PIC16C55-HSE/SO - 8-bit OTP MCU, 16MHz, 768B | Microchip
MPN: PIC16C55-HSE/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $6.5 | $6.50 |
| 10 | $5.85 | $58.50 |
| 100 | $5.1 | $510.00 |
| 500 | $4.45 | $2,225.00 |
| 1,000 | $3.95 | $3,950.00 |
PIC16C55-HSE/SO Overview
A microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory, working RAM, digital I/O, timers, and interrupt logic into one package. The PIC16C5x family uses a Harvard architecture with separated program and data paths, allowing instruction fetch and operand read to occur in the same cycle - this is why the baseline PIC executes nearly every instruction in a single 200 ns cycle at 20 MHz. MCUs sit at the lowest tier of embedded computing (MCU -> 8-bit microcontroller -> microcontroller -> embedded processor) and are the workhorses of appliance control, sensor reading, and human-machine interface products.
Key features of the PIC16C55-HSE/SO include the 20 MHz 'HS' high-speed oscillator option (the -HSE/ suffix selects the high-speed crystal mode with the part rated for 16 MHz at 5 V), 25 bytes of RAM, 20 source-capable digital I/O pins, a watchdog timer, a 4-channel 8-bit analog-to-digital converter is NOT present on this baseline part (the PIC16C55 is digital-only - the 'C' suffix variant adds ADC), and an 8-bit timer/counter. The part runs from 2.5 V to 6.25 V, allowing it to operate directly from a 5 V regulated rail or from a 3-cell battery stack.
The architecture is RISC-based with only 33 single-word/12-bit instructions, and the two-stage pipeline lets every instruction except branches execute in one cycle. The 25-byte general-purpose RAM is mirrored across all four banks of the data memory map (typical for the PIC16C5x baseline family), and I/O registers include the standard PORTA and PORTB latches, the TRIS direction registers, the OPTION register, and the TMR0 timer/counter. Brown-out detection is not present on the baseline 'C55' part but is available on the 'C55A' revision.
Typical applications include legacy industrial control boards, simple appliance controllers, low-end consumer electronics, sensor front-ends, and educational/hobby designs where deterministic timing and code efficiency matter more than RAM or peripheral richness. The 28-SOIC package also makes it easy to hand-solder prototypes and rework production boards. The PIC16C55-HSE/SO is widely used as a drop-in upgrade for older PIC16C54 designs that need more I/O and instructions, and is supported by the MPLAB PM3 universal programmer plus all current MPLAB X IDE toolchains.
When designing with this part, remember that OTP means the program memory cannot be erased - it is blank from the factory and must be programmed once at production. For prototyping, the PIC16C55/JW windowed ceramic version or the PIC16F55 Flash equivalent are recommended instead. Also note that the 'HSE' suffix selects the high-speed crystal oscillator mode; using a low-frequency crystal will halve the throughput and waste the part's capability.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the bare manufacturer datasheet.
Drop-in alternatives for PIC16C55-HSE/SO — 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-HSE/SO (same form factor and footprint) — differing in Package, Maximum Clock Frequency, Program Memory Size, Program Memory Type, RAM Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16F57-I/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C55A-20I/SO
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
PIC16C55-10I/SO
✅ Drop-In✓ In Stock
$1.18 / Unit
View Datasheet →PIC16C55-10/SO
✅ Drop-In✓ In Stock
$2.49 / Unit
View Datasheet →PIC16C55-HS/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C55-HSE/SP
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$4.36 / Unit
View Datasheet →PIC16C55-HSE/SO Maximum Ratings & Electrical Characteristics
| Product Family | PIC® 16C |
| Core | 8-bit RISC (PIC16C5x baseline) |
| Maximum Clock Frequency | 16 MHz (HS mode, 5V) |
| Instruction Cycle Time | 200 ns (at 20 MHz clock) |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 768 bytes (512 x 12 bits) |
| RAM Size | 25 bytes |
| Data EEPROM | Not present |
| I/O Pins | 20 |
| Timers | 1 x 8-bit (TMR0) + WDT |
| ADC | Not present (baseline part) |
| Operating Voltage Range | 2.5 V to 6.25 V |
| Package | 28-SOIC (0.295", 7.50 mm width) |
| Mounting Type | Surface Mount |
| MSL Level | 1 (unlimited floor life at <=30C/85% RH) |
| Lead-Free / RoHS | Compliant (per DigiKey listing) |
PIC16C55-HSE/SO Pin Configuration
| Pin 1 | RA2 — PORTA bit 2 (digital I/O) |
| Pin 2 | RA3 — PORTA bit 3 (digital I/O) |
| Pin 3 | RA4/T0CKI — PORTA bit 4 / Timer0 clock input |
