Renesas IDT7290820J

Overview

IDT7290820J from Integrated Device Technology, Inc. is a 5V, 2,048 × 2,048 non-blocking time slot interchange (TSI) digital switch optimized for PCM voice and N×64 kbit/s data routing in ST-BUS®/GCI telecommunication systems. It supports serial bit rates of 2.048 Mb/s, 4.096 Mb/s, or 8.192 Mb/s with per-channel variable or constant throughput delay, JTAG boundary scan (IEEE-1149.1), and microprocessor interface compatibility with Intel/Motorola buses. It is used in TDM-based central office switches, access multiplexers, and digital loop carriers.

For engineers reviewing the IDT7290820J datasheet, IDT7290820J pinout, IDT7290820J application, or IDT7290820J equivalent, key selection considerations include frame alignment mode (ST-BUS®/GCI vs. WFP), per-channel delay configuration (V/C bit), ODE-controlled output enable, connection memory addressing (A0–A7 + MS bit), and JTAG test port implementation (TCK/TMS/TDI/TDO/TRST).

Technical Context

The IDT7290820J implements a dual-mode TSI architecture with separate data memory (up to 2,048 bytes) and connection memory (16 streams × 128 channels = 2,048 locations), each configurable via a parallel microprocessor interface supporting both multiplexed (Motorola/Intel) and non-multiplexed bus protocols. Its timing unit synchronizes to F0i (8 kHz frame pulse) and CLK (4.096/8.192/16.384 MHz), with automatic ST-BUS®/GCI format detection when WFPS = LOW.

It provides per-stream input frame offset calibration via FE/HCLK, programmable per-channel control bits (PC, V/C, LPBK, OE, CCO), and hardware-level loopback for diagnostics. Throughput delay is selectable per channel: variable mode yields minimum 3-time-slot latency; constant mode guarantees fixed 1-frame delay using multi-buffered data memory to preserve frame integrity in wideband data applications.

Key Specifications

Pinout & Package

Package: 84-pin Plastic Leaded Chip Carrier (PLCC), 0.05″ pitch, 1.15″ × 1.15″ (order code J). Pin 1 marked by index corner; IC pin tied to GND for normal operation and IEEE-1149.1 compliance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with IDT7290815J and CY7C9251AV, the IDT7290820J delivers full 2K×2K scalability, IEEE-1149.1 testability, and hardware-accelerated frame alignment - making it the sole option for new carrier-grade designs requiring WFP mode, per-stream skew compensation, or CCO-based control signaling.

Availability

IDT7290820J is available at Aetrix Electronics and suitable for digital loop carriers, central office switches, access multiplexers, and ISDN PRI gateways requiring stable component supply across extended product lifecycles.

Supply support for IDT7290820J 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) was a fabless semiconductor company specializing in timing, memory interface, RF, and high-performance interconnect solutions before its acquisition by Renesas Electronics in 2019.

The IDT7290820J belongs to IDT's TSI digital switch product line, designed specifically for carrier-class TDM infrastructure requiring non-blocking, low-latency, frame-aligned time-slot routing in E1/T1, ST-BUS®, and GCI environments.

FAQ

What is the maximum serial data rate supported by the IDT7290820J?

The IDT7290820J supports three serial data rates: 2.048 Mb/s (512 × 512 channels), 4.096 Mb/s (1,024 × 1,024 channels), and 8.192 Mb/s (2,048 × 2,048 channels). The rate is selected via DR0 and DR1 bits in the IMS register, and the required master clock (CLK) must be exactly twice the selected data rate - i.e., 4.096 MHz, 8.192 MHz, or 16.384 MHz respectively. All 16 RX and TX streams operate at the same configured rate.

How does the IDT7290820J handle frame synchronization for ST-BUS® and GCI interfaces?

The IDT7290820J automatically detects and identifies ST-BUS® or GCI frame formats when the WFPS pin is LOW. It senses frame pulse polarity and bit-clock edge relationships (rising vs. falling edge alignment) on the F0i input and configures internal serial-to-parallel conversion accordingly. This hardware-level detection eliminates firmware-based frame parsing and ensures robust operation across mixed-interface systems without manual mode selection.

Can the IDT7290820J perform per-channel output disable independently of the ODE pin?

Yes. While the ODE pin provides global three-state control for all TX0–TX15 outputs, each channel's connection memory location contains an OE (Output Enable) bit that overrides ODE when active. If ODE is HIGH, the OE bit directly controls the corresponding TX output driver; if ODE is LOW, the OSB bit in the IMS register takes precedence. This enables fine-grained channel shutdown for maintenance or power management without affecting other active channels.

What is the purpose of the CCO pin on the IDT7290820J?

The CCO (Control Output) pin on the IDT7290820J outputs a serial stream of CCO bits from connection memory - one bit per time-slot, synchronized to the selected data rate (4.096/8.192/16.384 Mb/s). Each CCO bit corresponds to the CCO control bit stored in the connection memory location for that TX channel and is output one time-slot before the associated data. It enables external processors to monitor or act on per-channel control states (e.g., loopback status, mode selection) without reading memory over the microprocessor bus.

Does the IDT7290820J require external pull-up resistors on any pins?

Yes. The DTA (Data Transfer Acknowledgment) pin requires an external pull-up resistor to maintain a HIGH level when in high-impedance state between bus cycles. Additionally, while TMS, TDI, and TCK have internal pull-ups, system-level robustness recommends external 10 kΩ pull-ups on these JTAG pins - especially in noisy telecom environments - to prevent spurious state transitions during power-up or reset sequences. No pull-ups are needed on RESET or WFPS, which are actively driven.