Texas Instruments ADS7817PB

Overview

ADS7817PB from Texas Instruments is a 12-bit, 200kHz SAR analog-to-digital converter with fully differential high-impedance inputs, 2.3mW power consumption at full rate, ±2 LSB integral linearity, and operation over –40°C to +85°C. It uses an external reference (100mV–2.5V), supports bipolar input range, and delivers serial two's complement output via a 3-wire synchronous interface - ideal for transducer interfacing in battery-powered remote data acquisition systems.

For engineers reviewing the ADS7817PB datasheet, ADS7817PB pinout, ADS7817PB application, or ADS7817PB equivalent, key selection considerations include its differential input architecture, micro-power shutdown (3µA max), MSOP-8/SO-8/PDIP-8 package options, and reference-voltage-dependent resolution (49µV–1.22mV LSB).

Technical Context

The ADS7817PB implements a capacitive redistribution successive approximation register (SAR) architecture on a 0.6µm CMOS process, integrating sample-and-hold functionality. It requires an external clock (10kHz–3.2MHz), external reference, and single +5V supply - with conversion time fixed at 12 clock cycles and acquisition time of 1.5 clock cycles.

Its analog input accepts true differential signals (±VREF full-scale span) or single-ended configurations, with common-mode rejection >80dB and power supply rejection >82dB. The serial interface outputs 12-bit data MSB-first on DOUT synchronized to DCLOCK falling edges, with null-bit preamble and tri-state capability after transfer completion.

Key Specifications

Pinout & Package

ADS7817PB is housed in an 8-pin plastic DIP (PDIP-8) package with 0.3-inch width and through-hole mounting. Pin spacing is 0.1 inch, compatible with standard prototyping and legacy PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS7817PB, ADS7816PB trades half the sampling rate for reduced power and cost, while ADS8320EB doubles resolution at the expense of speed and increased susceptibility to reference noise - making ADS7817PB optimal for balanced performance in embedded industrial sensing.

Availability

ADS7817PB is available at Aetrix Electronics and suitable for transducer interface, battery-operated systems, and remote data acquisition requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for ADS7817PB 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 ADS7817PB belongs to TI's precision SAR ADC product line, engineered for high-fidelity signal acquisition in resource-constrained, battery-powered, and noise-sensitive applications - particularly where differential input, micro-power operation, and simple serial interfacing are essential.

FAQ

What is the maximum sampling rate supported by the ADS7817PB?

The ADS7817PB supports a maximum sampling rate of 200kHz, achieved with a 3.2MHz DCLOCK signal (16× oversampling). At this rate, conversion time is fixed at 12 clock cycles and acquisition time is 1.5 clock cycles. Lower rates reduce power consumption proportionally, with quiescent current dropping to 40µA at 12.5kHz sampling.

Does the ADS7817PB require an external reference, and what voltage range is supported?

Yes, the ADS7817PB requires an external reference applied to the VREF pin, supporting 100mV to 2.5V. This reference directly sets the full-scale input range (±VREF) and LSB size (e.g., 1.22mV at 2.5V, 49µV at 100mV). Reference current varies with sample rate and output code, reaching up to 25µA at 200kHz and positive full-scale output.

How does the ADS7817PB enter and exit power-down mode?

The ADS7817PB enters full power-down mode when the CS/SHDN pin is driven HIGH, reducing supply current to ≤3µA. Conversion initiates on the falling edge of CS/SHDN. After conversion completes, the device remains in low-power analog hold state until CS/SHDN is cycled; sustained LOW on CS/SHDN during idle periods prevents full shutdown and increases current draw.

What package type is used for the ADS7817PB, and is it pin-compatible with other ADS7817 variants?

The ADS7817PB uses an 8-pin plastic DIP (PDIP-8) package with 0.3-inch width. It shares identical pinout and electrical behavior with ADS7817P, ADS7817U, and ADS7817E variants - differing only in grade-specification (e.g., PB has ±2 LSB integral linearity vs. PC's ±1 LSB) and package form factor.

Can the ADS7817PB interface directly with a microcontroller's SPI port?

Yes, the ADS7817PB's 3-wire serial interface (CS/SHDN, DCLOCK, DOUT) is SPI-compatible in mode 0 (CPOL=0, CPHA=0), with data valid on DCLOCK falling edges. It outputs 12-bit two's complement data MSB-first after one null bit, requiring no additional framing or configuration - enabling direct connection to most MCU SPI peripherals with software-controlled CS timing.