Renesas 70121L25JG

Overview

IDT70121L25JG from Integrated Device Technology is a high-speed 2K × 9 dual-port static RAM configured as a MASTER device with independent left/right asynchronous ports, 25 ns maximum access time, push-pull BUSY output and INT flag, and TTL-compatible 5 V ±10% operation - used in real-time inter-processor communication buffers and shared-memory arbitration systems.

For engineers reviewing the IDT70121L25JG datasheet, IDT70121L25JG pinout, IDT70121L25JG application, or IDT70121L25JG equivalent, key selection criteria include master-mode arbitration logic, dual-port busy/interrupt timing (tBAA ≤ 20 ns), 52-pin PLCC package compatibility, and battery-backed data retention at 2 V.

Technical Context

The IDT70121L25JG implements on-chip port arbitration logic exclusively in MASTER configuration, asserting BUSY when both ports access the same address simultaneously - with BUSY output active as non-tri-stated push-pull signal. It supports fully asynchronous read/write operations per port without external logic.

Interrupt functionality uses dedicated mailbox addresses (7FE_H for INTL, 7FF_H for INTR), where write to one port sets the interrupt flag on the opposite port; clearing requires read-access to the same location with OE and CE asserted. Power management includes four standby current modes (ISB1–ISB4) controlled by CE level and input voltage thresholds.

Key Specifications

Pinout & Package

52-pin Plastic Leaded Chip Carrier (PLCC), body size ≈ 0.75 in × 0.75 in × 0.17 in; all V_CC and GND pins must be connected per datasheet note.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-port SRAM applications.

Compared with IDT70125L25JG and CY7C136-25JC, the IDT70121L25JG uniquely integrates master-mode arbitration, dual interrupt mailboxes, and push-pull BUSY outputs - enabling zero-software-latency shared memory in tightly coupled dual-CPU systems.

Availability

IDT70121L25JG is available at Aetrix Electronics and suitable for real-time inter-processor communication, digital signal processing buffering, and industrial PLC shared memory applications requiring stable component supply and long-term lifecycle support.

Supply support for IDT70121L25JG 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) is a fabless semiconductor company specializing in timing, memory interface, RF, and high-performance computing solutions for communications, computing, and industrial markets.

IDT70121L25JG belongs to the 70121/70125 dual-port SRAM product line, designed specifically for deterministic, low-latency shared-memory architectures in multi-processor systems requiring hardware arbitration and inter-processor signaling.

FAQ

What is the function of the BUSY pin on the IDT70121L25JG?

The BUSY pin on the IDT70121L25JG is a non-tri-stated push-pull output that signals contention when both ports access the same memory address simultaneously. It stalls the contending port's write operation and can be used directly to gate R/W control signals - eliminating need for external arbitration logic. In IDT70121L25JG, BUSY is always an output; it differs from the SLAVE IDT70125L25JG where BUSY is an input.

Does the IDT70121L25JG support battery backup operation?

Yes, the IDT70121L25JG supports battery backup operation with guaranteed data retention at V_CC = 2.0 V minimum. Its low ISB3 standby current (0.2 µA typical) enables extended retention from small coin-cell batteries. This feature is intrinsic to the "L" (low-power) version and verified per datasheet Table 7; IDT70121L25JG maintains valid data without refresh during main power loss.

How does interrupt functionality work in the IDT70121L25JG?

The IDT70121L25JG implements hardware interrupts using two dedicated SRAM mailbox addresses: writing to 7FE_H sets INTL (left-port flag), and writing to 7FF_H sets INTR (right-port flag). Each flag is cleared by reading the same address with OE and CE asserted. This enables lock-free, atomic inter-processor messaging - a core capability of IDT70121L25JG not dependent on software polling or external logic.

Can the IDT70121L25JG be used without the BUSY or interrupt features?

Yes, the IDT70121L25JG operates fully as a standard dual-port SRAM even when BUSY and interrupt functions are unused. Address locations 7FE_H and 7FF_H become regular memory cells, and BUSY can be ignored or tied high if write-inhibit behavior is unnecessary. All timing and functional specifications remain valid; disabling these features imposes no performance penalty on IDT70121L25JG.

What is the difference between IDT70121L25JG and IDT70125L25JG?

IDT70121L25JG is the MASTER dual-port SRAM with on-chip arbitration logic and push-pull BUSY output, while IDT70125L25JG is the SLAVE variant with BUSY as input-only and no arbitration circuitry. IDT70121L25JG operates standalone; IDT70125L25JG requires pairing with a master. Both share identical 2K × 9 organization, 25 ns speed, and 52-pin PLCC packaging - but their circuit roles in a system are fundamentally distinct.