Texas Instruments ADS7842EB

Overview

ADS7842EB from Texas Instruments is a 12-bit, 4-channel parallel-output SAR analog-to-digital converter with ±1 LSB INL/DNL, 72 dB SINAD, and 200 kHz sampling rate at 5 V. It integrates a sample-and-hold amplifier, 4-channel multiplexer, and 3-state parallel bus drivers - designed for precision data acquisition in battery-powered portable instrumentation.

For engineers reviewing the ADS7842EB datasheet, ADS7842EB pinout, ADS7842EB application, or ADS7842EB equivalent, key selection considerations include its SSOP-28 package, single-supply operation (2.7 V to 5 V), ±1 LSB linearity grade, power-down mode (3 µA), and straight-binary 12-bit parallel interface timing compatibility with microprocessor buses.

Technical Context

The ADS7842EB implements a capacitor-based successive approximation register (SAR) architecture with integrated sample-and-hold and 4-channel analog multiplexer. Its conversion process requires an external clock (0.2–3.2 MHz) and reference voltage (100 mV to V_CC), with BUSY output signaling completion and enabling synchronous latching of 12-bit parallel data.

It supports two operating modes: full-speed (200 kHz at 5 V, 125 kHz at 2.7 V) and low-power shutdown via RD/A0 control sequence. The device uses unbuffered reference input, making layout-sensitive performance dependent on clean V_REF, AGND/DGND separation, and local 0.1 µF ceramic bypassing at both supply and reference pins.

Key Specifications

Pinout & Package

ADS7842EB is housed in a 28-pin SSOP (DB) package with 0.65 mm pitch, JEDEC MO-153 compliant, moisture sensitivity level 2 (260°C peak reflow). Pin 1 is AIN0; pin 28 is VANA. Grounds are split into AGND (pin 6) and DGND (pin 14); supplies are VANA (pin 28) and VDIG (pin 27).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS7842EB, ADS7841EB sacrifices 4 bits of resolution and dynamic range for cost reduction, while ADS7822U replaces parallel timing control with SPI simplicity at the expense of deterministic read latency and bus resource usage.

Availability

ADS7842EB is available at Aetrix Electronics and suitable for portable data loggers, industrial sensor interfaces, and medical patient monitors requiring stable component supply and long-term production continuity.

Supply support for ADS7842EB 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, embedded processing, and high-reliability ICs for industrial, automotive, and medical markets.

The ADS7842EB belongs to TI's precision SAR ADC product line, engineered for high-accuracy, low-power data acquisition in portable and field-deployable instrumentation systems.

FAQ

What is the maximum sampling rate of the ADS7842EB and under what conditions?

The ADS7842EB achieves a maximum sampling rate of 200 kHz when operated at +5 V supply with a 3.2 MHz external clock (f_CLK = 16 × f_SAMPLE). At +2.7 V, the maximum rate drops to 125 kHz due to internal timing constraints. This rate defines the upper limit for sustained channel sequencing - e.g., 50 kHz per channel across all four inputs.

How does the ADS7842EB achieve ±1 LSB integral linearity, and is this guaranteed over temperature?

The ADS7842EB achieves ±1 LSB INL through laser-trimmed capacitor array matching and process-controlled SAR logic. This specification is guaranteed over the full –40°C to +85°C operating range per the Electrical Characteristics table, with typical drift of <±0.15 LSB across temperature as shown in Figure 7.

Can the ADS7842EB operate with a 2.7 V supply and still maintain full 12-bit performance?

Yes - the ADS7842EB is fully specified at 2.7 V, delivering 12-bit resolution, no missing codes, and 70 dB SINAD at 125 kHz sampling. Key parameters including ±1 LSB INL/DNL and 120 dB channel isolation remain valid, though reference voltage must be ≤2.7 V and clock frequency reduced to 2 MHz.

What is the function of the BUSY pin on the ADS7842EB, and how should it be used in system design?

The BUSY pin on the ADS7842EB is an open-drain status signal that goes LOW during conversion and rises HIGH when 12-bit output data is stable and valid on DB0–DB11. It must be used to synchronize read operations - typically as an interrupt source or gate signal for a latch - to avoid reading metastable or incomplete data.

Does the ADS7842EB require external components for stable operation, and which ones are mandatory?

Yes - the ADS7842EB requires mandatory external components: a 0.1 µF ceramic capacitor placed directly at the VREF pin, and separate 0.1 µF ceramics at VANA and VDIG pins. Additional 1–10 µF bulk capacitors with series resistors are recommended for noisy supplies. No external op-amp buffer is needed for VREF unless sub-100 µV noise is required.