PIC16C558T-20/SO - 8-bit 20MHz OTP MCU 3.5KB | Microchip
MPN: PIC16C558T-20/SO ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $1.74 | $1.74 |
| 10 | $1.56 | $15.60 |
| 100 | $1.39 | $139.00 |
| 500 | $1.21 | $605.00 |
| 1,000 | $1.05 | $1,050.00 |
PIC16C558T-20/SO Overview
An 8-bit microcontroller (MCU) is a single-chip computer that integrates a CPU, RAM, non-volatile program memory, and peripheral interfaces into one package. Within the system hierarchy, an MCU sits above discrete logic and below microprocessors: it is a self-contained compute subsystem optimized for embedded control rather than high-throughput computation. Microchip's PIC baseline family (PIC16C5xx) is the lowest-cost and simplest tier of the PIC16 lineup, designed for cost-sensitive applications where code density and ease of programming outweigh the need for interrupts and advanced peripherals.
Key features of the PIC16C558T-20/SO include the 35 single-word instruction RISC core that executes instructions in 200ns at 20MHz, a fixed watchdog timer (WDT) and Power-On Reset (POR) for unattended operation, and a wide operating voltage range of 3.0V to 5.5V. Unlike PIC16F and PIC16 enhanced mid-range parts, the PIC16C558 lacks interrupts, has a 12-bit program counter, and uses a 2-level hardware stack. The 13 I/O pins are organized as PORTA (RA0-RA3) and PORTB (RB0-RB7) plus RC0-RC1 in this 18-pin variant.
Typical applications for this device include simple appliance controls, LED drivers, fan controllers, battery chargers, security keypads, and consumer toys where the OTP memory is acceptable and code density in 12-bit-wide words is sufficient. The wide commercial temperature grade and low pin count make it well-suited to compact hand-held products. When designing with the PIC16C558T-20/SO, ensure the OTP memory capacity (3.5KB) is sufficient for the target firmware and verify that the lack of interrupts and 2-level stack depth are compatible with the application complexity. The external RC or crystal oscillator configuration must follow the baseline PIC16C5xx reference designs because this family does not include the internal oscillator blocks of later PIC generations.
Drop-in alternatives for PIC16C558T-20/SO — 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 PIC16C558T-20/SO (same form factor and footprint) — differing in Package, Program Memory Type, Program Memory Size, Core Architecture, Instruction Execution Time.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
PIC16C558-20/SO
✅ Drop-In✓ In Stock
$2.05 / Unit
View Datasheet →PIC16C558-20I/SO
✅ Drop-In✓ In Stock
$1.2 / Unit
View Datasheet →PIC16C558T-20E/SO
✅ Drop-In📋 Reference alternative (not in catalog)
PIC16C558T-20I/SO
✅ Drop-In✓ In Stock
$1.18 / Unit
View Datasheet →PIC16C554T-20/SO
✅ Drop-In✓ In Stock
$1.82 / Unit
View Datasheet →PIC16C558T-20/SO Maximum Ratings & Electrical Characteristics
| Core Architecture | PIC16C5xx 8-bit RISC |
| Program Memory Type | OTP (One-Time-Programmable) |
| Program Memory Size | 3.5KB (2K x 14) |
| RAM Size | 128 x 8 bytes |
| EEPROM Size | None |
| Maximum CPU Frequency | 20 MHz |
| Instruction Execution Time | 200 ns at 20 MHz |
| Instruction Set Size | 35 single-word instructions |
| Number of I/O Pins | 13 |
| Peripherals | POR, WDT (Watchdog Timer) |
| Operating Voltage Range | 3.0 V to 5.5 V |
| Operating Temperature Range | 0 C to +70 C (Commercial) |
| Package | 18-SOIC (300 mil) |
| Mounting Type | Surface Mount |
| Shipping Format | Tape and Reel (T suffix) |
PIC16C558T-20/SO Pin Configuration
