Analog Devices Inc. AD7780BRUZ

Overview

AD7780BRUZ from Analog Devices is a 24-bit, pin-programmable, ultralow power sigma-delta ADC optimized for bridge sensor front ends. It integrates a low-noise PGA (gain = 1 or 128), internal clock oscillator, and bridge power-down switch. With 115 μA typical current at gain = 1 and simultaneous 50 Hz/60 Hz rejection, it enables high-precision weigh scale and pressure measurement in battery-powered systems.

For engineers reviewing the AD7780BRUZ datasheet, AD7780BRUZ pinout, AD7780BRUZ application, or AD7780BRUZ equivalent, key selection considerations include update rate (10 Hz or 16.7 Hz), RMS noise (44 nV at gain = 128, 10 Hz), p-p resolution (17.6 bits), settling time (300 ms at 10 Hz), and dual-supply operation (AVDD: 2.7–5.25 V, DVDD: 2.7–5.25 V).

Technical Context

The AD7780BRUZ implements a single-channel, differential-input sigma-delta modulator with on-chip digital filtering and two selectable filter responses-10 Hz (high stop-band attenuation >−45 dB) and 16.7 Hz (fast settling, 120 ms). Its pin-controlled architecture eliminates software configuration overhead, enabling direct hardware setup of gain, filter, power-down, and reset functions.

It features a read-only 2-wire serial interface with Schmitt-triggered SCLK, DOUT/RDY dual-function pin (data output + conversion-ready indicator), and status-bit appending (8 bits per 24-bit conversion). The integrated bridge power-down switch (RON ≤ 9 Ω, 30 mA rating) is controlled via PDRST and enables system-level power gating of load cells or strain gages.

Key Specifications

Pinout & Package

AD7780BRUZ is available in a 14-lead, narrow-body SOIC package (body width 3.9 mm). Pin assignments are identical between SOIC and TSSOP variants per Analog Devices Rev. A datasheet Figure 6 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 AD7190BRUZ and ADS124S08IPW, AD7780BRUZ uniquely combines sub-120 μA operation, pin-programmable 10/16.7 Hz filtering, and integrated bridge power switching-making it the only solution that delivers 24-bit precision in coin-cell-powered weigh scales without external support components.

Availability

AD7780BRUZ is available at Aetrix Electronics and suitable for weigh scales, pressure transducers, and portable instrumentation requiring stable component supply, long-term lifecycle assurance, and guaranteed traceability.

Supply support for AD7780BRUZ 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, founded in 1965 and headquartered in Wilmington, MA.

The AD7780BRUZ belongs to Analog Devices' precision sigma-delta ADC product line, engineered specifically for low-power, high-accuracy bridge sensor measurement in industrial and portable instrumentation.

FAQ

What is the maximum update rate of the AD7780BRUZ?

The AD7780BRUZ supports two fixed update rates: 10 Hz and 16.7 Hz. These are selected exclusively via the FILTER pin (high = 10 Hz, low = 16.7 Hz). No intermediate or programmable rates are available. At 16.7 Hz, the settling time is 120 ms; at 10 Hz, it is 300 ms. The AD7780BRUZ does not support software-configurable data rates or oversampling ratios beyond these two hardware-defined modes.

Does the AD7780BRUZ require an external crystal or clock source?

No, the AD7780BRUZ includes a fully integrated 64 kHz ±3% internal clock oscillator. This eliminates the need for external crystals, capacitors, or clock generators. The oscillator powers up automatically upon exit from power-down mode (PDRST high), requiring approximately 1 ms to stabilize before valid conversions begin. The AD7780BRUZ cannot accept or synchronize to an external clock.

Can the AD7780BRUZ interface directly with a 3.3 V microcontroller?

Yes-the AD7780BRUZ supports independent DVDD and AVDD supplies. DVDD can be set to 3.3 V to match standard microcontroller I/O levels, while AVDD may be 5 V for improved analog SNR. All digital pins (SCLK, DOUT/RDY, GAIN, FILTER, PDRST) are referenced to DVDD, and the Schmitt-triggered SCLK accepts 1.8 V logic-high thresholds at DVDD = 3 V. The AD7780BRUZ requires no level shifters when interfacing with 3.3 V MCUs.

What is the function of the BPDSW pin on the AD7780BRUZ?

The BPDSW pin is not an input-it is the drain terminal of an internal NMOS bridge power-down switch connected to GND. When PDRST is high, BPDSW closes (RON ≤ 9 Ω), completing the ground path for the bridge sensor. When PDRST is low, BPDSW opens, disconnecting the bridge from ground and halting current flow. This feature is intrinsic to the AD7780BRUZ and requires no external FET or driver circuitry.

How does the AD7780BRUZ achieve simultaneous 50 Hz and 60 Hz rejection?

The AD7780BRUZ achieves simultaneous 50 Hz and 60 Hz rejection through its fixed digital filter architecture, which places deep notches at both frequencies regardless of update rate. At 10 Hz update, rejection is 72–90 dB; at 16.7 Hz, it is 63–75 dB. This is inherent to the sigma-delta modulator's decimation filter design and requires no external components, calibration, or software configuration-the AD7780BRUZ delivers this performance automatically in all operating modes.