AT87C51RB2-3CSUL Equivalent & Substitute Parts

Part Overview

The AT87C51RB2-3CSUL is an 8-bit microcontroller from Microchip Technology's 87C series, featuring 16KB OTP (One-Time Programmable) memory and a 40-pin DIP package. This device is classified as obsolete, making equivalent and substitute parts necessary for ongoing system support and new design implementations. The part operates across a wide supply voltage range of 2.7V to 5.5V and supports standard embedded system connectivity through UART/USART interfaces.

Key Parameters

Parameter	Value
Core Processor	80C51
Core Size	8-Bit
Program Memory Type	OTP
Program Memory Size	16KB (16K x 8)
RAM Size	512 x 8
Speed	30/20MHz
Voltage Supply (Vcc/Vdd)	2.7V ~ 5.5V
Number of I/O	32
Package Type	40-DIP (0.600", 15.24mm)
Operating Temperature	-40°C ~ 85°C
Mounting Type	Through Hole

Substitute Part Grouping Explanation

Substitution for the AT87C51RB2-3CSUL is determined by the following critical parameters: 80C51 core processor architecture, 8-bit core size, 16KB program memory capacity, 40-pin DIP package format, and compatible supply voltage range. The substitute parts maintain these core specifications while offering variations in program memory technology (OTP or FLASH), operating speed, RAM capacity, and temperature range.

The AT89C51RB2-3CSUM represents a direct functional upgrade within the Microchip 80C51 family, substituting OTP memory with FLASH technology and increasing operational speed. The DS87C520-MCL+ and DS87C520-MNL+ variants from Analog Devices Inc./Maxim Integrated provide 8051-compatible alternatives with OTP memory retention, maintaining the original memory technology while offering enhanced peripheral connectivity.

Parameter Comparison

Parameter	AT87C51RB2-3CSUL (Main)	AT89C51RB2-3CSUM	DS87C520-MCL+	DS87C520-MNL+
Manufacturer	Microchip Technology	Microchip Technology	Analog Devices Inc./Maxim Integrated	Analog Devices Inc./Maxim Integrated
Core Processor	80C51	80C51	8051	8051
Core Size	8-Bit	8-Bit	8-Bit	8-Bit
Program Memory Type	OTP	FLASH	OTP	OTP
Program Memory Size	16KB (16K x 8)	16KB (16K x 8)	16KB (16K x 8)	16KB (16K x 8)
RAM Size	512 x 8	1.25K x 8	1K x 8	1K x 8
Speed	30/20MHz	60MHz	33MHz	33MHz
Voltage Supply (Vcc/Vdd)	2.7V ~ 5.5V	2.7V ~ 5.5V	4.5V ~ 5.5V	4.5V ~ 5.5V
Number of I/O	32	32	32	32
Package Type	40-DIP (0.600", 15.24mm)	40-DIP (0.600", 15.24mm)	40-DIP (0.600", 15.24mm)	40-DIP (0.600", 15.24mm)
Operating Temperature	-40°C ~ 85°C	-40°C ~ 85°C	0°C ~ 70°C	-40°C ~ 85°C
Product Status	Obsolete	Active	Active	Active
RoHS Status	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

The AT89C51RB2-3CSUM is the primary substitute for new designs and system upgrades. This part maintains full compatibility with the AT87C51RB2-3CSUL pinout and package while offering FLASH memory technology for field reprogrammability, increased operational speed to 60MHz, and active product status with ongoing manufacturer support. Both parts comply with ROHS3 standards and operate across the same temperature range.

The DS87C520-MCL+ and DS87C520-MNL+ variants are suitable for applications requiring OTP memory retention and enhanced peripheral connectivity (EBI/EMI, SIO). The DS87C520-MNL+ maintains the full -40°C to 85°C temperature range of the original part, while the DS87C520-MCL+ operates within a narrower 0°C to 70°C range. Both DS87C520 variants require a minimum supply voltage of 4.5V, which may necessitate circuit modifications in systems designed for the 2.7V minimum of the AT87C51RB2-3CSUL.

Frequently Asked Questions (FAQ)

Q: Can the AT89C51RB2-3CSUM directly replace the AT87C51RB2-3CSUL?

A: Yes. Both parts share the 80C51 core processor, 8-bit architecture, 16KB program memory capacity, 32 I/O pins, and 40-pin DIP package. The AT89C51RB2-3CSUM operates at higher speed (60MHz vs. 30/20MHz) and uses FLASH memory instead of OTP, providing enhanced functionality while maintaining pin-for-pin compatibility.

Q: What is the key difference between OTP and FLASH memory in these microcontrollers?

A: OTP (One-Time Programmable) memory can be programmed once during manufacturing and cannot be erased or reprogrammed. FLASH memory can be erased and reprogrammed multiple times, offering flexibility for development, testing, and field updates. The AT89C51RB2-3CSUM uses FLASH, while the original AT87C51RB2-3CSUL and DS87C520 variants use OTP.

Q: Are there voltage supply considerations when substituting these parts?

A: Yes. The AT87C51RB2-3CSUL and AT89C51RB2-3CSUM operate across 2.7V to 5.5V. The DS87C520-MCL+ and DS87C520-MNL+ require a minimum of 4.5V. Systems designed for 2.7V operation must use the Microchip variants or implement voltage regulation to meet the 4.5V minimum for Analog Devices parts.

Q: Do all substitute parts support the same operating temperature range?

A: No. The AT87C51RB2-3CSUL, AT89C51RB2-3CSUM, and DS87C520-MNL+ all support -40°C to 85°C. The DS87C520-MCL+ operates within a narrower range of 0°C to 70°C. Applications requiring extended low-temperature operation must avoid the DS87C520-MCL+.

Q: What are the RAM capacity differences among these parts?

A: The AT87C51RB2-3CSUL provides 512 x 8 bytes of RAM. The AT89C51RB2-3CSUM offers 1.25K x 8 bytes, and both DS87C520 variants provide 1K x 8 bytes. Applications with high RAM requirements benefit from the increased capacity in the AT89C51RB2-3CSUM and DS87C520 variants.

Q: Are all parts RoHS compliant?

A: Yes. All four parts—AT87C51RB2-3CSUL, AT89C51RB2-3CSUM, DS87C520-MCL+, and DS87C520-MNL+—are ROHS3 compliant and REACH unaffected, meeting environmental and regulatory requirements for modern electronics manufacturing.

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