PIC16C55A-04/SS - 8-Bit 4MHz OTP MCU 0.75KB SSOP-28 | Microchip
MPN: PIC16C55A-04/SS ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.0634 | $3.06 |
| 10 | $2.85 | $28.50 |
| 100 | $2.65 | $265.00 |
| 500 | $2.45 | $1,225.00 |
| 1,000 | $2.25 | $2,250.00 |
PIC16C55A-04/SS Overview
An 8-bit OTP microcontroller is a single-chip computer that integrates CPU, non-volatile program memory (programmable once and not erasable in OTP variants), RAM, and peripheral I/O on one die. It belongs to the microcontroller hierarchy: microcontroller -> embedded MCU -> 8-bit MCU -> PIC16C5X family -> PIC16C55A derivative. OTP devices are favored in cost-sensitive, high-volume production where firmware is stable and in-system reprogrammability is unnecessary, offering lower per-unit cost than flash equivalents.
Key features include seven or eight special-function hardware registers, an 8-bit real-time clock/counter (TMR0) with programmable prescaler, direct/indirect/relative addressing modes for both data and instructions, an internal power-on reset, a watchdog timer with on-chip RC oscillator, power-saving SLEEP mode, and selectable oscillator options (RC, XT, HS, LP). The device operates from 2.5 V to 6.25 V across commercial 0C to +70C temperature range.
Typical applications include appliance control, electronic toys, automotive sub-systems (body controllers, lighting), industrial timers and counters, security-system keypads, low-end remote controls, smart sensors, and consumer white-goods. The 20 I/O pins easily drive LED arrays, key-scan matrices, character LCDs (via external driver), and discrete logic interfaces. The wide 2.5-6.25 V supply range permits direct battery operation from 3 V coin cells, two AA cells, or regulated 5 V rails.
When designing with PIC16C55A-04/SS, allocate the oscillator and decoupling capacitors adjacent to the device, and observe the 4 MHz oscillator ceiling. Because the program memory is OTP, code must be fully validated on a windowed (PIC16C55A/JW) or FLASH prototype (PIC16F equivalent) before committing to OTP volume production. Use the PICSTART Plus or MPLAB PM3 programmer for device programming.
Drop-in alternatives for PIC16C55A-04/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-04/SS (same form factor and footprint) — differing in Package, Program Memory Size, Core Architecture, Program Memory Type, Timers.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55A-04I/SS
✅ Drop-In✓ In Stock
$2.22 / Unit
View Datasheet →PIC16C55A-04E/SS
✅ Drop-In✓ In Stock
$2.05 / Unit
View Datasheet →PIC16C55A-04/SO
✅ Drop-In✓ In Stock
$1.48 / Unit
View Datasheet →PIC16C55-10I/SS
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.55 / Unit
View Datasheet →PIC16C54A-04/SS
✅ Drop-In✓ In Stock
$1.18 / Unit
View Datasheet →PIC16C55A-04/SS Maximum Ratings & Electrical Characteristics
| Product Type | 8-bit OTP Microcontroller |
| Core Architecture | RISC (PIC16C5X) |
| Program Memory Size | 768 B (512 x 12) OTP |
| Data RAM | 24 B |
| Number of I/O Pins | 20 |
| Maximum CPU Frequency | 4 MHz |
| Instruction Set Size | 33 single-word instructions |
| Instruction Width | 12 bits |
| Data Path Width | 8 bits |
| Hardware Stack Depth | 2 levels |
| Timers | 1 x 8-bit (TMR0) with prescaler |
| Supply Voltage | 2.5 V to 6.25 V |
| Operating Temperature | 0C to +70C (commercial) |
| Oscillator Options | RC, XT, HS, LP |
| Package | 28-pin SSOP (0.209", 5.30 mm) |
| Mounting Type | Surface Mount |
PIC16C55A-04/SS Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O Port A bit 2 |
| Pin 2 | RA3 — Bidirectional I/O Port A bit 3 |
| Pin 3 | RA4/T0CKI — Bidirectional I/O Port A bit 4 / Timer0 clock input |
| Pin 4 | MCLR — Master clear (reset) input, active low |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — Bidirectional I/O Port B bit 0 / External interrupt input |
| 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 | VDD — Positive supply voltage (2.5 V to 6.25 V) |
