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Analog Devices Inc./Maxim Integrated DS21448L+
- Part No.:
- DS21448L+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Telecom
- Package:
- 128-LQFP
- Datasheet:
-
DS21448L+.pdf
- Description:
- IC TELECOM INTERFACE 128LQFP
- Quantity:
- Payment:
- Shipping:
Inventory:2,137
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Product details
Overview
DS21448L+ from Maxim Integrated is a quad-port E1/T1/J1 line interface unit (LIU) supporting simultaneous short-haul and long-haul trunk interfaces. It integrates four independent transceivers, 3.3V operation, software-selectable 75Ω/100Ω/120Ω receive termination, and G.703/G.704-compliant waveshaping for E1 and DSX-1/CSU build-outs for T1 - deployed in multiservice access platforms and central-office switches.
For engineers reviewing the DS21448L+ datasheet, DS21448L+ pinout, DS21448L+ application, or DS21448L+ equivalent, key selection criteria include quad-channel E1/T1 compliance, 128-pin LQFP package with hardware/serial/parallel interface flexibility, jitter attenuation without external crystal, and integrated PRBS generation/detection for loopback diagnostics.
Technical Context
The DS21448L+ implements four fully independent LIU channels, each with separate transmit drivers (supporting AMI/HDB3/B8ZS encoding) and receivers (with carrier loss detection per G.775), all synchronized to a single 2.048MHz or 1.544MHz master clock. Its internal 32-bit or 128-bit crystal-less jitter attenuator synthesizes 16.384MHz/8.192MHz/4.096MHz/2.048MHz backplane clocks referenced to recovered RCLK.
It supports three configurable bus interfaces - multiplexed/nonmultiplexed parallel (Intel/Motorola timing), serial (SPI-like), or hardware mode - with dedicated chip selects (CS1–CS4), JTAG boundary scan (IEEE 1149.1), and analog I/O pins (RTIP/RRING, TTIP/TRING) isolated via transformer-coupled 75Ω/120Ω line interfaces.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| E1/T1/J1 Support | Fully compliant with ITU G.703, G.704, G.775, ANSI T1.403-1999, T1.408, AT&T TR 62411, ETSI ETS 300 166 - enables drop-in deployment in global telecom infrastructure. |
| Line Build-Out | Software-selectable E1 outputs (75Ω/120Ω) and T1 DSX-1/CSU outputs (0dB, -7.5dB, -15dB, -22.5dB) - eliminates need for external passive components in line driver stage. |
| Jitter Attenuation | Crystal-less 32-bit or 128-bit PLL-based jitter attenuator using only 2.048MHz (E1) or 1.544MHz (T1) master clock - removes crystal oscillator BOM cost and layout complexity. |
| Receive Termination | Internal software-selectable termination: 75Ω, 100Ω, or 120Ω - simplifies board design across E1 (75Ω), T1 (100Ω), and J1 (120Ω) deployments without external resistors. |
| Diagnostic Features | Integrated PRBS generation/detection, in-band loop code (1–16 bits), remote/local/analog/dual loopbacks, and BPV/CV/EXZ error counting - enables full channel-level validation without external test equipment. |
| Interface Options | 8-bit parallel (Intel/Motorola, multiplexed/nonmultiplexed), 3-wire serial (SDI/SCLK/SDO), or hardware mode (fixed-function pins) - supports legacy and space-constrained system architectures. |
| Power Supply | Single 3.3V supply (all devices rated at 3.3V) - compatible with modern low-voltage telecom control planes and reduces power conversion overhead. |
Pinout & Package
The DS21448L+ is housed in a 128-pin LQFP package (56-G4011-001), RoHS-compliant and lead-free. Pin assignments are defined for parallel, serial, and hardware interface modes per Table 2-B and Section 11.2 of the datasheet.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RTIP1–RTIP4 / RRING1–RRING4 | Analog Receive Inputs | Differential bipolar inputs for E1/T1/J1 line signal recovery; require 1:1 isolation transformer and support internal 75Ω/100Ω/120Ω termination selection. |
| TTIP1–TTIP4 / TRING1–TRING4 | Analog Transmit Outputs | Differential bipolar outputs driving line transformers; support programmable line build-out levels per G.703 (E1) or DSX-1/CSU (T1). |
| RPOS1–RPOS4 / RNEG1–RNEG4 | Recovered Data Outputs | NRZ or bipolar data outputs synchronized to RCLK; RNEG pulses on BPV/CV/EXZ errors - enables real-time error monitoring in host processor. |
| RCLK1–RCLK4 | Recovered Clock Outputs | Buffered, jitter-cleaned clock derived from line signal - used as timing reference for backplane clock synthesis or downstream logic. |
| CS1–CS4 | Channel Select Inputs | Active-low chip selects enabling independent register access per LIU channel - allows concurrent configuration of all four ports. |
| BIS0/BIS1 | Bus Interface Mode Select | Two-pin configuration defining parallel (BIS0=0/1), serial (BIS1=1,BIS0=0), or hardware (BIS1=1,BIS0=1) operation - determines pin function mapping and eliminates mode strapping jumpers. |
