PIC16C55-RCE/SO - 8-Bit 4MHz OTP MCU 768B 28-SOIC | Microchip
MPN: PIC16C55-RCE/SO β Last Time Buy| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.2 | $7.20 |
| 10 | $6.48 | $64.80 |
| 100 | $5.76 | $576.00 |
| 500 | $5.18 | $2,590.00 |
| 1,000 | $4.61 | $4,610.00 |
PIC16C55-RCE/SO Overview
An OTP microcontroller is a variant of EPROM-based MCU where the program memory can be written exactly once at programming time, after which it behaves like masked-ROM silicon. Compared with flash-based MCUs, OTP parts offer lower per-unit cost at high volume, smaller silicon area, and stronger data retention because there is no charge pump or Fowler-Nordheim tunnel oxide to age. These advantages made the PIC16C5x family ubiquitous in late-1990s and early-2000s appliance, sensor, and consumer products where code stability was final on first programming.
The PIC16C55-RCE/SO executes most instructions in a single 250 ns cycle (4 MHz / 4) thanks to a 4-clock-per-instruction core, yielding roughly 4 MIPS peak throughput. The 33-instruction RISC set is highly orthogonal, the 8-level deep hardware stack simplifies interrupt-free subroutines, and the 12-bit instruction width yields a typical 2:1 code density advantage over competing 8-bit CISC MCUs. Two hardware timers (8-bit RTCC + WDT), a Power-On Reset (POR), and brown-out protection are integrated. There is no on-chip ADC, UART, or I2C peripheral; the device is intended as a glue controller in simple digital subsystems.
The 28-pin SOIC footprint matches the PIC16C55A and PIC16C55A-EP successors that offer expanded RAM (72 B vs 24 B) and higher oscillator options, allowing PCB-level drop-in migration. Pin 1 (RA2), pin 20 (Vss) and pin 28 (VDD) keep the same port assignments, and the external RC/HS/LP/XT oscillator pins (OSC1 / OSC2 / CLKOUT / CLKIN) remain fixed across the family, easing engineering change orders.
Typical applications include washing-machine user-interface boards, dishwasher cycle controllers, microwave oven keypads, hobby servomotor drivers, low-end thermostat logic, fan and pump speed controllers, and PC peripheral front panels. Designers also use it as a supervisor companion next to a host processor - the 20 mA sink/source capability on every I/O pin is sufficient to drive relays through a discrete transistor.
A key design consideration: OTP cannot be re-programmed in-circuit. Provision a stable prototype path using a windowed JW or a flash sibling (PIC16F54 in SOIC-28) for firmware iteration, then move to the OTP -RCE/SO for production. The /RC oscillator option (suffix 'RC') allows an external resistor/capacitor timing network and eliminates the cost of a crystal in cost-sensitive designs.
This page synthesizes distributor pricing, parametric comparisons against active family members, and practical design notes (oscillator trade-offs, OTP programming flow, migration path to PIC16C55A and PIC16F54) not aggregated in the manufacturer datasheet alone.
Drop-in alternatives for PIC16C55-RCE/SO β 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-RCE/SO (same form factor and footprint) β differing in Package, Program Memory Type, Timers, Program Memory Size, MSL Level.
