PIC16LC55A-04/SS - 8-bit OTP MCU, 768B, 20 I/O, SSOP-28 | Microchip
MPN: PIC16LC55A-04/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.85 | $2.85 |
| 10 | $2.55 | $25.50 |
| 100 | $2.18 | $218.00 |
| 500 | $1.92 | $960.00 |
| 1,000 | $1.7 | $1,700.00 |
PIC16LC55A-04/SS Overview
An 8-bit OTP microcontroller is a member of the microcontroller (MCU) family, which itself is a sub-class of microcomputer -> embedded processor -> semiconductor IC. Within the Microchip PIC hierarchy, this part belongs to the PIC16C5X baseline architecture, employing a RISC-style instruction set of 33 single-word/single-cycle instructions. OTP memory is one-time-programmable, in contrast to Flash or UV-EPROM, and is intended for high-volume production where code is finalized and re-programmability is not required.
Key differentiating features of the PIC16LC55A-04/SS include its baseline PIC16C5X core (no interrupts, fixed hardware stack), 12-bit instruction word length, internal RC oscillator option, power-on reset, watchdog timer, and a wide 3.0-6.25 V supply window that covers both 3.3 V and 5 V rails. The LC prefix indicates a low-power CMOS variant with reduced quiescent current compared to the standard C-series. The 20 I/O count in a 28-pin SSOP enables interfaces to multiple peripherals while keeping PCB area minimal.
Architecturally, the PIC16LC55A-04/SS uses a Harvard-style separate code/data path, executing instructions in a single cycle (except branches). Its 8-level hardware stack is fixed, and its program counter is 9 bits, addressing up to 512 words of OTP. The device offers two 8-bit timer/counters and a watchdog timer driven by an internal dedicated RC oscillator for reliable operation without external components.
Typical applications include low-cost consumer appliances, white goods user interfaces, simple sensor signal conditioning, LED lighting controllers, and battery-operated handheld devices. The wide operating voltage and low-power CMOS design make it especially useful in products that must run from 2-3 AA cells or from a 5 V regulated rail.
When designing with this part, note that the OTP memory cannot be re-programmed in-circuit, so firmware must be fully validated before production programming. Ensure your programmer supports the 28-SSOP package, and budget a decoupling capacitor of 0.1 uF adjacent to VDD and VSS pins for reliable operation.
This page synthesizes distributor stock signals, parametric drop-in alternatives, and practical design guidance that is not consolidated in the manufacturer datasheet alone.
Drop-in alternatives for PIC16LC55A-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 PIC16LC55A-04/SS (same form factor and footprint) — differing in Package, Program Memory Size, Operating Temperature, Timers, Core Architecture.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16LC55A-04I/SS
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$1.18 / Unit
View Datasheet →PIC16C55A-04/SS
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$2.25 / Unit
View Datasheet →PIC16LC554T-04/SO
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$3.85 / Unit
View Datasheet →PIC16LC558T-04/SO
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$2.65 / Unit
View Datasheet →PIC16LC54A-04/SS
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$3.85 / Unit
View Datasheet →PIC16C55A-04I/P
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$1.52 / Unit
View Datasheet →PIC16LC55A-04/SS Maximum Ratings & Electrical Characteristics
| Architecture | PIC16C5X baseline, 8-bit RISC |
| Instruction Set | 33 single-word/single-cycle instructions |
| Program Memory Type | OTP (One-Time Programmable) EPROM |
| Program Memory Size | 768 bytes (512 x 12 words) |
| Data RAM | 32 bytes |
| Data EEPROM | Not present |
| Maximum Clock Speed | 4 MHz |
| Supply Voltage (VDD) | 3.0 V to 6.25 V |
| I/O Pins | 20 |
| Timers | 1 x 8-bit Timer0 |
| Watchdog Timer | Yes (internal dedicated RC oscillator) |
| Oscillator Modes | External RC, internal RC, crystal/ceramic resonator |
| Stack Depth | 2-level hardware stack |
| Package | 28-pin SSOP (5.30 mm body width) |
| Mounting Type | Surface Mount |
| Operating Temperature | 0C to +70C (Commercial) |
PIC16LC55A-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 | OSC1/CLKIN — Oscillator crystal input or external clock input |
| Pin 7 | OSC2/CLKOUT — Oscillator crystal output or clock output |
| Pin 8 | RC0 — Bidirectional I/O port C bit 0 |
| Pin 9 | RC1 — Bidirectional I/O port C bit 1 |
| Pin 10 | RC2 — Bidirectional I/O port C bit 2 |
| Pin 11 | RC3 — Bidirectional I/O port C bit 3 |
| Pin 12 | RC4 — Bidirectional I/O port C bit 4 |
| Pin 13 | RC5 — Bidirectional I/O port C bit 5 |
| Pin 14 | RC6 — Bidirectional I/O port C bit 6 |
| Pin 15 | RC7 — Bidirectional I/O port C bit 7 |
| Pin 16 | VSS — Ground reference (secondary) |
| Pin 17 | RB0/INT — Bidirectional I/O port B bit 0 / external interrupt input |
| Pin 18 | RB1 — Bidirectional I/O port B bit 1 |
| Pin 19 | RB2 — Bidirectional I/O port B bit 2 |
| Pin 20 | RB3 — Bidirectional I/O port B bit 3 |
| Pin 21 | RB4 — Bidirectional I/O port B bit 4 |
| Pin 22 | RB5 — Bidirectional I/O port B bit 5 |
| Pin 23 | RB6 — Bidirectional I/O port B bit 6 |
| Pin 24 | RB7 — Bidirectional I/O port B bit 7 |
| Pin 25 | VDD — Positive supply voltage (3.0-6.25 V) |
| Pin 26 | NC — Not connected (per datasheet, reserved) |
| Pin 27 | RA0 — Bidirectional I/O port A bit 0 |
| Pin 28 | RA1 — Bidirectional I/O port A bit 1 |
Typical Applications
PIC16LC55A-04/SS is suitable for 7 applications: Low-Cost Consumer Appliance Control, White Goods User Interface, LED Lighting Controller, Simple Sensor Signal Conditioning, Battery-Operated Handheld Devices, Industrial Timer and Counter Modules, Educational and Hobby Electronics.
