Texas Instruments ADS7822PC

Overview

ADS7822PC from Texas Instruments is a 12-bit, pseudo-differential SAR analog-to-digital converter with 0.75 LSB integral linearity error, 200 kHz maximum throughput at 5 V, and microPower operation (1.6 mW at full rate). It features a synchronous 3-wire serial interface (CS/SHDN, DCLOCK, DOUT), operates from 2.7 V to 5.25 V, and is packaged in an 8-pin plastic DIP for through-hole industrial sensor interfaces.

For engineers reviewing the ADS7822PC datasheet, ADS7822PC pinout, ADS7822PC application, or ADS7822PC equivalent, key selection considerations include its guaranteed ±0.75 LSB INL/DNL performance grade, power-down current ≤3 μA, pseudo-differential input architecture with user-defined reference (50 mV to V_CC), and compatibility with low-voltage microcontrollers via CMOS-level I/O.

Technical Context

The ADS7822PC implements a capacitive redistribution successive approximation register (SAR) architecture fabricated in 0.6 µm CMOS, integrating sample-and-hold functionality. Conversion is initiated by CS falling edge, with sampling occurring over 1.5–2.0 clock cycles and fixed 12-cycle conversion time.

Its pseudo-differential input accepts +In and –In signals where –In is referenced to remote ground (–0.2 V to +1.0 V range), enabling common-mode rejection in isolated or noisy environments. The serial output delivers straight-binary 12-bit data MSB-first on DOUT synchronized to DCLOCK falling edges, with no pipeline delay.

Key Specifications

Pinout & Package

ADS7822PC is housed in an 8-pin plastic DIP (dual in-line package) with 0.3-inch body width and through-hole mounting. Pin spacing is 0.1 inch, compatible with standard PCB layouts and socketing.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS7822U and ADS7822EB, the ADS7822PC provides the highest linearity grade in the DIP-8 package, making it uniquely suited for through-hole-based test equipment and calibration-sensitive instrumentation where traceable accuracy and mechanical serviceability are prioritized.

Availability

ADS7822PC is available at Aetrix Electronics and suitable for battery-operated systems, isolated data acquisition, and remote sensor nodes requiring stable component supply across extended product lifecycles.

Supply support for ADS7822PC 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 precision data converters and low-power design.

The ADS7822PC belongs to TI's legacy precision SAR ADC family, engineered specifically for ultra-low-power, high-accuracy measurement in portable and isolated industrial systems.

FAQ

What is the guaranteed integral linearity error specification for ADS7822PC?

The ADS7822PC guarantees ±0.75 LSB integral linearity error over the full operating temperature range (–40°C to +85°C), confirmed in the official TI SBAS062C datasheet ordering table. This performance grade is specific to the 'C' variant and distinguishes ADS7822PC from ADS7822P (±2 LSB) and ADS7822PB (±1 LSB). The value corresponds to <0.02% of full-scale range when using a 2.5 V reference.

Does ADS7822PC support true differential input operation?

No, ADS7822PC implements a pseudo-differential input architecture: it samples the voltage difference between +In and –In pins, but –In is not independently resampled and has a restricted voltage range (–0.2 V to +1.0 V). This configuration supports remote ground sensing and limited common-mode rejection, but does not provide full differential signaling like dedicated differential-input ADCs. The datasheet explicitly states that –In "is best used to sense a remote signal ground."

Can ADS7822PC operate from a 3.3 V supply while maintaining 200 kHz throughput?

No. ADS7822PC achieves 200 kHz maximum throughput only at V_CC = 4.75 V to 5.25 V, as specified in the Electrical Characteristics table for +V_CC = +5 V conditions. At 3.3 V, the maximum sample rate is 75 kHz (per +V_CC = +2.7 V characterization), due to internal timing constraints and reduced drive strength. Attempting 200 kHz operation at 3.3 V violates the recommended operating conditions and risks conversion errors.

How does the power-down mode function on ADS7822PC?

ADS7822PC enters full power-down mode when CS/SHDN is driven high, reducing supply current to ≤3 µA regardless of clock activity. This is distinct from the automatic post-conversion sleep state, where digital circuitry remains partially active. The datasheet confirms that shutdown current is "typically 50 nA" with CS high - a design feature enabling multi-year battery life in infrequently sampled systems. Pulling CS high is the sole method to achieve minimum quiescent current.

What is the purpose of the null bit in ADS7822PC's serial output format?

The ADS7822PC outputs a single null bit (logic low) immediately after CS falling edge and before the 12-bit data word begins. This null bit serves as a synchronization flag, indicating the start of valid conversion data on subsequent DCLOCK falling edges. As documented in the Digital Interface section and Figure 22, the null bit occupies the first clock period after CS activation, followed by B11 (MSB) on the second falling edge - ensuring unambiguous frame alignment for host controllers receiving the serial stream.