Texas Instruments ADS7818EB/250G4

Overview

ADS7818EB/250G4 from Burr-Brown (now Texas Instruments) is a 12-bit successive approximation register (SAR) analog-to-digital converter with integrated sample/hold, internal 2.5V reference, and synchronous serial interface. It delivers 500kHz throughput at 11mW, supports differential input (0–5V range), operates from single +5V supply, and guarantees no missing codes across –40°C to +85°C. It is used in portable spectrum analyzers and battery-powered data loggers requiring high-speed, low-power digitization.

For engineers reviewing the ADS7818EB/250G4 datasheet, ADS7818EB/250G4 pinout, ADS7818EB/250G4 application, or ADS7818EB/250G4 equivalent, key selection considerations include its MSOP-8 package, 12-bit unipolar differential input architecture, 500kHz sampling rate, power-down mode (2.5mW), and compatibility with microcontroller SPI-like interfaces via CONV/CLK/data timing control.

Technical Context

The ADS7818EB/250G4 implements a capacitive redistribution SAR architecture fabricated in 0.6µm CMOS, enabling inherent sample/hold functionality without external components. Its conversion is clocked externally (200kHz–8MHz), with asynchronous CONV control allowing flexible timing relative to CLK - supporting both DSP-synchronous and microcontroller-triggered operation modes.

It features dual reference operation: internal 2.5V bandgap (±1 LSB integral linearity, ±1 LSB differential linearity) or overdrivable external reference (2.0V–2.55V). The VREF pin includes a 10kΩ series resistor (±30%) and requires 0.1µF ceramic + 2.2µF tantalum bypassing to suppress SAR-induced glitches and maintain SNR >72dB at 100kHz.

Key Specifications

Pinout & Package

ADS7818EB/250G4 is packaged in an MSOP-8 (3.0mm × 3.0mm, 0.65mm pitch) surface-mount package, optimized for space-constrained portable systems. Pin assignments are identical to the plastic DIP-8 variant but with reduced footprint and thermal resistance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS7818EB/250G4, ADS7816EB/250 offers lower power at reduced speed, while ADS8320EB/250 trades speed for resolution and adds SPI-native framing - neither is pin-compatible, but all three share MSOP-8 packaging and Burr-Brown's analog design heritage for consistent layout and decoupling practices.

Availability

ADS7818EB/250G4 is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered data acquisition, and wireless transceiver monitoring requiring stable component supply, long-term industrial temperature support (–40°C to +85°C), and MSOP-8 assembly compatibility.

Supply support for ADS7818EB/250G4 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

Burr-Brown Corporation, acquired by Texas Instruments in 2000, specialized in high-precision analog signal conditioning and data conversion ICs for industrial, medical, and test equipment markets.

The ADS7818EB/250G4 belongs to Burr-Brown's early-generation low-power SAR ADC product line, designed specifically for portable and remote measurement systems demanding high speed, small size, and single-supply operation without performance compromise.

FAQ

What is the guaranteed integral linearity error for ADS7818EB/250G4?

The ADS7818EB/250G4 guarantees ±1 LSB integral linearity error over the full –40°C to +85°C temperature range. This specification is confirmed in the Package/Ordering Information table for the EB grade and distinguishes it from the E grade (±2 LSB). The value reflects worst-case deviation from ideal transfer function and ensures monotonic 12-bit operation without code skips.

Does ADS7818EB/250G4 support external reference voltage, and what is the valid range?

Yes, ADS7818EB/250G4 supports external reference voltage applied to the VREF pin. The valid range is 2.0V to 2.55V, corresponding to an analog input full-scale span of 4.0V to 5.1V. This is enabled by an internal 10kΩ series resistor (±30% tolerance) connecting the external source to the internal 2.5V bandgap reference, allowing overdrive without damage.

What package type and dimensions does ADS7818EB/250G4 use?

ADS7818EB/250G4 uses the MSOP-8 package (Package Drawing 337), measuring 3.0mm × 3.0mm with 0.65mm lead pitch. It is a surface-mount, thermally enhanced variant of the classic 8-pin layout, offering identical pinout to the plastic DIP-8 version but with 70% smaller footprint and improved thermal performance for compact portable designs.

How does the power-down mode function in ADS7818EB/250G4, and what is its current draw?

ADS7818EB/250G4 enters power-down mode when CONV is held LOW during conversion and remains LOW at the start of the 13th clock cycle. In this state, supply current drops to 0.5mA (2.5mW at +5V), reducing total power by ~77% versus active 500kHz operation. The first conversion after wake-up is fully valid - no latency or initialization delay is incurred.

Can ADS7818EB/250G4 output data LSB-first, and how is it enabled?

Yes, ADS7818EB/250G4 supports LSB-first serial output. It is enabled by driving CONV HIGH during the 12th clock cycle and then LOW during the 13th clock cycle (while D0, the LSB, is being transmitted). This action simultaneously triggers LSB-first retransmission of all 12 bits and enters power-down mode - a documented timing sequence shown in Figure 5 of the datasheet.