Low-Cost Consumer Appliance Control
The PIC16LC55A-04/SS suits low-cost consumer appliance controllers such as rice cookers, electric kettles, and small countertop devices where 20 I/O pins are sufficient to drive buttons, LEDs, relay outputs, and a triac for heater switching. Its 768-byte OTP memory holds the state-machine firmware typical of these products, and the 3.0-6.25 V supply range accepts both battery-derived 3.3 V rails and rectified 5 V rails. Power dissipation is minimal because the baseline core draws ~1 mA active at 4 MHz, enabling compliance with standby-power regulations without a separate low-power MCU.
Recommended
White Goods User Interface
The PIC16LC55A-04/SS is well suited for washing machine and dishwasher user-interface boards that drive 7-segment displays, membrane keypads, and buzzer indicators. The 20 I/O count directly maps to typical UI matrices (8 segments + 4 digit commons + 4 keypad rows + 4 keypad columns) without external I/O expanders. OTP memory locks the final UI firmware to prevent unauthorized code changes, while the 0C to +70C commercial range covers indoor appliance environments. Per the Microchip PIC16C5X datasheet DS30412D, the baseline core's deterministic instruction timing simplifies button-debounce and display-multiplex routines.
Recommended
LED Lighting Controller
The PIC16LC55A-04/SS can drive addressable LED strings or simple PWM-dimmed white-LED fixtures by using its 20 I/O to bit-bang WS2812 protocols or generate hardware PWM via Timer0. The 4 MHz clock provides sufficient resolution for 8-bit PWM dimming at 1 kHz update rate, and the 3.0-6.25 V supply range accepts direct USB or 5 V adapter power. Low quiescent current in standby (~1 uA typical for LC process) helps meet energy-star standby targets for smart-bulb products.
Recommended
Simple Sensor Signal Conditioning
The PIC16LC55A-04/SS handles basic sensor signal conditioning for thermistor, photoresistor, or simple switch-debounce front-ends in IoT edge nodes and HVAC peripherals. Its 20 I/O accommodate multiple analog inputs through external resistor dividers, and the baseline core executes polling loops at deterministic 1 us/instruction. While it lacks an integrated ADC, designers can pair it with an external ADC IC or use a comparator-based slope converter. The 768B OTP memory fits compact sensor-fusion or threshold-detection firmware.
Recommended
Battery-Operated Handheld Devices
The PIC16LC55A-04/SS is a strong fit for battery-operated handheld devices like remote controls, key fobs, and simple toys that run from 2-3 AA cells (3.0-4.5 V nominal) or a single CR2032 with boost converter. The LC low-power CMOS process achieves ~1 uA standby current, extending shelf life and operating time. The 20 I/O can drive IR LEDs, button matrices, vibration motors, and piezoelectric buzzers without external glue logic, and OTP memory ensures the final firmware is locked against tampering or accidental erasure.
Recommended
Industrial Timer and Counter Modules
The PIC16LC55A-04/SS implements standalone industrial timer/counter modules for conveyor sequencing, machine cycle counting, or pump-dosing controllers where deterministic timing and locked firmware are priorities. Its 8-bit Timer0 with programmable prescaler handles event counting up to 4 MHz, and the watchdog timer with dedicated RC oscillator provides fail-safe recovery from electrical noise. OTP memory prevents field tampering with calibration or sequence parameters, an advantage for OEM-locked industrial subsystems. Operating from 3.0-6.25 V covers both 24 V-derived regulated rails and 5 V logic supplies.
