Texas Instruments ADS7842E

Overview

ADS7842E from Texas Instruments is a 12-bit, 4-channel successive approximation register (SAR) analog-to-digital converter with parallel output, 200kHz maximum sampling rate at 5V, ±2 LSB integral nonlinearity, and SSOP-28 package. It integrates a sample-and-hold amplifier, 4-channel analog multiplexer, and 3-state parallel data bus-designed for portable multichannel dataloggers requiring low power and high accuracy.

For engineers reviewing the ADS7842E datasheet, ADS7842E pinout, ADS7842E application, or ADS7842E equivalent, this page delivers verified specifications, real-world timing behavior, validated alternative options, and precise interface guidance for embedded measurement systems operating from 2.7V to 5V.

Technical Context

The ADS7842E implements a capacitor-based SAR architecture with internal CDAC and unbuffered reference input, supporting external clock frequencies from 0.2MHz to 3.2MHz. Its conversion process requires exactly 12 clock cycles, with acquisition time of 1.5µs and aperture jitter under 100ps-enabling stable 12-bit resolution across –40°C to +85°C.

It uses straight binary coding, supports single-supply operation (2.7V–5.25V), and features dual ground separation (AGND/DGND), channel-to-channel isolation >100dB, and programmable power-down mode triggered via A0/RD handshake-no dedicated shutdown pin required.

Key Specifications

Pinout & Package

ADS7842E is housed in a 28-pin SSOP (DB) package with 0.65mm pitch, gull-wing leads, and moisture sensitivity level 2 (260°C peak reflow). Pin layout separates analog and digital sections to minimize coupling.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS7842E, ADS7841E offers more channels at lower speed and no power-down flexibility, while MAX11602EEE+ trades parallel simplicity for serial interface efficiency and reduced board area-neither is pin-compatible, but both serve overlapping measurement roles with distinct system-level trade-offs.

Availability

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

Supply support for ADS7842E 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 components for industrial, automotive, and medical markets.

The ADS7842E belongs to TI's precision SAR ADC product line, engineered for low-power, multi-channel data acquisition in battery-operated and field-deployable instrumentation where resolution, timing determinism, and supply flexibility are critical.

FAQ

What is the maximum sampling rate of the ADS7842E and what conditions must be met?

The ADS7842E achieves a maximum sampling rate of 200kHz when operated at +5V supply, with VREF = +5V and external clock frequency set to 3.2MHz (f_CLK = 16 × f_SAMPLE). At 2.7V supply, the maximum rate drops to 125kHz due to timing constraints. The ADS7842E datasheet specifies these limits under –40°C to +85°C, with proper bypassing and layout per SBAS103C Section 13.

Does the ADS7842E require an external reference, and what voltage range is supported?

Yes, the ADS7842E requires an external unbuffered reference applied to the VREF pin, supporting 0.1V to +VCC. With VREF = 5V, LSB size is 1.22mV; at VREF = 100mV, LSB shrinks to 24µV-though internal noise may cause code instability below ~200mV. The ADS7842E draws 13–40µA from the reference, varying with sample rate and conversion result.

How does the ADS7842E enter and exit power-down mode without a dedicated pin?

The ADS7842E uses A0 and RD pins for power management: after conversion completes (BUSY HIGH), hold CS LOW, then pulse RD HIGH while A0 = 1 to enter power-down (3µA typical current). To wake up, pulse RD HIGH again while A0 = 0. This sequence is defined in Table III of the ADS7842E datasheet and eliminates need for extra control lines in space-constrained designs.

What are the key layout recommendations for achieving specified ADS7842E performance?

TI recommends separate AGND/DGND traces routed to a single star point, 0.1µF ceramic bypass on VANA/VDIG/VREF, and avoidance of digital traces near analog inputs. The ADS7842E is sensitive to supply glitches during its 12-bit decision windows-so low-ESR bulk capacitors (1–10µF) with series resistors are advised. Layout guidelines are detailed in SBAS103C Section 13.

Is the ADS7842E pin-compatible with other members of the ADS784x family?

No-the ADS7842E is not pin-compatible with ADS7841E (8-channel) or ADS7843E (touch-screen controller), despite shared SSOP-28 packaging. Pin functions differ significantly: ADS7842E uses A0/A1 for channel selection and power-down, while ADS7843E repurposes those pins for touch coordinate conversion. Always verify pin mapping against the specific ADS7842E datasheet before substitution.