| Pin 4 | RA5 — PORTA bit 5 (digital I/O) |
| Pin 5 | RA6 — PORTA bit 6 (digital I/O) |
| Pin 6 | RA7 — PORTA bit 7 (digital I/O) |
| Pin 7 | OSC1/CLKIN — Oscillator crystal input / external clock input |
| Pin 8 | OSC2/CLKOUT — Oscillator crystal output / clock output (Fosc/4) |
| Pin 9 | MCLR/VPP — Master clear reset (active low) / programming voltage input |
| Pin 10 | VSS — Ground reference |
| Pin 11 | VDD — Positive supply voltage (2.5-6.25V) |
| Pin 12 | RB0/INT — PORTB bit 0 / external interrupt input |
| Pin 13 | RB1 — PORTB bit 1 (digital I/O) |
| Pin 14 | RB2 — PORTB bit 2 (digital I/O) |
| Pin 15 | RB3 — PORTB bit 3 (digital I/O) |
| Pin 16 | RB4 — PORTB bit 4 (digital I/O) |
| Pin 17 | RB5 — PORTB bit 5 (digital I/O) |
| Pin 18 | RB6 — PORTB bit 6 (digital I/O) |
| Pin 19 | RB7 — PORTB bit 7 (digital I/O) |
| Pin 20 | RA0 — PORTA bit 0 (digital I/O) |
| Pin 21 | RA1 — PORTA bit 1 (digital I/O) |
Typical Applications
PIC16C55-HSE/SO is suitable for 6 applications: Legacy Industrial Control Boards, Appliance Front-Panel Controllers, Sensor Front-End Readout Boards, Educational and Hobby Embedded Projects, Low-End Consumer Electronics, Simple PWM Motor Speed Controllers.
Legacy Industrial Control Boards
The PIC16C55-HSE/SO's deterministic 200 ns instruction cycle at 16 MHz and 20 source-capable I/O pins make it a strong fit for legacy industrial control boards that bit-bang older serial protocols (RS-485, I2C bit-bang) or sequence relays. Its 768-byte OTP program memory holds typical ladder-logic replacement routines for valve sequencing, motor start/stop interlocks, and sensor multiplexing. The 28-SOIC package allows dense through-hole-replacement layouts where the original design used a 28-pin PDIP socket. Wide 2.5-6.25V operating range means the part can run directly from a 24V industrial rail stepped down to 5V via a simple linear regulator, with no need for an additional DC-DC stage.
Recommended
Appliance Front-Panel Controllers
For consumer appliance front panels (washing machines, microwave ovens, HVAC thermostats), the PIC16C55-HSE/SO provides just enough program memory, RAM, and I/O to drive a multiplexed 7-segment or character LCD, scan a keypad matrix, and read a few NTC thermistors through an external ADC. Its 2.5-6.25V operating range covers direct 5V regulator and 3-cell alkaline battery operation. The HS-mode 16 MHz clock lets the MCU debounce keys and update displays without visible flicker. Pin-compatible Flash alternatives like the PIC16F57-I/SO are now preferred for new designs because the OTP limitation prevents last-minute firmware fixes during product validation cycles.
Recommended
Sensor Front-End Readout Boards
The PIC16C55-HSE/SO fits sensor front-end readouts where the MCU aggregates data from one or two SPI sensors, applies linearization or averaging in firmware, and forwards the result over UART. With 25 bytes of RAM the part can buffer a handful of recent samples, and the 768-byte program memory is enough for floating-point-free linearization tables. Operating at 16 MHz, the MCU can poll sensors at 1-10 kHz without DMA. Designers pair it with low-noise analog front ends such as the MCP3551 22-bit ADC for slow precision signals, or with digital sensors like the MCP9808 for temperature logging.
Recommended
Educational and Hobby Embedded Projects
The PIC16C55-HSE/SO remains popular in university embedded systems courses because its small instruction set (33 instructions of 12 bits each) lets students learn the entire ISA in one lab session. The 28-SOIC package is hand-solderable and breadboard-friendly with a SOIC-to-DIP adapter. The 16 MHz HS-mode clock supports real-time experiments in PWM generation, interrupt handling, and timer-based scheduling without aliasing. The baseline PIC16C5x architecture remains the canonical teaching example for Harvard-vs-von-Neumann design trade-offs. Hobbyists use it for retro projects like LED cubes, model-railroad controllers, and animatronic Halloween props.
Recommended
Low-End Consumer Electronics
Toys, remote controls, novelty lighting, and other low-end consumer products use the PIC16C55-HSE/SO because its 2.5-6.25V operating range can be powered directly from two or three AA cells without a regulator, and its 8-bit RISC core delivers more than enough MIPS for blinking LEDs, decoding IR remote protocols, and driving small sound chips. The 768-byte program memory comfortably fits NEC or RC5 IR-decoder state machines plus LED chase patterns. With the part now NRND, designers migrating to the PIC16F57-I/SO gain Flash reprogrammability for late-cycle firmware changes and at the same time reduce per-unit cost via Flash-versus-OTP pricing.
