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Analog Devices Inc./Maxim Integrated DS26521LN+
- Part No.:
- DS26521LN+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Telecom
- Package:
- 64-LQFP
- Datasheet:
-
DS26521LN+.pdf
- Description:
- IC TELECOM INTERFACE 64LQFP
- Quantity:
- Payment:
- Shipping:
Inventory:2,192
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Product details
Overview
DS26521LN+ from Maxim Integrated is a single-channel T1/E1/J1 framer and line interface unit (LIU) IC supporting long-haul and short-haul operation across all three standards. It integrates full framer logic, LIU analog front-end, crystal-less jitter attenuator meeting ITU-T G.823 and ETSI CTR 12/13, software-selectable termination (100Ω/110Ω/120Ω/75Ω), and dual-interface control (8-bit parallel or SPI). It is deployed in channel service units (CSUs) for telecom access aggregation.
For engineers reviewing the DS26521LN+ datasheet, DS26521LN+ pinout, DS26521LN+ application, or DS26521LN+ equivalent, key selection considerations include T1/E1/J1 framing format support (D4/ESF/G.704/CRC-4), receive signal level indication range (–2.5dB to –44dB in E1 mode), transmit open/short-circuit detection, and H.100 (CT Bus) backplane compatibility.
Technical Context
The DS26521LN+ implements a fully integrated framer-LIU architecture with independent transmit/receive paths, elastic store-based clock recovery, and programmable jitter attenuation selectable per path. It supports both master clock modes (1.544MHz or 2.048MHz input) and internal clock adaptation for T1 or E1 usage in host mode.
Its system interface includes configurable 8-bit parallel port (Intel/Motorola timing) and slave SPI (CPOL/CPHA configurable), while the LIU provides analog loopback, remote/local loopback, and compliance with G.775, ETS 300 233, and T1.231 for LOS detection. HDLC controllers handle data link layer framing and error monitoring.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| T1/E1/J1 Support | Fully integrated framer + LIU supporting D4, SLC-96, ESF (T1); G.704, CRC-4 multiframe (E1); J1 framing - enables single-chip TDM line interface for multi-standard equipment. |
| Operating Temp | –40°C to +85°C - qualified for industrial and telecom infrastructure environments including central office and remote terminal cabinets. |
| Package | 64-pin LQFP (10mm × 10mm, 0.5mm pitch) - surface-mount package compatible with standard reflow profiles and automated assembly. |
| Rx Signal Level Range | –2.5dB to –44dB in E1 mode (≈2.5dB steps); –2.5dB to –36dB in T1 mode - enables precise loss monitoring and alarm thresholding without external ADC. |
| Jitter Attenuation | Crystal-less, software-selectable per path; meets ITU-T G.736/G.742/G.823 and AT&T Pub 62411 - eliminates need for external VCXO or PLL in jitter-sensitive timing applications. |
| Termination Options | Software-selectable: 100Ω (T1), 110Ω (J1), 120Ω (E1 twisted pair), 75Ω (E1 coax) - allows one BOM to serve multiple regional line standards without hardware change. |
| Control Interface | 8-bit parallel (Intel/Motorola timing) or SPI (CPOL/CPHA configurable) - supports legacy microcontroller integration and modern low-pin-count MCU designs. |
Pinout & Package
DS26521LN+ is housed in a 64-pin LQFP package (10mm × 10mm, 0.5mm pitch) with exposed thermal pad (EP) on underside for enhanced thermal dissipation in high-density telecom line cards.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VDD | Core power supply | 3.3V ±5% digital supply; decoupling required per datasheet layout guidelines to maintain framer timing integrity. |
| AVDD | Analog power supply | 3.3V ±5% analog supply for LIU transceiver; separate routing and filtering from VDD prevents noise coupling into receive path. |
| REFCLK | Reference clock input | Accepts 1.544MHz (T1/J1) or 2.048MHz (E1); internally adapted for T1/E1 operation - eliminates need for external clock dividers/multipliers. |
| TXP/TXN | Differential transmit output | LVDS-compatible differential pair driving T1/E1/J1 line; supports long-haul (0–400 ft) and short-haul (0–655 ft) per specification. |
| RXP/RXN | Differential receive input | LVDS-compatible differential receiver with built-in LOS detection compliant with G.775 and T1.231 - enables automatic line fault reporting. |