| Pin 15 | OSC2/CLKOUT — Oscillator crystal output / Clock out (Fosc/4) |
| Pin 16 | OSC1/CLKIN — Oscillator crystal input / External clock input |
| Pin 17 | RC0 — Bidirectional I/O Port C bit 0 |
| Pin 18 | RC1 — Bidirectional I/O Port C bit 1 |
| Pin 19 | RC2 — Bidirectional I/O Port C bit 2 |
| Pin 20 | RC3 — Bidirectional I/O Port C bit 3 |
| Pin 21 | RC4 — Bidirectional I/O Port C bit 4 |
| Pin 22 | RC5 — Bidirectional I/O Port C bit 5 |
| Pin 23 | RC6 — Bidirectional I/O Port C bit 6 |
| Pin 24 | RC7 — Bidirectional I/O Port C bit 7 |
| Pin 25 | RA0 — Bidirectional I/O Port A bit 0 |
| Pin 26 | RA1 — Bidirectional I/O Port A bit 1 |
| Pin 27 | VDD — Positive supply voltage (2.5 V to 6.25 V) |
| Pin 28 | VSS — Ground reference |
Typical Applications
PIC16C55A-04/SS is suitable for 7 applications: Appliance Control Boards, Electronic Toys and Hobby Kits, Industrial Timer and Counter Modules, Security System Keypads, Remote Control Transmitters, Battery-Powered Smart Sensors, Automotive Body Controllers (Lighting/Accessories).
Appliance Control Boards
The PIC16C55A-04/SS fits appliance boards because its 20 I/O pins easily drive relay coils, keypad scan matrices, and 7-segment LED displays simultaneously. The 2.5-6.25 V supply range accommodates direct 5 V regulated rails or 3 V battery backup without an LDO. Its 4 MHz throughput executes simple state machines for wash-cycle timing, microwave power-level control, or HVAC mode sequencing within budget. Unlike flash parts, the OTP memory locks the firmware against field tampering - a plus for compliance-critical appliances.
Recommended
Electronic Toys and Hobby Kits
Toy designers choose the PIC16C55A-04/SS for its $0.91 LCSC pricing, 4 MHz performance sufficient for sound-effect synthesis, and 20 I/O capable of multiplexing LED matrices up to 64 LEDs. The PIC16C5X RISC architecture's 33 instructions let novices learn assembly quickly, and the wide supply range works directly from 3 V battery packs. OTP memory prevents end-user firmware piracy - a critical concern in mass-production consumer products.
Recommended
Industrial Timer and Counter Modules
Industrial timer applications exploit the PIC16C55A-04/SS's 8-bit TMR0 with programmable prescaler (up to 1:256) for long-duration event counting without CPU overhead. The hardware watchdog timer with dedicated on-chip RC oscillator protects against brown-out or RF-induced firmware lockup in factory environments. The 28-SSOP package supports automated pick-and-place assembly, and the 0C-70C commercial range tolerates most cabinet-mounted installations.
Recommended
Security System Keypads
Security keypad matrices scan up to 4x4 button grids using only 8 GPIO thanks to the PIC16C55A-04/SS's flexible I/O architecture. The 4 MHz clock debounces mechanical switches reliably via TMR0 interrupts. OTP storage makes reverse-engineering the keypad PIN-validation algorithm difficult, and the 2.5-6.25 V range accepts backup-battery power during mains failure. Combined with an external piezo buzzer driver, it forms a complete keypad controller.
Recommended
Remote Control Transmitters
Sub-1 GHz remote-control transmitters pair naturally with the PIC16C55A-04/SS because the device's SLEEP mode drops quiescent current to a few microamps, extending battery life. The TMR0 wakes the MCU on button-press edges, executes an RF encoder routine (such as a rolling-code algorithm), and returns to sleep. OTP memory prevents firmware cloning - essential for anti-piracy in aftermarket auto keys and garage-door openers.
Recommended
Battery-Powered Smart Sensors
Wireless sensor nodes use the PIC16C55A-04/SS to interface analog sensors via external ADC and stream data over UART to a radio module. The 2.5 V minimum supply accepts single LiCoin cell operation down to end-of-life voltage. SLEEP current and TMR0 wake-up permit multi-year battery life on a single CR2032. With OTP firmware locked at production, IP for proprietary sensor-calibration tables is protected.
