Texas Instruments ADS7822UB

Overview

ADS7822UB from Texas Instruments is a 12-bit pseudo-differential successive approximation register (SAR) analog-to-digital converter with 1 LSB integral linearity error, 200 kHz maximum throughput at 5 V, and 3 μA power-down current. It operates from 2.7 V to 5.25 V, uses a synchronous 3-wire serial interface (CS/SHDN, DCLOCK, DOUT), and targets ultra-low-power remote data acquisition.

For engineers reviewing the ADS7822UB datasheet, ADS7822UB pinout, ADS7822UB application, or ADS7822UB equivalent, key selection criteria include its SO-8 package, ±1 LSB INL/DNL accuracy grade, 75 kHz–200 kHz sample rate scalability, and compatibility with 2.7–5.25 V logic and supply rails.

Technical Context

The ADS7822UB implements a capacitive redistribution SAR architecture on 0.6 µm CMOS, integrating sample-and-hold functionality. Its pseudo-differential input accepts +In and –In signals with absolute ranges of –0.2 V to VCC + 0.2 V and –0.2 V to +1.0 V respectively, enabling remote ground sensing.

Conversion is initiated by CS/SHDN falling edge; data transfers synchronously on DCLOCK falling edges, outputting 12-bit straight-binary MSB-first over DOUT. The device supports reference voltages from 50 mV to VCC and achieves 71 dB SINAD at 1 kHz with 2.5 V reference.

Key Specifications

Pinout & Package

ADS7822UB is supplied in an SO-8 package (package designator D), with gull-wing leads, 1.27 mm pitch, and JEDEC MS-012AC footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12-bit SAR ADC applications.

Compared with ADS7822U and ADS7822EC, the ADS7822UB uniquely balances ±1 LSB precision, SO-8 manufacturability, and proven field reliability in remote data acquisition - making it optimal for applications demanding both accuracy and ease of assembly.

Availability

ADS7822UB is available at Aetrix Electronics and suitable for battery-operated systems, isolated data acquisition, and remote sensor networks requiring stable component supply across extended production lifecycles.

Supply support for ADS7822UB 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 ADS7822UB belongs to TI's legacy precision SAR ADC family, engineered specifically for ultra-low-power, high-accuracy measurement in resource-constrained environments like portable instrumentation and distributed sensing.

FAQ

What is the guaranteed integral linearity error specification for ADS7822UB?

The ADS7822UB has a guaranteed integral linearity error of ±1 LSB over the full operating temperature range (–40°C to +85°C). This corresponds to ±0.024% of full-scale range when using a 2.5 V reference voltage, and is confirmed in the Electrical Characteristics table for the 'B' grade under both 2.7 V and 5 V supply conditions. The ADS7822UB datasheet explicitly lists this performance in the Ordering Information and Electrical Characteristics sections.

Does ADS7822UB support true differential input operation?

No, the ADS7822UB implements a pseudo-differential input architecture. Its –In pin is not independently resampled during conversion and is limited to –0.2 V to +1.0 V - it functions primarily as a remote ground reference rather than a full differential input. True differential operation (e.g., ±VREF swing) is not supported; the device is optimized for single-ended signals with common-mode rejection via the –In connection, as detailed in the Theory of Operation section of the ADS7822UB datasheet.

What is the minimum clock frequency required for ADS7822UB to maintain specified performance?

The ADS7822UB does not specify a minimum clock frequency for DCLOCK, but its conversion timing depends on clock period. At 2.7 V, the minimum high/low time is 400 ns (2.5 MHz max clock), and at 5 V, it is 125 ns (8 MHz max). The lowest usable sample rate is determined by leakage limits - typical operation starts at ~625 Hz (10 kHz clock), though the device remains functional down to DC. The Electrical Characteristics table confirms specifications at 7.5 kHz and 75 kHz sample rates, with quiescent current dropping to 20 µA at 7.5 kHz.

Can ADS7822UB operate with a 2.0 V supply voltage?

Yes, the ADS7822UB supports operation down to 2.0 V per the Absolute Maximum Ratings and Recommended Operating Conditions, but specified performance (e.g., 75 kHz throughput, ±1 LSB INL) is only guaranteed from 2.7 V to 5.25 V. At 2.0 V, the maximum sample rate drops significantly - Figure 6 in the datasheet shows usable throughput falls below 10 kHz, and timing parameters like tCONV may degrade. For reliable 75 kHz operation, 2.7 V minimum is required, as stated in the Electrical Characteristics tables.

How does the reference voltage affect noise performance in ADS7822UB?

Lower reference voltages increase the effective noise contribution in LSB terms: with a 2.5 V reference, internal noise is ~0.32 LSB peak-to-peak, but at 50 mV it rises to ~16 LSB due to fixed 33 µVrms noise floor. This is explicitly quantified in the Theory of Operation section, which states "the potential error contribution from the internal noise will be 50 times larger-16 LSBs" at 50 mV. Therefore, ADS7822UB noise-limited resolution degrades as VREF decreases, requiring averaging or filtering for low-VREF applications.