Key Features
| Feature | Design Value |
|---|---|
| Quad Independent LIUs | Four fully isolated E1/T1/J1 transceivers sharing only power and clock domains - enables compact 4-channel line cards without inter-channel crosstalk or timing coupling. |
| Crystal-Less Jitter Attenuation | 32-bit or 128-bit digital PLL synthesizes stable backplane clocks (16.384MHz down to 2.048MHz) from MCLK alone - removes crystal, load caps, and associated PCB area. |
| Programmable Line Build-Out | On-chip DAC and filtering generate precise E1 pulse templates and T1 DSX-1/CSU outputs - eliminates discrete line driver ICs and calibration components. |
| JTAG Boundary Scan | Full IEEE 1149.1 test access port with instruction/data registers - enables production-level interconnect testing and fault isolation on dense telecom PCBs. |
| In-Band Loop Code Handling | Generates and detects 1–16-bit in-band loop codes including CSU-specific patterns - satisfies ANSI T1.403 and ITU G.775 remote loopback requirements without external logic. |
| Transmit Open-Circuit Detection | Monitors TTIP/TRING current and asserts fault flag on open-line condition - provides early warning of physical layer disconnect before service outage. |
Applications
| Integrated Multiservice Access Platforms | T1/E1 Cross-Connects |
|---|---|
Use Scenario: Aggregating legacy T1/E1 circuits into IP-based transport networks at edge aggregation points. IC Role / Device Role / Timing Role: DS21448L+ serves as the physical layer interface for four simultaneous T1/E1 lines, recovering clock and data while providing jitter-attenuated backplane clocks for packet processing ASICs. Use Value: Single-chip quad LIU reduces component count by 75% vs. discrete solutions and meets GR-474-CORE jitter accumulation limits for multi-hop transport. | Use Scenario: Reconfigurable digital cross-connect systems routing DS1/DS3 signals between central office switches and remote terminals. IC Role / Device Role / Timing Role: DS21448L+ acts as line-facing transceiver with programmable termination and loopback support, enabling automated provisioning and fault isolation per port. Use Value: Hardware-mode operation allows direct pin-controlled loopbacks and alarm injection - eliminating microcontroller dependency during maintenance and reducing firmware complexity. |
| Central-Office Switch Interfaces | Wireless Base Station Backhaul |
Use Scenario: Interfacing Class 5 switches and PBX systems to legacy TDM infrastructure in carrier-grade environments. IC Role / Device Role / Timing Role: DS21448L+ provides G.703-compliant E1 framing and AIS (Blue Alarm) generation/detection, synchronizing to network master clock via recovered RCLK. Use Value: Meets ITU G.823 wander and jitter transfer specifications - ensuring bit-error-rate stability over temperature and voltage variations in 24/7 switch environments. | Use Scenario: Connecting 2G/3G BTS controllers to E1-based microwave or fiber backhaul links in rural cell sites. IC Role / Device Role / Timing Role: DS21448L+ functions as framerless LIU, handling HDB3/AMI line coding and carrier loss detection (G.775) to trigger failover to backup links. Use Value: 50mARMS transmit current limiter and high-Z TRING/TTIP state prevent damage during hot-swap or lightning-induced surges - critical for unattended outdoor installations. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad E1/T1 line interface applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS21Q348+ | Same pinout and register map; adds quad T3/E3 capability and higher-speed backplane clock (32.768MHz); requires different transformer specs for T3/E3. | Targeted at next-generation muxes supporting T3/E3 alongside T1/E1; not suitable for cost-sensitive pure T1/E1 designs. | Select DS21Q348+ only if T3/E3 expansion is required; DS21448L+ remains optimal for dedicated quad T1/E1 line cards. |
| MC2288A | Triple-port T1/E1 LIU in 100-pin LQFP; lacks jitter attenuator, PRBS generator, and JTAG; uses external crystal for clock recovery. | Designed for lower-density applications where three ports suffice and jitter performance is less stringent (e.g., enterprise PBX). | Choose MC2288A for simpler, lower-cost 3-port designs; DS21448L+ is required when quad density, crystal-less jitter attenuation, or IEEE 1149.1 testability are mandatory. |
Compared with DS21Q348+, the DS21448L+ offers optimized cost and power for pure T1/E1 applications without T3/E3 overhead; versus MC2288A, it delivers higher port count, superior jitter performance, and built-in diagnostics - making it the preferred choice for carrier-class quad-line interface modules.
