PIC16C55AT-04I/SS - 8-bit 4MHz 768B OTP MCU SSOP-28 | Microchip
MPN: PIC16C55AT-04I/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.85 | $3.85 |
| 10 | $3.45 | $34.50 |
| 100 | $3.05 | $305.00 |
| 500 | $2.7 | $1,350.00 |
| 1,000 | $2.4 | $2,400.00 |
PIC16C55AT-04I/SS Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, memory, and peripherals. The PIC16C5X family uses a RISC architecture with only 33 single-word/single-cycle instructions, placing it within the broader taxonomy of microcontroller -> embedded processor -> semiconductor device. MCUs serve as the decision-making core in countless embedded systems, replacing discrete logic and reducing BOM cost while adding reprogrammability.
Key features of the PIC16C55AT-04I/SS include 12-bit wide instructions that yield 2:1 code compression versus competing 8-bit architectures, an operating voltage range of 3.0 V to 6.25 V, a wide operating temperature range, and low power consumption typical of CMOS designs. The device provides 20 bidirectional I/O pins and supports both internal and external reset options, making it adaptable to various embedded control scenarios.
The PIC16C55AT-04I/SS uses a Harvard architecture with separate program and data buses, executed through a two-stage pipeline. With 768 bytes of OTP program memory and only 24 bytes of data RAM, this part is targeted at cost-sensitive, low-volume applications where Flash reprogrammability is unnecessary and one-time-programmable (OTP) memory is acceptable. The 4 MHz maximum clock provides instruction cycle times of 1 microsecond.
Typical applications include appliance control, automotive subsystems, low-end consumer electronics, industrial control, and remote transmitters. The compact SSOP-28 footprint also makes it suitable for space-constrained designs.
When designing with this device, note that the OTP memory cannot be erased or rewritten, so firmware must be fully validated before programming. Engineers should use the appropriate Microchip programmer (e.g., PICSTART Plus, MPLAB PM3) for device programming.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes not found in the manufacturer datasheet, giving engineers and procurement teams a single source for evaluating the PIC16C55AT-04I/SS in new designs and legacy board reworks.
Drop-in alternatives for PIC16C55AT-04I/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 PIC16C55AT-04I/SS (same form factor and footprint) — differing in Package, Program Memory Size, Program Memory Type, RoHS Status, Core Architecture.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55AT-04/SS
✅ Drop-In✓ In Stock
$1.55 / Unit
View Datasheet →PIC16C55AT-04E/SS
✅ Drop-In✓ In Stock
$2.12 / Unit
View Datasheet →PIC16C55A-04I/SS
✅ Drop-In✓ In Stock
$2.22 / Unit
View Datasheet →PIC16C55A-20I/SS
✅ Drop-In✓ In Stock
$1.04 / Unit
View Datasheet →PIC16C55-04I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C558-04I/SO
✅ Drop-In✓ In Stock
$3.11 / Unit
View Datasheet →PIC16C55AT-04I/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | 8-bit PIC |
| Family | PIC16C5X |
| Program Memory Type | OTP (One-Time Programmable) |
| Program Memory Size | 768 bytes (512 x 12-bit) |
| Data RAM | 24 bytes |
| Maximum Clock Frequency | 4 MHz |
| Instruction Cycle Time | 1 us at 4 MHz |
| I/O Pins | 20 |
| Supply Voltage | 3.0 V to 6.25 V |
| Operating Temperature | -40C to +85C (Industrial) |
| Package | SSOP-28 |
| Mounting Type | Surface Mount |
| Instruction Set | 33 single-word/single-cycle instructions |
| Instruction Width | 12-bit |
| Architecture | Harvard, RISC |
| RoHS Status | Compliant |
PIC16C55AT-04I/SS Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O pin |