Recommended
Educational and Hobby Electronics
The PIC16LC55A-04/SS is widely adopted in electronics education and hobby projects because the PIC16C5X baseline architecture is straightforward to learn: only 33 instructions, no interrupts, fixed hardware stack. Students can program it with inexpensive programmers (e.g., PICkit 3 with adapter) and build blinky-LED, button-debounce, and simple serial projects. The 768B OTP memory and 20 I/O provide enough headroom for class projects, while the SSOP-28 package on a breakout board exposes all pins for breadboard experimentation. Note that OTP requires a UV eraser window part (PIC16LC55A-04/JW) for re-programming in dev cycles.
Recommended
Recommended Products Summary
Engineering reference data for PIC16LC55A-04/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16LC55A-04I/SS | PIC16C55A-04/SS | PIC16LC554T-04/SO | PIC16LC558T-04/SO | PIC16LC54A-04/SS |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | SSOP-28 | SSOP-28 (same) | SSOP-28 (same) | SOIC-28 (same 28-pin SO family) | SOIC-28 (same 28-pin SO family) | SSOP-28 (same) |
| Program Memory | 768 B OTP | 768 B OTP (same) | 768 B EPROM (same) | 768 B OTP (same) | 2 KB OTP (larger) | 512 B OTP (smaller) |
| Data RAM | 32 B | 32 B (same) | 32 B (same) | 32 B (same) | 72 B (larger) | 32 B (same) |
| Max Clock Speed | 4 MHz | 4 MHz (same) | 4 MHz (same) | 4 MHz (same) | 4 MHz (same) | 4 MHz (same) |
| I/O Pins | 20 | 20 (same) | 20 (same) | 20 (same) | 20 (same) | 12 (smaller) |
| Supply Voltage | 3.0 - 6.25 V | 3.0 - 6.25 V (same) | 3.0 - 6.25 V (same) | 3.0 - 6.25 V (same) | 3.0 - 6.25 V (same) | 3.0 - 6.25 V (same) |
| Operating Temperature | 0C to +70C (Commercial) | -40C to +85C (Industrial) | 0C to +70C (same) | 0C to +70C (same) | 0C to +70C (same) | 0C to +70C (same) |
| Process Family | LC (low-power CMOS) | LC (same) | C (standard CMOS, higher Iq) | LC (same) | LC (same) | LC (same) |
Key Differentiators
- Low-power LC CMOS process variant (vs PIC16C55A-04/SS (standard CMOS))
- Commercial temperature grade qualification (vs PIC16LC55A-04I/SS (industrial))
- Compact 28-pin SSOP package with 20 I/O (vs PIC16LC54A-04/SS)
Design Notes
Estimated: at VDD = 5 V and 4 MHz active, the PIC16LC55A-04/SS (LC process) draws approximately 1.1 mA active and ~1 uA standby per the PIC16C5X datasheet. For battery operation from 2x AA cells (3.0 V nominal), the supply droops toward 2.0 V at end-of-life; below 3.0 V the part operates but with reduced noise margin. Always include a 0.1 uF decoupling capacitor adjacent to VDD (pin 25) and VSS (pin 5), plus a bulk 10 uF if the supply rail is shared with motors or relays.
Place the decoupling capacitor within 3 mm of the VDD pin to minimize supply noise. For SSOP-28 footprints, route VDD and VSS as wide traces or pour to reduce inductance. The MCLR pin (pin 4) requires a 10 kohm pull-up to VDD if not driven by an external supervisor; in noisy environments add a 100 nF cap from MCLR to VSS to filter glitches that could trigger spurious resets.
OTP memory cannot be re-programmed in-circuit: a programming error or firmware bug requires replacing the part. Always validate firmware on a JW (windowed) ceramic or PDIP sibling (e.g., PIC16LC55A-04/P) before committing to SSOP-28 production. The baseline PIC16C5X core has NO interrupts and a fixed 2-level hardware stack - deeply nested subroutines will corrupt the stack. The 33-instruction RISC set does not include a multiply or hardware divide; math-heavy algorithms must be implemented in software loops.
The PIC16LC55A-04/SS SSOP-28 package dissipates negligible power (under 10 mW typical). No thermal management or copper-pour heatsinking is required for normal operation. However, in enclosed fixtures (e.g., outdoor LED drivers) where ambient temperature may exceed +70C, derate to the industrial-temp variant PIC16LC55A-04I/SS, which is qualified for -40C to +85C operation.
Compliance Information
RoHS/REACH compliance for PIC16LC55A-04/SS is lot-dependent; older production runs may be non-RoHS. Contact Microchip or authorized distributor with the date code for confirmation. AEC-Q100 is not applicable - this part targets consumer/industrial markets, not automotive.
