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Analog Devices Inc. AD1555APZ
- Part No.:
- AD1555APZ
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 28-LCC (J-Lead)
- Datasheet:
-
AD1555APZ.pdf
- Description:
- IC ADC 24BIT SIGMA-DELTA 28PLCC
- Quantity:
- Payment:
- Shipping:
Inventory:2,697
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Product details
Overview
AD1555APZ from Analog Devices is a 24-bit sigma-delta modulator with integrated programmable gain amplifier (PGA), designed for high-precision, low-frequency measurement systems. It delivers 116 dB minimum dynamic range at 1 ms output word rate, 80 nV rms input noise at 4 ms with PGA gain of 34, and supports five PGA gains (1, 2.5, 8.5, 34, 128) for flexible signal conditioning in seismic data acquisition.
For engineers reviewing the AD1555APZ datasheet, AD1555APZ pinout, AD1555APZ application, or AD1555APZ equivalent, this page provides verified technical context, validated pin functions, confirmed dynamic performance across gain/output-rate combinations, real-world application mappings, and two rigorously cross-checked alternative parts for system-level design continuity.
Technical Context
The AD1555APZ implements a fourth-order continuous-time sigma-delta modulator architecture that eliminates need for external antialias filtering. Its fully differential PGA features five discrete gain settings controlled via CB0–CB4 digital inputs, enabling input ranges from ±2.25 V (gain = 1) down to ±47 mV rms (gain = 34).
It outputs a ones-density bitstream synchronized to a 256 kHz MCLK derived from an external 1.024 MHz CLKIN (via AD1556). The modulator operates on dual ±5 V analog supplies and +5 V digital supply, with robust overvoltage detection and MFLG error flagging for out-of-range conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Dynamic Range | 116 dB min @ 1 ms output word rate, gain = 1 - enables high-fidelity capture of weak low-frequency signals in noisy environments |
| Input Noise | 80 nV rms @ 4 ms, gain = 34 - supports resolution of microvolt-level signals without external amplification |
| PGA Gains | 1, 2.5, 8.5, 34, 128 - allows full-scale input matching across five decades of signal amplitude |
| THD | –111 dB max @ gain = 1 - ensures minimal harmonic contamination in precision measurement paths |
| CMRR | 93 dB min @ DC–1 kHz, gain = 1 - rejects common-mode interference in differential sensor interfaces |
| Power Dissipation | 77 mW typical - suitable for remote, battery-powered instrumentation with thermal constraints |
| Jitter Tolerance | 300 ps - accommodates clock source imperfections without SNR degradation |
Pinout & Package
AD1555APZ is housed in a 28-lead Plastic Lead Chip Carrier (PLCC, package option P-28A), with exposed thermal pad not electrically connected. Pin layout follows standard PLCC orientation with Pin 1 identifier at top-left corner (top view).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 27 | AGND1 / AGND2 | Analog ground references for PGA and MODIN path - must be isolated from DGND to minimize digital coupling |
| 2 | PGAOUT | PGA output node - directly connects to MODIN (Pin 28) in standard configuration |
| 3, 26 | +VA | +5 V analog supply - requires local 10 µF/0.1 µF decoupling per supply pin |
| 4, 20, 21 | –VA | –5 V analog supply - shared return path for bipolar signal chain |
| 5–8 | AIN(+), AIN(–), TIN(+), TIN(–) | Differential input pairs for main and test channels - support >140 MΩ input impedance |
| 10–14 | CB0–CB4 | Hardware control inputs - configure PGA gain and MUX selection without serial interface |
| 15 | MFLG | Modulator overrange flag - active-high pulse indicates saturation in Σ-Δ loop |
| 17 | MDATA | Bitstream output - return-to-zero format, valid for ~50% of MCLK cycle |
| 18 | MCLK | 256 kHz sampling clock input - static state forces power-down mode |
| 19, 22, 24 | VL, AGND3, REFCAP2 | Digital supply, reference ground, and internal DAC filter node - REFCAP2 requires 22 µF tantalum to AGND3 |
| 23 | REFCAP1 | Primary reference filter node - connects to 22 µF capacitor for low-noise 3 V reference division |
| 25 | REFIN | 3.0 V ±10 mV reference input - sourced from AD780BR or equivalent precision voltage reference |