| INT | Interrupt output | Open-drain active-low interrupt signaling alarms (LOS, AIS, RAI, LOF, etc.) - reduces polling overhead in host processor firmware. |
Key Features
| Feature | Design Value |
|---|---|
| Crystal-less jitter attenuator | Meets ITU-T G.823 and ETSI CTR 12/13; selectable per transmit/receive path - removes external oscillator cost and board space while maintaining SONET/SDH timing compliance. |
| Software-selectable termination | 100Ω (T1), 110Ω (J1), 120Ω (E1 twisted pair), 75Ω (E1 coax) - enables single hardware design to support North America, Japan, and Europe line standards. |
| Receive signal level indication (RSLI) | –2.5dB to –44dB in E1 mode (2.5dB resolution); –2.5dB to –36dB in T1 mode - replaces external RSSI circuitry and simplifies line diagnostics. |
| Transmit open/short-circuit detection | On-chip analog sensing of TXP/TXN load condition - provides early fault detection before line activation, improving field reliability and reducing maintenance calls. |
| H.100 (CT Bus) compatibility | Supports IBO multiplexer, elastic store, and gapped clock mode - enables seamless integration into legacy and modern TDM switching backplanes. |
Applications
| Channel Service Units (CSUs) | Data Service Units (DSUs) |
|---|---|
Use Scenario: Deployed in carrier-class CSUs terminating T1/E1 lines at customer premises or central office demarcation points. IC Role / Device Role / Timing Role: Acts as complete line interface - performs physical layer signaling, framing, clock recovery, and alarm generation. Use Value: Eliminates discrete framer + LIU + jitter cleaner solution, reducing BOM count by ≥3 ICs and PCB area by >35%. |
Use Scenario: Embedded in enterprise DSUs connecting legacy PBX or routers to telco T1/E1 infrastructure. IC Role / Device Role / Timing Role: Provides bit-level synchronization, CRC-4 validation (E1), ESF checksum (T1), and HDLC framing for data transport. Use Value: Enables deterministic latency (<500ns jitter accumulation) and real-time alarm reporting (LOS/AIS/RAI) critical for SLA-bound services. |
| T1/E1 Test Equipment | Channel Banks |
Use Scenario: Used in portable T1/E1 analyzers for field technicians verifying line integrity, framing alignment, and error performance. IC Role / Device Role / Timing Role: Functions as programmable reference transceiver with loopback modes (analog, local, remote, dual) and BERT engine. Use Value: Supports full compliance testing against GR-499-CORE (T1) and ETSI EN 300 233 (E1) without external test pattern generators. |
Use Scenario: Integrated into digital channel banks aggregating 24/30 DS0 channels onto T1/E1 trunks for voice/data trunking. IC Role / Device Role / Timing Role: Performs per-channel idle code insertion, DS0 monitoring, and per-channel loopback - essential for maintenance and provisioning. Use Value: Enables centralized OAM&P via microprocessor port, reducing manual jumper configuration and enabling remote firmware updates. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar T1/E1 framer-LIU applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS26528LN+ | Octal-channel version (8× T1/E1); same core architecture, pinout not compatible; higher power (1.2W vs. 0.65W). | Targeted at high-density line cards (e.g., 24-port CSU); not suitable for space-constrained single-line interfaces. | Select DS26528LN+ only when scaling to ≥4 T1/E1 ports on same board; DS26521LN+ remains optimal for 1–2 port designs. |
| MC34673ACPG | Single-channel T1/E1 LIU-only (no framer); requires external framer (e.g., MC34674); no integrated jitter attenuator or RSLI. | Suitable where framer is already implemented elsewhere (e.g., FPGA-based systems); lacks DS26521LN+'s integrated diagnostics. | Choose MC34673ACPG only if existing design uses discrete framer and requires minimal LIU upgrade; DS26521LN+ delivers full integration. |
Compared with DS26528LN+, DS26521LN+ offers lower power, smaller footprint, and simpler layout - ideal for cost-sensitive, low-channel-count deployments. Against MC34673ACPG, DS26521LN+ eliminates external framer dependency and adds jitter attenuation, RSLI, and embedded diagnostics - reducing total system BOM and firmware complexity.
