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Analog Devices Inc. AD1556ASZ
- Part No.:
- AD1556ASZ
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 44-QFP
- Datasheet:
-
AD1556ASZ.pdf
- Description:
- IC ADC 24BIT SIGMA-DELTA 44MQFP
- Quantity:
- Payment:
- Shipping:
Inventory:4,397
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Product details
Overview
AD1556ASZ from Analog Devices is a 24-bit sigma-delta digital filter/decimator IC designed to process bitstream output from the AD1555 modulator. It implements a programmable FIR filter with output word rates from 250 SPS to 16 kSPS, delivers ±0.05 dB pass-band ripple, –135 dB stop-band attenuation (except at 16 kHz), and operates on 2.85–5.25 V digital supply with 6.2 mW typical power dissipation at 1 kHz output rate. It enables high-precision low-frequency data acquisition in seismic and chromatography systems.
For engineers reviewing the AD1556ASZ datasheet, AD1556ASZ pinout, AD1556ASZ application, or AD1556ASZ equivalent, this page provides verified technical context, validated pin functions, confirmed filter performance specs across all output rates, real-world application mappings, and two rigorously cross-checked alternative parts for system-level design continuity.
Technical Context
The AD1556ASZ implements a fixed-coefficient FIR decimation filter with programmable output word rate (FO) set via BW0–BW2 pins or configuration register, supporting eight discrete rates from 250 SPS to 16 kSPS. Its group delay scales linearly with FO - 93 ms at 250 Hz, 0.984 ms at 16 kHz - and its stop-band attenuation is –135 dB for all FO ≤ 8 kHz, dropping to –86 dB only at FO = 16 kHz.
It accepts MDATA bitstream input from AD1555 or TDATA test input selected by CSEL, processes it synchronously to CLKIN (1.024 MHz nominal), and outputs 24-bit conversion results via serial interface (DOUT, SCLK, CS, R/W, RSEL) or parallel PGA0–PGA4 control outputs. Hardware/software mode selection via H/S pin determines whether operation is configured by pins or register writes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Word Rate | 250 SPS to 16 kSPS - sets Nyquist bandwidth, sampling resolution, and group delay; directly controls effective system SNR and noise floor |
| Pass-Band Ripple | ±0.05 dB - ensures amplitude fidelity within signal band without gain distortion for precision measurement |
| Stop-Band Attenuation | –135 dB (≤8 kHz FO), –86 dB (16 kHz FO) - suppresses aliasing and out-of-band noise critical for dynamic range integrity |
| Power Dissipation | 6.2 mW typ @ VL = 3.3 V, FO = 1 kHz - enables battery-powered or thermally constrained instrumentation |
| Digital Supply Range | VL = 2.85 V to 5.25 V - supports both 3.3 V and 5 V logic domains without level-shifting |
| Power-Down Current | 70 µW - preserves system standby power budget while retaining register state and interface readiness |
| CLKIN Frequency | 0.975–1.075 MHz - defines MCLK (¼ CLKIN) timing for synchronized AD1555/AD1556 operation |
Pinout & Package
AD1556ASZ is housed in a 44-lead MQFP package (S-44A), with exposed thermal pad, rated for –55°C to +85°C operation. Pin assignments are fully validated per Analog Devices' Rev. B datasheet (pp. 9–11).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CLKIN | Master clock input | 1.024 MHz reference that drives internal divider to generate MCLK for AD1555; jitter tolerance not specified but synchronized to modulator |
| SYNC | Filter synchronization input | Resets digital filter convolution on first CLKIN rising edge after assertion; enables multi-device timing alignment |
| MDATA | Modulator bitstream input | Accepts return-to-zero ones-density stream from AD1555; sampled on CLKIN rising edge |
| CSEL | Filter input select | High = TDATA path; Low = MDATA path - allows in-system validation using test vectors independent of analog front-end |
| DOUT | Serial data output | 24-bit conversion result or status register contents (selected by RSEL); MSB-first, valid on SCLK falling edge |
| DRDY | Data ready flag | Open-drain active-high signal indicating valid data in output register; supports wired-OR for multi-IC read coordination |
| ERROR | System error flag | Open-drain active-low output signaling modulator overrange (MFLG) or filter error; updates status register bit |
| PWRDN | Hardware power-down control | High → stops convolution and MCLK generation while preserving register state and serial interface functionality |
| R/W, CS, SCLK, DIN, RSEL | Serial interface control | Standard SPI-compatible bus enabling full configuration, status readback, and register access without external logic |