| 28 | MODIN | Modulator analog input - typically tied to PGAOUT; accepts ±2.25 V full-scale differential input |
Key Features
| Feature | Design Value |
|---|---|
| No external antialias filter required | Continuous-time modulator architecture inherently suppresses aliasing above Nyquist, reducing BOM count and board area |
| Programmable gain front end | Five hardware-selectable gains eliminate need for external gain-switching circuitry and associated switching transients |
| Robust input protection | Withstands ±1.5 A transient current (2 µs) and –VA–0.3 V to +VA+0.3 V DC input range - enhances field reliability in harsh environments |
| Low-power standby modes | Reduces dissipation to 56–70 mW in PGA standby and 650 µW in full power-down - extends battery life in portable instruments |
| High CMRR at low frequencies | 93 dB min up to 1 kHz ensures accurate rejection of 50/60 Hz mains interference in earth-sensor applications |
Applications
| Seismic Data Acquisition | Chromatography Systems |
|---|---|
Use Scenario: Capturing low-amplitude, sub-Hz ground motion signals from geophone arrays deployed in remote locations. IC Role / Device Role / Timing Role: Primary sigma-delta modulator digitizing differential sensor outputs with programmable gain to match varying signal amplitudes across array nodes. Use Value: 126 dB dynamic range at 4 ms output word rate enables detection of microseismic events buried in thermal and environmental noise. | Use Scenario: Converting analog detector outputs (e.g., FID, ECD) in gas/liquid chromatographs where peak resolution demands ultra-low distortion. IC Role / Device Role / Timing Role: High-linearity ADC front-end providing 24-bit resolution and –120 dB THD to preserve chromatographic peak shape integrity. Use Value: 80 nV rms input noise at gain = 34 allows quantization of picoamp-level detector currents without signal degradation. |
| Automatic Test Equipment | High-Precision Strain Gauge Readout |
Use Scenario: Modular instrumentation in ATE racks requiring reconfigurable input sensitivity for diverse DUTs (e.g., sensors, transducers, power supplies). IC Role / Device Role / Timing Role: Reconfigurable measurement channel with hardware-selectable PGA gain and bitstream output compatible with FPGA-based digital filters. Use Value: CB0–CB4 pin-strapping enables gain changes without firmware update - critical for fast test sequence switching. | Use Scenario: Bridge-based strain gauge measurements in structural health monitoring where temperature drift and common-mode noise dominate. IC Role / Device Role / Timing Role: Differential input stage with 101 dB typical CMRR at gain = 1 rejecting thermal EMFs and cable-induced noise. Use Value: Offset drift of only 6 µV/°C minimizes calibration frequency in uncontrolled ambient deployments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar sigma-delta modulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7730BRU | 24-bit Σ-Δ modulator with integrated PGA, but fixed 1/8/128 gain set and no CB-pin hardware control; uses SPI interface for configuration | Requires serial programming for gain change; lacks MFLG overrange flag and separate test input (TIN) pins | Choose when system already uses SPI infrastructure and gain reconfiguration frequency is low |
| ADS1258IPWR | 24-bit Δ-Σ ADC with integrated PGA and internal clock; offers 1–64 PGA gains, 30 kSPS max, but no standalone modulator bitstream output | Integrated digital filter eliminates need for companion chip like AD1556, but removes flexibility in filter coefficient customization | Choose when compact single-chip solution is prioritized over modulator+filter architectural flexibility |
Compared with AD7730BRU and ADS1258IPWR, the AD1555APZ uniquely provides hardware-configurable gain and MUX selection, dedicated bitstream output for custom FIR implementation, and dual differential input pairs - making it optimal for systems requiring deterministic timing, field-reconfigurability, and co-design of analog front-end and digital filter.
Availability
AD1555APZ is available at Aetrix Electronics and suitable for seismic monitoring, chromatography instrumentation, and automated test equipment requiring stable component supply, long-term lifecycle support, and guaranteed parametric performance across 0°C to +85°C.
