AT28HC64B-70PI Equivalent & Substitute Parts

Part Overview

The AT28HC64B-70PI is a 64Kbit parallel EEPROM memory IC manufactured by Microchip Technology in a 28-DIP package with 70 ns access time. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing system support and new design implementations. The device operates across the industrial temperature range of -40°C to 85°C with a 4.5V to 5.5V supply voltage.

Key Parameters

Parameter	Value
Memory Size	64Kbit
Memory Organization	8K x 8
Memory Format	EEPROM
Memory Interface	Parallel
Access Time	70 ns
Write Cycle Time	10 ms
Voltage Supply	4.5V ~ 5.5V
Operating Temperature	-40°C ~ 85°C
Package Type	28-DIP
Mounting Type	Through Hole

Substitute Part Grouping Explanation

Substitution for the AT28HC64B-70PI is determined by the following critical parameters:

Memory capacity (64Kbit) and organization (8K x 8)
Parallel interface architecture
Supply voltage compatibility (4.5V ~ 5.5V)
Operating temperature range (-40°C ~ 85°C)
Package compatibility (28-DIP for through-hole mounting)

The substitute parts identified maintain these core electrical and mechanical specifications. Access time variations (70 ns, 90 ns, 120 ns) are acceptable within the same memory family, as faster access times are backward compatible with designs specified for slower devices. Package format differences (28-DIP versus 28-SOIC) represent distinct substitution paths based on mounting requirements.

Parameter Comparison

Parameter	AT28HC64B-70PI	AT28HC64B-90SU	X28HC64PIZ-12	X28HC64PZ-12
Manufacturer	Microchip Technology	Microchip Technology	Renesas Electronics	Renesas Electronics
Memory Size	64Kbit	64Kbit	64Kbit	64Kbit
Memory Organization	8K x 8	8K x 8	8K x 8	8K x 8
Memory Format	EEPROM	EEPROM	EEPROM	EEPROM
Memory Interface	Parallel	Parallel	Parallel	Parallel
Access Time	70 ns	90 ns	Not specified	120 ns
Write Cycle Time	10 ms	10 ms	Not specified	5 ms
Voltage Supply	4.5V ~ 5.5V	4.5V ~ 5.5V	5V	4.5V ~ 5.5V
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	Not specified	0°C ~ 70°C
Package Type	28-DIP	28-SOIC	28-DIP	28-DIP
Mounting Type	Through Hole	Surface Mount	Through Hole	Through Hole
Product Status	Obsolete	Active	Active	Active
RoHS Status	Non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

AT28HC64B-90SU is the manufacturer-recommended substitute from Microchip Technology. This part maintains identical electrical specifications and temperature range while offering improved product status (Active) and ROHS3 compliance. The primary design consideration is the package change from 28-DIP (through-hole) to 28-SOIC (surface mount), requiring PCB layout modification.

X28HC64PIZ-12 and X28HC64PZ-12 are Renesas Electronics alternatives that preserve the 28-DIP through-hole package format, eliminating PCB redesign requirements. Both parts are active products with ROHS3 compliance. The X28HC64PZ-12 offers a faster write cycle time (5 ms versus 10 ms) but operates within a narrower temperature range (0°C ~ 70°C), making it unsuitable for applications requiring the full -40°C ~ 85°C industrial temperature specification of the original part.

Selection between these substitutes depends on whether PCB layout modification is acceptable and whether the operating temperature range of the target application aligns with the available options.

Frequently Asked Questions (FAQ)

Q: Can AT28HC64B-90SU directly replace AT28HC64B-70PI in existing designs?

A: Electrical substitution is valid. The 90 ns access time is slower than the original 70 ns specification but maintains full backward compatibility. PCB layout modification is required due to the package change from 28-DIP to 28-SOIC.

Q: What is the difference between the Microchip and Renesas substitute options?

A: AT28HC64B-90SU uses surface-mount packaging (28-SOIC), while X28HC64PIZ-12 and X28HC64PZ-12 retain through-hole packaging (28-DIP). Microchip's part maintains the original temperature range; Renesas' X28HC64PZ-12 operates only to 70°C.

Q: Are all substitute parts RoHS compliant?

A: Yes. All three substitute parts carry ROHS3 compliance certification. The original AT28HC64B-70PI is RoHS non-compliant.

Q: Which substitute is recommended for industrial temperature applications?

A: AT28HC64B-90SU or X28HC64PIZ-12 both support the full -40°C ~ 85°C range. X28HC64PZ-12 is limited to 0°C ~ 70°C and is not suitable for extended industrial temperature requirements.

Q: What is the inventory status of these substitutes?

A: AT28HC64B-90SU: 1330 pcs in stock. X28HC64PIZ-12: 5200 pcs in stock. X28HC64PZ-12: 2050 pcs in stock.

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