PIC16C55-XTE/SP - 8-Bit OTP MCU, 768B EPROM, 20 I/O, SPDIP-28
MPN: PIC16C55-XTE/SP ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.42 | $7.42 |
| 10 | $6.78 | $67.80 |
| 100 | $5.95 | $595.00 |
| 500 | $5.21 | $2,605.00 |
| 1,000 | $4.68 | $4,680.00 |
PIC16C55-XTE/SP Overview
The PIC16C5X family represents the foundation of Microchip's mid-range 8-bit microcontroller legacy. A microcontroller (MCU) is a single-chip computer containing a CPU, RAM, non-volatile program memory, and peripheral I/O; 8-bit MCUs are used in cost-sensitive embedded applications where simple deterministic control is required. The PIC architecture uses a Harvard structure with separate program and data buses, 12-bit-wide instructions, and a fixed instruction cycle, delivering predictable 4:1 code density and deterministic interrupt latency that are valuable for low-power motor control, sensor signal conditioning, and legacy appliance designs.
Key features include a hardware 8-bit timer/counter (TMR0) with an 8-bit programmable prescaler, watchdog timer with dedicated on-chip RC oscillator, power-on reset, brown-out detection, and EPROM-based code storage. The device supports 33 single-word, single-cycle instructions with 2:1 code compression over comparable 8-bit MCUs of its era, and offers direct LED drive capability on all 20 I/O pins (sink/source up to 25 mA per pin). The fully static CMOS design eliminates minimum clock-rate constraints.
Typical applications include industrial control subsystems, automotive body electronics (non-safety-critical), appliance control boards, security panel keypads, and educational microcontroller training platforms. Because of its deterministic instruction timing and breadboard-friendly DIP package, the PIC16C55 family is widely used in university curricula and rapid prototyping environments. Modern replacements (PIC16F54, PIC16F57) provide flash memory but require software/firmware rewrites, as the OTP EPROM is not electrically re-programmable.
When designing with this OTP MCU, account for the one-time-programmable limitation: firmware revisions require re-masking or new silicon. Allocate 1-2 spare I/O pins for in-system test access, and ensure your oscillator circuit (ceramic resonator or crystal + 22 pF caps) matches the XT speed grade. The /MCLR reset pin must be tied to VDD through a 10 kohm pull-up for reliable operation. This part has been widely cloned and second-sourced, but Microchip originals remain the gold standard for longevity and documentation.
Drop-in alternatives for PIC16C55-XTE/SP — 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-XTE/SP (same form factor and footprint) — differing in Package, Program Memory Size, RoHS Status, Timers, Program Memory Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55-XTE/P
✅ Drop-In✓ In Stock
$1.9 / Unit
View Datasheet →PIC16C55-XT/P
✅ Drop-In✓ In Stock
$4.05 / Unit
View Datasheet →PIC16C55T-XT/SS
✅ Drop-In✓ In Stock
$2.64 / Unit
View Datasheet →PIC16C55A-20I/SP
✅ Drop-In✓ In Stock
$3.01 / Unit
View Datasheet →PIC16F54-I/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16F57-I/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C55-XTE/SP Maximum Ratings & Electrical Characteristics
| Architecture | PIC16C5X 8-bit RISC (Harvard) |
| Instruction Set Width | 12-bit, 33 instructions |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 768 bytes (512 x 12 words) |
| Data RAM | 24 bytes |
| I/O Pins | 20 |
| Maximum Clock Frequency | 4 MHz (XT grade) |
| Supply Voltage Range | 3.0 V to 6.25 V |
| Operating Temperature Range | -40 C to +125 C (Extended) |
| Timers | 1 x 8-bit TMR0 with prescaler |
| Watchdog Timer | Yes, dedicated on-chip RC oscillator |
| Reset Sources | POR, Brown-Out, /MCLR |
| I/O Sink/Source Current | 25 mA per pin (direct LED drive) |
| Package | 28-pin SPDIP (Skinny DIP), Tube |
| Lead Pitch | 2.54 mm (0.100 in) |
| RoHS Status | Non-compliant (contains Pb in PDIP package) |
| Programming Method | Parallel programming via MPLAB PM3 / PRO MATE II |
PIC16C55-XTE/SP Pin Configuration
| Pin 1 | RA2 — Port A bit 2 (digital I/O) |
| Pin 2 | RA3 — Port A bit 3 (digital I/O) |
| Pin 3 | T0CKI — Timer0 clock input |
| Pin 4 | /MCLR — Master Clear reset (active-low, tie to VDD via 10 kohm) |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0 — Port B bit 0 (digital I/O, 25 mA) |
| Pin 7 | RB1 — Port B bit 1 (digital I/O, 25 mA) |
| Pin 8 | RB2 — Port B bit 2 (digital I/O, 25 mA) |
| Pin 9 | RB3 — Port B bit 3 (digital I/O, 25 mA) |
| Pin 10 | RB4 — Port B bit 4 (digital I/O, 25 mA) |
| Pin 11 | RB5 — Port B bit 5 (digital I/O, 25 mA) |
| Pin 12 | RB6 — Port B bit 6 (digital I/O, 25 mA) |
| Pin 13 | RB7 — Port B bit 7 (digital I/O, 25 mA) |
| Pin 14 | VSS — Ground reference (also VSS on this pin per datasheet) |
| Pin 15 | OSC1 — Oscillator input (XT crystal or resonator) |
