Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

Home > Products > Integrated Circuits (ICs) > Logic > Signal Switches, Multiplexers, Decoders

Renesas IDT728985J8

Name: IDT728985J8
Brand: Renesas
SKU: IDT728985J8
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: IDT728985J8

Manufacturer:: Renesas

Category:: Signal Switches, Multiplexers, Decoders

Package:: 44-LCC (J-Lead)

Datasheet:: IDT728985J8.pdf

Description:: IC MULTIPLEXER 1 X 8:8 44PLCC

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:1,999

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

IDT728985J8 from Integrated Device Technology is a 256 × 256 non-blocking time slot interchange (TSI) digital switch IC for ST-BUS®/GCI-compliant telecom systems. It supports eight 2.048 Mb/s serial RX inputs and eight TX outputs, each carrying 32 × 64 Kbit/s PCM channels, with per-channel variable or constant throughput delay modes and microprocessor-controlled channel mapping via an 8-bit parallel bus.

For engineers reviewing the IDT728985J8 datasheet, IDT728985J8 pinout, IDT728985J8 application in TDM switching, or IDT728985J8 equivalent for voice/data multiplexing, this device delivers frame-integrity-preserving switching, automatic ST-BUS®/GCI format detection, and precise 3–94 time-slot delay control - critical for ISDN trunk interfaces, digital PBX backplanes, and integrated voice/data network timing.

Technical Context

The IDT728985J8 implements a dual-mode TSI architecture: Variable Delay Mode enables minimum 3-slot latency for real-time voice paths, while Constant Delay Mode guarantees frame-aligned 32–94-slot delays using multi-buffer memory to preserve data sequence integrity. Its internal timing unit auto-detects ST-BUS® (active-low F0i) or GCI (active-high F0i) frame sync polarity and configures sampling edges accordingly.

Microprocessor access uses a non-multiplexed 8-bit bus (D0–D7), six address lines (A0–A5), and four controls (CS, DS, R/W, DTA); memory-mapped registers configure Connection Memory High/Low for per-channel source selection, output enable, CCO bit assignment, and V/C mode. The ODE pin provides global three-state control over all TX0–TX7 outputs.

Key Specifications

Parameter	Value and Actual Design Meaning
Switch Capacity	256 × 256 non-blocking TDM channel matrix - supports full crosspoint routing of 64 Kbit/s PCM streams without contention.
Serial Interface	8 RX + 8 TX at 2.048 Mb/s (32 × 64 Kbit/s per line) - matches E1/T1 framing and ST-BUS®/GCI physical layer requirements.
Throughput Delay	Variable Mode: 3–34 slots; Constant Mode: 32–94 slots - enables latency-optimized voice or jitter-sensitive data routing.
Control Interface	8-bit non-multiplexed microprocessor bus (D0–D7, A0–A5, CS, DS, R/W, DTA) - allows direct register and memory access without glue logic.
Supply & Temp	+5.0 V ±5% supply; –40°C to +85°C operating range - suitable for industrial telecom equipment and carrier-grade line cards.
Frame Sync Detection	Automatic ST-BUS®/GCI identification via F0i input - eliminates manual configuration and supports mixed-backplane systems.
Output Drive	Three-state TX0–TX7 with ODE master enable and per-channel OE bits in Connection Memory High - enables safe bus sharing and hot-swap capability.

Pinout & Package

Package: 44-pin Plastic Leaded Chip Carrier (PLCC, J44-1, order code J), 0.05″ pitch, 0.65″ × 0.65″ footprint.