Quick Comparison Tool β Select alternative parts for side-by-side comparison:
PIC16C55A-04I/SO
β Drop-Inπ Reference alternative (not in catalog)
PIC16C55A-20I/SO
β Drop-Inπ Reference alternative (not in catalog)
PIC16F54-I/SO
β Drop-Inπ Reference alternative (not in catalog)
PIC16C55-10I/SO
β Drop-Inβ In Stock
$1.18 / Unit
View Datasheet βPIC16C55-10/SO
β Drop-Inβ In Stock
$2.49 / Unit
View Datasheet βPIC16C554-04I/SO
β Drop-Inπ Reference alternative (not in catalog)
PIC16C55-RCE/SO Maximum Ratings & Electrical Characteristics
| Core | PIC 8-bit RISC (Harvard) |
| Instruction Set Architecture | 12-bit wide, 33 instructions |
| Program Memory Type | OTP (One-Time Programmable) EPROM |
| Program Memory Size | 768 bytes (512 x 12) |
| RAM Size | 24 bytes |
| EEPROM | None (not present on die) |
| Maximum CPU Clock Frequency | 4 MHz |
| Instruction Cycle Time | 250 ns (4 MHz / 4) |
| Supply Voltage (Vdd) | 3.0 V to 6.0 V |
| I/O Pins | 20 (PORTA 4-bit + PORTB 8-bit + PORTC 8-bit) |
| Timers | 1 x 8-bit RTCC + 1 x Watchdog Timer (WDT) |
| Peripherals | POR (Power-On Reset), WDT |
| ADC | None |
| Communication Interfaces | None (no UART, SPI, or I2C on-die) |
| Oscillator Modes | RC, LP, XT, HS (selected by suffix and configuration bits) |
| Operating Temperature Range | 0C to +70C (commercial; see suffix) |
| Package | 28-pin SOIC (SO) - narrow body, 7.50 mm |
| Mounting Type | Surface Mount |
| Lead Finish | Matte tin (Pb-free) per JEDEC J-STD-020 |
| MSL Level | 1 (unlimited floor life at <30C/85% RH) |
PIC16C55-RCE/SO Pin Configuration
| Pin 1 | RA2 β PORTA bit 2 (bidirectional digital I/O) |
| Pin 2 | RA3 β PORTA bit 3 (bidirectional digital I/O) |
| Pin 3 | RTCC β Real-Time Clock/Counter input (T0CKI) |
| Pin 4 | MCLR β Master Clear reset input (active low) |
| Pin 5 | VSS β Ground reference |
| Pin 6 | RB0 β PORTB bit 0 (bidirectional digital I/O) |
| Pin 7 | RB1 β PORTB bit 1 (bidirectional digital I/O) |
| Pin 8 | RB2 β PORTB bit 2 (bidirectional digital I/O) |
| Pin 9 | RB3 β PORTB bit 3 (bidirectional digital I/O) |
| Pin 10 | RB4 β PORTB bit 4 (bidirectional digital I/O) |
| Pin 11 | RB5 β PORTB bit 5 (bidirectional digital I/O) |
| Pin 12 | RB6 β PORTB bit 6 (bidirectional digital I/O) |
| Pin 13 | RB7 β PORTB bit 7 (bidirectional digital I/O) |
| Pin 14 | VSS β Ground reference |
| Pin 15 | OSC1 β Oscillator input (RC, XT, HS, LP modes) |
| Pin 16 | OSC2 β Oscillator output / CLKOUT |
| Pin 17 | RC0 β PORTC bit 0 (bidirectional digital I/O) |
| Pin 18 | RC1 β PORTC bit 1 (bidirectional digital I/O) |
| Pin 19 | RC2 β PORTC bit 2 (bidirectional digital I/O) |
| Pin 20 | RC3 β PORTC bit 3 (bidirectional digital I/O) |
| Pin 21 | RC4 β PORTC bit 4 (bidirectional digital I/O) |
| Pin 22 | RC5 β PORTC bit 5 (bidirectional digital I/O) |
| Pin 23 | RC6 β PORTC bit 6 (bidirectional digital I/O) |
| Pin 24 | RC7 β PORTC bit 7 (bidirectional digital I/O) |
| Pin 25 | VSS β Ground reference |
| Pin 26 | RA0 β PORTA bit 0 (bidirectional digital I/O) |
| Pin 27 | RA1 β PORTA bit 1 (bidirectional digital I/O) |
| Pin 28 | VDD β Positive supply voltage (3.0 V to 6.0 V) |
Typical Applications
PIC16C55-RCE/SO is suitable for 7 applications: Washing Machine and Dishwasher Cycle Controllers, Microwave Oven and Cooktop User Interface Boards, Low-End Thermostat and HVAC Fan Controllers, PC Peripheral Front Panels (Printer, Scanner, Router LEDs), Hobby Servo and RC Motor Drivers, Sensor Front-End and Signal Conditioning Modules, Toy and Educational Electronics.