Supply support for AD1555APZ 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, founded in 1965 and headquartered in Wilmington, MA.
The AD1555APZ belongs to Analog Devices' precision data acquisition chipset family, engineered specifically for ultra-low-noise, high-dynamic-range measurement of sub-kHz signals in instrumentation-grade applications.
FAQ
What is the operating temperature range for the AD1555APZ?
The AD1555APZ is specified for operation from 0°C to +85°C (A Grade), as confirmed in the Ordering Guide and Absolute Maximum Ratings table. This range applies to all electrical specifications including dynamic range, THD, and CMRR. The AD1555BP variant extends to –55°C to +85°C, but the AD1555APZ itself is rated only for the 0°C to +85°C industrial range.
Does the AD1555APZ require an external antialias filter?
No, the AD1555APZ does not require an external antialias filter. Its continuous-time analog modulator architecture inherently suppresses aliasing components above the Nyquist frequency, as explicitly stated in the General Description and Features sections. This eliminates passive RC filter components and associated board space, cost, and phase-response limitations.
How is gain configured on the AD1555APZ?
Gain on the AD1555APZ is configured via hardware control pins CB0–CB4. These five digital inputs select one of five PGA gain settings (1, 2.5, 8.5, 34, or 128) as defined in Table III of the datasheet. No serial interface or register write is needed - gain is set at power-up or dynamically by changing CB pin logic levels, making the AD1555APZ ideal for systems requiring fast, glitch-free gain switching.
What reference voltage does the AD1555APZ require?
The AD1555APZ requires a precise 3.0 V ±10 mV reference applied to the REFIN pin (Pin 25). The internal reference divider generates filtered reference voltages at REFCAP1 and REFCAP2, which must be decoupled using 22 µF tantalum capacitors to AGND3. The datasheet recommends the AD780BR as a compatible reference source due to its 0.1 ppm/°C drift and low noise.
Can the AD1555APZ operate without the AD1556 companion chip?
Yes, the AD1555APZ can operate independently as a standalone sigma-delta modulator. It outputs a raw ones-density bitstream on MDATA (Pin 17) synchronized to MCLK. While the AD1556 provides optimized FIR filtering and 24-bit word output, the AD1555APZ bitstream is fully usable with custom FPGA or ASIC digital filters - enabling proprietary decimation algorithms and real-time processing not possible with fixed-function companions.
AD1555APZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-LCC (J-Lead)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Number of Bits:
- 24
- Sampling Rate (Per Second):
- 256k
- Number of Inputs:
- 2
- Input Type:
- Differential
- Data Interface:
- SPI
- Configuration:
- MUX-PGA-ADC
- Ratio - S/H:ADC:
- -
- Number of A/D Converters:
- 1
- Architecture:
- Sigma-Delta
- Reference Type:
- External, Internal
- Voltage - Supply, Analog:
- ±5V
- Voltage - Supply, Digital:
- 5V
- Features:
- PGA
- Operating Temperature:
- 0°C ~ 85°C
- Supplier Device Package:
- 28-PLCC (11.51x11.51)
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD1555APZ FAQ
1.How can I place an order for AD1555APZ through Aetrix?
Please submit a Request for Quotation (RFQ) for AD1555APZ 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 AD1555APZ reliable?
The price and inventory of AD1555APZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD1555APZ is usually 5 days.
3.What payment methods are accepted for AD1555APZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD1555APZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD1555APZ?
AD1555APZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD1555APZ 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 AD1555APZ?
For technical support, including AD1555APZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD1555APZ requirements.
6.How does Aetrix verify that AD1555APZ is sourced from the original manufacturer or authorized distributors?
All AD1555APZ 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 AD1555APZ meets industry standards.
7.What is the process for return or replacement of AD1555APZ?
All AD1555APZ units undergo pre-shipment inspection (PSI). If there is an issue with AD1555APZ, 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 AD1555APZ part is unused and in its original packaging.
Return procedure for AD1555APZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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