of opposite polarity is applied to the input of the integrator and allowed to ramp until the output of integrator becomes zero.

The time taken for the negative slope to reach zero is measured in terms of the IC’s clock cycle and it will be proportional to the voltage under measurement.

In simple words, the input voltage is compared to an internal reference voltage and the result is converted in a digital format.

Features

• 3 ½ bit (0-1999) ADC module with 4-digit 7-segemnt display driver
• Supply Voltage: Single Supply 0-6V
• Dual Supply -15 to +15V
• 3 ½ ADC module
• Analog input voltage is equal to supply voltage
• Internal Oscillator is available
• Typical operating frequency : 48kHz
• Digital output value : 0 - 1999
• Can drive four 7-segment display
• Available in 40-pin PDIP, and MQFP

Where to use a ICL7107

The ICL7107 is an ADC module with a resolution of 3 ½ bit, meaning it can display digital value from 0-1999. The ADC used here is a dual slop ADC, so the applied voltage is compared with a reference voltage and then is approximated to find the applied voltage. The speciality of this IC is that it has an in-built 4-digit 7-segment display driver inside it. So to display the measured voltage, we simply have to hook up 7-segment display to the output of the IC and everything is ready. IT eliminates the need for MCU/MPU or programming.

The IC can measure voltages of maximum from -15V to +15V which is equal to the supply voltage. The digital output can vary from 0-1999 where each digit is displayed on a single 7-segment display. So if you are trying to measure voltage and display them on a 7-segment display without the use of MCU or programming, then this IC might be the right choice for you.