PIC16C55-HS/P - 8-bit OTP MCU 20MHz 768B | Microchip
MPN: PIC16C55-HS/P ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $5.97 | $5.97 |
| 10 | $5.5 | $55.00 |
| 100 | $4.95 | $495.00 |
| 500 | $4.4 | $2,200.00 |
| 1,000 | $3.95 | $3,950.00 |
PIC16C55-HS/P Overview
What is an 8-bit OTP microcontroller? An OTP microcontroller integrates CPU, RAM, ROM/EPROM, and peripherals in a single chip; OTP (one-time programmable) means the program memory can be written once with a device programmer and is non-erasable, which lowers per-unit cost versus flash or EEPROM for high-volume fixed-function products. PIC microcontrollers belong to the Harvard-architecture RISC family (peripheral > microcontroller > embedded controller > semiconductor) and remain widely deployed where deterministic instruction timing and small pin counts dominate.
Key features of the PIC16C55-HS/P include a 2-level hardware stack, direct/indirect/relative addressing modes, one 8-bit real-time counter (TMR0) with programmable prescaler, watchdog timer, power-on reset, and a power-saving SLEEP mode. The device exposes 20 bidirectional I/O pins grouped into two ports (PORTA, PORTB) plus dedicated RESET, OSC1/OSC2 clock pins. All I/O pins source/sink up to 25 mA, enough to drive LEDs and small relays directly.
Architecturally, the PIC16C5x uses a fixed instruction set of 33 single-cycle commands executed from on-chip EPROM; the 12-bit opcode plus 2-stage pipeline yields most instructions completing in one oscillator cycle (~200 ns at 20 MHz). Self-programming is not supported; production code is loaded by MPLAB PM3 or compatible device programmers prior to PCB soldering or via ICSP-style test points.
Typical applications include appliance controllers, simple sensor/actuator boards, smart-card readers, hobby/education boards, and other high-volume fixed-function consumer products where cost dominates and field firmware updates are unnecessary. Designers value the deterministic instruction timing and the very low sleep current for battery-friendly idle states.
When designing with this part, derate I/O source/sink to stay below the absolute 25 mA per-pin / 200 mA per-package limits, and budget for an external R/C or crystal oscillator network on OSC1/OSC2 since no internal oscillator is provided. The 28-PDIP footprint is friendly to through-hole prototyping and hand-rework for low-volume production.
This page consolidates distributor stock, price tiers, drop-in alternatives from the PIC16C5x family, and applied design notes not all present on the manufacturer summary page.
Drop-in alternatives for PIC16C55-HS/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-HS/P (same form factor and footprint) — differing in Package, Timers, Program Memory Size, Program Memory Type, Mounting Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C54-HS/P
✅ Drop-In✓ In Stock
$1.15 / Unit
View Datasheet →PIC16C56-HS/P
✅ Drop-In✓ In Stock
$1.8 / Unit
View Datasheet →PIC16C55A-20I/P
✅ Drop-In✓ In Stock
$1.6 / Unit
View Datasheet →PIC16C55A-04E/P
✅ Drop-In✓ In Stock
$3.15 / Unit
View Datasheet →PIC16C55-10/SO
✅ Drop-In✓ In Stock
$2.49 / Unit
View Datasheet →PIC16C55-10/SP
✅ Drop-In✓ In Stock
$2.45 / Unit
View Datasheet →PIC16F54-I/P
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C55-HS/P Maximum Ratings & Electrical Characteristics
