ICL7107 ADC with Display Driver

25 May 2018 - 0 Comments

ICL7107 ADC with Display Driver

ICL7107 Pinout

ICL7107 Pinout Configuration

Pin Number	Pin Name	Description
1	Supply voltage (+)	Provides the operating voltage for the IC
2,3,4,5,6,7 and 8	7-Segment 4th digit	These pins are connected to the 7-segment display for displaying the once digit of output value.
9,10,11,12,13,14 and 25	7-segment 3rd digit	These pins are connected to 7-segment for displaying the tenth digit
15,16,17,18,22,23 and 24	7-sement 2nd digit	These pins are connected to 7-segment for displaying the hundredth digit
19 and 20	7-segment 1st digit	These pins are connected to 7-segment for displaying the thousandth digit
21	Ground	Connected to the round of the system
26	Supply voltage (-)	Provide the negative supply voltage
27	Signal integrate	Connected to a capacitor
28 and 29	Auto Zero and buff	Connected to capacitor and resistor network
30 and 31	Input High and Input Low	The analog voltage that has to be measured is connected here
32	Common	Connected to ground
33 and 34	Cref+ and Cref-	Capacitor is connected across these pins for neutralizing fluctuations in reference voltage
35 and 36	Reference High and Reference Low	Either can supply reference voltage or use internal reference voltage
37	Test pin	Not used during operation
38, 39 and 40	OSC1, OSC2, OSC3	Use RC network top set oscillator frequency

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

Note: Complete technical information can be found in the ICL7107 Datasheet linked at the bottom of this page.

ICL7107 Equivalent

CS7107

Alternatives ICs

ADC0804, ADC modules

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.

How to use ICL7107

Using ICL7107 is pretty straight forward, we just have to provide the reference voltage and set the internal clock for the ADC conversion to take place and we are all set. A basic sample circuit to measure voltage upto 200mV is shown below.

ICL7107 Circuit Diagram

The IC has an internal clock which can be set using the pins 38, 39 and 40 by using a Resistor capacitor network. The formulae to calculate the set oscillator frequency is shown below; typically the value is set to 48 kHz

FOSC = 0.45/RC

Once the clock is set we have to provide the reference voltage for the ADC conversion to take place. The value of the measured analog voltage will then be displayed on the 7-segment display the increment of count can be calculated using the following formulae

ICL7107 Increment Count Formula

The accuracy and the range of the measured voltage can be measured by using external circuits involving potential divider or op-amps but as always there is a trade off between the accuracy and range. You can refer the datasheet at the end of this page to know more technical details.