PIC16C55-10I/SS - 8-bit OTP MCU, 768B, 20 I/O, 10MHz, SSOP-28
MPN: PIC16C55-10I/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.67 | $4.67 |
| 10 | $4.2 | $42.00 |
| 100 | $3.65 | $365.00 |
| 500 | $3.1 | $1,550.00 |
| 1,000 | $2.55 | $2,550.00 |
PIC16C55-10I/SS Overview
A baseline 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, RAM, program memory, and I/O peripherals. The PIC16C5x baseline sits at the entry level of Microchip's PIC16 hierarchy (PIC16C5x baseline -> PIC16F mid-range -> PIC16 enhanced mid-range), providing the smallest pin count and memory footprint for cost-sensitive embedded control. The baseline architecture offers deterministic instruction timing (most instructions execute in one cycle) and a RISC-style instruction set, making it approachable for simple state-machine and control tasks where a full mid-range PIC16F would be overkill.
Key features of the PIC16C55-10I/SS include an 8-bit real-time clock/counter (TMR0) with a programmable prescaler, a watchdog timer for reliable operation, direct/indirect/relative addressing modes for both data and instructions, power-on reset, and an OTP program memory that is user-programmed once and cannot be erased - this suits low-cost, fixed-function products. The 20 I/O pins can source/sink up to 25 mA per pin, enabling direct drive of LEDs, optocouplers, and small relays.
Architecturally, the device uses a Harvard memory layout (separate program and data buses) and a fixed instruction set of approximately 33 opcodes. The OTP cell technology keeps per-unit cost low and programming fast, while the industrial temperature grade allows deployment in factory automation, automotive aftermarket, and outdoor equipment. Programming is supported through the Microchip MPLAB PM3 Universal Device Programmer.
Typical applications include appliance control boards, simple sensor interfaces, LED driving, hobby and education platforms, and low-cost consumer products. In an HVAC thermostat, for example, the 20 I/O lines can scan a keypad, drive a multiplexed LCD, read thermistor dividers, and switch a relay - all without external memory. The 10 MHz clock rate provides roughly 5 MIPS, sufficient for sampling rates up to ~250 kHz with polling-based firmware.
When designing with this part, remember that OTP cannot be reprogrammed during development - use a windowed (JW) or EPROM variant for prototyping and reserve the OTP PIC16C55 for production. Also note that the PIC16C55 is now considered an older part, so check Microchip's PCN list for any last-time-buy or EOL status before committing to a new design. This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found on the Microchip datasheet.
Drop-in alternatives for PIC16C55-10I/SS — 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 PIC16C55-10I/SS (same form factor and footprint) — differing in Program Memory Size, Package, Timers, Program Memory Type, Watchdog Timer.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55A-04I/SS
✅ Drop-In✓ In Stock
$2.22 / Unit
View Datasheet →PIC16C55T-10I/SS
✅ Drop-In✓ In Stock
$1.92 / Unit
View Datasheet →PIC16F54-I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C55-10I/SS Maximum Ratings & Electrical Characteristics
| Manufacturer | Microchip Technology |
| Series | PIC16C5x Baseline |
| Core Architecture | 8-bit RISC |
| Program Memory Type | OTP (One-Time-Programmable) |
| Program Memory Size | 768 bytes |
| RAM Size | 24 bytes |
| Maximum CPU Frequency | 10 MHz |
| Supply Voltage Range | 4.5 V to 5.5 V |
| Number of I/O Pins | 20 |
| Timers | 1 x 8-bit (TMR0) |
| Hardware Stack | 2 levels |
| Instruction Set | 12-bit wide, ~33 opcodes |
| Temperature Grade | Industrial (-40C to +85C) |
| Package | 28-pin SSOP (5.30 mm width) |
| Mounting Type | Surface Mount (Gull-wing) |
| I/O Sink/Source Current | 25 mA per pin |
| RoHS Status | Compliant |
PIC16C55-10I/SS Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O port A bit 2 |
| Pin 2 | RA1 — Bidirectional I/O port A bit 1 |
| Pin 3 | RA0 — Bidirectional I/O port A bit 0 |
| Pin 4 | /MCLR — Master Clear (active-low reset input) |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0 — Bidirectional I/O port B bit 0 |
| Pin 7 | RB1 — Bidirectional I/O port B bit 1 |
| Pin 8 | RB2 — Bidirectional I/O port B bit 2 |
| Pin 9 | RB3 — Bidirectional I/O port B bit 3 |