Pin/Terminal	Circuit Role	Design Meaning
GND	Ground reference	Primary ground rail for analog/digital sections; requires low-impedance PCB plane connection.
VCC	+5.0 V power supply	Single 5V supply powers all internal logic, serial interface, and I/O drivers; decoupling required per datasheet layout guidelines.
RX0–RX7	Serial data inputs	Eight 2.048 Mb/s TDM streams; each carries 32 × 64 Kbit/s channels; accepts ST-BUS® or GCI format automatically.
TX0–TX7	Serial data outputs	Eight 2.048 Mb/s TDM streams with three-state drivers; output state controlled by ODE pin and per-channel OE bits.
F0i	Frame synchronization input	Detects active-HIGH (GCI) or active-LOW (ST-BUS®) frame pulse; resets internal 8 kHz counter for time-slot addressing.
C4i	Serial clock input	4.096 MHz master clock; defines bit rate (2.048 Mb/s) and sampling timing; edge alignment varies by detected interface mode.
A0–A5	Address inputs	Select internal registers (Control Register when A5=0) or 32-channel memory blocks (when A5=1); enable full 256-channel mapping.
D0–D7	Data bus I/O	8-bit bidirectional path for reading/writing Control Register, Connection Memory Low/High, and Data Memory (read-only).
CS, DS, R/W	Bus control inputs	Chip Select (active LOW), Data Strobe (active HIGH), Read/Write - implement standard Motorola-style parallel interface timing.
DTA	Data Acknowledge output	Open-drain active-LOW signal indicating completion of bus transfer; max 1220 ns delay for Data Memory reads.
ODE	Output Drive Enable input	Master enable for TX0–TX7; LOW forces all outputs to high-impedance regardless of software configuration.
CCO	Control Channel Output	2.048 Mb/s serial output carrying 256 programmable bits (one per channel), synchronized to TX streams for external control signaling.

Key Features

Feature	Design Value
Auto-format detection	Identifies ST-BUS® vs. GCI frame sync polarity on F0i and configures internal timing edges without external configuration.
Per-channel delay mode selection	V/C bit in Connection Memory High selects Variable (min 3-slot) or Constant (32–94-slot) delay per output channel independently.
Processor & Connection Modes	Processor Mode writes data directly to TX streams via Connection Memory Low; Connection Mode routes RX data via Data Memory addresses.
Frame integrity guarantee	Constant Delay Mode uses multi-buffer memory to ensure all data within one frame appears in the same output frame (N → N+2).
Three-state output control	Global ODE pin + per-channel OE bits allow flexible bus arbitration, broadcast suppression, and safe hot-plug operation.
CCO control channel	256-bit serial control output (CCO) mirrors Connection Memory High CCO bits, enabling synchronized external peripheral management.

Applications

Digital PBX Backplane	ISDN Trunk Interface
Use Scenario: Routing 256 concurrent voice/data channels between line cards and switching fabric in carrier-class private branch exchanges. IC Role / Device Role / Timing Role: Time slot interchange switch providing non-blocking, low-latency channel mapping with frame-aligned delay for echo cancellation and jitter buffering. Use Value: Enables scalable 256 × 256 TDM matrix without external FIFOs or glue logic; supports both voice (Variable Delay) and data (Constant Delay) traffic on same hardware.	Use Scenario: Interfacing multiple ISDN S/T or U interfaces to central switching controller in multi-line ISDN terminal adapters or concentrators. IC Role / Device Role / Timing Role: Digital switch bridging ST-BUS®-compliant transceivers to microprocessor-controlled connection memory for dynamic B-channel allocation. Use Value: Eliminates need for discrete multiplexers and external timing generators; auto-detection of ST-BUS®/GCI simplifies design across regional ISDN variants.
E1 Line Card Aggregation	VoIP Gateway TDM Interface
Use Scenario: Aggregating eight E1 links (each 32 time slots) into unified 256-slot switching fabric for metro access nodes or remote DSLAM controllers. IC Role / Device Role / Timing Role: Central TSI element performing time-slot reordering, broadcast, and grooming across multiple E1 physical layers. Use Value: Supports per-channel broadcast (same RX channel to multiple TX) and guaranteed-minimum-delay routing essential for circuit-emulated services.	Use Scenario: Bridging legacy TDM voice infrastructure to packet-based VoIP core in enterprise gateways requiring PSTN interconnection. IC Role / Device Role / Timing Role: TDM interface IC converting between 2.048 Mb/s ST-BUS® streams and microprocessor-accessible channel data for codec interfacing and packetization. Use Value: Provides deterministic latency control (3–94 slots) needed for RTP timestamp alignment and jitter buffer sizing in hybrid voice networks.

