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Analog Devices Inc./Maxim Integrated DS21Q42TN
- Part No.:
- DS21Q42TN
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Telecom
- Package:
- 128-LQFP
- Datasheet:
-
DS21Q42TN.pdf
- Description:
- IC TELECOM INTERFACE 128LQFP
- Quantity:
- Payment:
- Shipping:
Inventory:239
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Product details
Overview
DS21Q42TN from Maxim Integrated is a quad T1 framer IC designed for telecom line interface units and channelized T1 access equipment. It integrates four fully independent T1 framers supporting D4, ESF, and SLC-96 framing, 8-bit parallel control port (Intel/Motorola compatible), 3.3V supply with 5V-tolerant I/O, and IEEE 1149.1 JTAG boundary scan. It enables carrier-grade T1 aggregation in industrial temperature (-40°C to +85°C) base station backplanes.
For engineers reviewing the DS21Q42TN datasheet, DS21Q42TN pinout, DS21Q42TN application, or DS21Q42TN equivalent, key selection considerations include per-framer elastic store slip buffer support up to 8.192 MHz, independent transmit/receive clock domains, HDLC controller with 64-byte buffers configurable for FDL/DS0, in-band loop code generation/detection (1–8 bits), and ANSI T1.403-1995 / ITU G.704 compliance.
Technical Context
The DS21Q42TN implements four autonomous T1 framing transceivers, each with dedicated receive framer, receive elastic store, transmit formatter, and transmit elastic store - no shared framing synchronizer. Each framer supports dual two-frame elastic stores for asynchronous backplane interfacing at up to 8.192 MHz, enabling phase/frequency tolerance between recovered T1 data and system clocks.
Its 8-bit parallel control port operates natively on multiplexed or nonmultiplexed buses (Intel/Motorola), while its integral HDLC controller handles both transmit and receive paths with 64-byte buffers, configurable for Facility Data Link (FDL) or DS0 channel access. The device also provides hardware signaling re-insertion, signaling freezing, and interrupt-on-signaling-change capability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Framing Standards | ANSI T1.403-1995, T1.231-1993, ITU G.704/G.706, AT&T TR 62411 & TR54016 - ensures full interoperability with North American and international T1 infrastructure. |
| Number of Framers | Four fully independent T1 framers - enables simultaneous processing of four T1 lines without resource contention or cross-framer timing coupling. |
| Elastic Store Clock Support | Up to 8.192 MHz burst-capable RSYSCLK/TSYSCLK - allows connection to high-speed asynchronous backplanes without external clock domain crossing logic. |
| Control Interface | 8-bit parallel port, multiplexed/nonmultiplexed, Intel/Motorola bus compatible - eliminates need for glue logic or protocol translation in microprocessor-based line cards. |
| Supply & I/O | 3.3V core supply with 5V-tolerant I/O - simplifies mixed-voltage board design and interfaces directly with legacy 5V logic without level shifters. |
| Temperature Range | -40°C to +85°C - qualified for deployment in outdoor cabinets, remote radio units, and industrial telecom environments. |
| HDLC Buffer Size | 64-byte transmit and receive buffers - supports full FDL frame handling and DS0-level packetized data transport without host CPU overhead. |
Pinout & Package
DS21Q42TN is housed in a 128-pin Thin Quad Flat Package (TQFP) with 0.4 mm pitch, optimized for high-density telecom PCB layouts and thermal dissipation in fanless line card applications.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RCLK0–RCLK3 | Receive Clock Inputs | Four independent 1.544 MHz inputs - enable simultaneous acquisition of four T1 data streams with separate clock recovery domains. |
| TCLK0–TCLK3 | Transmit Clock Inputs | Four independent 1.544 MHz transmit timing references - allow independent T1 line synchronization without master/slave dependency. |
| RLINK0–RLINK3 | Receive Link Data Outputs | Output FDL (ESF) or Fs-bit (D4) data one RCLK before frame start - provides direct access to embedded signaling for processor-based or hardware-based extraction. |
| TLINK0–TLINK3 | Transmit Link Data Inputs | Accept FDL/FS/Z-bit insertion data synchronized to TCLK - enables dynamic per-channel signaling updates without reconfiguring entire multiframe. |
| RSYSCLK0–RSYSCLK3 / TSYSCLK0–TSYSCLK3 | Elastic Store System Clocks | Independent 1.544/2.048 MHz or burst-mode (≤8.192 MHz) clocks - absorb frequency/phase misalignment between T1 links and backplane clocks without data loss. |
| INT* | Alarm Interrupt Output | Active-low open-drain interrupt aggregating RCL, RLOS, RRA, RAIS, and AIS-CI alarms across all four framers - reduces host polling and accelerates fault response. |
