Texas Instruments ADS7825UB/1K

Overview

ADS7825UB/1K from Burr-Brown (now Texas Instruments) is a 16-bit, 4-channel sampling analog-to-digital converter with ±10V input range, successive approximation architecture, and dual parallel/serial interface. It achieves 25µs max complete conversion cycle, ±2.0 LSB max INL, and 50mW max power dissipation at 40kHz throughput - deployed in industrial data acquisition systems requiring high-resolution multiplexed sensing.

For engineers reviewing the ADS7825UB/1K datasheet, ADS7825UB/1K pinout, ADS7825UB/1K application, or ADS7825UB/1K equivalent, key selection criteria include its SOIC-28 package, internal +2.5V reference, continuous conversion mode, bipolar input support, and compatibility with microprocessor buses via BYTE-selectable parallel output or synchronous serial interface.

Technical Context

The ADS7825UB/1K integrates a 4-channel analog multiplexer, track-and-hold amplifier, 16-bit SAR ADC core, internal trimmed ±10V scaling resistors (±0.1% channel-to-channel matching), and a programmable reference buffer. Its control logic supports both single-shot and continuous conversion modes, with CONTC pin enabling automatic cycling across AIN0–AIN3.

Digital interface flexibility is implemented via PAR/SER pin: when HIGH, it enables two-byte parallel output (MSB/LSB selectable via BYTE); when LOW, it activates serial mode with configurable clock source (internal DATACLK or external clock on same pin), plus SYNC pulse and TAG input for bidirectional timing coordination.

Key Specifications

Pinout & Package

ADS7825UB/1K is housed in a 28-pin SOIC (Package Number 217), 0.300" wide, RoHS-compliant, with standard JEDEC MS-012AC footprint and thermal resistance θ_JA = 75°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit SAR ADC applications.

Compared with ADS8325IPW and MAX1162BCAP+, the ADS7825UB/1K uniquely combines SOIC-28 packaging, pin-compatible 12-bit upgrade path, ±10V direct input, and dual parallel/serial interface - making it optimal for retrofitting legacy industrial controllers without layout changes.

Availability

ADS7825UB/1K is available at Aetrix Electronics and suitable for industrial process monitoring, test equipment design, motor drive feedback, and medical signal acquisition requiring stable component supply and long-term obsolescence management.

Supply support for ADS7825UB/1K 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

Burr-Brown Corporation, acquired by Texas Instruments in 2000, specialized in high-precision analog ICs including data converters, amplifiers, and references.

The ADS7825UB/1K belongs to Burr-Brown's industrial-grade SAR ADC product line, designed specifically for high-resolution, multiplexed data acquisition in harsh environments where accuracy, channel matching, and interface flexibility are critical.

FAQ

What is the maximum sampling rate supported by the ADS7825UB/1K?

The ADS7825UB/1K supports a maximum throughput rate of 40kHz, corresponding to a complete acquisition-and-conversion cycle of 25µs. This is achievable under specified conditions: TA = –40°C to +85°C, VS = +5V ±5%, and using either internal or external reference. At higher temperatures or with increased supply ripple, the effective rate may decrease due to timing margin reduction.

Does the ADS7825UB/1K require an external reference voltage?

No, the ADS7825UB/1K includes an internal +2.5V reference with ±0.25% full-scale error and ±5ppm/°C drift, sufficient for most industrial applications. However, REF pin can accept an external 2.3V–2.7V reference if higher initial accuracy or custom scaling is needed - in which case the internal reference is disabled and external buffering is mandatory to maintain linearity.

How does the continuous conversion mode work on the ADS7825UB/1K?

When CONTC = HIGH and CS/R/C remain LOW, the ADS7825UB/1K automatically cycles through AIN0 → AIN1 → AIN2 → AIN3 repeatedly, completing each 25µs conversion before advancing. Channel address pins A1/A0 output the active channel number, and BUSY pulses synchronously. This mode eliminates software polling overhead and ensures deterministic timing for cyclic sensor monitoring.

Can the ADS7825UB/1K interface directly with a 3.3V microcontroller?

The ADS7825UB/1K operates exclusively from a +5V supply (VS1/VS2), and its digital I/Os are 5V-tolerant with VIH ≥ +2.4V and VOL ≤ +0.4V. Direct connection to a 3.3V microcontroller is possible only if the MCU inputs accept 5V logic levels - otherwise, level-shifting circuitry is required on D0–D7, R/C, CS, and BUSY lines to prevent damage or misreads.

What is the purpose of the CAP pin on the ADS7825UB/1K?

The CAP pin on the ADS7825UB/1K is the output of the internal reference buffer and must be bypassed to AGND2 with a 2.2µF tantalum capacitor. This capacitor stabilizes the reference voltage during conversion, preventing noise-induced errors. Omitting or undersizing this capacitor degrades INL performance and increases reference drift - particularly during multiplexer switching transients.