Renesas 72V8980JG

Overview

72V8980JG from IDT (now Renesas Electronics) is a 3.3 V, 256 × 256 non-blocking time slot interchange (TSI) digital switch for ST-BUS®-compatible telecom systems. It supports eight 2.048 Mb/s serial RX inputs and eight TX outputs, each carrying 32 × 64 Kbit/s channels, with microprocessor interface (8-bit data bus), 3.3 V I/O, and 5 V tolerant inputs. It is used in TDM-based voice/data switching matrices in access networks and PBX systems.

For engineers reviewing the 72V8980JG datasheet, 72V8980JG pinout, 72V8980JG application, or 72V8980JG equivalent, key selection considerations include ST-BUS® frame alignment (F0i, C4i), per-channel connection memory control (CMH/CML), ODE-driven output enable, CCO bit-stream output, and 44-pin PLCC (JG) package compatibility with legacy telecom board layouts.

Technical Context

The 72V8980JG implements a dual-mode switching architecture: Connection Mode routes Data Memory contents via Connection Memory LOW address pointers, while Processor Mode directly outputs CML contents to TX streams. Its internal serial-to-parallel and parallel-to-serial conversion enforces minimum 2-channel delay across specific RX/TX stream pairs (e.g., RX0→TX1–TX7).

Control is managed through an 8-bit microprocessor bus with A0–A5 addressing, where A5=0 selects the Control Register (for SM, PE, MS, STA bits) and A5=1 enables channel-specific access to Data Memory or Connection Memory HIGH/LOW. The RESET input is absent in the JG (PLCC) package, requiring external power-on initialization sequencing via ODE.

Key Specifications

Pinout & Package

44-pin Plastic Leaded Chip Carrier (PLCC), J44-1 footprint, 0.05 in pitch, 0.65 in × 0.65 in body size. Pin 1 index corner marked with dot or notch; top-side view shown in datasheet Figure 2.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar time slot interchange applications.

Compared with 72V8980JG, the PV variant adds hardware reset convenience at the cost of package compatibility, while the DB variant offers smaller footprint and better thermal performance but demands higher-precision assembly - JG remains optimal for field-serviceable, wave-soldered legacy platforms.

Availability

72V8980JG is available at Aetrix Electronics and suitable for VoIP gateways, digital loop carriers, enterprise PBX expansion modules, and telecom test equipment requiring stable component supply and long-term obsolescence management.

Supply support for 72V8980JG 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

Integrated Device Technology, Inc. (IDT), now part of Renesas Electronics Corporation, is a fabless semiconductor company specializing in timing, memory interface, RF, and high-performance interconnect solutions.

The IDT72V8980 product line was designed specifically for ST-BUS®-based TDM switching in carrier-class access and enterprise telecom infrastructure - emphasizing deterministic latency, channel granularity, and robust 3.3 V operation.

FAQ

What is the function of the ODE pin on the 72V8980JG?

The ODE (Output Drive Enable) pin on the 72V8980JG is an active-HIGH global control that forces all eight TX0–TX7 serial outputs into high-impedance when held LOW. This is essential during power-up initialization to prevent bus contention before Connection Memory HIGH is configured. When ODE is HIGH, individual channel output states are governed by bit 0 (OE) in the corresponding CMH location. The 72V8980JG relies solely on ODE for output control since it lacks the RESET pin found in SSOP variants.

Does the 72V8980JG support both Connection Mode and Processor Mode?

Yes, the 72V8980JG supports both Connection Mode and Processor Mode. In Connection Mode, the Connection Memory LOW (CML) holds addresses pointing to Data Memory locations, enabling hardware-routed time-slot switching. In Processor Mode - activated by setting bit 6 (PE) in the Control Register - the CML contents are output directly to TX streams each frame. Both modes are fully implemented in the 72V8980JG and selected per-channel via bit 2 (CS) in Connection Memory HIGH.

What timing constraints apply to the F0i and C4i inputs on the 72V8980JG?

The F0i (frame pulse) input on the 72V8980JG must be an 8 kHz active-HIGH signal with minimum pulse width of 244 ns and setup/hold times of 5–190 ns relative to C4i. The C4i (serial clock) input is 4.096 MHz with 244 ns period, 122 ns high/low pulse widths, and ≤20 ns transition time. These signals must be phase-aligned per ST-BUS® specification: F0i rising edge occurs at the start of each 125 μs frame, and C4i edges sample serial data mid-bit. Violating these constraints causes framing loss or memory addressing errors in the 72V8980JG.

How is the 256 × 256 switching matrix implemented in the 72V8980JG?

The 256 × 256 switching matrix in the 72V8980JG is implemented using 256-location Data Memory (for storing incoming time-slot data) and 256 × 16-bit Connection Memory (split into 256 × 8-bit CMH and CML). Each output time slot references one CML location, which either provides direct output data (Processor Mode) or an address into Data Memory (Connection Mode). This architecture enables non-blocking, per-time-slot routing with zero blocking probability across all 256 input and output channels in the 72V8980JG.

Can the 72V8980JG operate without an external RESET signal?

Yes, the 72V8980JG can operate without an external RESET signal because the PLCC (JG) package does not include a RESET pin - unlike the SSOP (PV) variant. Initialization relies on holding ODE LOW at power-up, then writing valid Connection Memory HIGH values to disable unintended outputs before releasing ODE. Internal registers retain state during clock stoppage, but TX outputs enter high-impedance if C4i stops. Proper sequencing of ODE and memory writes replaces hardware reset functionality in the 72V8980JG.