PIC16C55-LP/P - 8-Bit 40MHz OTP MCU 768B | Microchip | DIP-28
MPN: PIC16C55-LP/P ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.4486 | $2.45 |
| 10 | $2.2 | $22.00 |
| 100 | $1.95 | $195.00 |
| 500 | $1.7 | $850.00 |
| 1,000 | $1.45 | $1,450.00 |
PIC16C55-LP/P Overview
An 8-bit microcontroller is a single-chip computer containing a CPU, program memory, data RAM, and programmable I/O peripherals on one die. Within the broader semiconductor taxonomy, the PIC16C55 belongs to the hierarchy: microcontroller -> embedded MCU -> 8-bit MCU -> CMOS RISC microcontroller -> semiconductor IC. The PIC16C5X family uses a Harvard architecture with separate program and data buses, enabling simultaneous instruction fetch and data access for higher throughput.
Key features include 20 I/O pins, an 8-bit real-time clock/counter (TMR0) with an 8-bit prescaler, a watchdog timer (WDT) with its own on-chip RC oscillator for reliable operation, power-on reset (POR), and a two-level hardware stack. The OTP program memory allows one-time field programming via Microchip device programmers such as the MPLAB PM3, making the part suitable for prototype and low-volume production runs.
The PIC16C55 employs an enhanced CMOS process with fully static design, meaning the clock can be stopped without losing internal register state - a feature useful for power-sensitive applications. Its RISC architecture with only 33 single-word instructions and mostly single-cycle execution provides deterministic timing suitable for real-time control. The 12-bit instruction word delivers approximately 2:1 code compression over competing 8-bit architectures.
Typical applications include appliance control, automotive body electronics, industrial control logic, sensor signal conditioning, low-cost consumer products, and legacy embedded systems. The wide operating temperature range and OTP memory make it well-suited to cost-sensitive, fixed-function embedded products.
When designing with this part, consider that OTP memory cannot be reprogrammed, so code must be fully validated before committing to production. For new designs, Microchip recommends flash-based PIC16F successors such as the PIC16F54 for drop-in compatibility and re-programmability.
This page consolidates distributor pricing, drop-in alternatives, parametric comparisons and practical design notes to help engineers rapidly evaluate the PIC16C55-LP/P for both new designs and legacy maintenance scenarios.
Drop-in alternatives for PIC16C55-LP/P — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with PIC16C55-LP/P (same form factor and footprint) — differing in Package, Maximum Clock Frequency, Mounting Type, Program Memory Size, Number of Instructions.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55-HS/P
✅ Drop-In✓ In Stock
$3.95 / Unit
View Datasheet →PIC16C55-10/P
✅ Drop-In✓ In Stock
$3.65 / Unit
View Datasheet →PIC16C55/JW
✅ Drop-In✓ In Stock
$10.4 / Unit
View Datasheet →PIC16F54-I/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C55A-20I/P
✅ Drop-In✓ In Stock
$1.6 / Unit
View Datasheet →PIC16C554-04/P
✅ Drop-In✓ In Stock
$2.85 / Unit
View Datasheet →PIC16C55-LP/P Maximum Ratings & Electrical Characteristics
| Core | PIC16C5X 8-bit RISC |
| Instruction Set Architecture | 12-bit wide instructions, Harvard |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 768 B (512 x 12-bit words) |
| Data RAM | 24 B |
| Maximum Clock Frequency | 40 MHz |
| Oscillator Type (LP suffix) | Low-power external RC/crystal |
| Number of I/O Pins | 20 |
| Timers | 1 x 8-bit (TMR0) with 8-bit prescaler |
| Watchdog Timer (WDT) | Yes, with on-chip RC oscillator |
| Power-On Reset (POR) | Yes |
| Hardware Stack | 2 levels |
| Addressing Modes | Direct, Indirect, Relative |
| Number of Instructions | 33 single-word |
| Package | 28-pin PDIP (DIP-28, 0.6 inch width) |
| Mounting Type | Through-Hole |
PIC16C55-LP/P Pin Configuration
