Analog Devices Inc. AD7853LARZ

Overview

AD7853LARZ from Analog Devices is a 12-bit, 100 kSPS pseudo-differential successive-approximation ADC optimized for low-power operation on single 3 V to 5.5 V supply. It features on-chip 2.5 V reference, self- and system-calibration, flexible SPI/QSPI/μP-compatible serial interface, and 4.5 mW typical power dissipation at 3 V - enabling use in battery-powered medical instruments and portable data acquisition systems.

For engineers reviewing the AD7853LARZ datasheet, AD7853LARZ pinout, AD7853LARZ application, or AD7853LARZ equivalent, key selection considerations include its 100 kSPS throughput, ±1 LSB integral nonlinearity (B-grade), 0–VREF or ±VREF/2 input ranges, automatic power-down after conversion, and SOIC-24 package compatibility with legacy AD7853 designs requiring reduced power.

Technical Context

The AD7853LARZ implements a SAR architecture with integrated track-and-hold (500 ns acquisition time), internal 2.5 V reference (±20 ppm/°C tempco), and programmable analog input mode (AMODE) supporting unipolar (0 to VREF) or bipolar (±VREF/2) configurations. Calibration logic supports autocal on power-up via CAL pin capacitor timing.

Its serial interface operates in five modes (selected by SM1/SM2), supporting external clock (SCLK input) or self-clocking (SCLK output), with POLARITY pin controlling SCLK idle state. BUSY and CONVST signals coordinate conversion timing, while SLEEP enables full or partial power-down with calibration data retention.

Key Specifications

Pinout & Package

AD7853LARZ is housed in a 24-lead SOIC (R-24) package with standard 0.3-inch width, gull-wing leads, and JEDEC MS-013AC compliance. Thermal impedance θ_JA = 75°C/W supports operation up to +85°C ambient without forced airflow.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7853ARZ, AD7853LARZ trades half the throughput for 62% lower power and retains full calibration capability; versus ADS7822U, it offers integrated reference and system-calibration support at the cost of larger SOIC-24 footprint and higher unit price.

Availability

AD7853LARZ is available at Aetrix Electronics and suitable for battery-powered medical instrumentation, portable data loggers, and industrial signal conditioning requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for AD7853LARZ 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

Analog Devices, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.

The AD7853LARZ belongs to Analog Devices' precision SAR ADC product line, designed specifically for low-power, high-accuracy data acquisition in portable and energy-sensitive applications where calibration integrity and supply flexibility are critical.

FAQ

What is the maximum sampling rate of the AD7853LARZ?

The AD7853LARZ achieves a maximum sampling rate of 100 kSPS under specified conditions (1.8 MHz CLKIN, 3 V supply). This is fixed by its internal architecture - the AD7853L variant is explicitly rated for 100 kSPS, unlike the 200 kSPS AD7853. Conversion time is 4.6 µs (max) at 1.8 MHz clock, and the device requires ≥400 ns acquisition time before the next CONVST edge to maintain 12-bit accuracy. The AD7853LARZ datasheet confirms this performance across its –40°C to +85°C operating range.

Does the AD7853LARZ require an external reference voltage?

No, the AD7853LARZ does not require an external reference voltage because it integrates a 2.5 V reference accessible via the REFIN/REFOUT pin. This internal reference has a typical tempco of 20 ppm/°C and can be overdriven by an external source from 1.2 V to AVDD. When using the internal reference, external capacitors CREF1 (0.1 µF) and CREF2 (0.01 µF) must be connected to AGND per the pinout diagram. The AD7853LARZ remains fully functional with or without external reference override.

How does the AD7853LARZ handle power management during idle periods?

The AD7853LARZ supports three distinct power states: normal operation (4.5 mW @ 3 V), partial power-down (400 µA), and full power-down (5 µA with external clock disabled). Power state is controlled via the SLEEP pin and internal power management bits (PMGT1/PMGT0) in the control register. Calibration data is retained in all states. Full power-down disables the internal reference and stops all clocks, making it ideal for battery-operated systems with infrequent sampling intervals - a key design advantage of the AD7853LARZ over standard-speed variants.

Can the AD7853LARZ interface directly with an 8051 microcontroller?

Yes, the AD7853LARZ supports direct 8051-compatible serial communication through its flexible interface modes (selected by SM1/SM2 pins). In Mode 1, it operates with external SCLK and SYNC as chip-select, matching standard 8051 SPI timing requirements. The AD7853LARZ accepts 3 V or 5 V logic levels, and its DIN/DOUT pins are compatible with 8051 I/O drive strength. No level-shifting or protocol translation is needed - the AD7853LARZ datasheet explicitly lists "8051 compatible" as a feature and provides timing diagrams validated for that interface.

What analog input configurations does the AD7853LARZ support?

The AD7853LARZ supports two analog input configurations via the AMODE pin: unipolar (0 to VREF) when AMODE = 0, and bipolar (±VREF/2) when AMODE = 1. In unipolar mode, AIN(+) must remain ≥ AIN(–); in bipolar mode, AIN(–) must be biased to +VREF/2 to allow AIN(+) to swing from 0 V to +VREF. Both modes use pseudo-differential sampling, rejecting common-mode noise while accepting single-ended sources with proper biasing - a capability confirmed in the AD7853LARZ functional description and pin function table.