| Pin 10 | RB4 — Bidirectional I/O port B bit 4 |
| Pin 11 | RB5 — Bidirectional I/O port B bit 5 |
| Pin 12 | RB6 — Bidirectional I/O port B bit 6 |
| Pin 13 | RB7 — Bidirectional I/O port B bit 7 |
| Pin 14 | VSS — Ground reference |
| Pin 15 | RC0 — Bidirectional I/O port C bit 0 |
| Pin 16 | RC1 — Bidirectional I/O port C bit 1 |
| Pin 17 | RC2 — Bidirectional I/O port C bit 2 |
| Pin 18 | RC3 — Bidirectional I/O port C bit 3 |
| Pin 19 | RC4 — Bidirectional I/O port C bit 4 |
| Pin 20 | VDD — Positive supply voltage (4.5V-5.5V) |
| Pin 21 | RC5 — Bidirectional I/O port C bit 5 |
| Pin 22 | RC6 — Bidirectional I/O port C bit 6 |
| Pin 23 | RC7 — Bidirectional I/O port C bit 7 |
| Pin 24 | VSS — Ground reference |
| Pin 25 | RA3 — Bidirectional I/O port A bit 3 |
| Pin 26 | OSC1 — Oscillator input |
| Pin 27 | OSC2 — Oscillator output |
| Pin 28 | RA4 — Bidirectional I/O port A bit 4 / T0CKI |
Typical Applications
PIC16C55-10I/SS is suitable for 6 applications: Appliance Control Boards, Simple Sensor Interface Modules, LED Display Drivers, Hobby and Education Platforms, Low-Cost Consumer Products, Industrial Timing and Relay Control.
Appliance Control Boards
The PIC16C55-10I/SS suits appliance control boards (washing machines, microwave ovens, dishwashers) thanks to its 20 I/O pins and 25 mA per-pin drive. Each I/O can directly sink the coil current of a small relay or the segment of an LED display, removing the need for external drivers. The 768-byte OTP holds a fixed state machine for the appliance's button matrix, timing loops, and safety interlocks. The 10 MHz / 5 MIPS throughput is more than adequate for keypad debounce, multiplexed 7-segment scanning at 100+ Hz, and triac zero-crossing delays. Industrial temperature grade (-40C to +85C) tolerates the heat inside an appliance cabinet.
Recommended
Simple Sensor Interface Modules
For low-cost sensor interface modules (temperature, humidity, contact closure), the PIC16C55-10I/SS integrates analog signal conditioning via its digital I/O and TMR0 timer without needing a separate ADC. A thermistor divider can be read using a discrete RC charge-time technique on one I/O pin, achieving effective 8-bit resolution at 10 MHz. The 24 bytes of RAM accommodate 8 to 12 sensor samples plus a moving average, while 768 bytes of OTP store calibration tables and Modbus-like UART framing. The 5V supply matches typical industrial sensor rails, and the 20 I/Os allow multi-channel scanning or 4-20 mA loop interfacing.
Recommended
LED Display Drivers
With 20 I/O pins each capable of 25 mA, the PIC16C55-10I/SS can directly drive a multiplexed 4-digit 7-segment LED display plus indicator LEDs without any external driver IC. Time-multiplexing the digits at 100 Hz avoids visible flicker while the baseline core's deterministic single-cycle instructions keep refresh timing precise. The 768-byte OTP holds custom font tables, blinking patterns, and brightness PWM via TMR0 interrupts. This eliminates external UDN2981 or similar source drivers, cutting BOM cost and board area in consumer products and panel meters.
Recommended
Hobby and Education Platforms
The PIC16C55-10I/SS is well suited to hobby and education platforms because its 33-opcode PIC16C5x instruction set is small enough to teach RISC fundamentals in a single semester. The 10 MHz clock and 768-byte OTP let students build blinking-LED projects, motor-PWM exercises, and UART demos without external memory. The 28-pin SSOP is breadboard-friendly via SSOP-to-DIP adapter boards, and the industrial temperature range tolerates classroom lab conditions. Programming via the MPLAB PM3 supports a learning path from hand-coded assembly through C compilers.
Recommended
Low-Cost Consumer Products
For ultra-low-cost consumer products (novelty gadgets, single-function remote controls, electronic candles), the PIC16C55-10I/SS's OTP memory minimizes per-unit programming cost compared to flash MCUs because the silicon area per bit is smaller. The 768-byte program space is enough for fixed-function firmware such as IR transmission sequences or fixed blink patterns. Twenty I/O pins drive 4-5 buttons plus multiple LEDs, and the 4.5-5.5V supply runs from a single CR2032 with boost or from 2xAA cells. Industrial temperature grade supports indoor and mild outdoor use.
