AD1555/AD1556 is a 24-bit low noise analog-to-digital converter (ADC) with a low noise programmable gain amplifier (PGA). The device features a fourth-order oversampled sigma-delta (O-S) modulator, which provides a large dynamic range, low input noise, and low distortion. AD1555/AD1556 employs a common-mode voltage (VCM) input, supporting input ranges from -2.25 V to +2.25 V. AD1555/AD1556 is powered from a single supply of 2.5 V to 5 V.
The document describes the AD1555, a complete sigma-delta modulator combined with a programmable gain amplifier for low-frequency, high dynamic range measurement applications. It features a fourth-order S-Δ modulator with large dynamic range and low input noise, eliminating the need for an external antialias filter.
The AD1556 is a companion FIR digital filter/decimator that works with the AD1555 to realize a high-performance ADC. The datasheet provides detailed specifications for both devices, including AC and DC accuracy, dynamic range, timing parameters, and power supply requirements across various gain settings and operating conditions.
| Dynamic Range (Typical) | 120 dB @ 1 ms |
|---|---|
| Input Noise (Typical) | 80 nV rms @ 4 ms with Gain of 34,128 |
| Sampling Rate | 256 kSPS |
| PGA Gain Settings | 1, 2.5, 8.5, 34, 128 |
| Common-Mode Rejection Ratio (Typical) | 101 dB @ Gain of 1 |
| Power Dissipation (Typical) | 77 mW |
| AD1556 Output Word Rates | 250 SPS to 16 kSPS |
| AD1556 Power Dissipation (Typical) | 6.2 mW |
| Temperature Range (A Grade) | 0°C to 85°C |
No, the continuous-time analog modulator input architecture avoids the need for an external antialias filter.
The programmable gain front end offers settings of 1, 2.5, 8.5, 34, and 128.
The AD1556 has a typical low power dissipation of 6.2 mW.
The AD1555 achieves a typical dynamic range of 120 dB at 1 ms.