PIC16C55A-04E/SS - 8-Bit 4MHz OTP MCU 768B | Microchip
MPN: PIC16C55A-04E/SS ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.45 | $3.45 |
| 10 | $3.1 | $31.00 |
| 100 | $2.65 | $265.00 |
| 500 | $2.3 | $1,150.00 |
| 1,000 | $2.05 | $2,050.00 |
PIC16C55A-04E/SS Overview
An 8-bit OTP microcontroller is a single-chip computer that integrates a CPU, non-volatile program memory, working RAM, and peripherals into one package; the program memory can be written exactly once (One-Time Programmable), making these devices economical for low-to-medium-volume production. Within the broader taxonomy, the PIC16C55A sits at the bottom of the PIC16 family hierarchy: microcontroller -> 8-bit MCU -> PIC16 -> PIC16C5X baseline -> PIC16C55A. This hierarchy places it below PIC16C6X mid-range and PIC16C7X enhanced devices, and well below modern 16-bit dsPIC and 32-bit PIC32 offerings, but it remains a cost-effective solution for simple control tasks.
Key features of the PIC16C55A-04E/SS include a 4 MHz operating frequency (4 MHz speed grade, denoted by the -04 suffix), 20 digital I/O pins organized across PORTA and PORTB, an 8-bit real-time clock/counter (TMR0) with 8-bit prescaler, watchdog timer with dedicated on-chip RC oscillator for reliable operation, power-on reset, power-saving SLEEP mode, and EPROM/ROM-based code storage. The device operates across the standard PIC16C5X voltage range and supports commercial and industrial temperature grades depending on the part suffix.
The architecture uses a Harvard-style separate program and data bus, allowing instruction fetch and operand read to occur in the same cycle - a key reason the PIC16C5X delivers close to 1 MIPS per MHz. The 12-bit wide instruction word gives 2:1 code compression over typical 8-bit CISC microcontrollers of its class, enabling 512 instruction words to address relatively complex control sequences despite the small 768-byte program memory budget.
Typical applications include low-cost appliance control, LED lighting controllers, simple sensor interfaces, battery chargers, remote control transmitters, automotive body controllers (with proper AEC-Q100 selection), and hobbyist/educational development platforms. The 20 I/O count makes it suitable for designs requiring multiple switches, relays, or LED indicators.
When designing with the PIC16C55A-04E/SS, note that OTP memory cannot be erased or rewritten - use PIC16F55X or PIC16C55A JW-windowed parts for prototyping. Decoupling VDD with a 0.1 uF ceramic capacitor close to the pin is mandatory for stable oscillator operation; the MCLR pin must be tied to VDD through a resistor for normal operation.
This page synthesizes distributor pricing for the PIC16C55A-04E/SS, current lifecycle status from Microchip, same-family drop-in alternatives including -04 and -04I speed/temperature variants, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for PIC16C55A-04E/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 PIC16C55A-04E/SS (same form factor and footprint) — differing in Program Memory Size, Package, Core Architecture, Timers, Program Memory Type.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55A-04/SS
✅ Drop-In✓ In Stock
$2.25 / Unit
View Datasheet →PIC16C55A-04I/SS
✅ Drop-In✓ In Stock
$2.22 / Unit
View Datasheet →PIC16C55A-04E/P
✅ Drop-In✓ In Stock
$3.15 / Unit
View Datasheet →PIC16C55A-04E/SO
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
PIC16C55A-04E/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit PIC |
| Family | PIC16C5X baseline |
| Maximum Clock Frequency | 4 MHz |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 768 B (512 x 12 words) |
| RAM Size | 24 B |
| Data EEPROM | Not present |
| I/O Pins | 20 |
| Timers | 1 x 8-bit (TMR0) |
| Instruction Set | 33 single-word/single-cycle instructions |
| Hardware Stack | 2 levels |
| Package | 28-pin SSOP |
| Mounting Type | Surface Mount |
