Hitachi HM6264B 64k-bit Static RAM (8k x 8)

Overview

The Hitachi HM6264B is a high-performance 64k-bit static random-access memory (SRAM) organized as 8,192 words by 8 bits. Manufactured using advanced 1.5 µm CMOS process technology, this device delivers superior performance while maintaining low power consumption. The HM6264B is designed for applications requiring fast, reliable memory with simple interfacing requirements.

Available in multiple package options including 450 mil SOP (with fine pitch width), 600 mil plastic DIP, and 300 mil plastic DIP, the HM6264B offers flexibility for various mounting density requirements. Its completely static operation eliminates the need for clock signals or complex timing strobes, making it ideal for both high-performance and low-power applications.

Key Features

• High-Speed Operation: Fast access times of 85 ns or 100 ns (maximum) depending on variant
• Ultra-Low Power Consumption:
  • Standby mode: 10 µW (typical)
  • Active operation: 15 mW (typical) at 1 MHz
• Single Power Supply: Operates from a single 5V ±10% power source
• Fully Static Design: Requires no refresh cycles or clock signals
• Symmetric Timing: Equal access and cycle times for simplified system design
• Three-State Output: Common data input/output with high-impedance state
• TTL Compatibility: All inputs and outputs directly interface with TTL logic levels
• Battery Backup Capable: Designed for reliable operation in battery-backed systems

Applications

The HM6264B is suitable for a wide range of applications requiring moderate-density, high-speed static RAM:

• Embedded systems and microcontroller-based designs
• Industrial control systems
• Telecommunications equipment
• Medical instrumentation
• Automotive electronics
• Battery-powered portable devices
• Cache memory for legacy systems
• Data logging equipment
• Test and measurement instruments
• Point-of-sale terminals

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (Vcc): -0.3V to +7V
• Input Voltage: -0.3V to Vcc + 0.3V
• Operating Temperature Range: 0°C to +70°C (commercial)
• Storage Temperature Range: -55°C to +125°C

Recommended Operating Conditions

• Supply Voltage (Vcc): 4.5V to 5.5V
• Input High Voltage (VIH): 2.2V min (Vcc = 4.5V)
• Input Low Voltage (VIL): 0.8V max (Vcc = 4.5V)
• Operating Temperature: 0°C to +70°C

DC Characteristics (TA = 0°C to 70°C, Vcc = 5V ±10%)

• Input Leakage Current (II): ±1 µA max
• Output Leakage Current (IOZ): ±1 µA max
• Supply Current (Active, f=1MHz): 3 mA max
• Supply Current (Standby, CMOS level): 10 µA max
• Supply Current (Standby, TTL level): 1 mA max

AC Characteristics

• Read Cycle Time (tRC): 85/100 ns (depending on speed grade)
• Access Time (tAA): 85/100 ns max
• Chip Enable to Output Valid (tACE): 85/100 ns max
• Output Enable to Output Valid (tOE): 35 ns max
• Chip Enable to Power-Up (tPU): 0 ns min
• Chip Enable to Power-Down (tPD): 30 ns max
• Write Cycle Time (tWC): 85/100 ns min
• Write Pulse Width (tWP): 75/90 ns min
• Data Setup Time (tDS): 40 ns min
• Data Hold Time (tDH): 0 ns min

Package Information

The HM6264B is available in three package options to accommodate different design requirements:

28-pin Plastic DIP (600 mil)

• Package Code: DIP28-P-600
• Body Size: 36.0mm x 13.8mm
• Lead Pitch: 2.54mm (100 mil)
• Lead Count: 28

28-pin Plastic DIP (300 mil)

• Package Code: DIP28-P-300
• Body Size: 36.0mm x 7.62mm
• Lead Pitch: 2.54mm (100 mil)
• Lead Count: 28

28-pin SOP (450 mil)

• Package Code: SOP28-P-450
• Body Size: 17.9mm x 7.5mm
• Lead Pitch: 1.27mm (50 mil)
• Lead Count: 28

Functional Description

The HM6264B features a standard SRAM architecture with eight data input/output lines (I/O0-I/O7), thirteen address inputs (A0-A12), and three control inputs: Chip Enable (CE), Output Enable (OE), and Write Enable (WE). The memory array is organized as 8,192 words of 8 bits each, providing 64 kilobits of storage capacity.

When CE is high, the device enters standby mode, reducing power consumption. During read operations, both CE and OE must be active (low) to enable the output buffers. Write operations are controlled by WE, which must be held low while CE is active and valid address and data are present.

Ordering Information

The HM6264B is available in different speed grades and package options. The complete ordering information is as follows:

• HM6264B-85: 85 ns access time
• HM6264B-100: 100 ns access time

Package options are specified by suffix:

• -P: Plastic DIP (600 mil)
• -P3: Plastic DIP (300 mil)
• -S: SOP (450 mil)

Design Considerations

When implementing the HM6264B in a system design, consider the following:

• Proper decoupling: Place 0.1 µF ceramic capacitors close to the Vcc pins
• Signal integrity: Maintain clean address and control signals, especially in high-speed systems
• Power management: Utilize the chip enable feature to minimize power consumption when the memory is not in use
• Bus contention: Ensure proper timing between output enable and chip enable signals to prevent bus conflicts
• Battery backup: When used in battery-backed applications, ensure proper power switching circuitry