| Pin 2 | RA3 — Bidirectional I/O pin |
| Pin 3 | RA4/T0CKI — Bidirectional I/O / Timer0 clock input |
| Pin 4 | MCLR/VPP — Master Clear (reset) input / programming voltage |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — Bidirectional I/O / External interrupt |
| Pin 7 | RB1 — Bidirectional I/O pin |
| Pin 8 | RB2 — Bidirectional I/O pin |
| Pin 9 | RB3 — Bidirectional I/O pin |
| Pin 10 | RB4 — Bidirectional I/O pin |
| Pin 11 | RB5 — Bidirectional I/O pin |
| Pin 12 | RB6 — Bidirectional I/O pin |
| Pin 13 | RB7 — Bidirectional I/O pin |
| Pin 14 | VSS — Ground reference |
| Pin 15 | OSC1/CLKIN — Oscillator input / external clock input |
| Pin 16 | OSC2/CLKOUT — Oscillator output / clock output |
| Pin 17 | RC0 — Bidirectional I/O pin |
| Pin 18 | RC1 — Bidirectional I/O pin |
| Pin 19 | RC2 — Bidirectional I/O pin |
| Pin 20 | RC3 — Bidirectional I/O pin |
| Pin 21 | RC4 — Bidirectional I/O pin |
| Pin 22 | RC5 — Bidirectional I/O pin |
| Pin 23 | RC6 — Bidirectional I/O pin |
| Pin 24 | RC7 — Bidirectional I/O pin |
| Pin 25 | VSS — Ground reference |
| Pin 26 | VDD — Positive supply voltage |
| Pin 27 | RA0 — Bidirectional I/O pin |
| Pin 28 | RA1 — Bidirectional I/O pin |
Typical Applications
PIC16C55AT-04I/SS is suitable for 6 applications: Appliance Control, Industrial Control Systems, Remote Control and RF Transmitters, Low-End Consumer Electronics, Sensor Interface Modules, Automotive Body Electronics (Non-Safety).
Appliance Control
The PIC16C55AT-04I/SS fits appliance control designs through its compact SSOP-28 footprint, 20 I/O pins, and OTP memory suited to locked firmware production. The 4 MHz clock and 768-byte OTP program space handle sensor reads, relay actuation, and user-interface scanning for washers, dryers, microwaves, and dishwashers. With 3.0-6.25 V supply range, the part accepts both 3.3 V logic sensors and legacy 5 V relay drivers without level shifters.
Recommended
Industrial Control Systems
For industrial control, the PIC16C55AT-04I/SS delivers -40C to +85C industrial temperature operation, 20 mA source/sink I/O for direct LED and relay drive, and CMOS low-power consumption suitable for always-on monitoring nodes. The OTP memory prevents accidental firmware modification in the field, while the 33-instruction RISC core enables responsive control loops. The SSOP-28 package supports compact PLC I/O modules and sensor interface boards.
Recommended
Remote Control and RF Transmitters
The PIC16C55AT-04I/SS suits remote control transmitters because its 768-byte OTP holds simple button-scan and RF encoding firmware, while the 20 I/O pins directly drive key matrixes and modulator circuits. CMOS low power extends battery life in handheld transmitters, and the SSOP-28 small footprint fits key-fob and remote enclosures. Industrial temperature rating supports outdoor or automotive-garage applications.
Recommended
Low-End Consumer Electronics
The PIC16C55AT-04I/SS fits cost-sensitive consumer devices including desk toys, novelty electronics, simple timers, and basic educational kits. OTP memory at $2-3 unit cost keeps BOM minimal, while 20 I/O drive LEDs, buttons, and small displays directly. The 33-instruction RISC core is straightforward for embedded beginners and hobbyists.
Recommended
Sensor Interface Modules
The PIC16C55AT-04I/SS operates as a sensor pre-processor in distributed I/O modules, reading analog sensors via external ADC and conditioning signals before forwarding to a host controller. Its 24-byte RAM and 768-byte OTP handle linearization, calibration, and digital filtering for thermistor, RTD, and basic pressure sensors. Industrial temperature and 3-6.25 V supply accommodate plant-floor 5 V systems.
