The AD7720 is a 7th-order sigma-delta modulator from Analog Devices that converts the analog input signal into a high-speed 1-bit data stream. The part operates from a +5V supply and accepts a differential input range of 0V to +2.5V or ±1.25V centered about a common-mode bias. The analog input is continuously sampled by the analog modulator, eliminating the need for external sample and hold circuitry. The input information is contained in the output stream as a density of ones. The original information can be reconstructed with an appropriate digital filter. The part provides an accurate on-chip 2.5V reference. A reference input/output function is provided, which allows either the internal or external reference to be used. The AD7720 is a low-power, low-noise, high-speed analog-to-digital converter suitable for a variety of applications.
The AD7720 sigma‑delta modulator converts analog signals to a high‑speed 1‑bit data stream. It operates from a +5 V supply, accepts differential inputs of 0 V to +2.5 V (or ±1.25 V) and includes an on‑chip 2.5 V reference. The device is offered in a 28‑lead TSSOP package and is rated for –40 °C to +85 °C operation.
Key features include a 12.5 MHz master clock, 16‑bit resolution, 90 dB dynamic range, and low‑power standby mode. Detailed pin functions, timing characteristics, and calibration procedures are provided for designers.
| Master Clock Frequency | 12.5 MHz |
|---|---|
| Input Range | 0 V to +2.5 V (unipolar) or ±1.25 V (bipolar) |
| Dynamic Range | 90 dB |
| Resolution | 16 Bits |
| Power Supply | AVDD/DVDD +5 V ±5 % |
| On‑chip Reference Voltage | 2.5 V |
The typical input sampling capacitance is 2 pF.
The maximum input voltage is limited to the AVDD supply voltage.