Texas Instruments ADS7825U/1K

Overview

ADS7825U/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 cycle time, ±2.0 LSB max INL, and 50mW max power dissipation at 40kHz throughput - used in industrial data acquisition systems requiring high-resolution multiplexed sensing.

For engineers reviewing the ADS7825U/1K datasheet, ADS7825U/1K pinout, ADS7825U/1K application, or ADS7825U/1K equivalent, key selection considerations include its SOIC-28 package, internal +2.5V reference, continuous conversion mode, and compatibility with microprocessor buses via BYTE-selectable parallel output or synchronous serial interface using SDATA/DATACLK.

Technical Context

The ADS7825U/1K integrates a 4-channel analog multiplexer, track-and-hold amplifier, 16-bit SAR ADC core, internal trimmed ±10V scaling resistors, and a programmable interface supporting both parallel (two-byte, MSB/LSB selectable) and serial (MSB-first, two's complement) output modes. Its CONTC pin enables automatic channel cycling without external sequencing logic.

It features dual reference operation (internal 2.5V ±0.25% or external 2.3–2.7V), PWRD pin for 50µW power-down state retention, and BUSY-driven timing control - allowing precise synchronization of data capture in real-time embedded systems operating across –40°C to +85°C.

Key Specifications

Pinout & Package

ADS7825U/1K is housed in a 28-pin SOIC (Package Number 217), 0.3" wide, with standard JEDEC outline 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 multiplexed ADC applications.

Compared with ADS8325IPW and MAX11620EUB+, the ADS7825U/1K uniquely combines ±10V bipolar input capability, internal 2.5V reference, parallel/serial dual interface, and hardware-controlled continuous conversion - making it optimal for legacy industrial controllers upgrading from 12-bit ADCs without changing firmware or layout.

Availability

ADS7825U/1K is available at Aetrix Electronics and suitable for industrial process monitoring, test equipment design, motor drive current sensing, and power quality analyzers requiring stable component supply and long-term obsolescence management.

Supply support for ADS7825U/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 signal conditioning and data conversion ICs for industrial and instrumentation markets.

The ADS7825U/1K belongs to Burr-Brown's legacy high-resolution sampling ADC product line, designed specifically for industrial data acquisition systems demanding ±10V input range, multi-channel multiplexing, and microprocessor-compatible digital interfaces.

FAQ

What is the maximum sampling rate supported by the ADS7825U/1K?

The ADS7825U/1K achieves a maximum throughput rate of 40kHz, corresponding to a 25µs maximum complete cycle (acquisition + conversion) time. This applies to single-channel operation; in continuous conversion mode, it cycles through all four channels at an effective 10kHz per channel. The device maintains full 16-bit accuracy and ±2.0 LSB INL within this specification across the full –40°C to +85°C temperature range.

Does the ADS7825U/1K require an external reference voltage?

No, the ADS7825U/1K includes an internal +2.5V reference with ±0.25% initial accuracy and ±5ppm/°C drift, sufficient for most industrial applications. However, it also supports external reference voltages between 2.3V and 2.7V when higher precision or custom full-scale ranges are required. When using the internal reference, a 2.2µF tantalum capacitor must be placed from REF to AGND2 to ensure stability and linearity performance.

How does the continuous conversion mode (CONTC) function on the ADS7825U/1K?

When CONTC is driven HIGH, the ADS7825U/1K automatically sequences through AIN0 to AIN3 in order, performing conversions continuously without external trigger pulses. The channel address pins A0 and A1 output the current active channel index. This mode eliminates host processor polling and reduces system latency - ideal for real-time monitoring applications where deterministic, jitter-free sampling across all four channels is required.

Can the ADS7825U/1K interface directly with a microcontroller using only parallel mode?

Yes, the ADS7825U/1K supports full parallel interface operation when PAR/SER is HIGH. Data is output on D0–D7 in two 8-bit bytes (MSB first), selected via the BYTE pin. BUSY's rising edge provides a natural latch signal for microcontrollers without dedicated strobes. The device is pin-compatible with the older ADS7824, allowing drop-in resolution upgrades in existing 8-bit or 12-bit parallel bus designs without layout changes.

What is the power consumption of the ADS7825U/1K in power-down mode?

In power-down mode (PWRD = HIGH), the ADS7825U/1K reduces total power dissipation to 50µW while retaining the last valid conversion result in its output register. All analog circuitry, including the reference buffer and sample-and-hold, is disabled. This ultra-low standby power enables use in battery-powered remote sensors or energy-harvesting systems where periodic wake-up and measurement are required.