Recommended
Industrial Timing and Relay Control
In industrial timer and relay-control cabinets, the PIC16C55-10I/SS provides deterministic timing using TMR0 with a programmable prescaler, replacing legacy 555-based timer boards with a single chip. Twenty I/O lines can switch up to 10 relays (using two I/O per relay coil via transistors), monitor limit switches, and drive status LEDs. The hardware watchdog timer and power-on reset ensure recovery from brownouts in 24V industrial control cabinets. Industrial -40C to +85C operation tolerates factory floor temperatures, and the SSOP-28 surface-mount package simplifies conformal-coated PCB assembly.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55-10I/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55-10I/SO | PIC16C55A-04I/SS | PIC16C55T-10I/SS | PIC16C55-10/SP | PIC16F54-I/SS |
|---|---|---|---|---|---|---|
| Package | SSOP-28 (5.30 mm) | SOIC-28 (7.50 mm) - different footprint | SSOP-28 (5.30 mm) - same | SSOP-28 (5.30 mm) - same | SPDIP-28 through-hole - different footprint | SSOP-28 (5.30 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Max CPU Frequency | 10 MHz | 10 MHz | 4 MHz | 10 MHz | 10 MHz | 20 MHz |
| Program Memory | 768 B OTP | 768 B OTP | 768 B OTP | 768 B OTP | 768 B OTP | 512 words x 12-bit Flash |
| RAM | 24 B | 24 B | 24 B | 24 B | 24 B | 25 B |
| Number of I/O Pins | 20 | 20 | 20 | 20 | 20 | 12 (SSOP-28; some pins differ from PIC16C5x) |
| Supply Voltage | 4.5 V - 5.5 V | 4.5 V - 5.5 V | 4.5 V - 5.5 V | 4.5 V - 5.5 V | 4.5 V - 5.5 V | 2.0 V - 5.5 V |
| Memory Type | OTP | OTP | OTP | OTP | OTP | Flash (reprogrammable) |
| Temperature Grade | Industrial (-40C to +85C) | Industrial (-40C to +85C) | Industrial (-40C to +85C) | Industrial (-40C to +85C) | Industrial (-40C to +85C) | Industrial (-40C to +85C) |
Key Differentiators
- Same SSOP-28 footprint as PIC16C55A-04I/SS with higher CPU clock (vs PIC16C55A-04I/SS)
- Surface-mount SSOP-28 suitable for high-volume reflow assembly (vs PIC16C55-10/SP (SPDIP-28))
- OTP memory prevents firmware reverse-engineering by competitors (vs PIC16F54-I/SS)
Design Notes
The PIC16C55-10I/SS requires a stable 4.5V to 5.5V supply; place a 100 nF decoupling capacitor within 5 mm of the VDD pin (pin 20) and a 10 uF bulk capacitor at the board entry. The internal brown-out detector (where present on baseline parts) and power-on reset require VDD to rise monotonically - avoid inrush currents on shared 5V rails that could cause the device to enter undefined states. Estimated: total current draw at 10 MHz with all 20 I/Os loaded is below 15 mA, but OTP programming pulses require brief 12-13V on /MCLR per the Microchip programming specification.
The SSOP-28 package has a 0.65 mm pin pitch and 5.30 mm body width - design your PCB land pattern to the IPC-7351 nominal SSOP-28 standard with at least 0.4 mm pad width and 0.2 mm solder mask expansion. Keep all 20 I/O traces short (under 25 mm) and routed away from the OSC1/OSC2 clock traces on pins 26/27 to avoid injecting noise into the oscillator. VSS pins (5, 14, 24) should each have their own via to a continuous ground plane rather than daisy-chained, since the baseline PIC16C5x is sensitive to ground bounce on the VSS return path during high-current I/O switching.
Do not use OTP parts like the PIC16C55-10I/SS for development: each programming attempt burns the OTP cells and the device becomes unusable once any bit is wrongly programmed. Instead, prototype with the JW (windowed CERDIP) variant PIC16C55/JW, then commit the final hex to the OTP PIC16C55-10I/SS for production. Also remember the PIC16C5x baseline uses a 12-bit instruction width and a 2-level hardware stack - C compilers targeting the PIC16F mid-range family will not produce compatible object code. Finally, the 25 mA per-pin current is the absolute maximum; sustained operation above 20 mA per pin shortens reliability, so add a series resistor when driving LEDs.
Compliance Information
RoHS and lead-free status confirmed via LCSC distributor listing (C641633). AEC-Q100 is not applicable because PIC16C55-10I/SS is not marketed as an automotive-grade MCU. Halogen-free status not explicitly stated in verified web data.
