Renesas HN58C257AT85SRE

Overview

HN58C257AT85SRE from Renesas Electronics is a 256-kbit (32-kword × 8-bit) parallel EEPROM with 85 ns maximum access time, Ready/Busy and RES pin functions, and 64-byte page programming capability. It operates from a single 5 V ±10% supply, supports industrial temperature range (−20 to +85°C), and uses MNOS memory cells on CMOS process for high reliability in embedded control and instrumentation systems.

For engineers reviewing the HN58C257AT85SRE datasheet, HN58C257AT85SRE pinout, HN58C257AT85SRE application, or HN58C257AT85SRE equivalent, key selection criteria include its TSOP-32 package, RDY/Busy status signaling, software data protection sequence, and write endurance of 10⁵ cycles in page mode.

Technical Context

The HN58C257AT85SRE implements a byte- and page-write architecture with automatic internal timing: byte writes complete in ≤10 ms, and 64-byte page writes also complete within ≤10 ms. Its control logic latches addresses and data on falling edges of CE or WE, and supports data polling via I/O7 and toggle-bit verification via I/O6 during internal programming.

It integrates dedicated hardware-level protection including power-on/off noise suppression (≤20 ns noise rejection), RES-driven reset inhibit, and software data protection requiring three-byte unlock sequences (5555H/2AAAH/5555H → A0H or 80H). The RDY/Busy pin outputs active-low during write cycles and returns to high-impedance upon completion.

Key Specifications

Pinout & Package

HN58C257AT85SRE is housed in a 32-pin plastic TSOP (Thin Small Outline Package) per JEITA standard PTSA0032KD-A (TFP-32DA), 8.0 mm × 12.4 mm body, 0.50 mm pitch, lead-free compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar EEPROM applications.

Compared with AT28C256-15PU and MX28F256J3F-12G, the HN58C257AT85SRE provides superior system-level reliability through integrated RDY/Busy signaling, hardware RES lock, and three-tier data protection-making it optimal for industrial and medical applications demanding deterministic write completion and robust power-cycle immunity.

Availability

HN58C257AT85SRE is available at Aetrix Electronics and suitable for industrial PLCs, medical calibration modules, automotive body controllers, and automated test equipment requiring stable component supply with long-term lifecycle assurance.

Supply support for HN58C257AT85SRE 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

Renesas Electronics Corporation is a global semiconductor leader specializing in microcontrollers, analog, power, and memory solutions for industrial, automotive, and infrastructure markets.

The HN58C257AT85SRE belongs to Renesas' legacy parallel EEPROM family designed for high-reliability, low-power, and noise-immune nonvolatile storage in resource-constrained embedded systems.

FAQ

What is the function of the RES pin on the HN58C257AT85SRE?

The RES pin on the HN58C257AT85SRE is an active-low hardware reset input that forces the device into an unprogrammable state when asserted. When RES is low, all read and write operations are inhibited, protecting stored data during power-up, power-down, or brown-out conditions. RES must be held high for at least 10 ms after the last data input to complete a write operation reliably. This feature is exclusive to the HN58C257A series and is not present in the HN58C256A series.

How does the RDY/Busy pin operate during a write cycle in the HN58C257AT85SRE?

The RDY/Busy pin on the HN58C257AT85SRE is an open-drain output that goes low (VOL) at the start of an internal write cycle and returns to high-impedance upon completion. It remains in high-impedance during read, standby, and deselect modes. This signal allows external logic or microcontrollers to synchronize without polling I/O7, reducing CPU overhead and enabling deterministic timing in real-time systems. RDY/Busy functionality is unique to the HN58C257A series.

What software data protection (SDP) sequence is required to enable writes on the HN58C257AT85SRE?

To enable writes on the HN58C257AT85SRE, a three-byte unlock sequence must be issued: first write AAH to address 5555H, then 55H to address 2AAAH, then A0H to address 5555H. Only after this sequence is completed can subsequent data writes proceed. To disable SDP, a six-byte sequence (AAH→55H→80H→AAH→55H→20H) is required. SDP is disabled at shipment and must be explicitly enabled per application requirements.

What is the difference between byte write and page write timing in the HN58C257AT85SRE?

In the HN58C257AT85SRE, a byte write completes in ≤10 ms and programs one location per command. A page write loads up to 64 contiguous bytes in a single operation, also completing in ≤10 ms total - significantly improving throughput for block updates. Page addressing uses A6–A14 as the page base; each additional byte must be loaded within 30 µs of the prior WE or CE falling edge. Both modes share the same maximum write cycle time (tWC = 10 ms) unless RDY/Busy or polling is used.

Is the HN58C257AT85SRE pin-compatible with other 32-pin TSOP EEPROMs like the AT28C256?

No, the HN58C257AT85SRE is not pin-compatible with the AT28C256, which uses a 28-pin DIP or SOIC package. While both are 256-kbit parallel EEPROMs, the HN58C257AT85SRE requires a 32-pin TSOP footprint (PTSA0032KD-A) with dedicated RDY/Busy and RES pins occupying pins 30 and 29 respectively - positions unused in 28-pin variants. Direct replacement would require PCB redesign and signal routing adjustments.