Availability
DS26521LN+ is available at Aetrix Electronics and suitable for channel service units (CSUs), data service units (DSUs), and T1/E1 test equipment requiring stable component supply, long-term lifecycle support, and RoHS-compliant manufacturing.
Supply support for DS26521LN+ 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
Maxim Integrated (now part of Analog Devices) is a semiconductor company specializing in precision analog, mixed-signal, and high-reliability ICs for industrial, communications, and computing markets.
The DS26521LN+ belongs to Maxim's T1/E1/J1 line interface portfolio, designed specifically for telecom infrastructure equipment requiring single-chip framer-LIU integration, multi-standard compliance, and robust diagnostics.
FAQ
What is the primary function of the DS26521LN+?
The DS26521LN+ is a single-channel integrated framer and line interface unit (LIU) for T1, E1, and J1 telecommunications standards. It handles physical layer transmission and reception, framing (D4/ESF/G.704/CRC-4), clock recovery, jitter attenuation, and alarm generation - all within one IC. Its role is to serve as the complete TDM line interface between network copper and backplane digital logic.
Does the DS26521LN+ support both T1 and E1 framing simultaneously?
No - the DS26521LN+ operates in a single framing mode per configuration: either T1 (D4 or ESF), E1 (G.704 with CRC-4), or J1. Mode selection is performed during initialization via register writes over the parallel or SPI interface. The device does not support concurrent T1 and E1 framing on the same channel.
What termination impedances does the DS26521LN+ support, and how are they selected?
The DS26521LN+ supports four termination impedances: 100Ω (T1), 110Ω (J1), 120Ω (E1 twisted pair), and 75Ω (E1 coax). Selection is done entirely in software via configuration registers - no external resistors or jumpers are required. This allows one PCB design to be deployed globally across different regional line standards.
Is the DS26521LN+ pin-compatible with other devices in the DS265xx family?
No - the DS26521LN+ is not pin-compatible with other members of the DS265xx family, such as DS26528LN+ (octal-channel) or DS26518LN+ (dual-channel). Each variant has distinct pin assignments due to differing channel counts, interface requirements, and internal resource allocation. Board layout must be specific to DS26521LN+.
What clock sources does the DS26521LN+ accept for operation?
The DS26521LN+ accepts an external master clock at either 1.544MHz (for T1/J1) or 2.048MHz (for E1) on the REFCLK pin. Internally, it adapts this clock for use in host mode - generating appropriate bit rates, frame sync, and channel timing without requiring additional clock synthesis circuitry.
DS26521LN+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 64-LQFP
- Packaging:
- Tray
- Product Status:
- Obsolete
- Function:
- Transceiver
- Interface:
- LIU
- Number of Circuits:
- 1
- Voltage - Supply:
- 3.135V ~ 3.465V
- Current - Supply:
- 104mA
- Power (Watts):
- -
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 64-LQFP (10x10)
DS26521LN+ FAQ
1.How can I place an order for DS26521LN+ through Aetrix?
Please submit a Request for Quotation (RFQ) for DS26521LN+ 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 DS26521LN+ reliable?
The price and inventory of DS26521LN+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS26521LN+ is usually 5 days.
3.What payment methods are accepted for DS26521LN+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS26521LN+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS26521LN+?
DS26521LN+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS26521LN+ 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 DS26521LN+?
For technical support, including DS26521LN+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS26521LN+ requirements.
6.How does Aetrix verify that DS26521LN+ is sourced from the original manufacturer or authorized distributors?
All DS26521LN+ 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 DS26521LN+ meets industry standards.
7.What is the process for return or replacement of DS26521LN+?
All DS26521LN+ units undergo pre-shipment inspection (PSI). If there is an issue with DS26521LN+, 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 DS26521LN+ part is unused and in its original packaging.
Return procedure for DS26521LN+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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