HM5225805B 256-Mbit SDRAM Technical Summary

Overview

The HM5225805B is a high-performance 256-Mbit Synchronous DRAM (SDRAM) component from Hitachi, organized as 8,388,608 words × 8 bits × 4 banks. This memory device is designed for applications requiring high-speed data transfer and efficient memory management. With its 3.3V power supply and LVTTL interface, it is suitable for a wide range of computing and embedded systems.

The device operates with a clock frequency of up to 133 MHz (or 100 MHz depending on the variant) and features a 54-pin plastic TSOP II package. All inputs and outputs are synchronized to the rising edge of the clock, ensuring reliable data transfer and timing consistency.

Features

• Memory Organization: 8,388,608 words × 8 bits × 4 banks (256 Mbit)
• Power Supply: 3.3V ± 0.3V
• Clock Frequency: Up to 133 MHz (max) or 100 MHz, depending on variant
• Interface: LVTTL-compatible
• Bank Operation: 4 independent banks for simultaneous access
• Burst Operation: Supports burst read/write and burst read/single write operations
• Programmable Burst Length: 1, 2, 4, or 8
• Burst Sequence Options: Sequential or interleave (selectable)
• CAS Latency: Programmable to 2 or 3 cycles
• Byte Control: Managed via DQM (Data Mask) signals
• Refresh Cycles: 8,192 refresh cycles every 64 ms
• Refresh Modes: Auto refresh and self-refresh

Applications

The HM5225805B is designed for use in a variety of high-performance applications, including:

• Computing Systems: Desktop PCs, workstations, and servers requiring high-speed memory access.
• Embedded Systems: Industrial control systems, networking equipment, and telecommunications devices.
• Graphics Processing: Video cards and display controllers where fast data throughput is critical.
• Consumer Electronics: High-end gaming consoles, set-top boxes, and digital TVs.
• Automotive Systems: Infotainment and advanced driver-assistance systems (ADAS).

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (V_DD): -0.5V to +4.6V
• Input Voltage (V_IN): -0.5V to V_DD + 0.5V
• Operating Temperature: 0°C to +70°C (commercial) or -40°C to +85°C (industrial)
• Storage Temperature: -55°C to +150°C

Recommended Operating Conditions

• Supply Voltage (V_DD): 3.3V ± 0.3V
• Input High Voltage (V_IH): 2.0V min
• Input Low Voltage (V_IL): 0.8V max
• Clock Frequency: 100 MHz or 133 MHz (depending on variant)

DC Characteristics

• Input Leakage Current (I_IN): ±1 μA max
• Output Leakage Current (I_OUT): ±1 μA max
• Operating Current (I_DD): 120 mA typ (at 133 MHz)
• Standby Current (I_SB): 20 mA typ

AC Characteristics

• Clock Cycle Time (t_CK): 7.5 ns (133 MHz) or 10 ns (100 MHz)
• CAS Latency (t_CL): 2 or 3 clock cycles (programmable)
• RAS to CAS Delay (t_RCD): 20 ns max
• Row Precharge Time (t_RP): 20 ns max
• Access Time (t_AC): 5.4 ns max (133 MHz)

Package Information

The HM5225805B is available in a standard 54-pin plastic TSOP II package. Key package details include:

• Package Type: TSOP II (Thin Small Outline Package)
• Pin Count: 54 pins
• Package Dimensions: 22.2 mm × 10.2 mm × 1.2 mm (typ)
• Pin Pitch: 0.8 mm
• Lead Material: Matte tin-plated copper alloy
• Moisture Sensitivity Level (MSL): MSL 3 (per IPC/JEDEC J-STD-020)

Pin Configuration

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

• Address Inputs (A0-A11): Row and column address inputs
• Bank Select (BA0, BA1): Bank address inputs
• Data Input/Output (DQ0-DQ7): 8-bit bidirectional data bus
• Clock (CLK): System clock input
• Clock Enable (CKE): Clock enable control
• Chip Select (CS): Chip select control
• RAS, CAS, WE: Command inputs (Row Address Strobe, Column Address Strobe, Write Enable)
• Data Mask (DQM): Controls byte masking during read/write operations
• Power (V_DD, V_SS): Power supply and ground pins

Ordering Information

The HM5225805B is available in multiple variants, differentiated by speed grade and operating temperature range. The ordering part number follows the format:

• HM5225805B-75: 133 MHz operation, commercial temperature range (0°C to +70°C)
• HM5225805B-A6: 100 MHz operation, commercial temperature range
• HM5225805B-B6: 100 MHz operation, industrial temperature range (-40°C to +85°C)