1. Device Overview

️· What they are: The TC7106A and TC7107A are dual-slope, integrating analog-to-digital converters (ADCs). They's designed for LCD display driving.
️· Dual-Slope Principle: They use a unique method. They integrate the input signal for a set time and then integrate a reference voltage until the integrator returns to zero. The time taken for the reference integration directly relates to the input signal's value.
️· Key Feature: Noise Immunity: The dual-slope technique is remarkably resistant to noise. Noise spikes are effectively averaged out during the integration phases. They're particularly good in environments with electrical interference.
️· Package: Designed for 40-pin PDIP packages.

2. Pin Functions (Important for Wiring!)

Pin Number (Normal)	Pin Number (Reversed)	Symbol	Description
1	40	V+	Positive supply voltage
9	32	VIN-	Analog LOW input
10	31	VIN+	Analog HIGH input
32	9	ANALOG COMMON	Sets the Analog Common mode voltage (important for battery operation).
36	5	VREF+	Reference voltage input for full-scale measurement.
27	15	VINT	Integrator output. Connection for integration capacitor.
39	2	OSC2	Part of the oscillator circuit.
29	12	CAZ	Auto-zero capacitor connection – crucial for noise performance.
40	1	OSC1	Oscillator circuit.
21	20	BP/GND	LCD Backplane drive output (TC7106A). Digital Ground (TC7107A).
7	34	CREF-	Reference Capacitor Negative connection
34	7	CREF+	Reference Capacitor Positive connection

3. Important Technical Details & Considerations

️· Oscillator Frequency: The standard oscillator frequency is 48 kHz, achieved with a 100kΩ resistor and a 100pF capacitor connected to pins 40 and 39.
️· Reference Voltage (VREF):
- For a full-scale range of 199.9 mV, connect 100 mV between pins 35 and 36 (VREF+ and VREF-).
- For a full-scale range of 2 V, connect 1 V between pins 35 and 36.
️· Auto-Zero Capacitor (CAZ):
- 0.47 µF for a 200 mV full scale range.
- 0.047 µF for a 2V full scale range.
️· Integrating Capacitor (VINT): Critical for proper operation.
️· Analog Common (ANALOG COMMON): Essential for battery operation.

4. Key Equations

️· Equation 3-1 (Conversion Relationship): A full equation is not provided, but it emphasizes the direct relationship between input signal, reference voltage, and integration times.
️· Equation 3-2: Illustrates the concept that complete conversion requires integrating a input signal for certain amount of time and then integrating a reference voltage until it "ramps-down"

5. Benefits of Dual-Slope Conversion (as highlighted in the datasheet)

️· High Noise Immunity: A key advantage; excellent for electrically noisy environments.
️· Simplicity: Relatively simple circuitry.
️· Accuracy: Accuracy is less dependent on component tolerances.