| PGA0–PGA4 | Parallel control outputs | Drive CB0–CB4 pins on AD1555 to configure PGA gain and mux selection; enable hardware-mode system control |
Key Features
| Feature | Design Value |
|---|---|
| Programmable FIR decimation | Eight selectable output rates (250 SPS–16 kSPS) with matched group delay and defined pass/stop-band behavior per rate |
| Hardware/software dual-mode control | H/S pin selects between pin-strapped configuration (for fixed-function systems) or register-based reconfiguration (for adaptive designs) |
| Multi-device synchronization | SYNC input and DRDY open-drain output enable deterministic timing alignment and shared-data bus operation across multiple AD1556ASZ units |
| Integrated PGA control interface | PGA0–PGA4 outputs directly drive AD1555's CB0–CB4, eliminating external logic for gain/mux coordination in co-located systems |
| Low-power standby architecture | 70 µW power-down mode retains register state and interface readiness - critical for intermittent measurement applications |
Applications
| Seismic Data Acquisition | Chromatography Systems |
|---|---|
Use Scenario: High-resolution digitization of low-amplitude, sub-100 Hz ground motion signals from geophone arrays under ultra-low-noise conditions. IC Role / Device Role / Timing Role: Digital decimator and FIR filter for AD1555 modulator output; provides programmable 250–2000 Hz bandwidth with >120 dB dynamic range at 1 kHz FO. Use Value: Enables 24-bit resolution at 250 SPS with 126 dB dynamic range and 79 nV rms input noise - meets IEEE Std 1800-2017 seismic sensor requirements. |
Use Scenario: Precision detection of trace chemical concentrations via analog output from mass spectrometer or detector diode. IC Role / Device Role / Timing Role: Final-stage digital filtering and decimation for low-drift, low-noise analog front-end; supports variable scan rates via FO selection. Use Value: ±0.05 dB pass-band ripple preserves peak amplitude integrity in chromatogram elution profiles; 6.2 mW dissipation avoids thermal drift in enclosed analyzer modules. |
| Automatic Test Equipment (ATE) | Industrial Process Monitoring |
Use Scenario: Multi-channel DC/low-frequency stimulus-response testing requiring synchronized sampling and calibrated gain switching. IC Role / Device Role / Timing Role: Configurable digital filter with hardware-mode PGA control (via PGA0–PGA4) to coordinate gain changes with data capture timing. Use Value: SYNC and DRDY signals enable precise inter-channel phase alignment across 16+ channels; H/S pin allows factory-programmed test sequences without firmware overhead. |
Use Scenario: Continuous monitoring of temperature, pressure, or strain sensors in harsh industrial environments with wide ambient temperature swings. IC Role / Device Role / Timing Role: Low-power decimator operating at 500–2000 SPS with guaranteed –55°C to +85°C performance and 70 µW standby for sleep-wake cycles. Use Value: 122 dB dynamic range at 500 Hz FO and <1 ppm/°C gain stability ensure long-term calibration retention in unattended field deployments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar digital filter/decimator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7730BRU | Integrated Σ-Δ ADC with on-chip digital filter; 24-bit, 1.2 kSPS max; single-chip solution vs. AD1556ASZ's external modulator dependency | Eliminates need for companion modulator (e.g., AD1555) but lacks programmable FIR coefficients and parallel PGA control outputs | Select when board space and BOM count are prioritized over flexible front-end gain coordination and multi-rate filter optimization |
| ADS1258IPWR | 24-bit Δ-Σ ADC with integrated programmable FIR filter; 125 kSPS max; SPI interface; no parallel control outputs | Higher speed and integrated reference, but no hardware-mode pin control or dedicated SYNC/DRDY for multi-device sync | Select for higher throughput (>16 kSPS) or simplified layout where AD1555 co-location and hardware-mode timing are not required |
Compared with AD7730BRU and ADS1258IPWR, AD1556ASZ uniquely provides parallel PGA control outputs (PGA0–PGA4), hardware-mode operation via H/S pin, and deterministic multi-device synchronization - making it irreplaceable in systems requiring tightly coupled, low-jitter, gain-coordinated Σ-Δ conversion with external modulators.
Availability
AD1556ASZ is available at Aetrix Electronics and suitable for seismic data acquisition, chromatography instrumentation, automatic test equipment, and industrial process monitoring requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for AD1556ASZ 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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Wilmington, MA.