Availability
DS21448L+ is available at Aetrix Electronics and suitable for integrated multiservice access platforms, T1/E1 cross-connects, and central-office switch interfaces requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant manufacturing.
Supply support for DS21448L+ 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 communications, computing, and industrial markets.
The DS21448L+ belongs to Maxim's telecom line interface product line, engineered specifically for carrier-grade T1/E1/J1 physical layer interfacing with emphasis on jitter control, diagnostic completeness, and multi-standard compliance.
FAQ
What is the operating temperature range for the DS21448L+?
The DS21448L+ is specified for 0°C to +70°C ambient operation, as confirmed in the Ordering Information table. This commercial temperature grade suits indoor telecom equipment such as multiservice access platforms and enterprise routers. The DS21448L+ variant differs from the industrial-grade DS21448LN+ (-40°C to +85°C) and shares the same 128-pin LQFP RoHS-compliant package.
Does the DS21448L+ require an external crystal oscillator?
No, the DS21448L+ does not require an external crystal. Its integrated 32-bit or 128-bit crystal-less jitter attenuator synthesizes all necessary clocks - including 16.384MHz, 8.192MHz, 4.096MHz, and 2.048MHz backplane outputs - from a single 2.048MHz (E1) or 1.544MHz (T1) master clock applied to the MCLK pin. This eliminates crystal BOM cost and layout sensitivity, confirmed in the Features section and Block Diagram.
How many independent line interfaces does the DS21448L+ support?
The DS21448L+ supports four independent E1/T1/J1 line interfaces, each with dedicated transmit drivers, receivers, clock recovery, and diagnostic circuitry. This quad-port architecture is explicitly stated in the General Description and Features sections, and validated by the pin assignments for RTIP1–4, TTIP1–4, RCLK1–4, and CS1–4 - enabling true parallel operation without shared analog resources.
What line coding standards does the DS21448L+ support?
The DS21448L+ supports AMI, HDB3, and B8ZS line coding/decoding per channel, as documented in the Features list and Figure 1-2/1-3 block diagrams. These standards cover E1 (HDB3), T1 (B8ZS), and legacy T1 (AMI) applications. The device automatically adapts based on ETS bit configuration (CCR1.7), and all three codings are verified in the "DETAILED DESCRIPTION" and "PORT OPERATION" sections.
Can the DS21448L+ operate in hardware mode without a microcontroller?
Yes, the DS21448L+ supports hardware mode (BIS1=1, BIS0=1) where key functions - including loopback control, transmit enable, receive sensitivity, and internal termination - are configured directly via dedicated pins (e.g., EGL1–4, ETS, NRZE, SCLKE). This mode eliminates microcontroller dependency for basic provisioning and maintenance tasks, as detailed in Table 2-A and Section 4.1 "HARDWARE MODE".
DS21448L+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 128-LQFP
- Packaging:
- Tray
- Product Status:
- Obsolete
- Function:
- Line Interface Unit (LIU)
- Interface:
- -
- Number of Circuits:
- 4
- Voltage - Supply:
- 3.135V ~ 3.465V
- Current - Supply:
- 320mA
- Power (Watts):
- -
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 128-LQFP (14x20)
DS21448L+ FAQ
1.How can I place an order for DS21448L+ through Aetrix?
Please submit a Request for Quotation (RFQ) for DS21448L+ 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 DS21448L+ reliable?
The price and inventory of DS21448L+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS21448L+ is usually 5 days.
3.What payment methods are accepted for DS21448L+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS21448L+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS21448L+?
DS21448L+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS21448L+ 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 DS21448L+?
For technical support, including DS21448L+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS21448L+ requirements.
6.How does Aetrix verify that DS21448L+ is sourced from the original manufacturer or authorized distributors?
All DS21448L+ 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 DS21448L+ meets industry standards.
7.What is the process for return or replacement of DS21448L+?
All DS21448L+ units undergo pre-shipment inspection (PSI). If there is an issue with DS21448L+, 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 DS21448L+ part is unused and in its original packaging.
Return procedure for DS21448L+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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