Analog Devices Inc. AD7789BRM

Overview

AD7789BRM from Analog Devices is a low-power, 24-bit sigma-delta analog-to-digital converter (ADC) with fully differential input, internal clock oscillator, and simultaneous 50 Hz/60 Hz rejection. It delivers 19-bit peak-to-peak resolution, 1.5 µV rms noise, ±15 ppm integral nonlinearity, and operates from 2.5 V to 5.25 V supply - optimized for precision sensor measurement in battery-powered instrumentation.

For engineers reviewing the AD7789BRM datasheet, AD7789BRM pinout, AD7789BRM application, or AD7789BRM equivalent, key selection criteria include its 16.6 Hz output update rate, 10-lead MSOP package, 3-wire SPI-compatible serial interface, VDD monitor channel, and guaranteed 24-bit no-missing-codes performance over −40°C to +105°C.

Technical Context

The AD7789BRM integrates a low-noise Σ-Δ modulator with on-chip digital filtering, enabling high-resolution DC and low-frequency AC signal acquisition without external clocking. Its internal oscillator fixes the output data rate at 16.6 Hz, ensuring inherent 50 Hz and 60 Hz line-frequency rejection without software post-processing.

It features a single unbuffered differential analog input (AIN(+) / AIN(−)), programmable unipolar/bipolar coding via the mode register, and dedicated VDD monitor channel that measures supply voltage (divided by 5) using an internal 1.17 V reference. All digital I/Os are Schmitt-triggered and compatible with 3 V or 5 V logic levels.

Key Specifications

Pinout & Package

AD7789BRM is housed in a 10-lead MSOP (3 mm × 3 mm) package with exposed pad for thermal enhancement. Pin functions are validated per Analog Devices Rev. C datasheet Figure 5 and Table 6.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar precision sigma-delta ADC applications.

Compared with AD7789BRM, AD7124-4BRUZ adds channel count and PGA at higher power and cost, while ADS124S08IPW trades off noise performance and rejection robustness for broader vendor availability and simpler supply requirements.

Availability

AD7789BRM is available at Aetrix Electronics and suitable for smart transmitters, battery-powered instrumentation, and precision temperature measurement systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for AD7789BRM 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 AD7789BRM belongs to Analog Devices' precision sigma-delta ADC product line, designed specifically for low-power, high-accuracy measurement of low-frequency industrial and scientific sensor signals.

FAQ

What is the guaranteed resolution and noise performance of the AD7789BRM?

The AD7789BRM guarantees 24-bit no-missing-codes operation with 19-bit peak-to-peak resolution and 1.5 µV rms noise (typical) at 16.6 Hz output rate. These values are specified over the full −40°C to +105°C temperature range and confirmed in the Rev. C datasheet Tables 1 and 9. The AD7789BRM achieves this using a low-noise Σ-Δ modulator and on-chip digital filtering, making it suitable for demanding applications such as weigh scales and RTD measurement where LSB stability is critical.

Does the AD7789BRM require an external clock source?

No, the AD7789BRM does not require an external clock source. It contains an internal clock oscillator that fixes the output data rate at 16.6 Hz, enabling simultaneous 50 Hz and 60 Hz rejection without external timing components. This feature is explicitly documented in the General Description section and functional block diagram of the AD7789BRM datasheet Rev. C, simplifying system design and reducing component count in space-constrained applications.

How does the VDD monitor function work in the AD7789BRM?

The AD7789BRM's VDD monitor channel measures the supply voltage by dividing VDD by 5 internally and applying the result to the modulator using a 1.17 V ±5% on-chip reference. This allows real-time monitoring of power rail health without external resistive dividers or dedicated ADC channels. The monitored value appears as a conversion result when CH1/CH0 = 11 in the communications register, and is detailed in the On-Chip Registers section of the AD7789BRM datasheet Rev. C.

What are the absolute maximum ratings for the AD7789BRM analog inputs?

The AD7789BRM analog input voltage range is specified as GND − 30 mV minimum and VDD + 30 mV maximum per Table 5 (Absolute Maximum Ratings) and Table 6 (Pin Descriptions) in the Rev. C datasheet. Exceeding these limits risks permanent damage. The device also specifies ±400 nA/V average input current and 90 dB minimum common-mode rejection at DC, confirming its suitability for direct connection to low-output-impedance sensor bridges when proper external protection is applied.

Is the AD7789BRM pin-compatible with the AD7788 series?

Yes, the AD7789BRM is pin-compatible with the AD7788 series, sharing identical 10-lead MSOP packaging and identical pin configuration (SCLK, CS, AIN(+), AIN(−), REFIN(+), REFIN(−), GND, VDD, DOUT/RDY, DIN) as shown in Figure 5 of the AD7788/AD7789 Rev. C datasheet. However, the AD7789BRM provides 24-bit resolution and 19-bit p-p performance versus the AD7788's 16-bit specification - both share the same timing, interface, and register structure, enabling drop-in upgrades in existing designs where higher resolution is needed.