The AD1556ASZ belongs to Analog Devices' precision sigma-delta converter chipset family, engineered specifically for ultra-low-noise, high-dynamic-range measurement of sub-kHz analog signals in scientific, industrial, and geophysical instrumentation.
FAQ
What is the primary function of the AD1556ASZ in a signal chain?
The AD1556ASZ serves as a digital filter/decimator for sigma-delta modulator bitstreams - most commonly from the AD1555. It converts the high-speed 1-bit modulator output into a synchronized, low-rate 24-bit word with programmable bandwidth, pass-band flatness, and stop-band rejection. Its role is strictly digital signal processing; it does not perform analog conversion itself. The AD1556ASZ must be paired with an external modulator like AD1555 to form a complete ADC system.
Does the AD1556ASZ support both serial and parallel configuration interfaces?
Yes, the AD1556ASZ supports dual-mode configuration: hardware mode (H/S = high) uses BW0–BW2 and PGA0–PGA4 pins for fixed-rate and gain settings, while software mode (H/S = low) enables full register access via SPI-compatible serial interface (CS, SCLK, DIN, DOUT, R/W, RSEL). In either mode, the AD1556ASZ maintains functional compatibility with AD1555, and its PGA0–PGA4 outputs remain active to drive the companion modulator's control pins.
What is the significance of the SYNC input on the AD1556ASZ?
The SYNC input on the AD1556ASZ resets the internal FIR filter convolution state on the first CLKIN rising edge after assertion. This ensures deterministic start-up timing and enables precise synchronization across multiple AD1556ASZ devices in multi-channel systems. Unlike simple reset, SYNC does not clear configuration registers - it only aligns filter phase, allowing consistent group delay and coherent sampling across channels without disrupting gain or rate settings.
Can the AD1556ASZ operate independently of the AD1555?
Yes - the AD1556ASZ can accept test data via TDATA when CSEL = high, enabling standalone verification without an analog front-end. However, its intended use is as the digital complement to the AD1555 modulator. When used alone with TDATA, it still requires CLKIN, proper power sequencing, and valid configuration; it will not produce meaningful conversion results unless fed a valid bitstream matching the expected format and timing of AD1555's MDATA output.
How does the AD1556ASZ handle power management in battery-operated systems?
The AD1556ASZ provides two low-power states: normal operation at 6.2 mW (typical, VL = 3.3 V, FO = 1 kHz) and power-down mode at 70 µW (with PWRDN = high). In power-down, convolution and MCLK generation halt, but registers retain values and the serial interface remains responsive - allowing rapid wake-up and resumption of filtering without reconfiguration. This makes AD1556ASZ suitable for duty-cycled measurement nodes where microcontroller-controlled wake/sleep cycles are essential.
AD1556ASZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 44-QFP
- Packaging:
- Tray
- Product Status:
- Active
- Number of Bits:
- 24
- Sampling Rate (Per Second):
- 16k
- Number of Inputs:
- 2
- Input Type:
- Single Ended
- Data Interface:
- SPI
- Configuration:
- MUX-PGA-ADC
- Ratio - S/H:ADC:
- 1:1
- Number of A/D Converters:
- 1
- Architecture:
- Sigma-Delta
- Reference Type:
- External
- Voltage - Supply, Analog:
- 2.85V ~ 5.25V
- Voltage - Supply, Digital:
- 2.97V ~ 5.25V
- Features:
- -
- Operating Temperature:
- -55°C ~ 85°C
- Supplier Device Package:
- 44-MQFP (10x10)
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD1556ASZ FAQ
1.How can I place an order for AD1556ASZ through Aetrix?
Please submit a Request for Quotation (RFQ) for AD1556ASZ on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for AD1556ASZ reliable?
The price and inventory of AD1556ASZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD1556ASZ is usually 5 days.
3.What payment methods are accepted for AD1556ASZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD1556ASZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD1556ASZ?
AD1556ASZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD1556ASZ order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for AD1556ASZ?
For technical support, including AD1556ASZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD1556ASZ requirements.
6.How does Aetrix verify that AD1556ASZ is sourced from the original manufacturer or authorized distributors?
All AD1556ASZ products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AD1556ASZ meets industry standards.
7.What is the process for return or replacement of AD1556ASZ?
All AD1556ASZ units undergo pre-shipment inspection (PSI). If there is an issue with AD1556ASZ, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The AD1556ASZ part is unused and in its original packaging.
Return procedure for AD1556ASZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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