Renesas 72V8985JG

Overview

IDT72V8985JG from Integrated Device Technology is a 3.3 V ST-BUS®/GCI-compatible digital time slot interchange (TSI) switch with 256 × 256 non-blocking channel capacity, 8 RX and 8 TX serial streams at 2.048 Mb/s, microprocessor-controlled 8-bit parallel interface, and per-channel variable or constant throughput delay modes - deployed in voice/data TDM switching systems for ISDN trunk interfaces and digital PBXs.

For engineers reviewing the IDT72V8985JG datasheet, IDT72V8985JG pinout, IDT72V8985JG application, or IDT72V8985JG equivalent, key selection considerations include frame integrity support (GCI/ST-BUS® auto-detection), 3.3 V I/O with 5 V tolerant inputs, PLCC-44 package compatibility, -40°C to +85°C industrial temperature range, and microprocessor-accessible connection memory for dynamic path reconfiguration.

Technical Context

The IDT72V8985JG implements a dual-mode TSI architecture: Variable Delay Mode delivers minimum 3-slot latency for real-time voice switching, while Constant Delay Mode guarantees frame-aligned 32–94 slot delays for data integrity across all input-output mappings. Its internal timing unit automatically detects ST-BUS® (active-low F0i) or GCI (active-high F0i) frame formats and configures sampling edges accordingly.

Microprocessor access uses a non-multiplexed 8-bit bus (D0–D7), six address lines (A0–A5), and control signals (CS, DS, R/W, DTA); memory mapping supports Control Register, Connection Memory HIGH/LOW, and read-only Data Memory. The ODE pin provides master three-state control over TX0–TX7 outputs, independent of per-channel OE bits in Connection Memory HIGH.

Key Specifications

Pinout & Package

Package: 44-pin Plastic Leaded Chip Carrier (PLCC), 0.65 in × 0.65 in, 0.05 in pitch (J44-1, order code J). Pin 1 index corner marked; pins 1–22 and 33–44 on top row, pins 23–32 on bottom row.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT72V8984JG and CY7C266-10JC, the IDT72V8985JG uniquely delivers full 256 × 256 non-blocking switching at 3.3 V with automatic multi-standard frame recognition - making it the sole choice for scalable, future-proof E1/T1 infrastructure where latency, frame integrity, and voltage compatibility are jointly critical.

Availability

IDT72V8985JG is available at Aetrix Electronics and suitable for digital PBX core switching, ISDN PRI multiplexing, VoIP gateway TDM interfaces, and industrial TDM backplane interconnect requiring stable component supply across extended product lifecycles.

Supply support for IDT72V8985JG 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 (IDT), now part of Renesas Electronics, is a fabless semiconductor company specializing in timing, memory interface, RF, and high-performance interconnect solutions for communications and computing markets.

The IDT72V8985JG belongs to IDT's legacy TSI switch family designed specifically for carrier-grade and enterprise telecom infrastructure - emphasizing deterministic latency, multi-standard protocol support, and industrial temperature reliability.

FAQ

What is the primary function of the IDT72V8985JG in a TDM system?

The IDT72V8985JG serves as a time slot interchange (TSI) switch that dynamically routes individual 64 kbit/s PCM time slots between eight 2.048 Mb/s serial input (RX0–RX7) and eight output (TX0–TX7) streams. It enables non-blocking 256 × 256 channel interconnection with per-channel programmable delay modes, supporting both voice-optimized low-latency and data-optimized frame-aligned switching in E1/T1 infrastructure.

Does the IDT72V8985JG support both ST-BUS® and GCI protocols simultaneously?

Yes, the IDT72V8985JG incorporates automatic signal identification circuitry that detects and adapts to either ST-BUS® (active-low frame pulse) or GCI (active-high frame pulse) formats on the F0i input. It configures internal sampling edges and synchronization logic accordingly - no external configuration or firmware intervention is required to switch between standards.

How does the Variable Delay Mode differ from Constant Delay Mode in the IDT72V8985JG?

In Variable Delay Mode, the IDT72V8985JG achieves minimum 3-slot latency (e.g., input channel n → output channel n+3), ideal for voice. In Constant Delay Mode, it guarantees fixed frame-aligned delays (32–94 slots) by buffering across two frames - preserving byte ordering for HDLC/PPP data. Both modes are configurable per channel via Connection Memory HIGH V/C bits.

What is the role of the ODE pin on the IDT72V8985JG?

The ODE (Output Drive Enable) pin on the IDT72V8985JG acts as a master three-state control for all TX0–TX7 serial outputs. When ODE is LOW, all eight outputs enter high-impedance state regardless of software settings in Connection Memory HIGH. When ODE is HIGH, individual channel output enable is controlled by bit 0 (OE) in each Connection Memory HIGH location.

Is the IDT72V8985JG compatible with 5 V microprocessors?

Yes, the IDT72V8985JG features 5 V tolerant digital inputs (including CS, DS, R/W, A0–A5, F0i, C4i), allowing direct connection to 5 V microprocessors without level shifters. However, its core supply and I/O drivers operate at 3.3 V, so output voltages comply with 3.3 V logic levels while safely accepting 5 V input signals.