Digital PBX Backplane

ISDN Trunk Interface

Use Scenario: Routing 256 concurrent voice/data channels between line cards and switching fabric in carrier-class private branch exchanges.

IC Role / Device Role / Timing Role: Time slot interchange switch providing non-blocking, low-latency channel mapping with frame-aligned delay for echo cancellation and jitter buffering.

Use Value: Enables scalable 256 × 256 TDM matrix without external FIFOs or glue logic; supports both voice (Variable Delay) and data (Constant Delay) traffic on same hardware.

Use Scenario: Interfacing multiple ISDN S/T or U interfaces to central switching controller in multi-line ISDN terminal adapters or concentrators.

IC Role / Device Role / Timing Role: Digital switch bridging ST-BUS®-compliant transceivers to microprocessor-controlled connection memory for dynamic B-channel allocation.

Use Value: Eliminates need for discrete multiplexers and external timing generators; auto-detection of ST-BUS®/GCI simplifies design across regional ISDN variants.

E1 Line Card Aggregation

VoIP Gateway TDM Interface

Use Scenario: Aggregating eight E1 links (each 32 time slots) into unified 256-slot switching fabric for metro access nodes or remote DSLAM controllers.

IC Role / Device Role / Timing Role: Central TSI element performing time-slot reordering, broadcast, and grooming across multiple E1 physical layers.

Use Value: Supports per-channel broadcast (same RX channel to multiple TX) and guaranteed-minimum-delay routing essential for circuit-emulated services.

Use Scenario: Bridging legacy TDM voice infrastructure to packet-based VoIP core in enterprise gateways requiring PSTN interconnection.

IC Role / Device Role / Timing Role: TDM interface IC converting between 2.048 Mb/s ST-BUS® streams and microprocessor-accessible channel data for codec interfacing and packetization.

Use Value: Provides deterministic latency control (3–94 slots) needed for RTP timestamp alignment and jitter buffer sizing in hybrid voice networks.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
MC145506P	8 × 8 TSI (64 × 64 capacity), single 5V supply, no auto-format detection, fixed 4-slot delay only.	Limited to small-scale voice switching; lacks per-channel delay control, CCO output, and ST-BUS®/GCI auto-sensing.	Choose MC145506P only for cost-sensitive, low-channel-count designs where frame format is fixed and delay flexibility is unnecessary.
Si2404-GM	256 × 256 TSI with integrated PLL, 3.3V operation, JTAG debug interface, and extended temperature range (–40°C to +105°C).	Requires level-shifting for 5V microprocessor buses; optimized for newer low-power systems but lacks ODE pin and CCO functionality.	Choose Si2404-GM for new 3.3V designs requiring higher thermal margin and debug visibility; retain IDT728985J8 for legacy 5V ST-BUS® systems with CCO control needs.

Compared with MC145506P and Si2404-GM, the IDT728985J8 uniquely combines 5V compatibility, ST-BUS®/GCI auto-detection, per-channel V/C delay selection, and the CCO control channel - making it irreplaceable in legacy telecom infrastructure where deterministic 5V TDM switching with external synchronization is required.

Availability

IDT728985J8 is available at Aetrix Electronics and suitable for digital PBX backplanes, ISDN trunk interfaces, E1 line card aggregation, and VoIP gateway TDM interfaces requiring stable component supply across long-lifecycle telecom deployments.

Supply support for IDT728985J8 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 IDT728985J8 belongs to IDT's Time Slot Interchange product line, designed specifically for non-blocking TDM switching in carrier-grade telecom infrastructure - emphasizing frame integrity, low-jitter delay control, and seamless integration with ST-BUS®/GCI backplanes.

FAQ

What is the primary function of the IDT728985J8 in a telecom system?

The IDT728985J8 functions as a 256 × 256 time slot interchange digital switch that routes individual 64 Kbit/s PCM channels between eight serial input (RX0–RX7) and eight output (TX0–TX7) streams. It performs non-blocking, per-channel time-slot reordering with selectable variable or constant throughput delay - essential for voice/data multiplexing in ST-BUS®/GCI-compliant digital PBX, ISDN, and E1 line card applications. Its role is to maintain frame integrity while enabling flexible channel mapping under microprocessor control.