| Core | PIC16C5x 8-bit RISC (12-bit instructions) |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 768 B (512 x 12) |
| RAM | 24 B |
| Data EEPROM | Not present |
| Maximum Clock Frequency | 20 MHz |
| Supply Voltage | 3.3 V to 5.5 V |
| I/O Pins | 20 |
| Timers | 1 x 8-bit (TMR0 with prescaler) |
| Hardware Stack | 2-level |
| Instruction Set | 33 instructions, single-cycle |
| Watchdog Timer | Yes |
| Power-on Reset | Yes |
| Brown-out Reset | Not present |
| ICSP / In-Circuit Programming | Not supported on PIC16C5x |
| Oscillator Modes | RC, XT, HS, LP (external) |
| Operating Temperature Range | 0 C to +70 C (commercial, per HS speed grade) |
| I/O Source/Sink | 25 mA per pin |
| Package | 28-PDIP (0.600 in, 15.24 mm) |
| Mounting Type | Through-Hole |
PIC16C55-HS/P Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O, PORTA bit 2 |
| Pin 2 | RA3 — Bidirectional I/O, PORTA bit 3 |
| Pin 3 | RA4/T0CKI — Bidirectional I/O / TMR0 clock input |
| Pin 4 | MCLR — Master Clear (active-low reset) |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RA0 — Bidirectional I/O, PORTA bit 0 |
| Pin 7 | RA1 — Bidirectional I/O, PORTA bit 1 |
| Pin 8 | RA2 — Bidirectional I/O (port-mirror in baseline PIC16C5X) |
| Pin 9 | RA3 — Bidirectional I/O (port-mirror in baseline PIC16C5X) |
| Pin 10 | RB0/INT — Bidirectional I/O, PORTB bit 0 |
| Pin 11 | RB1 — Bidirectional I/O, PORTB bit 1 |
| Pin 12 | RB2 — Bidirectional I/O, PORTB bit 2 |
| Pin 13 | RB3 — Bidirectional I/O, PORTB bit 3 |
| Pin 14 | RB4 — Bidirectional I/O, PORTB bit 4 |
| Pin 15 | RB5 — Bidirectional I/O, PORTB bit 5 |
| Pin 16 | RB6 — Bidirectional I/O, PORTB bit 6 (also programming clock) |
| Pin 17 | RB7 — Bidirectional I/O, PORTB bit 7 (also programming data) |
| Pin 18 | VSS — Ground reference (second VSS pin) |
| Pin 19 | VDD — Positive supply, +3.3 V to +5.5 V |
| Pin 20 | OSC2/CLKOUT — Oscillator crystal / clock output |
| Pin 21 | OSC1/CLKIN — Oscillator crystal / clock input |
| Pin 22 | RB7 — PORTB bit 7 (port-mirror in baseline PIC16C5X) |
| Pin 23 | RB6 — PORTB bit 6 (port-mirror in baseline PIC16C5X) |
| Pin 24 | RB5 — PORTB bit 5 (port-mirror in baseline PIC16C5X) |
| Pin 25 | RB4 — PORTB bit 4 (port-mirror in baseline PIC16C5X) |
| Pin 26 | RB3 — PORTB bit 3 (port-mirror in baseline PIC16C5X) |
| Pin 27 | RB2 — PORTB bit 2 (port-mirror in baseline PIC16C5X) |
| Pin 28 | RB1 — PORTB bit 1 (port-mirror in baseline PIC16C5X) |
Typical Applications
PIC16C55-HS/P is suitable for 6 applications: Appliance Controller Board, Smart Card / RFID Reader Slave Controller, Hobby / Education Development Board, Simple Sensor / Actuator Board, LED Display / Marquee Driver, Industrial Push-Button / Keypad Front Panel.
Appliance Controller Board
The PIC16C55-HS/P suits appliance controller boards (washing machines, dishwashers, microwave ovens) because its 20 MHz HS grade delivers the cycle-budget to scan a 4x4 keypad matrix, multiplex a 4-digit 7-segment display, and drive TRIACs for load switching within a 10 ms main loop. The 20 I/O pins are partitioned as PORTA (keypad rows + TRIAC triggers) and PORTB (display segments + status LEDs) with TMR0 providing the 1 ms tick. OTP memory is acceptable in this application because firmware is finalized at production and cost dominates. The 28-PDIP through-hole package also survives the higher mechanical and thermal stress of white-goods manufacturing versus SMD.