| FS0/FS1, CS*, RD*, WR*, MUX, BTS | Parallel Port Control | Enable framer-select decoding, chip select, read/write strobes, and bus topology configuration - supports seamless integration with ARM, PowerPC, or FPGA host controllers. |
| JTMS, JTDO, JTDI, JTCLK, JTRST | JTAG Boundary Scan | IEEE 1149.1-compliant test access port - enables in-system verification of interconnect integrity and framer I/O functionality during manufacturing and field diagnostics. |
Key Features
| Feature | Design Value |
|---|---|
| Per-framer dual elastic stores | Enables independent asynchronous backplane interfacing per T1 link - eliminates need for external FIFOs or clock-domain-crossing logic in multi-T1 systems. |
| Programmable output clocks for Fractional T1 | Supports 384 kbps, 768 kbps, and ISDN-PRI service provisioning via software-configurable clock dividers - avoids discrete clock generator components. |
| Integral HDLC controller (64-byte buffers) | Handles full FDL frames or DS0 channel payloads in hardware - offloads CPU from bit-level HDLC framing and CRC computation. |
| In-band loop code generation/detection (1–8 bits) | Supports CSU loopback testing and in-service diagnostics without external pattern generators - reduces test equipment dependency in field maintenance. |
| Signaling freezing & interrupt-on-change | Preserves signaling state during host latency and triggers interrupt on any signaling bit transition - enables real-time SS7 or CAS monitoring with minimal CPU intervention. |
| Pin compatibility with DS21Q44 | Allows migration path from T1 to E1 infrastructure using same PCB layout - lowers redesign cost when upgrading to E1-based networks. |
Applications
| Remote Terminal Unit (RTU) | Cellular Base Station Abis Interface |
|---|---|
Use Scenario: Aggregating multiple T1 lines from legacy PBX and analog trunk gateways into a centralized DSLAM or MSAN. IC Role / Device Role / Timing Role: T1 line interface framer providing D4/ESF framing, robbed-bit signaling extraction, and alarm monitoring for each T1 span. Use Value: Enables deterministic T1 signal recovery and low-latency alarm reporting (RLOS, AIS, RAI) across four concurrent lines - critical for SLA-compliant service assurance. | Use Scenario: Connecting GSM BSC to multiple BTS sites over T1 backhaul with embedded OAM signaling. IC Role / Device Role / Timing Role: Framing and HDLC processing engine for Abis interface, handling LAPD frames and FDL-based OAM channels. Use Value: Hardware-accelerated 64-byte HDLC buffering and per-channel loopback support reduce host processor load and accelerate BTS commissioning and troubleshooting. |
| ISDN-PRI Access Gateway | Digital Loop Carrier (DLC) Remote Node |
Use Scenario: Supporting 23B+D PRI services for enterprise SIP trunking gateways requiring T1 physical layer termination. IC Role / Device Role / Timing Role: T1 framer with programmable fractional clock outputs and per-channel signaling insertion for B-channel mapping. Use Value: Fractional T1 clock synthesis and hardware-based signaling insertion eliminate external clock synthesizers and reduce component count by ≥3 ICs per T1 line. | Use Scenario: Deploying subscriber loop carrier nodes in rural exchanges where environmental temperature swings exceed commercial grade limits. IC Role / Device Role / Timing Role: Industrial-temperature quad T1 framer performing SLC-96 framing, CRC6 checking, and yellow/blue alarm detection. Use Value: -40°C to +85°C qualification and ANSI one's density enforcer ensure reliable operation in uncontrolled outdoor cabinets - extends field lifetime beyond 10 years. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar quad T1 framer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS21Q42T | Identical functionality and pinout, but rated for 0°C to +70°C commercial temperature range only. | Suitable for indoor, climate-controlled central office or enterprise equipment where ambient temperature remains stable. | Select DS21Q42T only if operating environment stays within 0°C–70°C; DS21Q42TN required for outdoor, mobile, or industrial deployments. |
| DS21Q44TN | E1-focused quad framer supporting ITU G.704 E1 framing (2.048 Mbps), not T1; includes enhanced E1-specific features like CRC4 generation/checking. | Designed for European/Asian E1 infrastructure; incompatible with T1 line rates, framing, or signaling formats. | Choose DS21Q44TN only when migrating to E1-based networks; not a functional substitute for T1 applications. |
Compared with DS21Q42T, DS21Q42TN adds extended temperature qualification without sacrificing performance or feature set; compared with DS21Q44TN, it maintains full T1 protocol stack compliance but lacks E1-specific capabilities - making DS21Q42TN the sole fit for ruggedized quad-T1 line interface designs.
