Overview
The AD7781BRZ, produced by Analog Devices Inc., is a 20-bit, pin-programmable, ultralow power sigma-delta analog-to-digital converter (ADC). This device is particularly suited for low frequency measurement applications, such as bridge sensor systems, due to its low power consumption and high precision. The AD7781 operates with a power supply ranging from 2.7 V to 5.25 V and is available in a narrow body, 14-lead SOIC package and a 16-lead TSSOP package. It features an on-board clock, eliminating the need for an external clock, and includes a low noise instrumentation amplifier and an on-chip PGA with gain options of 1 or 128.
Key Specifications
| Parameter | Value |
|---|---|
| Resolution | 20 bits |
| Power Consumption | 330 μA |
| Power Supply | 2.7 V to 5.25 V |
| Output Data Rate | 10 Hz or 16.7 Hz |
| Gain Options | 1 or 128 |
| Input Range | ±VREF or ±VREF/128 |
| RMS Noise (at 10 Hz, gain 128) | 44 nV |
| Package Options | 14-lead SOIC, 16-lead TSSOP |
| Settling Time (at 10 Hz) | 300 ms |
| Settling Time (at 16.7 Hz) | 120 ms |
Key Features
- Low power consumption of 330 μA, making it suitable for battery-operated devices.
- Pin-programmable features for ease of use.
- On-board clock eliminates the need for an external clock.
- On-chip PGA with gain options of 1 or 128.
- Low noise instrumentation amplifier.
- Simultaneous 50 Hz/60 Hz rejection at both output data rates.
- Power-down mode to increase battery life.
- Eight status bits appended to the 20-bit conversion for data validity confirmation.
Applications
The AD7781 is primarily used in low frequency measurement applications such as:
- Bridge sensor systems.
- Load cell applications, where it can reject low frequency mechanical vibrations.
- Portable or battery-operated products requiring very low power consumption.
Q & A
- What is the resolution of the AD7781?
The AD7781 has a resolution of 20 bits.
- What are the power consumption and supply requirements of the AD7781?
The AD7781 consumes 330 μA and operates with a power supply ranging from 2.7 V to 5.25 V.
- What are the output data rates available for the AD7781?
The output data rates can be programmed to 10 Hz or 16.7 Hz.
- What gain options are available on the AD7781?
The AD7781 has gain options of 1 or 128.
- Does the AD7781 have an on-board clock?
Yes, the AD7781 has an on-board clock, eliminating the need for an external clock.
- What is the RMS noise at the 10 Hz update rate with a gain of 128?
The RMS noise is 44 nV at the 10 Hz update rate with a gain of 128.
- What package options are available for the AD7781?
The AD7781 is available in a 14-lead SOIC package and a 16-lead TSSOP package.
- Does the AD7781 support simultaneous 50 Hz/60 Hz rejection?
Yes, the AD7781 supports simultaneous 50 Hz/60 Hz rejection at both output data rates.
- How does the power-down mode of the AD7781 help in battery-operated devices?
The power-down mode allows the user to switch off the power to the bridge sensor and power down the AD7781 when not converting, thus increasing the battery life of the product.
- What additional information is provided with each data read from the AD7781?
Eight status bits are appended to the 20-bit conversion to confirm the validity of the serial transfer.
