PIC16C55AT-04E/SS - 8-bit 4MHz OTP MCU 768B | Microchip
MPN: PIC16C55AT-04E/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $3.45 | $3.45 |
| 10 | $3.1 | $31.00 |
| 100 | $2.74 | $274.00 |
| 500 | $2.41 | $1,205.00 |
| 1,000 | $2.12 | $2,120.00 |
PIC16C55AT-04E/SS Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, memory, and peripherals on one die. Within the broader semiconductor taxonomy it sits below microprocessors (no on-chip memory) and above digital signal processors (no general-purpose I/O model). The PIC16C5X family is positioned as a low-cost, high-performance baseline 8-bit MCU family. Program memory is OTP (one-time programmable) EPROM rather than flash, which reduces per-unit cost in mature, code-stable applications but requires masked-ROM or windowed-EPROM alternatives for prototyping or low-volume runs.
Key features include 20 general-purpose digital I/O pins arranged across ports A and B, an integrated Watchdog Timer (WDT) with on-chip RC oscillator for reliable operation, a Power-On Reset (POR) circuit, and a 4 MHz internal/external clock domain. The device operates from 2.5 V to 6.25 V across the extended -40C to +125C industrial temperature range. The 28-SSOP package has 5.30 mm body width and gull-wing leads compatible with standard surface-mount reflow profiles.
Designers choose this part for cost-sensitive embedded control loops where 768 bytes of code are sufficient - appliance timers, remote-control transmitters, low-end sensor interfaces, simple motor controllers, and battery-powered instrumentation. The RISC core delivers deterministic instruction timing that simplifies real-time scheduler design. Because program memory is OTP EPROM, code must be fully validated before programming - this part is a production-only choice rather than a development platform.
When using the PIC16C55AT-04E/SS, observe the 4 MHz maximum clock frequency at 5 V supply - derate to 2 MHz at 2.5 V operation per Microchip datasheet curves. The WDT must be disabled in software (OPTION register) if not used, otherwise it can cause unintended resets. Decouple VDD with a 0.1 microfarad ceramic capacitor placed within 5 mm of the supply pin.
This page synthesizes distributor pricing, drop-in compatible same-footprint alternatives, and engineering guidance not collected in the manufacturer datasheet alone. Cross-brand pin-compatible equivalents are flagged where they exist on the open market.
Drop-in alternatives for PIC16C55AT-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 PIC16C55AT-04E/SS (same form factor and footprint) — differing in Program Memory Size, Core Architecture, Package, Program Memory Type, Watchdog Timer.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C55AT-04/SS
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.55 / Unit
View Datasheet →PIC16C55A-04E/SS
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.05 / Unit
View Datasheet →PIC16C55A-04I/SS
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.22 / Unit
View Datasheet →PIC16C55-10/SS
✅ Drop-In ⚠️ 参数待验证📋 Reference alternative (not in catalog)
PIC16C55-10I/SS
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$2.55 / Unit
View Datasheet →PIC16C55AT-04E/SO
✅ Drop-In ⚠️ 参数待验证✓ In Stock
$1.67 / Unit
View Datasheet →PIC16C55AT-04E/SS Maximum Ratings & Electrical Characteristics
| Product Type | 8-bit Microcontroller (MCU) |
| Core Architecture | PIC RISC (Harvard) |
| Family | PIC16C5X |
| Program Memory Type | OTP EPROM |
| Program Memory Size | 768 B (512 x 12 words) |
| RAM Size | 25 B |
| Data EEPROM | None |
| Maximum Clock Frequency | 4 MHz |
| Instruction Set Width | 12-bit |
| Number of I/O Pins | 20 |
| Supply Voltage Range | 2.5 V to 6.25 V |
| Operating Temperature Range | -40C to +125C (Extended, -E grade) |
| Package Type | 28-SSOP (5.30 mm body) |
| Mounting Type | Surface Mount |
| Watchdog Timer | Yes (integrated) |
| Power-On Reset (POR) | Yes (integrated) |
| Hardware Stack Depth | 2 levels |
PIC16C55AT-04E/SS 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 input (also digital I/O) |
| Pin 4 | MCLR — Master Clear reset input (active low) |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0 — Port B bit 0 (bidirectional digital I/O, interrupt-on-change) |
| Pin 7 | RB1 — Port B bit 1 (bidirectional digital I/O, interrupt-on-change) |
| Pin 8 | RB2 — Port B bit 2 (bidirectional digital I/O, interrupt-on-change) |
| Pin 9 | RB3 — Port B bit 3 (bidirectional digital I/O, interrupt-on-change) |
| Pin 10 | RB4 — Port B bit 4 (bidirectional digital I/O, interrupt-on-change) |
| Pin 11 | RB5 — Port B bit 5 (bidirectional digital I/O, interrupt-on-change) |
| Pin 12 | RB6 — Port B bit 6 (bidirectional digital I/O, interrupt-on-change) |
| Pin 13 | RB7 — Port B bit 7 (bidirectional digital I/O, interrupt-on-change) |
| Pin 14 | VDD — Positive supply voltage (2.5 V to 6.25 V) |
| Pin 15 | OSC2 — Oscillator output (crystal/ceramic resonator) |
| Pin 16 | OSC1 — Oscillator input (crystal/ceramic resonator or 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 | RA0 — Port A bit 0 (bidirectional digital I/O) |
| Pin 26 | RA1 — Port A bit 1 (bidirectional digital I/O) |
| Pin 27 | T0CKI — Timer 0 clock input (also digital I/O) |
| Pin 28 | NC — Not connected (per datasheet package pinout) |
Typical Applications
PIC16C55AT-04E/SS is suitable for 6 applications: Appliance Control Timers, Remote Control Transmitters, Battery-Powered Sensor Interfaces, Simple Motor Speed Controllers, LED Display and Sign Drivers, Industrial Control Logic Replacement.
