Microchip Technology TC7109CPL

Overview

TC7109CPL from Microchip Technology is a 12-bit plus sign, dual-slope integrating analog-to-digital converter (ADC) in 40-pin PDIP package, operating from 0°C to +70°C. It delivers ±0.2 count non-linearity, 15 µV_P-P input noise, 1 pA typical input leakage, true differential input/reference, and zero integrator cycle for fast overload recovery - used in precision weigh scales, strain gauge interfaces, and industrial bridge transducer measurement systems.

For engineers reviewing the TC7109CPL datasheet, TC7109CPL pinout, TC7109CPL application, or TC7109CPL equivalent, this page provides verified technical context, real-world timing behavior, interface mode trade-offs (Direct vs. UART Handshake), and validated alternative options for high-accuracy DC-coupled measurement designs requiring auto-zero stability and cross-talk elimination in multiplexed environments.

Technical Context

The TC7109CPL implements a four-phase dual-slope conversion cycle: Auto-Zero (AZ), Signal Integrate (INT), Reference De-integrate (DE), and Zero Integrator (ZI). Its AZ phase achieves <10 µV input-referred offset via closed-loop compensation of buffer, integrator, and comparator offsets using CAZ.

ZI phase activates only after over-range detection and clears residual integrator charge in ≤1024 clock cycles, eliminating hysteresis between successive channels - critical for thermocouple arrays with open inputs tied to rails. The device supports both Direct parallel output (via CE/LOAD, HBEN, LBEN) and UART Handshake mode (MODE HIGH, SEND-controlled byte sequencing), with buffered oscillator output (BUFF OSC OUT) usable for RUN/HOLD synchronization.

Key Specifications

Pinout & Package

TC7109CPL uses a 40-pin plastic dual in-line package (PDIP) with 0.6-inch width, through-hole mounting, and industry-standard pin spacing (0.1 inch). Pin 1 is GND; pins 2–16 carry data/status/control signals; analog section occupies pins 28–40 (V+, V-, REF IN±, IN HI/LO, COMMON, REF CAP±, BUFF, AZ, INT).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar integrating ADC applications.

Compared with ICL7109CPL and MAX134ACPP, the TC7109CPL uniquely combines ZI-based crosstalk immunity, true differential reference capability, and hardware UART handshake - making it optimal for cost-sensitive, multi-sensor industrial instruments needing guaranteed overload recovery and minimal external components.

Availability

TC7109CPL is available at Aetrix Electronics and suitable for industrial weigh scales, strain gauge data acquisition systems, thermocouple input modules, and portable digital multimeters requiring stable component supply across extended production lifecycles.

Supply support for TC7109CPL includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microchip Technology is a U.S.-based semiconductor company specializing in microcontrollers, analog devices, and interface ICs for industrial, automotive, and consumer applications.

The TC7109CPL belongs to Microchip's legacy precision analog converter product line, designed specifically for high-stability, low-drift DC measurement systems where dual-slope integration, auto-zero, and overload resilience are essential.

FAQ

What is the maximum recommended clock frequency for stable operation of the TC7109CPL?

The TC7109CPL is specified for use with a 3.58 MHz crystal oscillator per the DS21456D datasheet test circuit. While RC oscillator configurations are supported via OSC SEL, crystal operation ensures ±0.1% frequency stability over temperature - critical for maintaining fixed 8192-clock conversion timing and minimizing scale factor drift. Operating above 3.58 MHz may violate internal timing margins and increase non-linearity beyond ±0.2 count.

Does the TC7109CPL require external zero calibration during system startup?

No, the TC7109CPL performs automatic zero calibration during every conversion cycle in its Auto-Zero (AZ) phase, eliminating the need for external zero adjustment. The internal CAZ capacitor is charged to null offset voltages in the buffer amplifier, integrator, and comparator - achieving <10 µV input-referred offset without user intervention. This behavior is inherent to the dual-slope architecture and applies to every TC7109CPL unit regardless of manufacturing variance.

How does the ZI (Zero Integrator) phase improve performance in multiplexed sensor systems?

The ZI phase in the TC7109CPL actively discharges residual integrator capacitor charge after an over-range event, preventing that charge from transferring to the auto-zero capacitor (CAZ) and corrupting the next conversion. In multiplexed systems - such as 8-channel thermocouple scanners - this eliminates cross-talk where an open (over-ranged) channel would otherwise induce errors in subsequent valid measurements. The ZI phase executes in ≤1024 clock cycles and is fully automatic, requiring no host firmware control.

Can the TC7109CPL interface directly with a modern UART like the SP3232 without level-shifting?

Yes, the TC7109CPL's UART Handshake mode outputs (CE/LOAD, HBEN, LBEN) are TTL-compatible (VOH ≥ 3.5 V at 700 µA sink) and match the input thresholds of SP3232's TTL-level control pins. However, the SP3232's RS-232 driver outputs (TX, RX) operate at ±3–±5.5 V and must not be connected directly to TC7109CPL's digital pins. The TC7109CPL interfaces only to the SP3232's control inputs - not its RS-232 data lines - preserving safe voltage compatibility.

What is the purpose of the BUFF OSC OUT pin on the TC7109CPL, and how is it typically used?

The BUFF OSC OUT pin on the TC7109CPL provides a buffered, low-impedance copy of the internal oscillator signal - either crystal-derived (when OSC SEL = LOW) or RC-derived (when OSC SEL = HIGH). It is commonly used to drive the RUN/HOLD input for synchronized conversion triggering, or to clock external logic such as sample-and-hold circuits. Its 2 mA drive capability ensures clean edge transitions without loading the main oscillator, maintaining timing accuracy across the TC7109CPL's 8192-clock conversion cycle.