HM5251805B 512-Mbit SDRAM Technical Summary

Overview

The Hitachi HM5251805B is a high-performance 512-Mbit Synchronous DRAM (SDRAM) component designed for applications requiring high-speed data access and large memory capacity. Organized as 16,777,216 words × 8 bits × 4 banks, this memory device offers flexible configuration options and efficient data handling capabilities. The device operates with a 3.3V power supply and features a low-voltage TTL (LVTTL) interface, making it compatible with modern digital systems.

All input and output operations are synchronized to the rising edge of the clock signal, providing precise timing control. The HM5251805B is packaged in a space-efficient 54-pin plastic TSOP II package, suitable for high-density PCB layouts.

Key Features

• Memory Organization: 16,777,216 words × 8 bits × 4 banks (512 Mbit total)
• Power Supply: 3.3V ± 0.3V
• Clock Frequency: Up to 133 MHz (HM5251805B-75) or 100 MHz (HM5251805B-6)
• Interface: LVTTL-compatible inputs and outputs
• Bank Architecture: Four independent banks supporting concurrent operations
• Burst Operations:
  • Burst read/write and burst read/single write modes
  • Programmable burst lengths: 1, 2, 4, or 8
  • Selectable burst sequence: sequential or interleaved
• CAS Latency: Programmable to 2 or 3 clock cycles
• Data Control: Byte-wise control via DQM (Data Input/Output Mask)
• Refresh Management:
  • 8,192 refresh cycles every 64ms
  • Support for both auto refresh and self refresh modes

Applications

The HM5251805B is designed for use in a wide range of electronic systems requiring high-density memory with fast access times. Typical applications include:

• Computer systems and workstations
• Networking equipment (routers, switches)
• Telecommunications infrastructure
• High-performance embedded systems
• Graphics and video processing systems
• Industrial control systems
• Test and measurement equipment

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (VDD): -0.5V to +4.6V
• Input Voltage (VI): -0.5V to VDD + 0.5V
• Output Voltage (VO): -0.5V to VDD + 0.5V
• Operating Temperature Range: 0°C to +70°C
• Storage Temperature Range: -55°C to +125°C

Recommended Operating Conditions

• Supply Voltage (VDD): 3.3V ± 0.3V
• Input High Voltage (VIH): 2.0V min (VDD = 3.3V)
• Input Low Voltage (VIL): 0.8V max (VDD = 3.3V)
• Operating Temperature: 0°C to +70°C

DC Characteristics

• Input Leakage Current (II): ±1 μA max
• Output Leakage Current (IOZ): ±1 μA max
• Operating Current (IDD): 120 mA max (133 MHz operation)
• Standby Current (IDD2): 20 mA max
• Self Refresh Current (IDD6): 400 μA max

AC Characteristics

• Clock Cycle Time (tCK): 7.5 ns min (133 MHz) / 10 ns min (100 MHz)
• CAS Latency: 2 or 3 clock cycles
• Access Time (tAC): 5.4 ns max (CL = 2, 133 MHz)
• Row Address to Column Address Delay (tRCD): 20 ns max
• Row Precharge Time (tRP): 20 ns max
• Row Active Time (tRAS): 45 ns min, 120 μs max

Package Information

54-pin TSOP II Package

• Package Type: Plastic Thin Small Outline Package (TSOP) Type II
• Package Dimensions: 22.2mm × 10.2mm × 1.2mm (typical)
• Pin Count: 54 pins (0.8mm pitch)
• Lead Material: Alloy 42 or copper alloy
• Lead Finish: Matte tin or solder plating

Pin Configuration

The 54-pin TSOP II package includes the following signal groups:

• Power Supplies: VDD (core power), VDDQ (I/O power), VSS (ground)
• Clock Signals: CLK (system clock), CKE (clock enable)
• Control Signals: CS (chip select), RAS (row address strobe), CAS (column address strobe), WE (write enable)
• Address Inputs: A0-A11 (row/column addresses), BA0-BA1 (bank select)
• Data I/O: DQ0-DQ7 (data input/output), DQM (data mask)

Ordering Information

The HM5251805B is available in different speed grades and package options:

• HM5251805B-75: 133 MHz operation
• HM5251805B-6: 100 MHz operation

Additional variants include the HM5251165B (16-bit organization) and HM5251405B (4-bit organization) for different application requirements.

Conclusion

The Hitachi HM5251805B 512-Mbit SDRAM provides a high-performance memory solution for demanding applications. With its 3.3V operation, flexible bank architecture, and programmable timing parameters, it offers system designers a balance of performance, power efficiency, and design flexibility. The device's support for multiple burst modes and refresh options makes it suitable for a wide range of computing and embedded applications where reliable high-speed memory access is required.