| Pin 16 | OSC2 — Oscillator output (XT crystal or resonator) |
| Pin 17 | RC0 — Port C bit 0 (digital I/O, 25 mA) |
| Pin 18 | RC1 — Port C bit 1 (digital I/O, 25 mA) |
| Pin 19 | RC2 — Port C bit 2 (digital I/O, 25 mA) |
| Pin 20 | RC3 — Port C bit 3 (digital I/O, 25 mA) |
| Pin 21 | RC4 — Port C bit 4 (digital I/O, 25 mA) |
| Pin 22 | RC5 — Port C bit 5 (digital I/O, 25 mA) |
| Pin 23 | RC6 — Port C bit 6 (digital I/O, 25 mA) |
| Pin 24 | RC7 — Port C bit 7 (digital I/O, 25 mA) |
| Pin 25 | RD0 — Port D bit 0 (digital I/O, 25 mA) |
| Pin 26 | RD1 — Port D bit 1 (digital I/O, 25 mA) |
| Pin 27 | RD2 — Port D bit 2 (digital I/O, 25 mA) |
| Pin 28 | VDD — Positive supply (3.0 V to 6.25 V) |
Typical Applications
PIC16C55-XTE/SP is suitable for 6 applications: Industrial Control Subsystems, Appliance Control Boards, Security Panel Keypads, Automotive Body Electronics (Non-Safety), Educational Microcontroller Training, Sensor Signal Conditioning Front-Ends.
Industrial Control Subsystems
The PIC16C55-XTE/SP is well suited for industrial control subsystems such as conveyor belt sequencers, motor starter controllers, and sensor multiplexer boards. Its 20 digital I/O lines with 25 mA sink/source capability can directly drive relays, optocouplers, and status LEDs without external drivers, while the 8-bit TMR0 with prescaler handles pulse counting from incremental encoders or flow meters. The Extended -40C to +125C temperature range tolerates harsh factory floor environments, and the 768-byte OTP EPROM is adequate for fixed-function sequencing logic. For firmware-update flexibility, consider migrating to the PIC16F54-I/P, which uses the same 28-pin SPDIP footprint and PIC16C5X instruction set but offers flash reprogrammability for field-tunable sequencing parameters.
Recommended
Appliance Control Boards
The PIC16C55-XTE/SP is widely deployed in washing machine, dishwasher, microwave oven, and HVAC thermostat control boards where deterministic interrupt response and low BOM cost are priorities. The Harvard architecture executes each 12-bit instruction in a single 4-clock cycle, providing predictable timing for sensor sampling loops, while the Brown-Out Reset (BOR) protects against supply dips during compressor inrush. The 24 bytes of RAM suffice for keypad debounce, display multiplexing, and a small state machine. Because OTP EPROM is mask-programmed by Microchip at production, appliance OEMs benefit from low unit cost after NRE amortization. For new designs the flash-based PIC16F54-I/P is preferred, allowing firmware revisions via ICSP without re-masking.
Recommended
Security Panel Keypads
The PIC16C55-XTE/SP serves as the scan-controller in security alarm keypads, reading 4x4 matrix key inputs while driving LED indicators and piezo buzzer feedback. The 20 I/O pins accommodate up to 16 keys via matrix scanning with 8 wires, plus 4 LED status indicators and a buzzer driver, leaving pins for zone LED expansion. Watchdog timer prevents lockup if keypad scan logic stalls, and OTP EPROM prevents firmware reverse engineering - an anti-tamper benefit in security applications. The 4 MHz clock is more than adequate for debounced 50 ms key scanning. For designs requiring encrypted firmware, the PIC16F57-I/P offers flash with code protection, but the PIC16C55-XTE/SP remains preferred where cost dominates over reprogrammability.
Recommended
Automotive Body Electronics (Non-Safety)
The PIC16C55-XTE/SP appears in non-safety automotive body electronics such as HVAC blend door actuators, mirror position controllers, seat heater timers, and interior lighting dimmers. The Extended -40C to +125C temperature range is AEC-Q100-ish in spirit (though the part is not formally qualified), and the 25 mA I/O capability directly drives small relays and LED strings. Brown-Out Reset handles automotive load-dump voltage transients paired with an external TVS. OTP EPROM prevents warranty fraud via unauthorized firmware swaps. For new designs targeting formal AEC-Q100, the PIC16F54-I/P in industrial grade or higher-tier automotive PIC MCUs are recommended instead.
Recommended
Educational Microcontroller Training
The PIC16C55-XTE/SP is a classic teaching platform for university embedded systems courses due to its breadboard-friendly 28-pin SPDIP package, simple PIC16C5X architecture, and comprehensive documentation. Students learn RISC pipelining, fixed-cycle timing, and assembly programming using only 33 instructions - a manageable scope for first-time embedded learners. The 20 I/O pins interface directly with lab breadboard LEDs, switches, and 7-segment displays without level shifters. The MPLAB X IDE is free and the MPASM assembler handles PIC16C5X assembly. The PIC16F54-I/P has largely replaced it in curricula due to flash reprogrammability (students can iterate without UV erasure), but the PIC16C55-XTE/SP remains in legacy course materials.
