A/D Converter with LT1018

Description: The converter has a 60 ms conversion time, consuming 460 pA of current from a 5 V power supply, while maintaining an accuracy of 10 bits at 15 °C within a temperature range of 35 °C. A pulse applied to the conversion command line activates Q3, which operates in reverse mode, creating a discharge path through a 10 kΩ diode, thus forcing its collector low. The result of Q3's reverse mode switching leads to a capacitor discharge down to 1 mV relative to ground. During the ramp time, when the ramp value is less than the input voltage, the output of the CIA remains low.

This setup allows pulses from a stabilized quartz oscillator, ClB, to modulate Q4. The output data is present at the collector of Q4. When the ramp voltage exceeds the initial value, the output voltage of the CIA begins to rise, polarizing Q4 and enabling continuous output data. The number of output pulses is directly proportional to the input voltage. To calibrate, applying 0.5 V to the input and adjusting the TRIM to 10 kΩ results in exactly 1000 pulses generated each time the conversion command line is pulsed.

The described converter circuit is designed for precise analog-to-digital conversion, utilizing a low-power architecture suitable for battery-operated devices. The 60 ms conversion time indicates a balance between speed and power consumption, making it effective for applications where rapid data acquisition is necessary without compromising battery life. The 460 pA current draw is indicative of a design optimized for energy efficiency.

The operation of Q3 in reverse mode is critical for initiating the discharge cycle, allowing for rapid voltage stabilization across the capacitor. The diode's role in the discharge path ensures that the collector of Q3 is pulled low, facilitating a quick response time. The low output of the CIA during the ramp phase confirms that the system is in a waiting state until the input voltage surpasses the ramp value.

The modulation of Q4 by the stabilized quartz oscillator represents a key feature in maintaining output consistency, ensuring that the data output remains synchronized with the input signal. The continuous output of Q4 once the ramp voltage exceeds the initial threshold indicates a robust feedback mechanism that enhances the accuracy of the conversion process.

Calibration is an essential aspect of this converter's performance, with the ability to precisely adjust the TRIM resistor allowing for fine-tuning of the output pulses generated in response to the input voltage. This feature is particularly beneficial in applications requiring high precision and reliability, as it allows for compensation of variations in component tolerances and environmental conditions.

In summary, the converter's architecture, characterized by its low power consumption, precise calibration capabilities, and efficient modulation techniques, makes it suitable for a wide range of electronic applications that demand accurate digital representation of analog signals.The converter has a 60-ms conversion consumes 460 pA of 1's. 5 V power supply and maintains an accuracy of 10 bits on a 15 ° C in the temperature range of 35 ° C. A pulse applied to convert the command line causes Q3, operating in reverse mode, the discharge path through the diode 10 kO, forcing its collector low.

Q3 results of reverse mode switching in a capacitor discharge to 1 mV of ground. During the time of the ramp value is less than the input voltage, output of the CIA is low. This allows pulses ClB stabilized quartz oscillator, modulating Q4. The output data appears at the collector of Q4. When the ramp crosses the starting value of the output voltages of the CIA is going up, Q4 polarization and output data continuously. The number of pulses at the output is directly proportional to the input voltage. To celebrate cali apply 0.5V to the input and the TRIM-10 kO exactly 1000 pulses each time the conversion from the command line is pulsed.