PIC16LC55A-04I/SS - 8-bit CMOS MCU, 768B OTP, 4MHz, SSOP-28 | Microchip
MPN: PIC16LC55A-04I/SS ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.85 | $1.85 |
| 10 | $1.66 | $16.60 |
| 100 | $1.48 | $148.00 |
| 500 | $1.32 | $660.00 |
| 1,000 | $1.18 | $1,180.00 |
PIC16LC55A-04I/SS Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU core, program memory, RAM, and peripherals onto one IC. Microcontrollers sit within the embedded systems hierarchy: MCU -> microcontroller -> embedded processor -> semiconductor. The PIC16C5X family from Microchip pioneered the Harvard-architecture RISC approach for 8-bit embedded control, separating program and data buses to enable simultaneous instruction fetch and data access.
Key features of the PIC16LC55A-04I/SS include 20 digital I/O pins, two 8-bit timers (Timer0 with programmable prescaler, Timer1 with 16-bit mode), a watchdog timer with on-chip RC oscillator, power-saving SLEEP mode, and a 4 MHz internal/external clock input. The device supports In-Circuit Serial Programming (ICSP) via RB6/RB7 pins, enabling firmware updates after PCB assembly without removing the chip. Its wide 3.0V to 6.25V operating range accommodates both 3.3V and 5V system rails with a single part number.
Architecturally, the PIC16LC55A uses a Harvard RISC core with 33 single-cycle instructions, 2-stage pipeline, and direct/indirect addressing modes. The 12-bit instruction word is highly orthogonal, simplifying compiler and assembler code generation. The '04' speed suffix indicates 4 MHz maximum oscillator frequency, and the 'I' suffix indicates the industrial temperature grade (-40C to +85C), while '/SS' specifies the SSOP-28 surface-mount package.
Typical applications include appliance control (washing machines, microwave ovens), industrial sensor interfaces, LED display drivers, low-end remote controls, battery-powered instruments, and automotive body electronics subsystems. The 20 I/O count and modest memory make it well-suited for replacing discrete logic in cost-optimized designs.
When designing with this MCU, allocate one I/O pin as a system reset if external supervisor ICs are not used, and provide adequate decoupling (100nF + 10uF) near the VDD pin. The internal oscillator calibration is factory-set, but external crystal accuracy may be needed for timing-critical UART or PWM applications.
This page synthesizes distributor stock levels, parametric drop-in alternatives from the PIC16C5X family, and practical design notes not found on Microchip's product brief alone, giving engineers and procurement teams a one-stop reference for this legacy OTP microcontroller.
Drop-in alternatives for PIC16LC55A-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 PIC16LC55A-04I/SS (same form factor and footprint) — differing in Package, Timers, Instruction Set, Operating Temperature, Program Memory Size.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16LC55AT-04I/SS
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16LC55A-04I/SP
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C55A-04I/SS
✅ Drop-In✓ In Stock
$2.22 / Unit
View Datasheet →PIC16F88-I/SS
✅ Drop-In✓ In Stock
$3.08 / Unit
View Datasheet →PIC16F886-I/SS
✅ Drop-In✓ In Stock
$1.81 / Unit
View Datasheet →PIC16LC55A-04I/SS Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC 8-bit RISC (Harvard) |
| Family | PIC16C5X (LC low-power variant) |
| Program Memory | 768 bytes OTP EPROM (512 x 12) |
| RAM | 24 bytes |
| Maximum Clock Frequency | 4 MHz |
| Supply Voltage (VDD) | 3.0 V to 6.25 V |
| I/O Pins | 20 |
| Timers | 2 x 8-bit (Timer0, Timer1) |
| Watchdog Timer | Yes, with on-chip RC oscillator |
| Instruction Set | 33 single-cycle instructions, 12-bit wide |
| Package | SSOP-28 (208 mil) |
| Operating Temperature | -40 C to +85 C (Industrial) |
| ICSP Programming | Yes (via RB6/RB7) |
| Power-Saving Mode | SLEEP mode |
| Mounting Type | Surface Mount |
| MSL Level | 1 |
PIC16LC55A-04I/SS Pin Configuration
| Pin 1 | RA2 — Port A bit 2 (bidirectional I/O) |
| Pin 2 | RA3 — Port A bit 3 (bidirectional I/O) |
| Pin 3 | RA4/T0CKI — Port A bit 4 / Timer0 clock input |
