PIC16C55A-04/SP - 8-bit OTP MCU, 768B, 20 I/O | Microchip
MPN: PIC16C55A-04/SP ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.4 | $3.40 |
| 10 | $3.06 | $30.60 |
| 100 | $2.72 | $272.00 |
| 500 | $2.41 | $1,205.00 |
| 1,000 | $2.13 | $2,130.00 |
PIC16C55A-04/SP Overview
A baseline PIC microcontroller is a member of Microchip's PIC16C5x family — a family of 8-bit Harvard-architecture RISC microcontrollers built around a 12-bit program word, 8-bit data path, and a small register file. Within the broader taxonomy, a PIC baseline MCU is a microcontroller (MCU) — a single-chip processor integrating core, non-volatile program memory, RAM, I/O, and timers — which itself is a sub-category of embedded microcontrollers and ultimately of integrated circuits for embedded control. The PIC16C5x baseline family targets cost-sensitive, deterministic, interrupt-free control loops where predictability and small code size outweigh the need for analog peripherals or large RAM.
Key features of the PIC16C55A-04/SP include: a two-level deep hardware stack for subroutine nesting, direct/indirect/relative addressing modes for compact pointer arithmetic, 8-bit real-time clock/counter (TMR0) with software-programmable prescaler, and a wide 2.5 V to 6.25 V operating voltage range. The device is specified over the commercial 0°C to +70°C temperature range, supports an external oscillator or RC clock source, and offers brown-out protection variants across the broader PIC16C5x family. The '04' speed suffix denotes the 4 MHz maximum oscillator grade.
Typical applications for the PIC16C55A-04/SP include consumer appliance control, low-end toys and education, simple sensor signal conditioning, replacement of discrete logic in glue-controller roles, and white-goods timer/sequencer boards. The 20-pin-equivalent of GPIO and small code footprint also make it a popular choice for learning and hobbyist platforms that emulate older PIC16C5x development kits.
When designing with the PIC16C55A-04/SP, observe that OTP memory requires masked-programmer flow at production time — engineering builds typically use a windowed (JW) or UV-erasable variant for iteration. Pin compatibility with the PIC16C54 and PIC16C56 families enables a single PCB layout to support several memory-density options across the product line.
This page synthesizes distributor stock and pricing, drop-in PIC16C5x pin-compatible alternatives, and practical design notes not present in the bare Microchip datasheet, providing an engineering decision aid rather than a re-statement of specifications.
Drop-in alternatives for PIC16C55A-04/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 PIC16C55A-04/SP (same form factor and footprint) — differing in Package, Mounting Type, Program Memory Type, Timers, Program Memory Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55-10/SP
✅ Drop-In✓ In Stock
$2.45 / Unit
View Datasheet →PIC16C554-04/P
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.85 / Unit
View Datasheet →PIC16C54A-04/P
✅ Drop-In✓ In Stock
$3.75 / Unit
View Datasheet →PIC16C558-04/P
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$4.2 / Unit
View Datasheet →PIC16F54-I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C55A-04/SP Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC16C5x (8-bit RISC, 12-bit instruction word) |
| CPU Speed (Max) | 4 MHz |
| Program Memory | 768 bytes (512 x 12-bit words), OTP |
| Data RAM | 24 bytes |
| Digital I/O Pins | 20 |
| Timers | 1 x 8-bit (TMR0) |
| Hardware Stack | 2-level deep |
| Addressing Modes | Direct, Indirect, Relative |
| Operating Voltage | 2.5 V to 6.25 V |
| Operating Temperature | 0°C to +70°C (commercial) |
| Package | 28-pin SPDIP (Skinny Plastic DIP, through-hole) |
| Mounting Type | Through-Hole |
| MSL Level | 1 (unlimited) |
| Pin Count | 28 |
| Program Memory Type | OTP (One-Time Programmable) |
PIC16C55A-04/SP Pin Configuration
| Pin 1 | RA2 — Port A bit 2 (bidirectional digital I/O) |
| Pin 2 | RA3 — Port A bit 3 (bidirectional digital I/O) |
| Pin 3 | RTCC — Real-Time Clock/Counter (TMR0) external clock input |
| Pin 4 | NC — Not connected (per datasheet) |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0 — Port B bit 0 (bidirectional digital I/O) |
| Pin 7 | RB1 — Port B bit 1 (bidirectional digital I/O) |
| Pin 8 | RB2 — Port B bit 2 (bidirectional digital I/O) |
| Pin 9 | RB3 — Port B bit 3 (bidirectional digital I/O) |
| Pin 10 | RB4 — Port B bit 4 (bidirectional digital I/O) |
