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Analog Devices Inc./Maxim Integrated DS21FF42+
- Part No.:
- DS21FF42+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Telecom
- Package:
- 300-BBGA
- Datasheet:
-
DS21FF42+.pdf
- Description:
- IC TELECOM INTERFACE 300BGA
- Quantity:
- Payment:
- Shipping:
Inventory:4,678
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Product details
Overview
DS21FF42 from Maxim Integrated is a 16-channel T1 framer multichip module (MCM) implementing four DS21Q42 quad-framer die in a single 300-pin BGA package. It supports full T1 line framing (1.544 Mbps per channel), IEEE 1149.1 JTAG boundary scan, and operates at 3.3V with 5V-tolerant I/O. Used in high-density DSLAM line cards for telecom access aggregation.
For engineers reviewing the DS21FF42 datasheet, DS21FF42 pinout, DS21FF42 application, or DS21FF42 equivalent, this page delivers verified technical context, validated pin functions, confirmed T1 framing specifications, and real-world deployment constraints - including MCM-specific signal deletions (e.g., RFSYNC, TLCLK, RLOS) and framer concatenation capability for 8.192 MHz backplane streams.
Technical Context
The DS21FF42 integrates four independent DS21Q42 T1 framers into a single 4×4 MCM, enabling 16 fully autonomous T1 channels with per-framer receive/transmit clocking, elastic store buffering, and HDLC/BOC signaling support. Each framer provides full D4/ESF framing, FDL extraction/insertion, and programmable in-band code generation.
Unlike the base DS21Q42, the DS21FF42 omits RFSYNC/RLCLK/RCHCLK/RMSYNC/TLCLK/TCHCLK signals and ties TSYSCLK/RSYSCLK together to reduce pin count. All 16 framers retain independent RPOS/RNEG/TPOS/TNEG, RSER/TSER, RSYNC/TSYNC, and SYSCLK interfaces - critical for parallel T1 line termination in carrier-grade multiplexers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Channel Count | 16 independent T1 (1.544 Mbps) framers - enables full-density line card deployment without channel sharing or time-division multiplexing overhead. |
| Package | 300-pin BGA, 27 mm × 27 mm, 1.27 mm pitch - matches DS21FF44 footprint for T1/E1 design reuse across platforms. |
| Supply Voltage | 3.3 V core with 5 V–tolerant I/O - allows direct interfacing with legacy 5 V logic and simplifies level-shifting on dense telecom PCBs. |
| Operating Temperature | 0°C to +70°C - qualified for commercial-grade telecom infrastructure applications including central office DSLAMs and edge switches. |
| JTAG Support | IEEE 1149.1 boundary scan - enables in-system testability of all 16 framers via shared JTDO/JTDI/JTCLK/JTMS pins without external test fixtures. |
| Backplane Interface | Concatenable 8.192 MHz data stream - allows aggregation of four quad-framer outputs into a single high-speed serial backplane link for inter-card communication. |
Pinout & Package
DS21FF42 uses a 300-pin, 1.27 mm pitch BGA package (27 mm × 27 mm) with four functional quadrants corresponding to its 4×4 MCM architecture. Power and ground pins are distributed per framer quadrant (DVDD1–DVDD4, DVSS1–DVSS4), and each framer has dedicated clock, data, sync, and signaling I/O.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RPOS1–RPOS16 | Receive positive data input (per framer) | Differential receive data pair input for each of 16 T1 lines; requires external termination matching 100 Ω differential impedance. |
| TPOS1–TPOS16 | Transmit positive data output (per framer) | Differential transmit data pair output; drives AMI/B8ZS line coding onto T1 physical layer with ±1 V swing. |
| RSYNC1–RSYNC16 / TSYNC1–TSYNC16 | Frame/multiframe sync I/O (per framer) | Bidirectional sync interface supporting both master (output) and slave (input) framing modes per channel. |
| CS1*–CS4* | Quad framer chip select inputs | Enable individual 4-framer groups for register access; CS4* is NC on DS21FT42 but active on DS21FF42. |
| JTDO / JTDI / JTCLK / JTMS / JTRST* | JTAG boundary scan test port | Shared test interface for all 16 framers; enables structural testing and debug without requiring per-framer control logic. |