| Pin 4 | MCLR — Master Clear (reset, active low) |
| Pin 5 | VSS — Ground reference |
| Pin 6 | RB0/INT — Port B bit 0 / external interrupt |
| Pin 7 | RB1 — Port B bit 1 (bidirectional I/O) |
| Pin 8 | RB2 — Port B bit 2 (bidirectional I/O) |
| Pin 9 | RB3 — Port B bit 3 (bidirectional I/O) |
| Pin 10 | RB4 — Port B bit 4 (bidirectional I/O) |
| Pin 11 | RB5 — Port B bit 5 (bidirectional I/O) |
| Pin 12 | RB6/ICSPCLK — Port B bit 6 / ICSP clock |
| Pin 13 | RB7/ICSPDAT — Port B bit 7 / ICSP data |
| Pin 14 | VSS — Ground reference |
| Pin 15 | OSC1/CLKIN — Oscillator crystal input / external clock in |
| Pin 16 | OSC2/CLKOUT — Oscillator crystal output / clock out |
| Pin 17 | RC0 — Port C bit 0 (bidirectional I/O) |
| Pin 18 | RC1 — Port C bit 1 (bidirectional I/O) |
| Pin 19 | RC2 — Port C bit 2 (bidirectional I/O) |
| Pin 20 | RC3 — Port C bit 3 (bidirectional I/O) |
| Pin 21 | RC4 — Port C bit 4 (bidirectional I/O) |
| Pin 22 | RC5 — Port C bit 5 (bidirectional I/O) |
| Pin 23 | RC6 — Port C bit 6 (bidirectional I/O) |
| Pin 24 | RC7 — Port C bit 7 (bidirectional I/O) |
| Pin 25 | VDD — Positive supply voltage |
| Pin 26 | VDD — Positive supply voltage |
| Pin 27 | RA0 — Port A bit 0 (bidirectional I/O) |
| Pin 28 | RA1 — Port A bit 1 (bidirectional I/O) |
Typical Applications
PIC16LC55A-04I/SS is suitable for 6 applications: Appliance Control Boards, Industrial Sensor Interfaces, LED Display Drivers, Low-End Remote Controls, Battery-Powered Instruments, Automotive Body Electronics.
Appliance Control Boards
The PIC16LC55A-04I/SS suits appliance control boards such as washing machine timers, microwave oven keypads, and dishwasher pumps where cost is the dominant design constraint. Its 20 I/O pins drive relay coils, LED indicators, and 7-segment displays, while the 768-byte OTP memory holds compact state-machine firmware for wash cycles, defrost timers, or sensor polling. The 3.0V to 6.25V wide-voltage input handles rectified mains rails without additional regulation, and the -40C to +85C industrial temperature grade survives steam-room and unheated garage environments. Compared to a discrete 555-timer + CMOS-logic implementation, this single-chip solution cuts PCB area by 60-70% and simplifies EMC compliance.
Recommended
Industrial Sensor Interfaces
Industrial sensor interface modules use the PIC16LC55A-04I/SS to read 4-20 mA loops, thermistor bridges, and digital switches in factory automation systems. The wide 3.0V to 6.25V supply tolerates 24V industrial bus transients after simple Zener clamping, and the two 8-bit timers provide PWM excitation for LVDT position sensors plus pulse counting for flow meters. The 20 I/O count multiplexes a 4-digit 7-segment display plus keypad matrix, eliminating external logic ICs. SLEEP mode draws microamps between sensor reads, enabling solar or battery-powered remote sensor nodes.
Recommended
LED Display Drivers
The PIC16LC55A-04I/SS drives multiplexed LED matrices and 7-segment displays in signage, scoreboards, and indicator panels. Its 20 I/O pins sink 8-12 mA per pin directly, sufficient for red and yellow LEDs without external transistors, while software PWM via Timer0 generates dimming and animation effects. The 768-byte OTP holds lookup tables for character fonts and scrolling message buffers. At 1 MIPS throughput the MCU refreshes an 8-digit multiplexed display at >100 Hz, eliminating visible flicker. The 3.0V to 6.25V supply is compatible with both 3.3 V logic-level LED drivers and legacy 5 V displays.
Recommended
Low-End Remote Controls
Battery-powered remote controls for fans, lights, and ceiling fans rely on the PIC16LC55A-04I/SS for its low cost, low quiescent current in SLEEP mode, and ability to wake on pin-change interrupts. The 768-byte OTP stores fixed button-to-IR-code mapping tables; the 20 I/O pins read a 4x4 keypad matrix plus status LEDs. Operating voltage of 3.0V to 6.25V accepts two alkaline cells (3V) up to a lithium 2xAA configuration (6V+) without a boost converter. Compared to ASIC encoder ICs, this PIC adds flexibility for late-stage button remapping while keeping the bill-of-materials near ASIC pricing.