| Pin 1 | RA2 — Port A bit 2 (bidirectional I/O) |
| Pin 2 | RA3 — Port A bit 3 (bidirectional I/O) |
| Pin 3 | RA4/T0CKI — Port A bit 4 / Timer0 clock input |
| Pin 4 | MCLR — Master clear (reset) input, active low |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — Port B bit 0 / external interrupt input |
| Pin 7 | RB1 — Port B bit 1 (bidirectional I/O) |
| Pin 8 | RB2 — Port B bit 2 (bidirectional I/O) |
| Pin 9 | RB3 — Port B bit 3 (bidirectional I/O) |
| Pin 10 | RB4 — Port B bit 4 (bidirectional I/O) |
| Pin 11 | RB5 — Port B bit 5 (bidirectional I/O) |
| Pin 12 | RB6 — Port B bit 6 (bidirectional I/O) |
| Pin 13 | RB7 — Port B bit 7 (bidirectional I/O) |
| Pin 14 | VSS — Ground reference (second VSS) |
| Pin 15 | OSC1 — Oscillator input (LP crystal/RC) |
| Pin 16 | OSC2 — Oscillator output (LP crystal/RC) |
| Pin 17 | RC0 — Port C bit 0 (bidirectional I/O) |
| Pin 18 | RC1 — Port C bit 1 (bidirectional I/O) |
| Pin 19 | RC2 — Port C bit 2 (bidirectional I/O) |
| Pin 20 | RC3 — Port C bit 3 (bidirectional I/O) |
| Pin 21 | RC4 — Port C bit 4 (bidirectional I/O) |
| Pin 22 | RC5 — Port C bit 5 (bidirectional I/O) |
| Pin 23 | RC6 — Port C bit 6 (bidirectional I/O) |
| Pin 24 | RC7 — Port C bit 7 (bidirectional I/O) |
| Pin 25 | RA0 — Port A bit 0 (bidirectional I/O) |
| Pin 26 | RA1 — Port A bit 1 (bidirectional I/O) |
| Pin 27 | VDD — Positive supply voltage |
| Pin 28 | VDD — Positive supply voltage (second VDD) |
Typical Applications
PIC16C55-LP/P is suitable for 6 applications: Appliance Control, Automotive Body Electronics, Industrial Control Logic, Sensor Signal Conditioning, Low-Cost Consumer Products, Legacy Embedded Maintenance.
Appliance Control
The PIC16C55-LP/P suits appliance control boards where fixed firmware and low unit cost dominate the BOM. The 20 I/O pins directly drive relays, triacs, LEDs and seven-segment displays, while TMR0 plus watchdog timer manage washing-machine timing, microwave duty cycles and HVAC fan control. The 40 MHz LP clock reaches 10 MHz LP-range operation with deterministic single-cycle instructions, ideal for closed-loop PID loops. Designers pair it with the ULN2003 driver array, and choose OTP for sub-$0.50 firmware cost at 100k+ volume.
Recommended
Automotive Body Electronics
Legacy automotive body modules - seat controllers, window lifters, mirror adjusters, simple lighting controllers - were designed around the PIC16C55-LP/P. Its wide operating voltage tolerates 12 V automotive rails with proper regulation, while the watchdog timer with on-chip RC oscillator provides the autonomous fault recovery demanded by ISO 7637 transient environments. The LP oscillator driver suits the low-frequency clocks used in body modules. Engineers maintain these products via PIC16F54 migration or PIC16C55-HS/P for higher-speed variants.
Recommended
Industrial Control Logic
Factory-floor PLCs, motor starters and conveyor controllers historically leveraged the PIC16C55-LP/P for fixed-function glue logic. Its deterministic instruction timing executes deterministic control loops without RTOS overhead, while 20 I/O bits interface to opto-isolated inputs and zero-cross triac outputs. The two-level hardware stack limits subroutine depth but matches ladder-logic replacement applications. Designers replace it with PIC16F54-I/P for in-system reprogrammability in calibration/test fixtures.
Recommended
Sensor Signal Conditioning
Simple sensor signal-conditioning boards - thermocouple cold-junction compensation, RTD linearization, bridge excitation - use the PIC16C55-LP/P for fixed lookup-table conversion. With TMR0 capturing period/frequency inputs and 20 I/O driving MUX/PGAs, the part delivers calibrated analog outputs to higher-level controllers. The 768-byte OTP stores calibration coefficients unique to each sensor batch. Maintain production by stocking PIC16C55-LP/P or migrating to PIC16F54-I/P.