Availability
DS21Q42TN is available at Aetrix Electronics and suitable for telecom infrastructure, wireless backhaul, and industrial communications requiring stable component supply, long-term lifecycle assurance, and extended temperature reliability.
Supply support for DS21Q42TN 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 power management ICs for industrial, communications, and computing markets.
The DS21Q42TN belongs to Maxim's telecom line interface product line, engineered specifically for carrier-class T1/E1 framer applications in base stations, remote terminals, and access gateways demanding high reliability and standards compliance.
FAQ
What is the operating temperature range of the DS21Q42TN?
The DS21Q42TN is specified for industrial temperature operation from -40°C to +85°C. This rating is confirmed in the Ordering Information section of the official Maxim datasheet (revision 062602), where DS21Q42TN explicitly denotes the extended temperature grade. It is validated for use in outdoor cabinets, remote radio units, and other thermally demanding telecom environments where commercial-grade parts would fail.
Does the DS21Q42TN support both D4 and ESF framing formats?
Yes, the DS21Q42TN supports D4 (Superframe), ESF (Extended Superframe), and SLC-96 framing formats across all four framers. This is explicitly stated in the FEATURES section (page 2) and FUNCTIONAL DESCRIPTION (page 3) of the datasheet. Each framer independently configures its framing mode, enabling mixed-format operation - for example, two framers in ESF and two in D4 - without hardware or timing conflict.
Is the DS21Q42TN pin-compatible with the DS21Q44 E1 framer?
Yes, the DS21Q42TN is pin-compatible with the DS21Q44 E1 framer, as confirmed in the FEATURES section on page 1 and page 2 of the datasheet. This mechanical and electrical compatibility allows reuse of the same PCB footprint when transitioning between T1 and E1 infrastructure, though firmware and configuration must be updated to match the respective framing standards and clocking requirements.
What clock frequencies does the DS21Q42TN elastic store support?
The DS21Q42TN elastic store supports receive and transmit system clocks (RSYSCLK/TSYSCLK) at 1.544 MHz, 2.048 MHz, or burst-mode operation up to 8.192 MHz. This is documented in the FEATURES list (page 1) and elaborated in the Functional Description (page 3), where RSYSCLK is described as "a burst clock with speeds up to 8.192 MHz." The 8.192 MHz capability enables direct connection to high-speed asynchronous backplanes without external clock domain crossing circuitry.
Does the DS21Q42TN include an integrated HDLC controller?
Yes, the DS21Q42TN includes an integral HDLC controller with 64-byte transmit and receive buffers, configurable for either Facility Data Link (FDL) or DS0 channel operation. This is stated in the FEATURES section (page 1) and expanded in Section 14 of the datasheet. The controller handles frame assembly/disassembly, CRC computation, and flag detection in hardware - eliminating the need for host CPU involvement in basic HDLC processing.
DS21Q42TN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 128-LQFP
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- -
- Interface:
- Parallel/Serial
- Number of Circuits:
- 4
- Voltage - Supply:
- 2.97V ~ 3.63V
- Current - Supply:
- 75mA
- Power (Watts):
- -
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 128-LQFP (14x20)
DS21Q42TN FAQ
1.How can I place an order for DS21Q42TN through Aetrix?
Please submit a Request for Quotation (RFQ) for DS21Q42TN 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 DS21Q42TN reliable?
The price and inventory of DS21Q42TN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS21Q42TN is usually 5 days.
3.What payment methods are accepted for DS21Q42TN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS21Q42TN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS21Q42TN?
DS21Q42TN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS21Q42TN 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 DS21Q42TN?
For technical support, including DS21Q42TN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS21Q42TN requirements.
6.How does Aetrix verify that DS21Q42TN is sourced from the original manufacturer or authorized distributors?
All DS21Q42TN 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 DS21Q42TN meets industry standards.
7.What is the process for return or replacement of DS21Q42TN?
All DS21Q42TN units undergo pre-shipment inspection (PSI). If there is an issue with DS21Q42TN, 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 DS21Q42TN part is unused and in its original packaging.
Return procedure for DS21Q42TN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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