| Pin 11 | RB5 — Port B bit 5 (bidirectional digital I/O) |
| Pin 12 | RB6 — Port B bit 6 (bidirectional digital I/O) |
| Pin 13 | RB7 — Port B bit 7 (bidirectional digital I/O) |
| Pin 14 | VDD — Positive supply voltage (2.5 V to 6.25 V) |
| Pin 15 | OSC2 — Oscillator output (crystal/RC mode) |
| Pin 16 | OSC1 — Oscillator input (crystal/RC/external clock) |
| Pin 17 | RC7 — Port C bit 7 (bidirectional digital I/O) |
| Pin 18 | RC6 — Port C bit 6 (bidirectional digital I/O) |
| Pin 19 | RC5 — Port C bit 5 (bidirectional digital I/O) |
| Pin 20 | RC4 — Port C bit 4 (bidirectional digital I/O) |
| Pin 21 | RC3 — Port C bit 3 (bidirectional digital I/O) |
| Pin 22 | RC2 — Port C bit 2 (bidirectional digital I/O) |
| Pin 23 | RC1 — Port C bit 1 (bidirectional digital I/O) |
| Pin 24 | RC0 — Port C bit 0 (bidirectional digital I/O) |
| Pin 25 | RA7 — Port A bit 7 (bidirectional digital I/O) |
| Pin 26 | RA6 — Port A bit 6 (bidirectional digital I/O) |
| Pin 27 | RA5 — Port A bit 5 (bidirectional digital I/O) |
| Pin 28 | RA4 — Port A bit 4 (bidirectional digital I/O, open-drain on PIC16C5x) |
Typical Applications
PIC16C55A-04/SP is suitable for 6 applications: Consumer Appliance Timer / Sequencer, Toy and Hobbyist Embedded Controller, Glue-Logic Replacement / Discrete Logic Consolidation, Industrial Sensor Signal Conditioning Front-End, Education and PIC16C5x Training Platforms, Legacy Embedded Controller Board Replacement.
Consumer Appliance Timer / Sequencer
The PIC16C55A-04/SP fits white-goods timer boards because its deterministic PIC16C5x instruction set, 2-level hardware stack, and 768-byte OTP memory are sufficient for fixed sequence programs (wash cycles, microwave duty cycles, defrost timers). The 20 GPIO pins directly drive relays, triacs, and 7-segment displays without external logic; the 8-bit TMR0 with programmable prescaler generates the 1 ms / 10 ms / 1 s timing bases needed in appliance control. Unlike mid-range PICs, the baseline core has no interrupt latency, so the firmware loop runs with predictable branch timing — exactly what a UL/CE appliance watchdog expects.
Recommended
Toy and Hobbyist Embedded Controller
The PIC16C55A-04/SP's small code footprint and 28-pin SPDIP through-hole package are ideal for hobbyist robotics, RC train controllers, animatronic puppets, and STEM education kits. The 12-bit instruction word compresses 8-bit logic so 768 bytes of OTP holds a complete sequence of PWM, debounced inputs, and motor drive logic without external ROM. The exposed 20 I/O drive LEDs, servos, and H-bridge motor drivers directly; the 4 MHz oscillator is fast enough for 1 ms servo refresh without jitter.
Recommended
Glue-Logic Replacement / Discrete Logic Consolidation
The PIC16C55A-04/SP replaces 4-6 discrete 74HC logic ICs in glue-controller roles by collapsing state machines into 768 bytes of OTP firmware. Its 20 GPIO pins absorb multiple latch, mux, and counter functions, while TMR0 implements the system timing tick. Operating from 2.5 V to 6.25 V it sits directly on legacy 5 V logic rails. Compared to mid-range PICs, the baseline core's 2-level hardware stack and 12-bit instruction word keep the cycle count predictable for hard real-time logic replacement.
Recommended
Industrial Sensor Signal Conditioning Front-End
The PIC16C55A-04/SP serves as a low-cost front-end for industrial 4-20 mA loop transmitters, basic thermistor/RTD linearizers, and threshold-detection modules. While the chip lacks an internal ADC, its 20 GPIO drive an external delta-sigma ADC or comparator chain, and the deterministic baseline core executes linearization lookup tables in fixed timing — a key advantage for safety-rated loops. The wide 2.5-6.25 V supply tolerates 24 V industrial rails after external regulation, while the 0-70°C commercial range covers indoor cabinet installations.
Recommended
Education and PIC16C5x Training Platforms
The PIC16C55A-04/SP remains a popular PIC16C5x family training part because the 28-pin SPDIP package is breadboard-compatible and the baseline PIC instruction set is the easiest of any microcontroller family to teach. Universities use the PIC16C55A-04/SP to demonstrate Harvard architecture, 12-bit instruction encoding, and 2-level stack behavior. Engineering students can still program it with MPLAB-X + PICkit 3 through the in-circuit debug header on a socketed carrier, making it the canonical introduction to Microchip's ecosystem.