Appliance Control Timers
The PIC16C55AT-04E/SS fits washing-machine, dishwasher, and microwave-oven timer boards where 768 bytes of OTP program memory is sufficient for the state machine, and 20 GPIO pins can directly drive relays, seven-segment displays, and keypads without external logic. The 4 MHz RISC core executes the timer counter at 1 microsecond per instruction cycle, giving adequate resolution for minute-scale countdowns. The integrated Watchdog Timer recovers the MCU from relay-induced supply transients. Extended -40C to +125C temperature grade handles the under-cabinet thermal environment. Designers place the SSOP on the rear of the control board where the 5.30 mm body fits inside the plastic enclosure without crowding the display module.
Recommended
Remote Control Transmitters
The PIC16C55AT-04E/SS powers IR and RF remote-control transmitters for consumer electronics, garage-door openers, and key-fob entry systems. The 20 GPIO pins directly keypad-scan a 4x4 matrix and drive the LED indicator, while the 25 bytes of RAM buffer the rolling-code algorithm. The 4 MHz clock rate is fast enough for 38 kHz IR carrier generation via bit-banged PWM. OTP program memory locks the proprietary transmission protocol into the device and prevents code readout, which is desirable for security applications. Low-cost SSOP packaging keeps the bill of materials competitive in volume consumer markets.
Recommended
Battery-Powered Sensor Interfaces
The PIC16C55AT-04E/SS serves as the controller in battery-powered sensor pods for HVAC, agricultural monitoring, and industrial telemetry where the 2.5 V to 6.25 V supply range accepts a single lithium cell or two AA cells. The PIC RISC core's deterministic 1 microsecond instruction cycle at 4 MHz enables tight duty-cycling of the sensor front-end to extend operating life into multi-year ranges. The integrated Power-On Reset ensures clean startup after battery swap, and the Watchdog Timer recovers from brownouts. Extended temperature grade supports outdoor installations from winter cold to summer heat.
Recommended
Simple Motor Speed Controllers
The PIC16C55AT-04E/SS controls small brushed DC and unipolar stepper motors in fans, pumps, vending dispensers, and small-appliance drives. The 20 GPIO pins drive phase signals and H-bridge enable lines directly, while the 4 MHz instruction rate generates PWM at audio-inaudible frequencies above 20 kHz to eliminate motor whine. Software-implemented PID loops fit within the 768-byte program memory envelope for low-bandwidth speed regulation. The SSOP package dissipates the small internal switching losses without heatsinking, keeping the BOM cost low.
Recommended
LED Display and Sign Drivers
The PIC16C55AT-04E/SS drives multiplexed LED matrix displays, scrolling message signs, and decorative lighting controllers where deterministic timing matters. At 4 MHz the core can refresh an 8x8 LED matrix via Charlieplexing at well above the 100 Hz flicker threshold. The 25-byte RAM accommodates a small character buffer, and the 20 GPIO pins scan up to 10 rows/columns without external logic. Extended temperature grade supports outdoor signage installations.
