Texas Instruments ADS7842E/1K

Overview

ADS7842E/1K from Texas Instruments is a 12-bit, 4-channel parallel-output SAR analog-to-digital converter with integrated sample-and-hold, 4-channel multiplexer, and 3-state parallel interface. It delivers ±2 LSB INL, 68 dB SINAD, and 200 kHz sampling rate at 5 V, operating from 2.7 V to 5.25 V supply. It is used in portable multichannel dataloggers requiring low power and precise multi-sensor acquisition.

For engineers reviewing the ADS7842E/1K datasheet, ADS7842E/1K pinout, ADS7842E/1K application, or ADS7842E/1K equivalent, key selection factors include its SSOP-28 package, 12-bit straight-binary parallel output, channel-select address logic (A0/A1), BUSY-driven read timing, and reference voltage scalability from 100 mV to VCC.

Technical Context

The ADS7842E/1K implements a capacitor-based successive approximation register (SAR) architecture with inherent sample-and-hold functionality. Its conversion process requires an external clock (0.2–3.2 MHz) and unbuffered reference input (100 mV to VCC), where LSB resolution scales linearly with VREF (e.g., 1.22 mV at 5 V, 610 µV at 2.5 V).

It uses CMOS-compatible digital I/O with active-low CS, WR, and RD controls, and supports power-down mode via A0/RD sequencing-reducing supply current from 550 µA to 3 µA at 5 V. Channel selection is latched on rising edges of WR or RD, and data is valid after BUSY transitions high.

Key Specifications

Pinout & Package

ADS7842E/1K is housed in a 28-pin SSOP (DB) package with 0.65 mm pitch, optimized for compact PCB layouts and automated assembly. Thermal and mechanical characteristics comply with JEDEC MO-153.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12-bit, 4-channel SAR ADC applications.

Compared with ADS7841E/1K and ADS8320EB/250, the ADS7842E/1K uniquely balances 12-bit precision, integrated 4-channel MUX, parallel interface, and sub-5 mW power-making it optimal for compact, multichannel, microcontroller-based acquisition where timing determinism and pin efficiency matter.

Availability

ADS7842E/1K is available at Aetrix Electronics and suitable for portable dataloggers, industrial process monitors, and medical patient monitors requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ADS7842E/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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and connectivity technologies, with decades of expertise in precision data converters and industrial-grade ICs.

The ADS7842E/1K belongs to TI's precision SAR ADC product line, designed specifically for low-power, multichannel data acquisition in portable and industrial instrumentation where integration, accuracy, and supply flexibility are critical.

FAQ

What is the maximum sampling rate of the ADS7842E/1K and what clock frequency is required?

The ADS7842E/1K achieves a maximum sampling rate of 200 kHz when operated at +5 V, requiring an external clock frequency of 3.2 MHz (fCLK = 16 × fSAMPLE). At +2.7 V, the maximum rate drops to 125 kHz with a 2 MHz clock. The ADS7842E/1K datasheet specifies minimum clock HIGH/LOW times of 150 ns and a minimum period of 300 ns to ensure reliable SAR bit decisions.

How does the reference voltage affect the LSB size and measurement accuracy of the ADS7842E/1K?

The LSB size of the ADS7842E/1K equals VREF / 4096-so at 5 V, LSB = 1.22 mV; at 2.5 V, LSB = 610 µV. While offset and gain errors remain constant in volts, their expression in LSBs increases as VREF decreases (e.g., a 1.22 mV offset becomes 2 LSBs at 5 V but 10 LSBs at 0.5 V). The ADS7842E/1K must therefore use clean, low-noise references at low VREF to maintain effective resolution.

Can the ADS7842E/1K perform automatic channel sequencing across AIN0–AIN3?

No-the ADS7842E/1K does not support automatic round-robin or continuous channel cycling. Channel selection is static per conversion and determined by the A0/A1 logic levels present at the falling edge of WR. To sequence channels, the host processor must update A0/A1 between WR assertions. The ADS7842E/1K relies on external control for multiplexer addressing rather than embedded sequencing logic.

What is the purpose of the BUSY pin on the ADS7842E/1K and how should it be used in system design?

The BUSY pin on the ADS7842E/1K is an active-low status signal that goes LOW at conversion start and returns HIGH upon completion-indicating when 12-bit parallel output data (DB0–DB11) is valid. It serves as a hardware-ready strobe: systems commonly tie BUSY to an interrupt input or use it to gate CS/RD activation. The ADS7842E/1K timing spec mandates holding CS/RD LOW for ≥25 ns after BUSY rises to ensure reliable data capture.

Does the ADS7842E/1K support power-down mode, and how is it activated?

Yes-the ADS7842E/1K supports a low-power shutdown mode drawing just 3 µA (typical). It is activated after conversion completion by asserting CS LOW, then raising RD HIGH while A0 is HIGH-a sequence defined in Table III of the ADS7842E/1K datasheet. To wake up, RD is pulsed HIGH again while A0 is LOW. This dual-role use of A0 eliminates the need for a dedicated power-down pin, preserving the SSOP-28 pin count.