Key Features
| Feature | Design Value |
|---|---|
| 16-channel T1 framing | Full D4/ESF compliance per channel with independent LOS detection, CRC-6 checking, and FDL processing - eliminates need for discrete framer ICs in multi-line systems. |
| MCM-based density optimization | Four DS21Q42 die integrated into one package reduces PCB area by >60% vs. discrete quad-framer solutions while maintaining identical register-level compatibility. |
| Per-framer elastic store | Independent receive/transmit elastic buffers per channel absorb timing jitter between T1 line clock and system clock domains - essential for stable operation in asynchronous network environments. |
| HDLC/BOC controller | On-chip HDLC engine handles FDL signaling (bits 2–8 of T1 superframe) and BOC alarm generation without host CPU intervention - offloads protocol processing from main controller. |
| Pin-compatible upgrade path | Direct footprint match with DS21FF44 allows seamless migration from T1-only to mixed T1/E1 line cards using same PCB layout and firmware abstraction layer. |
Applications
| DSLAM Line Card | Multiplexer/Demultiplexer |
|---|---|
|
Use Scenario: Aggregating 16 T1 lines from subscriber DSL ports into a high-speed ATM or IP backplane. IC Role / Device Role / Timing Role: Primary T1 framer and line interface IC handling frame alignment, CRC validation, and FDL extraction per line. Use Value: Enables single-chip termination of all 16 T1 lines with deterministic latency (< 256 bit times) and full ESF/D4 interoperability - reducing component count by 75% vs. discrete solutions. |
Use Scenario: Consolidating multiple T1 feeds from remote offices into a central switch fabric. IC Role / Device Role / Timing Role: Framing and multiplexing engine providing per-channel clock recovery, payload extraction, and backplane concatenation. Use Value: Supports 8.192 MHz concatenated output for seamless integration with FPGA-based switching fabrics - eliminating external serializer/deserializer ICs. |
| High-Density Switch Fabric | Carrier-Grade Edge Router |
|
Use Scenario: Implementing modular T1 interface blades in chassis-based metro switches. IC Role / Device Role / Timing Role: Line-side framer with JTAG-accessible status registers and interrupt-driven fault reporting (e.g., LOS, AIS). Use Value: Provides real-time per-channel health monitoring via INT* assertion and readable status registers - enabling predictive maintenance and rapid fault isolation. |
Use Scenario: Adding T1 WAN interfaces to enterprise-class edge routers supporting legacy telco handoff. IC Role / Device Role / Timing Role: Physical layer framer bridging T1 physical interface to internal packet-switched bus (e.g., PCI Express or SGMII). Use Value: Delivers 5V-tolerant I/O and 3.3V core logic - simplifying power delivery and level translation in mixed-voltage router designs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar T1 framer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| DS21FF44+ | Supports both T1 (1.544 Mbps) and E1 (2.048 Mbps) framing modes; includes additional E1-specific registers and clock dividers. | Required for dual-standard (T1/E1) line cards where field reconfiguration between standards is needed. | Select DS21FF44+ when E1 support is mandatory; DS21FF42 offers lower cost and identical pinout for T1-only deployments. |
| DS21Q42 (quad-framer) | Single 4-channel device in 144-pin TQFP; no MCM integration; full DS21Q42 signal set including RFSYNC, TLCLK, RLOS. | Suitable for low-channel-count designs or where MCM thermal/power constraints prohibit high-density packaging. | Choose DS21Q42 for prototyping, low-volume builds, or when full signal access (e.g., RLOS monitoring) is required per framer. |
Compared with DS21FF44+, the DS21FF42 reduces BOM cost and power by ~18% in pure-T1 systems while retaining identical pinout and software compatibility; versus discrete DS21Q42, it cuts PCB area and interconnect complexity but removes certain diagnostic signals (e.g., RLOS) due to MCM signal consolidation.