Recommended
Automotive Body Controllers (Lighting/Accessories)
Interior lighting controllers, seat-position memories, and accessory multiplexers use the PIC16C55A-04/SS for its 20 GPIO capable of driving multiple MOSFET switches directly. The 4 MHz speed suffices for PWM-based dimming and CAN/LIN bit-banging (when paired with external transceivers). Note: For under-hood or AEC-Q100-required applications, the automotive-qualified PIC16C55A-04I/SS variant in industrial temperature range is required instead.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55A-04/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55A-04I/SS | PIC16C55A-04E/SS | PIC16C55A-04/SO | PIC16C55-10I/SS | PIC16C54A-04/SS |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SSOP (5.30 mm) | 28-SSOP (5.30 mm) - same | 28-SSOP (5.30 mm) - same | 28-SOIC (7.50 mm) - wider body, same pin count | 28-SSOP (5.30 mm) - same | 28-SSOP (5.30 mm) - same |
| CPU Frequency | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 10 MHz | 4 MHz |
| Program Memory | 768 B OTP | 768 B OTP | 768 B OTP | 768 B OTP | 768 B OTP | 768 B OTP |
| RAM | 24 B | 24 B | 24 B | 24 B | 24 B | 24 B |
| I/O Pins | 20 | 20 | 20 | 20 | 20 | 12 |
| Temperature Range | 0C to +70C (Commercial) | -40C to +85C (Industrial) | -40C to +125C (Extended) | 0C to +70C (Commercial) | -40C to +85C (Industrial) | 0C to +70C (Commercial) |
| Supply Voltage | 2.5 V to 6.25 V | 2.5 V to 6.25 V | 2.5 V to 6.25 V | 2.5 V to 6.25 V | 2.5 V to 6.25 V | 2.5 V to 6.25 V |
Key Differentiators
- Industrial temperature range upgrade available in same SSOP-28 footprint (vs PIC16C55A-04/SS vs PIC16C55A-04I/SS)
- Extended temperature range variant for harsh environments (vs PIC16C55A-04/SS vs PIC16C55A-04E/SS)
- Faster 10 MHz speed grade upgrade within same SSOP-28 package (vs PIC16C55A-04/SS vs PIC16C55-10I/SS)
- Higher I/O count than smaller PIC16C5X siblings (vs PIC16C55A-04/SS vs PIC16C54A-04/SS)
Design Notes
Decouple both VDD pins (14 and 27) individually with 100 nF ceramic capacitors placed within 5 mm of the respective package leads, and add a bulk 10 uF tantalum or aluminum electrolytic near the device. PIC16C5X devices have two VDD/VSS pairs to reduce digital switching noise coupling into analog paths - bypassing both is essential. Estimated: total dynamic current at 4 MHz x 5 V with all 20 I/O toggling is roughly 10 mA, so the bulk cap must source this during GPIO transitions without rail sag.
Route the MCLR pin (pin 4) directly to the reset circuit with no stubs. Use a 10 kohm pull-up to VDD and a 100 nF cap to ground for a simple power-on-reset delay; for noisy environments add a TVS diode (such as PESD5V0L1BA) from MCLR to VSS to clamp ESD. The OSC2/CLKOUT pin can drive a buffered clock to neighboring peripherals - keep traces short to avoid EMI. Place the crystal/oscillator within 10 mm of pins 15-16 with guard traces grounded on both sides.
Do not exceed the 4 MHz oscillator ceiling on the -04 speed grade - attempting 10 MHz operation on a -04 part will cause unstable execution and EEPROM/flash verify failures during programming. Always enable the watchdog timer (WDT) in fuse bits for deployed systems to recover from brown-outs or RF glitches; disable WDT only during development to ease debugging. Remember OTP memory cannot be erased - validate code on a windowed PIC16C55A/JW or flash-based PIC16F57 prototype before committing to production OTP volume.
The PIC16C55A-04/SS in 28-SSOP package has a theta_JA of approximately 100 C/W (estimated, datasheet value to be confirmed). At maximum supply of 6.25 V with all I/O loaded, total device dissipation rarely exceeds 50 mW, so junction temperature rise is negligible. However, in enclosed industrial cabinets above 60 C ambient, derate I/O sourcing current from 20 mA per pin to 10 mA to keep the die below +125 C.
Compliance Information
PIC16C55A is NRND per Microchip product page. Compliance certificates not retrieved from Verified Web Data - see [DATA_NEEDED] markers in specs. PIC16C5X OTP devices are legacy parts and many predate RoHS-era manufacturing.
