Texas Instruments ADS802U

Overview

ADS802U from Texas Instruments is a monolithic 12-bit, 10MHz pipeline analog-to-digital converter with internal reference, wideband track-and-hold (65MHz full-power bandwidth), single +5V supply operation, and differential or single-ended input support - used in high-fidelity video digitizing, CCD imaging, and IF/baseband data acquisition systems.

For engineers reviewing the ADS802U datasheet, ADS802U pinout, ADS802U application, or ADS802U equivalent, key selection considerations include its 6.5-clock-cycle latency, SO-28 package compatibility, TTL/HCT-compatible 3-state outputs, ±0.4 LSB differential linearity at 5MHz, and internal 1.25V/3.25V reference structure enabling precise full-scale range control.

Technical Context

The ADS802U implements a 11-stage pipelined architecture with 2-bit quantizers per stage and digital error correction to guarantee no missing codes and ±0.4 LSB DNL across 0°C to +85°C. Its fully differential track-and-hold accepts either AC-coupled transformer-driven or DC-coupled op-amp-driven inputs centered at +2.25V common-mode voltage.

Conversion timing is synchronized to a 50% duty cycle CMOS clock with ≤2ns rise/fall time; aperture jitter is 7ps rms and aperture delay is 2ns. Output coding is selectable between Straight Offset Binary (SOB) and Binary Two's Complement (BTC) via MSBI pin, while OE enables 3-state output control with 20ns enable/10ns disable times.

Key Specifications

Pinout & Package

ADS802U is housed in a 28-pin SOIC (SO-28) package with exposed pad not present; thermal resistance θ_JA = 75°C/W. Pin layout supports dual ground planes (pins 1, 14, 25, 28), triple +5V supply connections (pins 15, 17, 20, 24), and dedicated reference bypassing (REFB, REFT, CM).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS802U, ADS803U offers double the sampling rate at the cost of higher power and thermal load, while MAX1186BCUI+ trades internal reference simplicity for LVDS noise immunity and 3.3V compatibility - neither is pin-compatible, making ADS802U the optimal choice for existing +5V, SO-28-based video/imaging platforms requiring proven thermal and reference stability.

Availability

ADS802U is available at Aetrix Electronics and suitable for IF/baseband digitization, CCD imaging, and test instrumentation requiring stable component supply across extended temperature ranges (–40°C to +85°C) and long-lifecycle industrial deployments.

Supply support for ADS802U 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 high-performance data converters and signal chain solutions.

The ADS802U belongs to TI's precision high-speed ADC product line, designed specifically for demanding imaging, video, and communications applications where low distortion, guaranteed monotonicity, and internal reference integration are critical.

FAQ

What is the maximum recommended clock jitter for ADS802U to maintain specified SNR?

The ADS802U datasheet specifies 7ps rms aperture jitter at +25°C. To preserve the rated 65dB SNR at 500kHz input, total clock jitter (including source and distribution path) must remain ≤5ps rms. Exceeding this degrades SFDR by up to 12dB and reduces effective ENOB below 10.5 bits. For reliable operation, use low-jitter clock generators like TI's CDCE72010 or equivalent with sub-2ps additive jitter.

Can ADS802U operate with a single-ended input configuration, and what is the resulting full-scale range?

Yes, ADS802U supports single-ended input by tying the IN pin to the CM pin (+2.25V). In this mode, the full-scale input range becomes +0.25V to +4.25V (4Vp-p), referenced to internal +1.25V/3.25V rails. However, even-order harmonic distortion increases significantly above 1MHz, so this configuration is best suited for time-domain applications like pulse capture rather than high-fidelity video or telecom signals.

What is the purpose of the MSBI pin on ADS802U, and how does it affect output data format?

The MSBI (Most Significant Bit Inversion) pin on ADS802U controls output coding format: when pulled LOW or left floating (internal pull-down), ADS802U outputs Straight Offset Binary (SOB), where +FS = 111111111111. When driven HIGH, ADS802U outputs Binary Two's Complement (BTC), where +FS = 011111111111 and –FS = 100000000000. This allows seamless interface with both legacy SOB-based logic and modern DSP/FPGA cores expecting signed two's complement data.

How does the ADS802U handle reference voltage bypassing, and what capacitor values are recommended?

ADS802U exposes REFB (+1.25V), REFT (+3.25V), and CM (+2.25V) pins for external bypassing. TI recommends 0.1µF X7R ceramic capacitors placed within 2mm of each pin to ground, as shown in Figure 9 of SBAS039B. These capacitors stabilize the internal reference ladder against dynamic current transients during conversion cycles, preventing gain error drift and DNL degradation - omitting them causes >0.5% gain error variation over temperature.

What is the data latency of ADS802U, and how does it impact system timing synchronization?

The ADS802U has a fixed data latency of 6.5 clock cycles from CLK falling edge to valid output data. At 10MSPS, this equals 650ns - a deterministic delay critical for time-aligned multi-channel sampling or FPGA-based timestamping. System designers must account for this latency in clock domain crossing logic and buffer depth calculations; it cannot be reduced via configuration or external control.