Washing Machine and Dishwasher Cycle Controllers
The PIC16C55-RCE/SO fits appliance-control boards where firmware is fixed at first programming and cost-per-unit matters more than field re-programmability. The 4 MIPS throughput comfortably executes motor-timer state machines, water-level sequencing, and latched relay drive patterns, while 20 mA sink/source per pin drives triacs through MOC3021 optocouplers. The 4 MHz RC oscillator option eliminates the crystal cost in price-sensitive washer SKUs. Designers value the 28-SOIC footprint because it is shared with PIC16C55A drop-in upgrades that add 72-byte RAM.
Recommended
Microwave Oven and Cooktop User Interface Boards
Microwave keypads, LED indicators, and buzzer patterns map cleanly onto 20 digital I/O lines and the 8-bit RTCC timer. The PIC16C55-RCE/SO's 768-byte OTP holds the standard cooking-cycle code, and 24-byte RAM is sufficient for the cook-time buffer and current state. The Harvard 12-bit instruction width gives roughly 2:1 code density versus 8051 CISC, allowing longer preset menus without stepping up to PIC16C55A. The 28-SOIC footprint reflows reliably on the wave-solder-line consumer-appliance lines common in white-goods manufacturing.
Recommended
Low-End Thermostat and HVAC Fan Controllers
Residential thermostats typically sample temperature every 5-10 seconds, run a hysteresis control loop, and switch a relay. The PIC16C55-RCE/SO handles this loop in <5% of CPU time at 4 MHz, leaving the rest for debounced keypad scanning. The 24-byte RAM holds current setpoint, measured temperature, and relay state, while the 768-byte OTP holds the full state machine and NTC-thermistor linearization table. Industrial-grade (-40C to +85C) PIC16C55-10I/SO is the drop-in alternative for outdoor HVAC cabinets.
Recommended
PC Peripheral Front Panels (Printer, Scanner, Router LEDs)
Older PC peripherals use a small MCU to drive status LEDs, scan buttons, and respond to host commands over a proprietary 1-wire or UART link. The PIC16C55-RCE/SO drives 20 mA LEDs directly from PORTB pins and reads a 4 x 5 keypad matrix via PORTA/PORTC. The lack of on-die UART is compensated by bit-banged serial firmware. The 28-SOIC footprint is compatible with PIC16C55A when product variants need higher RAM for status logging.
Recommended
Hobby Servo and RC Motor Drivers
The PIC16C55-RCE/SO is widely used in hobby robotics to generate up to 8 simultaneous 50 Hz PWM servo-control signals from software loops and bit-banged timing. The 250 ns instruction cycle yields ~20 servo-position steps per millisecond, which exceeds standard RC servo resolution. The 24-byte RAM holds up to 8 servo targets and a main-loop counter, and the 20 I/O pins drive eight servos plus an enable line. The 28-SOIC is small enough for quadcopter flight-controller daughter boards.
Recommended
Sensor Front-End and Signal Conditioning Modules
Many industrial sensor modules use a PIC16C55-RCE/SO as a watchdog and lead-zero generator for an external ADC such as MCP3202. The MCU commands the ADC via SPI bit-banging, reads the result, and drives a 4-20 mA current loop. The 768-byte OTP holds the calibration table for the sensor range, and the 24-byte RAM holds the latest sample plus moving-average buffer. The 28-SOIC footprint reflows on the same line as 4-20 mA transmitter boards, and PIC16C55A is the drop-in when more RAM is needed for self-calibration sequences.