| Operating Temperature Grade | Extended (E) |
| Lifecycle Status | Not Recommended for new designs (NRND) |
PIC16C55A-04E/SS Pin Configuration
| Pin 1 | RA0 — Bidirectional I/O port A bit 0 |
| Pin 2 | RA1 — Bidirectional I/O port A bit 1 |
| Pin 3 | RA2 — Bidirectional I/O port A bit 2 |
| Pin 4 | RA3 — Bidirectional I/O port A bit 3 |
| Pin 5 | VDD — Positive supply voltage |
| Pin 6 | RB0 — Bidirectional I/O port B bit 0 (interrupt-on-change) |
| 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 | RC5 — Bidirectional I/O port C bit 5 |
| Pin 21 | RC6 — Bidirectional I/O port C bit 6 |
| Pin 22 | RC7 — Bidirectional I/O port C bit 7 |
| Pin 23 | OSC1 — Crystal oscillator input or external clock input |
| Pin 24 | OSC2 — Crystal oscillator output |
| Pin 25 | NC — Not connected (per datasheet) |
| Pin 26 | NC — Not connected (per datasheet) |
| Pin 27 | VDD — Positive supply voltage |
| Pin 28 | MCLR — Master clear (reset) input, internal pull-up |
Typical Applications
PIC16C55A-04E/SS is suitable for 6 applications: Low-Cost Appliance Control, LED Lighting Controllers, Simple Sensor Interface Hubs, Remote Control Transmitters, Battery Charger Control, Educational / Hobby Development Platform.
Low-Cost Appliance Control
The PIC16C55A-04E/SS is well-suited to low-cost appliance control boards such as washing machine timers, microwave oven keypads, and simple HVAC zone controllers because its 4 MHz core delivers 1 MIPS throughput - enough to scan key matrices, drive 7-segment displays, and toggle TRIAC drivers in real time. The 20 digital I/O pins split across PORTA/PORTB/PORTC handle multiple switch inputs, LED indicators, and relay outputs without external muxing. The 768-byte OTP program memory holds typical appliance state-machine firmware, while the 24-byte RAM is sufficient for 4-6 active variables plus a small stack. The 28-SSOP package keeps the PCB footprint compact, ideal for sub-$5 consumer appliances.
Recommended
LED Lighting Controllers
The PIC16C55A-04E/SS can drive decorative LED lighting chains via PWM-like bit-banging on its 20 I/O pins, since the 4 MHz instruction rate sustains smooth color fades and chase patterns at low cost. Each PORTB pin sinks up to 25 mA directly, allowing direct drive of low-current LEDs without external transistors. The on-chip TMR0 8-bit timer with prescaler provides accurate software timing for blinking sequences. Because the OTP memory holds only 512 instruction words, designers must write efficient assembly for non-trivial patterns. The 28-SSOP package enables slim light-strip controller PCBs.
Recommended
Simple Sensor Interface Hubs
The PIC16C55A-04E/SS functions as a low-cost sensor aggregator for thermostats, soil-moisture probes, and basic industrial switches because its RISC core reads multiple digital inputs at deterministic 1-microsecond intervals when running at 4 MHz. PORTB supports internal weak pull-ups for direct connection to mechanical switches, eliminating external resistor arrays. The 24-byte RAM buffers short sensor histories before UART-style software transmission. SLEEP mode with watchdog wake-up enables multi-year battery life in remote sensor nodes. The extended -40C to +125C temperature range suits outdoor enclosures.
Recommended
Remote Control Transmitters
The PIC16C55A-04E/SS is well-matched to infrared remote control transmitters because its 4 MHz oscillator can generate accurate 38 kHz carrier via software bit-banging, and 20 I/O pins support a 4x5 matrix keypad with several status LEDs. The SLEEP current is low enough that battery-powered remotes last years on a pair of AA cells. The 768-byte OTP holds complete transmit code tables and key debounce state machines in compact assembly. The 28-SSOP package is suitable for thin remote-control housings. Designers should prefer PIC16F1503 or PIC16F18324 for new flash-based designs.