Recommended
Sensor Signal Conditioning Front-Ends
The PIC16C55-XTE/SP acts as a low-cost sensor front-end for thermocouple cold-junction compensation, thermistor linearization, and ratiometric bridge excitation in weighing scales and process meters. Its deterministic 1 us instruction cycle at 4 MHz (4 clocks per cycle) enables precise software-implemented sigma-delta ADC using a single comparator pin and a reference resistor, achieving 12-16 effective bits at low sample rates. The Watchdog Timer recovers from software lockup during long integration cycles. OTP EPROM stores per-sensor calibration coefficients in production. Migrating to PIC16F57-I/P enables field recalibration via ICSP for weighing scale or pH meter applications where sensor drift requires periodic adjustment.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55-XTE/SP — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55-XTE/P | PIC16C55-XT/P | PIC16F54-I/P | PIC16F57-I/P | PIC16C55A-20I/SP |
|---|---|---|---|---|---|---|
| Package | SPDIP-28 | SPDIP-28 | SPDIP-28 | SPDIP-28 | SPDIP-28 | SPDIP-28 |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory | 768 B OTP EPROM | 768 B OTP EPROM | 768 B OTP EPROM | 768 B Flash | 3 KB Flash | 768 B OTP EPROM |
| Max Clock Frequency | 4 MHz | 4 MHz | 4 MHz | 20 MHz | 20 MHz | 20 MHz |
| Data RAM | 24 B | 24 B | 24 B | 25 B | 72 B | 24 B |
| Operating Temperature | -40 C to +125 C | -40 C to +125 C | 0 C to +70 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| Memory Type | OTP EPROM (one-time) | OTP EPROM | OTP EPROM | Flash (reprogrammable) | Flash (reprogrammable) | OTP EPROM |
| ICSP Support | No (parallel programmer required) | No | No | Yes (ICSP) | Yes (ICSP) | No |
| RoHS Status | Non-compliant (SnPb SPDIP) | Non-compliant (SnPb) | Non-compliant (SnPb) | Compliant (Pb-free) | Compliant (Pb-free) | Non-compliant (SnPb) |
| Unit Price (1-pc, USD) | 7.42 | ~7.00 | ~6.50 | ~1.95 | ~2.40 | ~8.10 |
Key Differentiators
- Extended -40C to +125C temperature grade vs commercial grade alternatives (vs PIC16C55-XT/P)
- Flash reprogrammability via ICSP for development iterations (vs PIC16F54-I/P)
- 20 MHz clock headroom for compute-intensive tasks (vs PIC16C55A-20I/SP)
Design Notes
The /MCLR pin (pin 4) MUST be tied to VDD through a 10 kohm pull-up resistor - leaving it floating causes intermittent resets and unpredictable behavior. The PIC16C55-XTE/SP does not have an internal weak pull-up on /MCLR like newer PIC MCUs. Additionally, do not place a decoupling capacitor larger than 0.1 uF directly on /MCLR; large capacitance slows the VDD rise time and prevents proper Power-On Reset. Use a 100 nF decoupling cap on VDD within 5 mm of the pin.
Place the 4 MHz crystal or ceramic resonator (with 22 pF load capacitors on each leg) within 5 mm of pins 15 (OSC1) and 16 (OSC2). Keep oscillator traces short and away from high-current switching traces to prevent injection of clock noise. Ground the crystal can to VSS via a short trace. For board layouts exceeding 5 cm square, use a ground plane to stabilize the oscillator and reduce EMI. The XT speed grade supports 4 MHz; using the HS grade crystal topology with this part may cause oscillator failure - stay within the XT specification.
Estimated power budget: PIC16C55-XTE/SP draws ~2 mA active at 4 MHz/5V and ~4 uA in SLEEP mode. At 5V supply the I/O pin current of 25 mA per pin allows direct LED drive without transistors - useful for status indicators. Brown-Out Reset (BOR) is enabled via the configuration word to protect against VDD drops below ~4V; ensure BOR is enabled for safety-critical or industrial applications. Total package dissipation must remain below 800 mW - simultaneous high-current sink on multiple pins can approach this limit.
The 768-byte OTP EPROM can be programmed ONLY ONCE - there is no electrical erase. Use the PIC16C55/JW windowed CERDIP variant during development for UV-erasable iterations, then transition to PIC16C55-XTE/SP for production OTP mask programming. Verify all firmware logic on the JW variant before committing to a mask run; mask NRE charges apply. Code-protect (CP) fuse can be set to prevent firmware readback via the programmer, providing a basic anti-tamper measure.
Compliance Information
SnPb finish on SPDIP-28 package makes this part non-RoHS. Not formally AEC-Q100 qualified despite Extended temperature rating. Migrate to PIC16F54-I/P for RoHS-compliant designs.