Recommended
Toy and Educational Electronics
Mass-market toys use the PIC16C55-RCE/SO because the OTP cost structure is the lowest in the Microchip 8-bit family, and the 28-SOIC is easily assembled by automated pick-and-place. Sound playback, motor sequencing, and LED animations fit comfortably in 768 bytes with 4 MIPS throughput. The wide 3.0 V to 6.0 V supply range accepts two, three, or four AA cells without a boost regulator, simplifying the BOM for educational-kits and entry-level consumer electronics.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55-RCE/SO β comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55A-04I/SO | PIC16C55A-20I/SO | PIC16F54-I/SO | PIC16C55-10I/SO | PIC16C55-10/SO | PIC16C554-04I/SO |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SOIC | 28-SOIC (same) | 28-SOIC (same) | 28-SOIC (same) | 28-SOIC (same) | 28-SOIC (same) | 28-SOIC (same) |
| Core | PIC16C5x 8-bit RISC | PIC16C5x 8-bit RISC (same) | PIC16C5x 8-bit RISC (same) | PIC16F5x 8-bit RISC flash | PIC16C5x 8-bit RISC (same) | PIC16C5x 8-bit RISC (same) | PIC16C55x 8-bit RISC (14-bit opcodes) |
| Program Memory | 768 B (512 x 12) OTP | 768 x 12 OTP (same) | 768 x 12 OTP (same) | 512 B flash (-33%) | 768 x 12 OTP (same) | 768 x 12 OTP (same) | 512 x 14 OTP (different op width) |
| RAM Size | 24 B | 72 B (+200%) | 72 B (+200%) | 25 B (+4%) | 24 B (same) | 24 B (same) | 80 B (+233%) |
| Maximum CPU Clock | 4 MHz (1 MIPS) | 4 MHz (same) | 20 MHz (+400%) | 20 MHz (+400%) | 4 MHz (same) | 4 MHz (same) | 4 MHz (same) |
| Operating Temperature | 0C to +70C | -40C to +85C (industrial) | -40C to +85C (industrial) | -40C to +85C (industrial) | -40C to +85C (industrial) | 0C to +70C (same) | -40C to +85C (industrial) |
| UART / ADC | None | None (same) | None (same) | None (same) | None (same) | None (same) | UART (added) |
Key Differentiators
- Larger RAM than -RCE variant only after upgrade to PIC16C55A (vs PIC16C55A-04I/SO)
- OTP is one-time programmable - flash alternative exists at lower cost (vs PIC16F54-I/SO)
- Industrial temperature grade sibling available in same footprint (vs PIC16C55-10I/SO)
Design Notes
Place a 100 nF ceramic decoupling capacitor within 5 mm of pin 28 (VDD), with a short trace to pin 5/14/25 VSS. PIC16C5x I/O transitions create ~20 mA current spikes from each PORTB/PORTC pin; an insufficient bypass causes VDD droop that can spuriously trigger brown-out or WDT resets. For motor-control boards sharing VDD with relay coils, add a 47 uF bulk electrolytic plus a series ferrite bead to the MCU supply rail. Estimated: 20 mA peak per pin x 8 simultaneously-switched pins = 160 mA peak step; 100 nF must recharge the rail between 1 us and 10 us.
OTP cells can be written exactly once. Never program a production part with development firmware - the part is bricked. For iteration, use a windowed JW package (PIC16C55/JW) or a flash sibling such as PIC16F54-I/SO. Verify programming socket alignment and supply levels (13.5 V Vpp for PIC16C5x) on a programmer like MPLAB PM3 before any production run. The 'RCE' suffix uses an external Crystal/Resonator oscillator and requires correct configuration-bit settings to enable the XT/HS/LP feedback network.
Route OSC1 and OSC2 traces as a short differential pair under 10 mm to prevent oscillator jitter. Place the crystal/resonator within 5 mm of the MCU and ground both leads through 10 pF to 33 pF capacitors. Avoid routing noisy digital signals under the oscillator area. For HS oscillator at 4 MHz or above, add a 100 ohm series resistor on OSC2 to dampen reflections. Keep RB and RC port-traces short to limit EMI radiation on edges switching simultaneously.
PIC16C5x does not support interrupts - the 33-instruction set is purely polled. Plan firmware as a cooperative round-robin state machine rather than relying on ISR handlers. Hardware stack is only 8 deep; recursion and deep nesting will crash. WDT is not disabled by default; set the WDTE configuration bit off if not used, or service the CLRWDT instruction within every 18 ms to 2.3 s window depending on the post-divider.
Compliance Information
Pb-free matte-tin lead finish per JEDEC J-STD-020; MSL 1 per J-STD-033. No AEC-Q100 automotive variant exists for PIC16C55-RCE/SO; for AEC-Q100 in 28-SOIC footprint, migrate to PIC16F54-I/SO or PIC16F886-I/SP automotive. REACH SVHC declared compliant per Microchip product declaration.