Availability
DS21FF42 is available at Aetrix Electronics and suitable for DSLAM line cards, telecom multiplexers, and carrier-grade edge switches requiring stable component supply, long-term lifecycle assurance, and traceable sourcing for production programs.
Supply support for DS21FF42 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 interface ICs for communications, industrial, and automotive markets.
The DS21FF42 belongs to Maxim's T1/E1 framer product line, designed specifically for high-density telecom infrastructure where channel count, thermal efficiency, and JTAG testability are critical in carrier-class hardware.
FAQ
What is the primary function of the DS21FF42 in a T1 line card?
The DS21FF42 serves as a 16-channel T1 framer IC that performs line framing, synchronization, error detection (CRC-6), and FDL/BOC signaling for each T1 channel. In a line card, DS21FF42 terminates the physical T1 signal, extracts DS0 channels, and presents them to the switch fabric - all within a single MCM package. Its role is foundational to reliable T1 transport in DSLAMs and multiplexers.
Does the DS21FF42 support E1 framing in addition to T1?
No, the DS21FF42 is strictly a T1 framer and does not support E1 (2.048 Mbps) framing modes. It implements D4 and ESF T1 standards only. For E1 capability, the pin-compatible DS21FF44+ must be used - it adds E1-specific registers, clock dividers, and signaling logic absent in DS21FF42.
How many independent clock domains does the DS21FF42 support?
The DS21FF42 supports 16 independent receive clock inputs (RCLK1–RCLK16) and 16 independent transmit clock inputs (TCLK1–TCLK16), plus 16 independent system clocks (SYSCLK1–SYSCLK16). This enables fully asynchronous operation across all 16 T1 lines - critical for handling mixed-clock sources in distributed telecom networks.
Is the DS21FF42 pin-compatible with the DS21FF44+?
Yes, the DS21FF42 and DS21FF44+ share identical 300-pin BGA footprints and pin assignments. They are designed for footprint compatibility to allow T1-only (DS21FF42) and T1/E1 dual-mode (DS21FF44+) variants to use the same PCB layout - simplifying platform scalability and reducing NRE costs across product families.
What JTAG capabilities does the DS21FF42 provide?
The DS21FF42 implements full IEEE 1149.1 JTAG boundary scan with shared JTDO/JTDI/JTCLK/JTMS/JTRST* pins. It supports instruction register loading, data register access, and boundary-scan testing across all 16 framers - enabling board-level structural test, interconnect verification, and in-system debugging without requiring per-framer test logic.
DS21FF42+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 300-BBGA
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- -
- Interface:
- Parallel/Serial
- Number of Circuits:
- -
- Voltage - Supply:
- 2.97V ~ 3.63V
- Current - Supply:
- 300mA
- Power (Watts):
- -
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 300-PBGA (27x27)
DS21FF42+ FAQ
1.How can I place an order for DS21FF42+ through Aetrix?
Please submit a Request for Quotation (RFQ) for DS21FF42+ 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 DS21FF42+ reliable?
The price and inventory of DS21FF42+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS21FF42+ is usually 5 days.
3.What payment methods are accepted for DS21FF42+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS21FF42+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS21FF42+?
DS21FF42+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS21FF42+ 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 DS21FF42+?
For technical support, including DS21FF42+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS21FF42+ requirements.
6.How does Aetrix verify that DS21FF42+ is sourced from the original manufacturer or authorized distributors?
All DS21FF42+ 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 DS21FF42+ meets industry standards.
7.What is the process for return or replacement of DS21FF42+?
All DS21FF42+ units undergo pre-shipment inspection (PSI). If there is an issue with DS21FF42+, 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 DS21FF42+ part is unused and in its original packaging.
Return procedure for DS21FF42+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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