PIC18C858-I/L Equivalent & Substitute Parts

Part Overview

The PIC18C858-I/L is an 8-bit microcontroller from Microchip Technology's PIC® 18C series, featuring 32KB OTP program memory, 1.5KB RAM, and 68 I/O pins in an 84-PLCC package. This device is actively produced and suitable for embedded applications requiring CANbus, I2C, SPI, and UART/USART connectivity with integrated peripherals including PWM, watchdog timer, and brown-out detection.

Substitute parts become necessary when design requirements shift toward higher program memory capacity, different memory technology (FLASH vs. OTP), alternative packaging formats, or when OTP inventory constraints require FLASH-based alternatives for production flexibility.

Substiute Parts

PIC18C858-I/L

Microchip TechnologyIn Stock: 995PIC18C858-I/L Datasheet

Current PartRFQ

PIC18F8585-I/PT

Microchip TechnologyIn Stock: 5767PIC18F8585-I/PT Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the PIC18C858-I/L is determined by the following critical parameters:

Core Compatibility Requirements:

• Processor family: PIC microcontroller architecture
• Core size: 8-bit processing capability
• Operating frequency: 40MHz maximum speed
• Voltage supply range: 4.2V ~ 5.5V compatibility
• I/O count: Minimum 68 pins to maintain pin-compatible functionality
• Operating temperature range: -40°C ~ 85°C

Memory Considerations:

• Program memory technology transition from OTP to FLASH is permissible when production volumes or design iterations require reprogrammability
• Program memory size may increase without functional impact on existing designs
• RAM and EEPROM capacity increases are backward compatible

Package Constraints:

• Surface mount technology requirement must be maintained
• Pin count and I/O configuration must support existing PCB layouts or allow controlled redesign

The PIC18F8585-I/PT qualifies as a substitute based on matching core processor architecture, identical operating frequency, compatible voltage supply range, equivalent I/O count, and identical temperature operating range. The transition from OTP to FLASH memory and from 84-PLCC to 80-TQFP packaging represents controlled design modifications within acceptable engineering parameters.

Parameter Comparison

Engineering Selection Recommendations

When to Select PIC18C858-I/L:

• Existing designs with 84-PLCC footprint and no PCB redesign budget
• Applications requiring OTP memory for cost optimization in high-volume production
• Designs where 16 ADC channels are required
• Pin-for-pin compatibility is mandatory

When to Select PIC18F8585-I/PT:

• Design iterations or prototype phases requiring firmware reprogrammability
• Applications benefiting from increased program memory (48KB vs. 32KB)
• Designs requiring additional RAM (3.25K vs. 1.5K) for complex algorithms
• New designs where 80-TQFP package footprint is acceptable
• Applications requiring EEPROM functionality
• Production environments where FLASH memory provides supply chain flexibility

Both devices maintain ROHS3 compliance and identical operating temperature ranges. The PIC18F8585-I/PT is Microchip Technology's manufacturer-recommended substitute, indicating full functional compatibility within the specified parameter constraints.

Frequently Asked Questions (FAQ)

Q: Can PIC18F8585-I/PT be used as a direct replacement without PCB modification?

A: No. The PIC18C858-I/L uses 84-PLCC packaging while the PIC18F8585-I/PT uses 80-TQFP packaging. These packages have different footprints, pin counts, and physical dimensions. PCB redesign is required for package substitution.

Q: What are the key differences between OTP and FLASH memory in these devices?

A: OTP (One-Time Programmable) memory in the PIC18C858-I/L is programmed once during manufacturing and cannot be reprogrammed. FLASH memory in the PIC18F8585-I/PT can be erased and reprogrammed multiple times, enabling firmware updates and development flexibility.

Q: Are the I/O pin counts identical between these devices?

A: Yes, both devices provide 68 I/O pins. However, the physical pin arrangement differs due to different package types (84-PLCC vs. 80-TQFP), requiring schematic and PCB redesign.

Q: Does the PIC18F8585-I/PT have sufficient memory for applications designed for the PIC18C858-I/L?

A: Yes. The PIC18F8585-I/PT provides 48KB program memory compared to 32KB in the PIC18C858-I/L, and 3.25KB RAM compared to 1.5KB. Existing firmware will operate with additional memory headroom.

Q: What is the impact of reduced ADC channels on substitution?

A: The PIC18C858-I/L provides 16 ADC channels while the PIC18F8585-I/PT provides 12 ADC channels. Applications using more than 12 ADC channels cannot substitute to the PIC18F8585-I/PT without design modification.

Q: Are both devices suitable for the same operating temperature range?

A: Yes, both devices operate across -40°C to 85°C, maintaining identical thermal specifications.

Q: What connectivity features differ between these devices?

A: Both support CANbus, I2C, SPI, and UART/USART. The PIC18F8585-I/PT additionally includes EBI/EMI (External Bus Interface/External Memory Interface) connectivity not present in the PIC18C858-I/L.