Recommended
Smart Card / RFID Reader Slave Controller
The PIC16C55-HS/P operates as a slave protocol converter in legacy smart-card and 125 kHz RFID reader boards, where the 20 MHz clock gives 200 ns instruction cycles - enough to bit-bang ISO 7816 T=0 character frames at 9600 baud while servicing the host UART. Twenty I/O pins accommodate the smart-card socket (VCC, RST, CLK, I/O, PRES), the host interface (TX, RX, RTS), the LED indicators, and the beeper driver. The deterministic instruction timing of the baseline PIC core is preferred over interrupt-driven parts because the synchronous card clock must be generated without jitter. OTP is acceptable because the reader protocol is fixed at production.
Recommended
Hobby / Education Development Board
The PIC16C55-HS/P is a popular MCU on legacy hobby and education boards (e.g. PICSTART-compatible training kits) because the 28-PDIP package is easy to socket, hand-solder, and replace when students accidentally short outputs. The 33-instruction baseline PIC instruction set is the simplest in Microchip's portfolio, making it the canonical teaching device for Harvard-architecture, accumulator-based programming. Each instruction executes in one cycle (200 ns at 20 MHz), letting students observe exact timing on an oscilloscope without instruction-pipeline ambiguity. The OTP requirement teaches the full programming workflow: write code, compile with MPASM, program with PM3, and verify.
Recommended
Simple Sensor / Actuator Board
The PIC16C55-HS/P is well-suited to fixed-function sensor and actuator boards such as thermostat remotes, fan controllers, and irrigation valves, where the firmware reads a thermistor via RC time on T0CKI, debounces a few buttons, and pulses a relay driver. The single 8-bit TMR0 with prescaler delivers 1 s ticks from a 32.768 kHz timebase or 50 ms ticks from the 20 MHz system clock without needing additional timer peripherals. Twenty I/O pins cover sensor inputs, button matrix, status LEDs, and relay drivers; the 25 mA I/O source rating directly drives small relays and LED indicators. The SLEEP mode reduces quiescent current to the low-microamp range for battery-friendly idle.
Recommended
LED Display / Marquee Driver
The PIC16C55-HS/P drives 8x8 or smaller multiplexed LED marquees at 20 MHz, where each row refresh must complete within 1.25 ms to avoid visible flicker (i.e. <125 microseconds per row at 100 Hz refresh). Twenty I/O pins accommodate an 8-row + 8-column multiplex matrix with spare pins for brightness PWM via TMR0 compare and serial configuration via a UART bit-bang on RB0/RB1. The deterministic instruction timing of the baseline PIC core produces clean row-multiplex timing without DMA or interrupts. OTP is acceptable because display patterns are pre-computed and stored in lookup tables; PIC16C56-HS/P (1k x 12) is preferred when more font tables are required.
Recommended
Industrial Push-Button / Keypad Front Panel
The PIC16C55-HS/P serves as the front-panel MCU in industrial equipment where a 4x4 metal keypad, status LEDs, and a beeper must be scanned while a host PLC communicates over RS-485. The 20 MHz clock provides 200 ns instruction cycles to debounce and scan the keypad in under 1 ms, freeing the main task to forward keystrokes to the host. Twenty I/O pins cover the keypad (8 lines), status LEDs (6 lines), beeper (1 line), and the RS-485 interface (TX, RX, DE). The hardware 2-level stack simplifies the deterministic keypad scanner - one level for the main loop, one level for the UART byte handler.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55-HS/P — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C54-HS/P | PIC16C56-HS/P | PIC16C55A-20I/P | PIC16C55-10/SO | PIC16F54-I/P |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-PDIP | 28-PDIP - same | 28-PDIP - same | 28-PDIP - same | 28-PDIP - same (SOIC body on -10/SO variant) | 28-PDIP - same |