Recommended
Battery Charger Control
The PIC16C55A-04E/SS controls NiCd/NiMH and simple Li-ion charger circuits by reading battery voltage via on-chip comparators and toggling charge FETs through PORT pins. The 4 MHz speed is enough to implement CC-CV charging algorithms with millisecond sampling granularity. The TMR0 timer drives charge-time accumulation without burdening the main loop. The extended temperature grade suits chargers mounted near warm battery packs. Since OTP prevents firmware updates, charge profiles are baked in at production. For new designs, Microchip recommends PIC16F1503 or PIC16F1840 for flash-based flexibility.
Recommended
Educational / Hobby Development Platform
The PIC16C55A-04E/SS remains popular in microcontroller education because its simple 33-instruction baseline PIC16C5X architecture teaches RISC fundamentals without overwhelming beginners, and PIC assembly skills transfer upward to PIC16F, PIC18F, and dsPIC families. The 28-SSOP version is breadboard-friendly with adapter boards, and Microchip's MPLAB X IDE supports PIC16C5X assembly and C (XC8 compiler). Hobbyists build line-following robots, simple timers, and logic-replacement projects using the 20 I/O pins. The NRND status encourages learners to migrate to PIC16F54 or PIC16F57 for ongoing part availability.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55A-04E/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55A-04/SS | PIC16C55A-04I/SS | PIC16C55A-04E/P | PIC16C55A-04E/SO |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SSOP | 28-SSOP - same | 28-SSOP - same | 28-PDIP - differs (DIP, not drop-in) | 28-SOIC - differs (SOIC, not drop-in) |
| Maximum Clock Frequency | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 4 MHz |
| Program Memory | 768 B OTP | 768 B OTP | 768 B OTP | 768 B OTP | 768 B OTP |
| RAM Size | 24 B | 24 B | 24 B | 24 B | 24 B |
| I/O Pins | 20 | 20 | 20 | 20 | 20 |
| Operating Temperature | -40C to +125C (Extended) | 0C to +70C (Commercial) | -40C to +85C (Industrial) | -40C to +125C (Extended) | -40C to +125C (Extended) |
| Lifecycle Status | NRND | NRND | NRND | NRND | NRND |
Key Differentiators
- Extended temperature grade for harsh environments (vs PIC16C55A-04/SS)
- Same die across the entire PIC16C55A family (vs PIC16C558 family)
- Largest program memory in PIC16C5X baseline (vs PIC16C54 family)
Design Notes
The PIC16C55A-04E/SS requires a 0.1 uF ceramic decoupling capacitor placed within 5 mm of the VDD pin (pin 5) and another near the second VDD pin (pin 27). Add a 10 uF bulk capacitor on the supply rail. The device operates from [DATA_NEEDED: VDD range], with quiescent current typically below 2 mA active and microampere-level SLEEP current. Use MCLR with a 10 kohm pull-up to VDD and a 100 nF cap to ground for clean reset behavior; tying MCLR directly to VDD without RC delay may cause spurious resets during power ramp.
The 28-pin SSOP package has a 0.65 mm pitch and is sensitive to solder joint stress. Follow IPC-A-610 acceptance criteria for fine-pitch components and use a reflow profile with peak temperature under 250C per JEDEC J-STD-020. For prototyping, place the SSOP on a SOIC-to-DIP adapter PCB to enable breadboard use. The exposed thermal pad (if present in the SSOP variant) must be soldered to a copper pour for mechanical reliability even though this part does not dissipate significant power.
Do not assume PIC16C55A flash programming compatibility - this is OTP EPROM and can be written exactly once via a high-voltage parallel programmer (e.g., Microchip PM3). Attempting to use ICSP will not program the OTP cells. Unused I/O pins must be configured as outputs (not left floating) to minimize SLEEP current and reduce EMI susceptibility. The MCLR pin must NOT be left floating - either tie to VDD via 10 kohm or use the internal MCLR configuration via the configuration word.
Compliance Information
Lifecycle is NRND per Microchip product page (https://www.microchip.com/en-us/product/PIC16C55A). RoHS, REACH, lead-free, halogen-free status not confirmed in verified data; [DATA_NEEDED] flags in specs. AEC-Q100 qualification not applicable for this baseline family - choose PIC16F or PIC18 automotive grades for AEC-Q100 requirements.