Recommended
Low-Cost Consumer Products
Toy controllers, remote controls, fitness bands and disposable medical blister-pack electronics rely on the PIC16C55-LP/P for sub-$1 BOM cost with adequate compute. The LP oscillator draws minimal current from coin-cell or AAA batteries; the on-chip watchdog keeps firmware responsive during battery droop. Although obsolete, Microchip authorized distributors still supply PIC16C55-LP/P for these legacy high-volume products where redesign cost exceeds ongoing part cost.
Recommended
Legacy Embedded Maintenance
Repair depots and long-life programs (medical, aerospace, industrial) maintain installed PIC16C55-LP/P based boards for 15-25 year service windows. The PIC16C55-LP/P remains the only authentic replacement for these designs; the PIC16F54-I/P serves as a flash-based substitute when the firmware is updated. Stockpile PIC16C55-LP/P at OEM-quantity pricing for repair inventory and consider Microchip's product-change notification system for last-time-buy opportunities.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55-LP/P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55-HS/P | PIC16C55-10/P | PIC16F54-I/P | PIC16C55A-20I/P |
|---|---|---|---|---|---|
| Package | 28-pin PDIP (DIP-28) | 28-pin PDIP (DIP-28) - same | 28-pin PDIP (DIP-28) - same | 28-pin PDIP (DIP-28) - same | 28-pin PDIP (DIP-28) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory Type | OTP (768 B / 512 x 12-bit) | OTP (768 B) - same | OTP (768 B) - same | Flash (768 B) - reprogrammable | OTP (768 B) |
| Maximum Clock Frequency | 40 MHz (LP oscillator) | 40 MHz (HS oscillator) | 10 MHz | 20 MHz | 20 MHz |
| Data RAM | 24 B | 24 B | 24 B | 25 B | 24 B |
| Number of I/O Pins | 20 | 20 | 20 | 20 | 20 |
| Watchdog Timer | Yes (on-chip RC osc) | Yes | Yes | Yes | Yes |
| Memory Type (Reprogrammable?) | No (OTP) | No (OTP) | No (OTP) | Yes (Flash, 1000+ cycles) | No (OTP) |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Active | Obsolete |
Key Differentiators
- Active lifecycle vs obsolete PIC16C5X OTP family (vs PIC16C55-LP/P (itself))
- Reprogrammable flash memory vs OTP (vs PIC16C55-LP/P)
- Same 28-pin PDIP footprint across all PIC16C5X family members (vs PIC16C55-HS/P and PIC16C55-10/P)
Design Notes
The PIC16C55-LP/P is optimized for low-power operation; the LP oscillator driver supports crystal frequencies from DC to ~200 kHz, drawing minimal quiescent current. Estimated: at 32 kHz LP crystal with all peripherals disabled, the part draws < 15 uA from VDD (per typical PIC16C5X family characteristics). For battery-powered designs, ensure MCLR is tied to VDD via 10 kohm and the watchdog timer is enabled with a long prescaler to maximize sleep-mode recovery. When upgrading to PIC16F54-I/P, the sleep current is typically < 100 nA.
Place the LP-mode crystal or ceramic resonator within 0.25 inch (6 mm) of the OSC1/OSC2 pins to minimize parasitic capacitance. For RC-oscillator mode, place the timing resistor and capacitor close to OSC1 with the capacitor return trace short and direct to the VSS pin. Add a 0.1 uF decoupling capacitor between VDD (pin 27 or 28) and VSS (pin 14) within 0.1 inch of the IC. A bulk 10 uF electrolytic cap on the VDD rail handles motor/relay switching transients.
Critical pitfall: OTP memory cannot be erased or rewritten. Once programmed, any firmware bug requires physical device replacement, so production-volume PCBs must use sockets or buy-and-rework flow. Another pitfall: the LP oscillator suffix is unsuitable for designs above ~200 kHz clock - using a high-frequency crystal with LP driver fails startup. Always verify the suffix matches your oscillator frequency: LP (low-power, DC-200 kHz), XT (200 kHz-4 MHz), HS (4-40 MHz). Migration tip: PIC16F54-I/P accepts the same crystal frequencies with broader driver support.
Compliance Information
Original PIC16C55-LP/P is not lead-free / not RoHS compliant (pre-RoHS OTP design). For RoHS-compliant drop-in replacements in the same footprint, choose PIC16F54-I/P. PIC16C55A variants may have RoHS-compliant lead-free options; verify per-lot before ordering.
