Analog Devices Inc./Maxim Integrated DS21Q352

Overview

DS21Q352 from Dallas Semiconductor is a quad-channel 3.3V T1 transceiver Multi-Chip Module (MCM) integrating four DS21352 die in a single 256-ball BGA package. It delivers independent T1 line interface, framing, elastic store, per-DS0 signaling control, and HDLC support per channel, operating at 1.544 Mbps with short/long-haul compatibility. It targets telecom access equipment requiring high-density T1 aggregation.

For engineers reviewing the DS21Q352 datasheet, DS21Q352 pinout, DS21Q352 application, or DS21Q352 equivalent, key selection considerations include its 3.3V supply requirement, T1-only operation (not E1), quad-channel independence, JTAG boundary-scan capability, and absence of XTALD/8XCLK/RDATA/RCL signals versus the base DS21352 die.

Technical Context

The DS21Q352 implements four fully independent T1 transceiver subsystems (SCT1–SCT4), each comprising a line interface unit (LIU), framer with alarm detection/generation, elastic store, hardware-based signaling engine, and HDLC controller. Each channel supports both short-haul (100Ω) and long-haul (75Ω) T1 line configurations via RTIP/RRING and TTIP/TRING analog I/O.

It uses a 256-ball MCM BGA package with dedicated power domains per channel (DVDD1–DVDD4, RVDD1–RVDD4, TVDD1–TVDD4) and supports concatenated 8.192 MHz backplane data streaming across all four channels. IEEE 1149.1 JTAG boundary scan is implemented with shared JTCLK/JTMS/JTRST and per-SCT JTDO outputs (JTDO2–JTDO4).

Key Specifications

Pinout & Package

DS21Q352 uses a 256-ball MCM BGA package (27 mm × 27 mm) with four independent channel domains (SCT1–SCT4), each with dedicated analog/digital power and ground balls, plus shared control and JTAG signals. Power distribution follows strict separation: DVDD/DVSS for digital logic, RVDD/RVSS for receive analog, TVDD/TVSS for transmit analog - all per channel.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad T1 transceiver applications.

Compared with DS21Q352, DS21Q552 offers identical functionality at 5V for legacy compatibility, while DS21Q354 shifts to E1 standards - both share footprint and JTAG architecture but differ in voltage and protocol stack, requiring careful system-level alignment.

Availability

DS21Q352 is available at Aetrix Electronics and suitable for telecom access equipment, central office line cards, and PRI gateways requiring stable component supply, long-lifecycle support, and verified legacy semiconductor sourcing.

Supply support for DS21Q352 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

Dallas Semiconductor (now part of Maxim Integrated, then Analog Devices) specialized in precision timing, data communication, and mixed-signal ICs for telecom and industrial markets.

The DS21Q352 belongs to the DS21x5y quad transceiver MCM product line, designed specifically to reduce footprint and interconnect complexity in high-channel-count T1/E1 line interface applications.

FAQ

What is the supply voltage requirement for DS21Q352?

The DS21Q352 requires a nominal 3.3V ±0.3V supply for all digital (DVDD), receive analog (RVDD), and transmit analog (TVDD) domains. Each of the four channels has dedicated DVDD1–DVDD4, RVDD1–RVDD4, and TVDD1–TVDD4 pins - decoupling must be applied per channel per the recommended 33µF + 0.33µF + 0.01µF scheme. DS21Q352 does not support 5V operation; use DS21Q552 for 5V systems.

Is DS21Q352 pin-compatible with DS21Q552 and DS21Q354?

Yes, DS21Q352 is pin-compatible with DS21Q552 (5V T1), DS21Q354 (3.3V E1), and DS21Q554 (5V E1) - all share the identical 256-ball MCM BGA footprint and ball map. This allows a single PCB layout to support multiple T1/E1 and 3.3V/5V variants via firmware and power rail configuration. However, DS21Q352 cannot be substituted for E1 variants without reconfiguration of framer and signaling logic.

Does DS21Q352 support E1 framing or only T1?

DS21Q352 supports T1 framing exclusively - it is based on the DS21352 die and implements ANSI T1.102, T1.403, and GR-499-CORE compliance. It does not support E1 rates (2.048 Mbps), G.704 multiframe, or E1-specific signaling. For E1 operation, DS21Q354 or DS21Q554 must be used - DS21Q352 cannot be reconfigured for E1 via software or pin strapping.

Which signals are omitted in DS21Q352 compared to the standalone DS21352 die?

DS21Q352 omits XTALD, 8XCLK, RDATA, and RCL signals to minimize package size - these pins are left unconnected and open-circuited per datasheet Table 1. As a result, DS21Q352 relies on external clock sources (e.g., RCLKI/TCLK inputs) and does not support crystal oscillator drive or certain diagnostic data paths available on the monolithic DS21352. System design must accommodate this reduced signal set.

How is JTAG boundary scan implemented on DS21Q352?

DS21Q352 implements IEEE 1149.1 JTAG with shared JTCLK, JTDI, JTMS, and JTRST pins, plus dedicated JTDO outputs for SCT2 (JTDO2), SCT3 (JTDO3), and SCT4 (JTDO4). JTDO1 is not exposed. This enables daisy-chained boundary scan testing across multiple DS21Q352 devices on a board - each device's JTDO drives the next's JTDI, allowing full chain visibility without multiplexing.