Recommended
Simple PWM Motor Speed Controllers
Small DC motors, hobby servos, and low-power fans can be driven directly from PIC16C55-HSE/SO PWM output pins using the TMR0 overflow interrupt or a software PWM loop. With 16 MHz clocking, the part generates PWM frequencies up to 78 kHz (8-bit resolution) which exceeds the 25 kHz typically needed to drive past audible motor whine. The 20 I/O pins let the MCU read speed-command potentiometers, limit switches, and tachometer feedback simultaneously. A discrete half-H driver like the L293D or a logic-level MOSFET completes the power stage. For new designs the PIC16F57-I/SO with its Flash memory lets designers tune acceleration curves in the field without scrapping programmed parts.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55-HSE/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16F57-I/SO | PIC16C55A-20I/SO | PIC16C55-10I/SO | PIC16C55-10/SO | PIC16C55-HS/SO |
|---|---|---|---|---|---|---|
| Package | 28-SOIC (0.295", 7.50 mm) | 28-SOIC (same) | 28-SOIC (same) | 28-SOIC (same) | 28-SOIC (same) | 28-SOIC (same) |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory Type | OTP (768 bytes / 512 x 12) | Flash (2K words) | OTP (768 bytes) | OTP (768 bytes) | OTP (768 bytes) | OTP (768 bytes) |
| Maximum Clock Frequency | 16 MHz (HS mode) | 20 MHz | 20 MHz | 10 MHz | 10 MHz | 16-20 MHz |
| RAM Size | 25 bytes | 25 bytes | 25 bytes | 25 bytes | 25 bytes | 25 bytes |
| I/O Pins | 20 | 20 | 20 | 20 | 20 | 20 |
| Operating Voltage | 2.5-6.25V | 2.0-5.5V | 2.5-6.25V | 2.5-6.25V | 2.5-6.25V | 2.5-6.25V |
| Brown-Out Reset | Not present | Present | Present | Not present | Not present | Not present |
| Lifecycle Status | Obsolete / NRND | Active | NRND | Obsolete | Obsolete | Obsolete |
Key Differentiators
- 20 MHz instruction throughput at 16 MHz oscillator (4:1 internal divider, single-cycle execution) (vs PIC16C54-HSE/SO)
- NRND status signals end-of-supply risk to procurement (vs PIC16F57-I/SO)
- 20 I/O pins for dense parallel interfaces (vs PIC16C554-04I/SO)
Design Notes
OTP memory cannot be erased. A single firmware bug on the PIC16C55-HSE/SO means the entire programmed unit is scrap - there is no recovery path. For prototyping, use the PIC16C55/JW windowed ceramic variant or the PIC16F57-I/SO Flash equivalent; only switch to the OTP SOIC version when the firmware is locked down and you are committing to high-volume production. Stockpile OTP parts before going to production because the PIC16C5x family is NRND.
The HSE suffix selects the HS-mode high-speed oscillator with 4-20 MHz external crystal or ceramic resonator support. Per the PIC16C5x datasheet (DS30412), HS mode uses a different bias level on the oscillator inverter than XT or LP modes; using an HS-rated part with a low-frequency 32.768 kHz watch crystal will not start the oscillator and the MCLR pin will stay asserted. Also note that C1 and C2 load capacitor values must follow the crystal manufacturer's datasheet - typical 16 MHz HC-49S crystals need 22-33 pF on each side.
The 28-SOIC (7.50 mm body width) variant of the PIC16C55-HSE/SO has a thermal pad only on the SPDIP package - the SOIC relies entirely on the four ground pins (VSS on pin 10 plus PORTA and PORTB drive capacity) for heat removal. Keep digital outputs sourcing or sinking less than 20 mA per pin (25 mA absolute max) and less than 100 mA total package dissipation to stay within the 200 mW absolute-max rating. Place a 0.1 uF ceramic decoupling capacitor within 5 mm of the VDD pin (pin 11) on the 28-SOIC layout.
Route the MCLR/VPP pin (pin 9) away from any high-frequency switching signals because the MCLR comparator is sensitive to capacitive coupling. The standard Microchip recommendation is to place a 10 kohm pull-up to VDD and a 100 nF cap to VSS on the MCLR line; the cap filters out narrow noise pulses that can falsely reset the part. Also, keep the OSC1/OSC2 traces short (under 10 mm) and surround them with a ground pour to minimize radiated EMI at 16 MHz.
Compliance Information
RoHS and lead-free compliant per DigiKey listing (319791). Not AEC-Q100 qualified - this is a commercial/industrial-grade baseline MCU, not automotive. REACH compliance stated by distributor catalog. The OTP die has no erase cycle and thus no halogenated packaging concern per Microchip environmental documentation.