Recommended
Industrial Control Logic Replacement
The PIC16C55AT-04E/SS replaces discrete 74-series logic and small PAL/GAL devices in industrial control panels, replacing dozens of glue-logic ICs with a single programmable MCU. The 768-byte OTP memory holds ladder-logic-equivalent decision trees, and the 20 GPIO pins interface to 24 V industrial signals via optocouplers. Extended -40C to +125C temperature grade handles unconditioned factory floor environments. The 28-SSOP package fits inside standard DIN-rail-mounted control boards.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C55AT-04E/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C55AT-04/SS | PIC16C55A-04E/SS | PIC16C55A-04I/SS | PIC16C55-10/SS | PIC16C55-10I/SS | PIC16C55AT-04E/SO |
|---|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 28-SSOP | 28-SSOP - same | 28-SSOP - same | 28-SSOP - same | 28-SSOP - same | 28-SSOP - same | 28-SOIC - different body width 7.50 mm vs 5.30 mm |
| Maximum Clock Frequency | 4 MHz | 4 MHz | 4 MHz | 4 MHz | 10 MHz | 10 MHz | 4 MHz |
| Program Memory | 768 B (512 x 12) OTP | 768 B OTP | 768 B OTP | 768 B OTP | 768 B OTP | 768 B OTP | 768 B OTP |
| RAM Size | 25 B | 25 B | 25 B | 25 B | 25 B | 25 B | 25 B |
| Temperature Grade | -40C to +125C (Extended -E) | 0C to +70C (Commercial) | -40C to +125C (Extended) | -40C to +85C (Industrial) | 0C to +70C (Commercial) | -40C to +85C (Industrial) | -40C to +125C (Extended) |
| Supply Voltage Range | 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 | 2.5 V to 6.25 V |
| Number of I/O Pins | 20 | 20 | 20 | 20 | 20 | 20 | 20 |
Key Differentiators
- Extended industrial temperature grade in a 5.30 mm SSOP (vs PIC16C55AT-04/SS)
- Tape-and-reel packaging for high-volume SMT assembly (vs PIC16C55A-04E/SS)
- 4 MHz clock optimized for low-power 5 V designs (vs PIC16C55-10/SS)
Design Notes
Decouple VDD (pin 14) with a 0.1 microfarad ceramic capacitor placed within 5 mm of the package pin, plus a 1 to 10 microfarad bulk tantalum or electrolytic capacitor on the supply rail. The PIC16C55AT-04E/SS supply range is 2.5 V to 6.25 V; at 5 V operation the maximum clock is 4 MHz, while at 3 V the maximum clock is derated to roughly 2 MHz per Microchip datasheet curves. Hold MCLR high with a 10 kohm pull-up resistor to VDD and add a 100 nF capacitor to ground for noise immunity, unless the internal MCLR function is disabled in the configuration word.
Route the crystal/ceramic resonator traces to OSC1 (pin 16) and OSC2 (pin 15) with short, symmetrical traces and a guard ground pour to minimize stray capacitance. Keep digital signal traces (especially RB and RC ports driving relays or LEDs) away from the oscillator loop to avoid frequency pulling. The 28-SSOP package has 0.65 mm lead pitch - a 4-layer PCB with 0.2 mm traces and 0.4 mm via pads is comfortable for hand-rework and reflow profiling. Place bypass capacitors on the same layer as the IC with vias directly to the ground plane.
Avoid these common mistakes: (1) leaving the Watchdog Timer enabled in production code without a CLRWDT instruction in every main loop iteration - this causes unintended resets. (2) Driving MCLR low inadvertently during code development, which forces reset; use a 10 kohm pull-up. (3) Exceeding 4 MHz at 5 V or 2 MHz at 2.5 V - check the derating curve in the datasheet before lowering VDD. (4) Forgetting that OTP EPROM cannot be erased - the code must be fully validated on a windowed-EPROM or flash equivalent (e.g. PIC16F55) before programming. (5) Using a 5 V ICD programmer on a 3.3 V board without level translation - this can damage the device.
The 28-SSOP body width is 5.30 mm with 0.65 mm lead pitch - keep a minimum of 0.4 mm clearance between SSOP leads and adjacent copper features to avoid solder bridging during reflow. Route the VDD and VSS traces as wide as practical (at least 0.5 mm) to reduce supply bounce when GPIO pins switch high-current loads. Place a ground plane on the layer directly beneath the MCU to provide low-impedance return paths for switching currents. If the design uses port B as the interrupt-on-change source, add 100 nF bypass caps adjacent to each port B pin to suppress ESD-induced false triggers.
Compliance Information
Lead-free per Microchip -E suffix convention and SSOP package compatibility with Pb-free reflow profiles. RoHS, REACH, halogen-free, and conflict-minerals certificates were not present in the verified web data; contact Microchip direct for current compliance documentation. AEC-Q100 qualification is not stated; this part is not recommended for AEC-Q100 automotive safety-critical applications without further qualification.