| Program Memory | 768 B (512 x 12) OTP | 512 B (384 x 12) OTP | 1.5 KB (1k x 12) OTP | 768 B (512 x 12) OTP | 768 B (512 x 12) OTP | 512 B (384 x 12) Flash |
| Maximum Clock Frequency | 20 MHz (HS grade) | 20 MHz (HS grade) | 20 MHz (HS grade) | 20 MHz | 10 MHz | 20 MHz |
| Supply Voltage | 3.3 V to 5.5 V | 3.3 V to 5.5 V | 3.3 V to 5.5 V | 2.0 V to 6.25 V (wider window) | 3.3 V to 5.5 V | 2.0 V to 5.5 V |
| I/O Pins | 20 | 20 | 20 | 20 | 20 | 20 |
| RAM | 24 B | 24 B | 24 B | 24 B | 24 B | 24 B |
| Program Memory Type | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM | OTP EPROM | Flash (re-programmable, ICSP-capable) |
| ICSP Support | No | No | No | No | No | Yes |
| Lifecycle Status | Obsolete (per Microchip PIC16C5X EOL) | Obsolete | Obsolete | Obsolete | Obsolete | Active |
Key Differentiators
- Highest-density baseline 5x OTP part with HS grade (vs PIC16C54-HS/P)
- Industry-standard PIC16C5X baseline core with deterministic 1-cycle instructions (vs PIC16C55A-20I/P)
- OTP EPROM enables lowest-cost production programming (vs PIC16F54-I/P)
- HS grade supports 20 MHz maximum clock (vs PIC16C55-10/SO)
Design Notes
PIC16C5X baseline parts do NOT support ICSP; you must program the OTP memory externally with an MPLAB PM3 (or older PICSTART Plus) device programmer BEFORE soldering or via test-points that expose VPP, RB6 (clock), RB7 (data), and MCLR. Production boards need a programming header or in-test programming fixture, otherwise unsoldered parts cannot be reworked. Design PCBs to bring MCLR, RB6, RB7, VDD and VSS to accessible test points.
VDD decoupling: place a 100 nF ceramic capacitor as close as possible to the VDD pin (pin 20 on 28-PDIP) with a short trace to the VSS pin (pin 19). For boards with high-noise relay drivers, add a bulk 10 uF tantalum or aluminum electrolytic cap on the VDD rail. The PIC16C5X does not have an internal voltage regulator, so VDD noise directly couples into the oscillator; poor decoupling causes intermittent HS-mode start-up failures at cold temperature.
Oscillator layout: keep the HS-grade crystal (or ceramic resonator) and its loading capacitors within 5 mm of OSC1/OSC2 (pins 20/21). Guard the oscillator traces with a ground pour and avoid running digital signals under the crystal. For 20 MHz HS operation, the oscillator is sensitive to stray capacitance beyond ~20 pF; long traces or proximity to I/O toggling lines will detune the resonator. Series resistor (Rs ~100 ohm) may be required for AT-cut crystals to prevent overdrive.
I/O current derating: each I/O pin can source or sink 25 mA DC, but the absolute maximum for the entire PORTA is 100 mA and for PORTB is 100 mA, with a per-package limit of 200 mA. Driving 8 LEDs at 20 mA continuously (160 mA total) approaches the PORTB limit; if your design uses parallel LED arrays, switch to a driver IC (ULN2003, TPIC6B595) rather than sourcing from the MCU directly. Verify worst-case sink current with all LEDs on simultaneously.
Estimated: at 20 MHz clock, 5.0 V VDD and all CMOS inputs at VDD, the PIC16C55-HS/P Icc is typically 10 mA (50 mW). At max commercial temperature +70 C, power dissipation is well within the 28-PDIP package rating (1 W thermal, theta-JA ~50 C/W); no heatsink is required. Sleep mode reduces Icc to under 5 uA for battery-friendly idle. If your design uses HS-grade operation at extended temperature, derate clock frequency above +70 C per the family derating curve.
Compliance Information
PIC16C5X is a long-discontinued family; specific lot/date-code RoHS and lead-free status varies. Modern production parts from Microchip are RoHS compliant per Microchip product-page statement, but pre-discontinued lots may be non-RoHS. Always check the date code and lot with your distributor before committing to a RoHS-critical BOM.
