Microchip Technology TC7109CKW

Overview

TC7109CKW from Microchip Technology is a 12-bit plus sign dual-slope integrating analog-to-digital converter (ADC) with true differential input and reference, auto-zero architecture, zero integrator cycle for overload recovery, and TTL-compatible tri-state parallel outputs. It operates from ±5V supplies, delivers 15µV_P-P input noise, 1pA typical input bias current, and supports both Direct and UART Handshake digital interfaces. It is used in precision weigh scales, strain gauge readouts, and industrial bridge sensor systems.

For engineers reviewing the TC7109CKW datasheet, TC7109CKW pinout, TC7109CKW application, or TC7109CKW equivalent, key selection considerations include its 44-pin PQFP package, differential bridge measurement capability, ±4V full-scale integrator swing, 8192-clock-cycle conversion timing, and absence of zero adjustment requirements.

Technical Context

The TC7109CKW implements a four-phase dual-slope integration cycle: Auto-Zero (AZ), Signal Integrate (INT), Reference De-integrate (DE), and Zero Integrator (ZI). Its AZ phase compensates for offset voltage in the buffer amplifier, integrator, and comparator using CAZ, achieving <10µV input-referred offset.

The ZI phase activates only after over-range detection to eliminate residual integrator charge-preventing cross-talk in multiplexed systems and enabling reliable thermocouple open-circuit detection. Its differential input and reference paths support ratiometric measurements of load cells and strain gauges with CMRR >86dB and rollover error <0.5 count.

Key Specifications

Pinout & Package

TC7109CKW is housed in a 44-pin Plastic Quad Flat Pack (PQFP) with 0.8 mm lead pitch and exposed thermal pad. Pin numbering follows standard PQFP convention, matching the 40-pin PDIP functional layout with additional NC pins for package adaptation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TC7107CPL, TC7109CKW adds zero integrator recovery and UART handshake at the cost of higher pin count and dual-supply requirement; compared with MAX134ACPP, it trades resolution for inherent ratiometric bridge support and deterministic dual-slope timing.

Availability

TC7109CKW is available at Aetrix Electronics and suitable for industrial weigh scales, strain gauge readouts, temperature transducer interfaces, and remote data loggers requiring stable component supply across extended production lifecycles.

Supply support for TC7109CKW 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 Inc. is a U.S.-based semiconductor company specializing in microcontrollers, analog devices, and interface ICs for industrial, automotive, and consumer applications.

The TC7109 family was designed specifically for high-accuracy, low-drift, dual-slope ADC applications in bridge-based sensor systems - emphasizing ratiometric measurement integrity, overload resilience, and minimal external component count.

FAQ

What is the function of the ZI (Zero Integrator) phase in the TC7109CKW?

The ZI phase in the TC7109CKW activates only after an over-range condition to discharge residual integrator capacitor charge. This prevents hysteresis and cross-talk in multiplexed systems - for example, ensuring a broken thermocouple on one channel does not corrupt the next channel's reading. The ZI phase lasts up to 1024 clock periods and is a defining feature distinguishing TC7109CKW from earlier TC7107 variants.

Does the TC7109CKW require external zero calibration components?

No, the TC7109CKW does not require external zero calibration components. Its auto-zero architecture uses internal CAZ capacitor and feedback loop to compensate for offset voltage in the buffer amplifier, integrator, and comparator - achieving <10 µV input-referred offset without manual trim. This eliminates potentiometers or DAC-based calibration circuits in production designs.

How does the TC7109CKW support differential bridge measurements?

The TC7109CKW supports differential bridge measurements via dedicated IN HI/IN LO and REF IN+/REF IN− pins. When REF IN+ is tied to bridge excitation and REF IN− to bridge mid-point, the ADC performs ratiometric conversion - canceling supply voltage drift. Its true differential topology and 86 dB CMRR reject noise while maintaining linearity across the full ±4 V integrator swing.

What are the supply voltage requirements for proper operation of the TC7109CKW?

The TC7109CKW requires dual analog supplies: V+ = +5 V and V− = −5 V, referenced to GND (Pin 1). These rails establish the ±4 V full-scale integrator swing essential for specified linearity and noise performance. Operating outside this range - e.g., with single +5 V - will cause integrator saturation and invalid conversions. The REF OUT pin provides −2.8 V (relative to V+) for external reference use.

Can the TC7109CKW interface directly with a UART without a microcontroller?

Yes, the TC7109CKW can interface directly with industry-standard UARTs like the HD6403 or CDP1854 using its UART Handshake mode. When MODE is held HIGH, CE/LOAD, HBEN, and LBEN become synchronized flag outputs that control UART data loading - eliminating the need for a microcontroller or FPGA in simple remote data loggers.