Analog Devices Inc. AD7780BRZ

Overview

AD7780BRZ from Analog Devices is a 24-bit, ultralow power sigma-delta ADC optimized for bridge sensor front ends, featuring pin-programmable gain (1 or 128), dual update rates (10 Hz / 16.7 Hz), simultaneous 50 Hz/60 Hz rejection, and integrated bridge power-down switch - deployed in high-accuracy weigh scales and pressure transducers.

For engineers reviewing the AD7780BRZ datasheet, AD7780BRZ pinout, AD7780BRZ application, or AD7780BRZ equivalent, key selection considerations include its 115–500 μA supply current range, ±6 ppm INL, 17.1–19.4 bits peak-to-peak resolution, differential input architecture with internal PGA, and SOIC/TSSOP package compatibility for low-power industrial sensing.

Technical Context

The AD7780BRZ implements a single-channel, 24-bit sigma-delta modulator with on-chip programmable gain amplifier (PGA) and digital filter - all controlled via dedicated pins (GAIN, FILTER, PDRST). Its two-stage filter architecture delivers either fast settling (120 ms at 16.7 Hz) or high stop-band attenuation (>−45 dB at 10 Hz).

It uses an internal 64 kHz oscillator and supports ratiometric operation with unbuffered differential reference inputs (REFIN±). The analog input channel accepts ±VREF/gain differential signals, with absolute voltage limits dependent on gain and FILTER setting - enabling direct connection to strain gages and load cells without external amplification.

Key Specifications

Pinout & Package

AD7780BRZ is available in a 14-lead narrow-body SOIC package (suffix BRZ), with pin 1 marked by a notch or dot. All pins are electrically defined per Analog Devices Rev. A datasheet; NC pins must remain unconnected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS1232IPW and MAX11200EEE+, the AD7780BRZ uniquely integrates pin-controlled gain, dual filter modes, and a bridge power switch - reducing component count and firmware overhead in battery-powered weigh scale and pressure sensor designs.

Availability

AD7780BRZ is available at Aetrix Electronics and suitable for weigh scales, pressure transducers, and portable instrumentation requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.

Supply support for AD7780BRZ 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, serving industrial, automotive, communications, and healthcare markets since 1965.

The AD7780BRZ belongs to Analog Devices' precision sigma-delta ADC product line, designed specifically for low-power, high-resolution bridge sensor measurement in demanding industrial and portable applications.

FAQ

What is the maximum allowed analog input voltage range for AD7780BRZ at gain = 128?

The AD7780BRZ supports a differential input voltage range of ±VREF/gain. With gain = 128 and a 5 V reference, the full-scale range is ±39 mV. Absolute voltage limits depend on FILTER setting and AVDD: for FILTER = 0 and AVDD ≤ 3.6 V, AIN(+) and AIN(−) must stay within GND + 1.1 V to AVDD − 1.1 V. These constraints prevent degradation in linearity and noise performance - always verify common-mode voltage ≥ 0.5 V. The AD7780BRZ datasheet specifies these limits in Table 2 under "Absolute AIN Voltage Limits".

Does AD7780BRZ require an external crystal or clock source?

No, the AD7780BRZ includes an internal 64 kHz ±3% oscillator - eliminating need for external crystals, capacitors, or clock generators. This simplifies layout and reduces BOM cost. The internal clock drives the sigma-delta modulator and digital filter; no external timing components are required for basic operation. The AD7780BRZ uses this clock exclusively - it does not accept external clock inputs. Startup time is ~1 ms after PDRST goes high, as documented in the Timing Characteristics section.

How does the AD7780BRZ achieve simultaneous 50 Hz and 60 Hz rejection?

The AD7780BRZ achieves simultaneous 50 Hz and 60 Hz rejection through its fixed digital filter architecture - not software or external components. At both 10 Hz and 16.7 Hz update rates, the filter's notch characteristics inherently attenuate both frequencies: 72–90 dB rejection is guaranteed per Table 2. This hardware-based rejection occurs regardless of gain or reference voltage, and requires no configuration or calibration. The AD7780BRZ delivers this performance natively - making it ideal for global deployments where mains frequency varies.

Can AD7780BRZ operate with separate analog and digital supply voltages?

Yes, the AD7780BRZ features independent AVDD (analog supply, 2.7–5.25 V) and DVDD (digital interface supply, 2.7–5.25 V) pins. This allows AVDD to be set at 5 V for optimal sensor excitation while DVDD runs at 3 V to interface with low-voltage microcontrollers - without level shifters. Logic thresholds scale with DVDD, and the SCLK input includes Schmitt triggering for noise immunity. This separation is explicitly supported in the Power Requirements table and Pin Function Descriptions of the AD7780BRZ datasheet.

What happens to the DOUT/RDY pin during AD7780BRZ power-down mode?

When the PDRST pin is driven low, the AD7780BRZ enters power-down mode and the DOUT/RDY pin is actively tristated - meaning it disconnects from the bus and presents high impedance. This prevents bus contention in multi-device systems and eliminates leakage paths. The pin remains tristated until PDRST returns high and the internal oscillator stabilizes (~1 ms). During this time, no data is output, and the serial interface is reset. This behavior is confirmed in the "Power-Down/Reset (PDRST)" section and Pin Function Descriptions for the AD7780BRZ.