TC835CPI

ADCs/DACs - Special Purpose Overview

The TC835CPI is a low-power, 4-1/2 digit (0.005% resolution) BCD analog-to-digital converter in a 28-pin PDIP package. It supports 200 kHz clock operation with a conversion rate of five per second. The device features multiplexed BCD data outputs and interfaces with UARTs or microprocessors via BUSY and STROBE signals. It operates on single +5V supplies when paired with an ICL7660 charge pump, or dual ±5V supplies. Key electrical characteristics include 100 µV input sensitivity, 1 µA positive supply current at 0 Hz clock, and 0.7 mA negative supply current.

ADCs/DACs - Special Purpose Feature Summary

• Dual-slope integrating architecture with system zero and integrator output zero phases for enhanced accuracy
• Multiplexed BCD data outputs compatible with LCD and LED display decoder/drivers
• Control outputs including OVERRANGE, UNDERRANGE, POLARITY, BUSY, and STROBE for auto-ranging and processor interfacing
• Pin-compatible upgrade to TC7135 and ICL7135 without requiring external diode resistor rollover error compensation

ADCs/DACs - Special Purpose Applications

• Personal computer data acquisition systems
• Electronic scales and panel meters
• Process control instrumentation
• HP-IL bus instrumentation

ADCs/DACs - Special Purpose Procurement Notes

Verify the suffix 'CPI' corresponds to the 28-pin Plastic DIP package and commercial temperature range (0°C to +70°C). Confirm that the datasheet DS21478C is the authoritative source for pinout and electrical limits. Ensure ordering documentation specifies the correct voltage supply requirements for the target application.

ADCs/DACs - Special Purpose Selection Notes

Select this component for applications requiring high-resolution DC measurements with microprocessor interfaces. Ensure the integrating capacitor has low dielectric absorption to prevent ratiometric errors. For single-supply designs, integrate an ICL7660 to generate the required negative rail. Verify that the clock frequency does not exceed 200 kHz for standard line noise rejection unless comparator delay compensation is implemented.

ADCs/DACs - Special Purpose Part Context

The TC835 serves as a direct pin-compatible replacement for the TC7135 and ICL7135, offering improved speed with a 200 kHz clock capability compared to the older 100 kHz limit. It eliminates the need for external rollover error compensation circuits found in the ICL7135. The device is part of Microchip's legacy precision ADC portfolio, designed for cost-effective high-resolution data acquisition.

ADCs/DACs - Special Purpose Replacement Considerations

The TC835 is functionally equivalent to the TC7135 and ICL7135 in terms of pinout and basic operation. Designers upgrading from ICL7135 can remove external diode resistor networks. No other specific substitute part numbers are documented in the provided source material.