Texas Instruments ADS1225IRGVT

Overview

ADS1225IRGVT from Texas Instruments is a 24-bit delta-sigma analog-to-digital converter with single-channel differential input, internal oscillator, and 2-wire serial interface. It delivers 16SPS (high-resolution mode) or 100SPS (high-speed mode), 4µV_RMS noise, ±V_REF full-scale range, and operates from 2.7V to 5.5V supplies. It is used in precision portable instrumentation requiring low-power, single-cycle settling, and ratiometric measurement capability.

For engineers reviewing the ADS1225IRGVT datasheet, ADS1225IRGVT pinout, ADS1225IRGVT application, or ADS1225IRGVT equivalent, key selection criteria include its 24-bit resolution with no missing codes, dual operating modes (16SPS/100SPS), integrated temperature sensor, internal high-impedance buffer (1 GΩ), and QFN-16 (4mm × 4mm) package with dedicated START and MODE control pins.

Technical Context

The ADS1225IRGVT implements a delta-sigma modulator with programmable gain-free architecture, using an internal 2.048MHz oscillator and digital filter optimized for single-cycle settling. Its analog front-end includes a selectable high-impedance input buffer (enabled via BUFEN) and supports ratiometric measurements through independent VREFP/VREFN inputs.

Conversion is initiated by a pulse on the START pin; completion is signaled by DRDY/DOUT going low, followed by 24-bit two's complement data output on the same pin synchronized to SCLK. The MODE pin selects between high-resolution (4µV_RMS, 16SPS) and high-speed (15µV_RMS, 100SPS) operation - both with guaranteed monotonicity and no missing codes over –40°C to +105°C.

Key Specifications

Pinout & Package

ADS1225IRGVT is housed in a 4mm × 4mm QFN-16 package (RGV) with exposed thermal pad. Pin 1 is START; pins 5 and 12 are GND (analog/digital common); pins 13–14 accept differential reference voltage; pins 10–11 are AINP1/AINN1 for single differential input channel.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 24-bit delta-sigma ADC applications.

Compared with ADS1220IPWR and AD7124-4BRUZ, the ADS1225IRGVT provides the smallest QFN-16 footprint, lowest active power (1 mW), and simplest 2-wire interface - making it uniquely suited for space-constrained, battery-operated instrumentation where single-channel precision and minimal external components are critical.

Availability

ADS1225IRGVT is available at Aetrix Electronics and suitable for portable medical equipment, industrial process transmitters, and hand-held test instrumentation requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for ADS1225IRGVT 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

Texas Instruments is a global semiconductor leader specializing in analog and embedded processing technologies, with decades of expertise in precision data converters and low-power design.

The ADS1225IRGVT belongs to TI's high-precision delta-sigma ADC product line, engineered specifically for portable, battery-powered instrumentation demanding 24-bit resolution, ultra-low power, and minimal external component count.

FAQ

What is the maximum differential input voltage range supported by the ADS1225IRGVT?

The ADS1225IRGVT supports a differential input voltage range of ±V_REF, where V_REF = VREFP – VREFN. With VREFP up to AVDD and VREFN down to GND, the maximum usable V_REF is 5V, yielding a full-scale range of ±5V. Absolute input limits are GND + 0.05V to AVDD – 1.5V per input pin when the buffer is enabled - exceeding this degrades INL and gain accuracy. The ADS1225IRGVT does not support rail-to-rail input operation.

How does the START pin control conversion timing in the ADS1225IRGVT?

The START pin initiates conversions via a minimum 17 µs high pulse. After pulsing START, the ADS1225IRGVT begins conversion and automatically shuts down upon completion. DRDY/DOUT goes low to signal data readiness. In high-resolution mode, conversion time is 45.5–83.3 ms; in high-speed mode, it is 8.0–13.3 ms. Holding START high enables continuous conversion - a new cycle starts immediately after the previous one finishes. The ADS1225IRGVT remains in shutdown until START is pulsed again.

Can the ADS1225IRGVT perform ratiometric measurements, and how is this implemented?

Yes, the ADS1225IRGVT supports true ratiometric measurements via independent VREFP and VREFN inputs. When the reference voltage is derived from the same supply powering a resistive sensor (e.g., RTD or strain gauge bridge), variations in supply voltage cancel out in the ratio (AINP – AINN)/(VREFP – VREFN). This eliminates system-level gain drift. The ADS1225IRGVT's 1.5 MΩ reference input impedance and recommended 0.1 µF bypass capacitor between VREFP and VREFN ensure stable reference coupling. Ratiometric operation is inherent to the ADS1225IRGVT's architecture and requires no configuration.

What is the function of the TEMPEN pin on the ADS1225IRGVT, and how accurate is the on-chip temperature sensor?

The TEMPEN pin (Pin 6) enables the ADS1225IRGVT's internal diode-based temperature sensor. When TEMPEN is high, the ADC input is internally connected to two scaled diodes (1× and 64×), generating a voltage difference proportional to absolute temperature. At +25°C, the output is typically 106 mV with a coefficient of 360 µV/°C. Accuracy is ±2.5°C over –40°C to +105°C after system-level calibration. The sensor is intended for ambient die temperature monitoring - not for external probe interfacing - and shares the same conversion path as analog inputs, requiring no additional pins or external circuitry.

Does the ADS1225IRGVT require external calibration, and how does self-calibration work?

The ADS1225IRGVT supports on-chip self-calibration that corrects offset and gain errors without external components. Calibration is triggered by applying two extra SCLK pulses after reading 24 bits of conversion data, while START remains high. During calibration, internal switches disconnect analog inputs and connect internal references; the ADC measures its own offset and gain against these references. Completion is signaled by DRDY/DOUT going low. Self-calibration takes ~2× conversion time and can be performed at power-up or periodically in-system. No external calibration equipment is needed - the ADS1225IRGVT performs full correction autonomously.