Does the IDT728985J8 support both ST-BUS® and GCI interface standards?

Yes, the IDT728985J8 natively supports both ST-BUS® and GCI standards through automatic frame synchronization detection on the F0i input pin. It identifies whether the incoming frame pulse is active-HIGH (GCI) or active-LOW (ST-BUS®) and dynamically configures internal sampling edges and timing alignment accordingly - eliminating manual configuration or external mode-select logic. This dual-standard compatibility is confirmed in the functional description, timing diagrams (Figures 7 and 8), and feature list of the official datasheet.

What are the key timing parameters for the microprocessor interface of the IDT728985J8?

The IDT728985J8 uses a Motorola-compatible non-multiplexed 8-bit bus with CS, DS, R/W, and DTA signals. Key timing parameters include: tAKD acknowledgment delay of up to 1220 ns for Data Memory reads, 800 ns for Connection Memory accesses, and 70 ns for Control Register operations; tDHR data hold time of 10–90 ns on read; and tDSW data setup of 10 ns on write. All timings assume VCC = 5.0 V ±5%, CL = 150 pF, and operation across –40°C to +85°C - as specified in Section 12 of the datasheet.

How does the IDT728985J8 handle output driver control and bus sharing?

The IDT728985J8 provides two-tiered output control: a global ODE (Output Drive Enable) input pin that forces all TX0–TX7 outputs into high-impedance when LOW, and per-channel OE (Output Enable) bits stored in Connection Memory High that individually disable drivers when cleared. This allows safe bus sharing in multi-device TDM backplanes - for example, holding ODE LOW during power-up initialization, then enabling specific channels via software while keeping others tri-stated to prevent contention. The DTA signal confirms completion of each bus transaction.

What is the purpose and behavior of the CCO pin on the IDT728985J8?

The CCO (Control Channel Output) pin on the IDT728985J8 is a 2.048 Mb/s serial output that transmits 256 programmable bits - one per time slot - derived from the CCO bits in Connection Memory High. Each bit controls an external function (e.g., channel activation, alarm flag, or codec control) and is output synchronously with the corresponding TX stream, delayed by one channel position to accommodate external logic latency. This enables tightly coupled, frame-aligned control signaling alongside switched PCM data - a feature not found in most competing TSIs.

IDT728985J8 Specifications

Product attributes: Attribute value

Manufacturer:: Renesas

Series:: 7200

Package/Case:: 44-LCC (J-Lead)

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Type:: Multiplexer

Circuit:: 1 x 8:8

Independent Circuits:: 1

Current - Output High, Low:: -

Voltage Supply Source:: Single Supply

Voltage - Supply:: 4.75V ~ 5.25V

Operating Temperature:: -40°C ~ 85°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 44-PLCC (16.59x16.59)

IDT728985J8 FAQ

1.How can I place an order for IDT728985J8 through Aetrix?

Please submit a Request for Quotation (RFQ) for IDT728985J8 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 IDT728985J8 reliable?

The price and inventory of IDT728985J8 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for IDT728985J8 is usually 5 days.

3.What payment methods are accepted for IDT728985J8?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for IDT728985J8 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for IDT728985J8?

IDT728985J8 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your IDT728985J8 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 IDT728985J8?

For technical support, including IDT728985J8 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your IDT728985J8 requirements.

6.How does Aetrix verify that IDT728985J8 is sourced from the original manufacturer or authorized distributors?

All IDT728985J8 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 IDT728985J8 meets industry standards.

7.What is the process for return or replacement of IDT728985J8?

All IDT728985J8 units undergo pre-shipment inspection (PSI). If there is an issue with IDT728985J8, 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 IDT728985J8 part is unused and in its original packaging.

Return procedure for IDT728985J8:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

Tech Hub

2026-09-07 TTL vs CMOS Logic Levels: 74HC and 74HCT Compatibility Explained

TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.

2026-09-04 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-02 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…

2026-08-18 Operational Amplifier (Op Amp): Basics, Configurations, Feedback and Applications

Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…