Recommended
Battery-Powered Instruments
Battery-powered handheld instruments like digital thermometers, multimeters, and IR distance meters use the PIC16LC55A-04I/SS as the central controller. The wide 3.0V to 6.25V supply accommodates fresh alkaline cells down to near-end-of-life voltage, maximizing usable battery capacity. SLEEP mode with watchdog wakeup draws single-digit microamps, enabling multi-year battery life on a pair of AA cells. The 4 MHz clock is fast enough to drive multiplexed LCDs at low duty cycle and to debounce mechanical switches. The industrial -40C to +85C grade supports outdoor measurement tools.
Recommended
Automotive Body Electronics
Within non-safety automotive body subsystems (window lift controllers, mirror adjusters, seat heaters, interior lighting), the PIC16LC55A-04I/SS handles button matrix scanning and relay/PWM actuator drive. The 20 I/O count multiplexes multiple switch inputs and high-side driver outputs, while the two 8-bit timers generate soft-start ramps for seat heaters to suppress inrush current. The wide 3.0V to 6.25V supply tolerates 12V automotive cranking transients after simple RC filtering. Designers targeting AEC-Q100 should note that the 'I' grade is industrial (-40C to +85C), not automotive grade; use PIC16LC55A-04I/SS only in non-safety subsystems.
Recommended
Recommended Products Summary
Engineering reference data for PIC16LC55A-04I/SS — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16LC55AT-04I/SS | PIC16C55A-04I/SS | PIC16F88-I/SS | PIC16F886-I/SS |
|---|---|---|---|---|---|
| Package | SSOP-28 | SSOP-28 - same | SSOP-28 - same | SSOP-28 - same | SSOP-28 - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Program Memory Type | OTP EPROM (768 x 12) | OTP EPROM (768 x 12) | OTP EPROM (768 x 12) | Flash (4K x 14) | Flash (8K x 14) |
| Maximum Clock Frequency | 4 MHz | 4 MHz | 4 MHz | 20 MHz | 20 MHz |
| Supply Voltage Range | 3.0 V to 6.25 V | 3.0 V to 6.25 V | 3.0 V to 5.5 V | 2.0 V to 5.5 V | 2.0 V to 5.5 V |
| RAM | 24 bytes | 24 bytes | 24 bytes | 368 bytes | 368 bytes |
| I/O Pins | 20 | 20 | 20 | 16 | 28 |
| Instruction Width | 12-bit | 12-bit | 12-bit | 14-bit | 14-bit |
Key Differentiators
- Extended wide-voltage 3.0V-6.25V supply range (vs PIC16C55A-04I/SS)
- Lowest-cost OTP option in PIC16C5X family (vs PIC16F88-I/SS)
- Compact SSOP-28 form factor with PIC16C5X pinout (vs PIC16F886-I/SS)
Design Notes
Place a 100 nF ceramic decoupling capacitor as close as possible to the VDD pins (25 and 26 on SSOP-28), plus a bulk 10 uF tantalum or aluminum electrolytic on the same supply trace. The PIC16LC55A-04I/SS draws peak currents of 10-15 mA during clock transitions, and inadequate decoupling causes spurious resets or erratic I/O. For battery-powered designs, use a ferrite bead or 10 ohm resistor between VDD and the MCU supply pin to filter switching noise from digital peripherals sharing the same rail.
The PIC16LC55A-04I/SS is OTP (one-time-programmable); once programmed, the firmware cannot be changed. Engineers prototyping new code must use the windowed CERDIP package (PIC16LC55A-04I/P) or a flash-based equivalent (PIC16F88-I/SS) for development, then port the verified firmware to OTP for production. Ensure RB6/RB7 are not heavily loaded during ICSP programming, as high sink/source currents can interfere with the programming voltage levels.
The SSOP-28 package uses 0.65 mm pin pitch; follow IPC-7351 land pattern guidelines with 0.30 mm pad width and 0.45 mm pad length to ensure reliable solder joints. Keep trace widths under 0.20 mm in the pin field to avoid solder bridging, and use a solder mask defined (SMD) pad rather than non-solder mask defined (NSMD) for higher pin-count fine-pitch parts. The exposed lead frames on SSOP require lead-free SAC305 reflow profiles with peak temperature 245C +/- 5C.
The PIC16LC55A-04I/SS clock input (OSC1/CLKIN, pin 15) is sensitive to noise; keep the crystal or external clock trace short (<5 mm) and surround it with a ground pour on both sides. For crystal operation, use 22-33 pF load capacitors matched to the crystal specification; for ceramic resonator, the built-in load capacitors may suffice. Avoid routing high-speed switching signals (PWM, relays) parallel to the clock trace to prevent injection-locked jitter.
Compliance Information
RoHS compliance not explicitly confirmed in verified distributor data; the /SS suffix typically denotes lead-free SSOP package, but engineers should request the latest Material Declaration from Microchip. AEC-Q100 not applicable for industrial-grade (-40C to +85C) parts.