Recommended
Automotive Body Electronics (Non-Safety)
The PIC16C55AT-04I/SS handles non-safety automotive body functions such as interior lighting, seat-position memory, and accessory timing where AEC-Q100 is not strictly required. Industrial temperature rating covers cabin environments, and the OTP memory prevents field reprogramming of certified firmware. For under-hood or safety-critical modules, choose AEC-Q100-qualified PIC16F or PIC18F Q1 variants instead.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55AT-04I/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55AT-04/SS | PIC16C55AT-04E/SS | PIC16C55A-04I/SS | PIC16C55A-20I/SS | PIC16C55-04I/SS | PIC16C558-04I/SO |
|---|---|---|---|---|---|---|---|
| Package | SSOP-28 | SSOP-28 - same | SSOP-28 - same | SSOP-28 - same | SSOP-28 - same | SSOP-28 - same | SOIC-28 wider (pin-compatible) |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Maximum Clock Frequency | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 20 MHz | 4 MHz | 4 MHz |
| Program Memory | 768 bytes OTP | 768 bytes OTP | 768 bytes OTP | 768 bytes OTP | 768 bytes OTP | 768 bytes OTP | 2 KB OTP |
| Data RAM | 24 bytes | 24 bytes | 24 bytes | 24 bytes | 24 bytes | 24 bytes | 128 bytes |
| I/O Pins | 20 | 20 | 20 | 20 | 20 | 20 | 20 |
| Operating Temperature | -40C to +85C (Industrial) | 0C to +70C (Commercial) | -40C to +125C (Extended) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | -40C to +85C (Industrial) | -40C to +85C (Industrial) |
| Supply Voltage | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 6.25 V |
| Memory Type | OTP | OTP | OTP | OTP | OTP | OTP | OTP |
Key Differentiators
- Compact SSOP-28 with industrial temperature range (vs PIC16C558-04I/SO)
- OTP memory prevents accidental firmware modification (vs PIC16F54-I/SS)
- 33-instruction RISC core with 2:1 code compression (vs PIC16C55-04I/SS)
Design Notes
Place a 0.1 uF ceramic decoupling capacitor as close as possible to the VDD pin (pin 26) and a bulk capacitor (e.g., 10 uF tantalum or ceramic) on the supply rail. The PIC16C55AT-04I/SS operates from 3.0-6.25 V, so a regulated supply is recommended for sensitive analog applications. Power-on rise time should be less than the oscillator start-up time to ensure clean reset behavior; add an external RC delay on MCLR if the supply ramp is slow.
OTP memory cannot be erased or rewritten - verify firmware with a Flash-equivalent emulator (e.g., PIC16F54) before committing to OTP programming. Code-protect fuses, once set, prevent verification of programmed memory, so ensure firmware is fully debugged before enabling code protection. Use the appropriate Microchip programmer (PICSTART Plus, MPLAB PM3, or MPLAB ICD) with a known-good adapter socket to avoid programming failures.
The SSOP-28 has a 0.65 mm pitch - keep-out zone and trace width are tight; use 0.1 mm traces and 0.2 mm spaces minimum. Place the MCLR pull-up resistor (typically 10 kOhm) close to the pin to avoid noise-induced resets. If using an external crystal or resonator, place it within 5 mm of OSC1/OSC2 with short, symmetric traces and a ground guard ring to reduce EMI susceptibility.
I/O pins can source or sink up to 25 mA per pin, but the total package dissipation must not exceed 800 mW. If driving multiple high-current loads, distribute current across multiple ports to stay within thermal limits. For noisy industrial environments, add 100 nF capacitors near each I/O connector and use series resistors on signal lines to dampen ringing.
Compliance Information
RoHS compliant per Microchip product page. Industrial temperature grade, not AEC-Q100 qualified - not suitable for automotive safety-critical applications. Use PIC16F or PIC18F Q1 variants for AEC-Q100.