Recommended
Legacy Embedded Controller Board Replacement
The PIC16C55A-04/SP serves as a 1:1 replacement in legacy industrial controllers, point-of-sale terminals, and field-deployed telemetry modules originally designed around the PIC16C5x baseline family. The 28-pin SPDIP pinout matches PIC16C54/55/56/57/58 family boards, so a swap to the PIC16C55A-04/SP restores 768-byte code density in legacy slots that may have been out of production for years. The NRND status still allows authorized Microchip channels to manufacture the part for long-life customers with verified last-time-buy schedules.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55A-04/SP — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55-10/SP | PIC16C554-04/P | PIC16C54A-04/P | PIC16C558-04/P | PIC16F54-I/SP |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-pin SPDIP (Skinny PDIP) | 28-pin SPDIP — same | 28-pin PDIP — same footprint, wider body | 28-pin PDIP — same footprint, wider body | 28-pin PDIP — same footprint, wider body | 28-pin SPDIP — same |
| Program Memory | 768 bytes (512 x 12-bit OTP) | 768 bytes (same) | 768 bytes (same) | 512 bytes (-33%) | 2048 bytes (+167%) | 768 bytes (Flash, reprogrammable) |
| Max CPU Speed | 4 MHz | 10 MHz (+150%) | 4 MHz (same) | 4 MHz (same) | 4 MHz (same) | 20 MHz (+400%) |
| Data RAM | 24 bytes | 24 bytes (same) | 80 bytes (+233%) | 25 bytes (same) | 128 bytes (+433%) | 25 bytes (same) |
| Digital I/O Pins | 20 | 20 (same) | 20 (same) | 12 (-40%) | 22 (+10%) | 12 (only 12 exposed) |
| Program Memory Type | OTP (One-Time Programmable) | OTP | OTP | OTP | OTP | Flash (reprogrammable) |
| Lifecycle Status | NRND (Not Recommended for New Designs) | NRND | NRND | NRND | NRND | Active |
Key Differentiators
- Lower risk for legacy baseline-family replacements (vs PIC16F54-I/SP)
- Higher program memory than the smallest baseline sibling (vs PIC16C54A-04/P)
- Lower-cost entry into the PIC16C5x baseline family (vs PIC16C558-04/P)
Design Notes
OTP memory cannot be re-programmed — every firmware revision on the PIC16C55A-04/SP discards a part. For engineering development, use a windowed UV-erasable variant (PIC16C55A-04/JW) or switch to the flash-based PIC16F54-I/SP. Production programmers must also support 12-bit OTP programming voltages (typically 13 V on the MCLR/VPP pin), which not all modern programmers handle — verify programmer support before committing to OTP.
The 28-pin SPDIP pinout of the PIC16C55A-04/SP is identical to the PIC16C54/55/56/57/58 baseline family. PCB layouts should reserve a 0.300-inch-wide DIP-28 land pattern (skinny DIP) to accommodate the '/SP' suffix. If a 0.600-inch-wide PDIP footprint is already on the board, the wider PIC16C54A-04/P will also fit, but the narrower SPDIP body cannot be soldered into a PDIP footprint — verify footprint before substituting.
Place the decoupling capacitor (0.1 µF ceramic) within 5 mm of the VDD pin 14, with a direct low-impedance ground return to VSS pin 5. The OSC1/OSC2 crystal or resonator should sit within 10 mm of pins 15-16 with short, symmetrical traces to minimize stray capacitance that detunes the oscillator. Avoid routing high-speed switching signals (relay coils, triac outputs) under or near the oscillator traces — the baseline core's lack of interrupts makes it sensitive to oscillator jitter on TMR0.
Estimated: at VDD=5 V and 4 MHz clock, the PIC16C55A-04/SP draws approximately 2-5 mA active and <1 µA in sleep mode (per PIC16C5x datasheet DS30453D family typical values). Power-on reset requires VDD rise within 50 ms and a minimum 72 ms power-on delay before code execution begins. For battery-powered designs, the baseline core's sleep current is much lower than mid-range PIC parts — a key reason it persists in long-life-cycle products.
Compliance Information
RoHS, REACH, lead-free, halogen-free, and conflict-minerals compliance were not explicitly listed in the Verified Web Data for PIC16C55A-04/SP. PIC16C5x OTP parts in SPDIP packages were historically through-hole-leaded and may predate full RoHS transition — verify with Microchip's environmental compliance documents before committing to a RoHS-only BOM.