| Pin 1 | RA2 — Bidirectional I/O pin, PORTA bit 2 |
| Pin 2 | RA3 — Bidirectional I/O pin, PORTA bit 3 |
| Pin 3 | VSS — Ground reference |
| Pin 4 | /MCLR — Master Clear reset input (active low) |
| Pin 5 | OSC1 — Oscillator input / external clock |
| Pin 6 | RB0 — Bidirectional I/O pin, PORTB bit 0 |
| Pin 7 | RB1 — Bidirectional I/O pin, PORTB bit 1 |
| Pin 8 | RB2 — Bidirectional I/O pin, PORTB bit 2 |
| Pin 9 | RB3 — Bidirectional I/O pin, PORTB bit 3 |
| Pin 10 | RB4 — Bidirectional I/O pin, PORTB bit 4 |
| Pin 11 | RB5 — Bidirectional I/O pin, PORTB bit 5 |
| Pin 12 | RB6 — Bidirectional I/O pin, PORTB bit 6 |
| Pin 13 | RB7 — Bidirectional I/O pin, PORTB bit 7 |
| Pin 14 | RC0 — Bidirectional I/O pin, PORTC bit 0 |
| Pin 15 | RC1 — Bidirectional I/O pin, PORTC bit 1 |
| Pin 16 | VDD — Positive supply voltage |
| Pin 17 | RA0 — Bidirectional I/O pin, PORTA bit 0 |
| Pin 18 | RA1 — Bidirectional I/O pin, PORTA bit 1 |
Typical Applications
PIC16C558T-20/SO is suitable for 6 applications: Consumer Appliance Control, LED Lighting Driver Controller, Battery-Powered Remote Keypad, Industrial Fan and Pump Controller, Simple Toy and Hobby Electronics, Automotive Aftermarket Accessory Module.
Consumer Appliance Control
The PIC16C558T-20/SO suits cost-sensitive appliance controls such as toaster timers, coffee maker controllers, and small kitchen device interfaces. Its 3.5KB OTP memory accommodates typical 1.5-2K-instruction control firmware while 13 I/O pins drive keypads, LEDs, relay coils, and triac gates. At 20MHz the 200ns instruction cycle provides responsive debounce and timing logic without requiring interrupts - the polled TRIS-based I/O matches the simple sequential control loops common in these products. The 3.0-5.5V supply range tolerates unregulated rectified DC rails after bulk capacitance.
Recommended
LED Lighting Driver Controller
The PIC16C558T-20/SO drives LED lighting controllers including decorative RGB strips, signage dimmers, and Christmas light sequencers. The 20MHz instruction rate enables software PWM generation for dimming via the 13 I/O pins, while the 3.5KB OTP holds lookup tables for color sequences and breathing patterns. The wide 3.0-5.5V supply operates directly from 5V USB or 3.3V regulated rails, and the 18-SOIC footprint fits compact bulb-base PCBs. Power-On Reset (POR) ensures clean startup sequences for synchronized lighting arrays.
Recommended
Battery-Powered Remote Keypad
The PIC16C558T-20/SO fits wireless remote keypads for security systems, garage door openers, and RF keyfobs where its low pin count, OTP memory, and commercial temperature grade balance cost against functionality. The 13 I/O pins scan a 4x4 matrix keypad, drive an RF transmitter enable line, and read status LEDs, while the 3.5KB OTP stores custom rolling codes and button debounce state machines. The 3.0V minimum supply enables 2xAA battery operation, and the simple polled I/O architecture keeps sleep-mode firmware straightforward for battery-life optimization.
Recommended
Industrial Fan and Pump Controller
The PIC16C558T-20/SO serves in industrial fan and small pump controllers where its 13 I/O pins read tachometer feedback, drive TRIAC gates, and monitor temperature sensors via discrete ADC techniques (ratiometric with reference resistors). The 200ns instruction cycle at 20MHz executes PID loops fast enough for thermal regulation in fan-speed control, and the 3.5KB OTP accommodates calibration tables and fault-detection state machines. The 18-SOIC package mounts on standard control board footprints and the industrial-grade sibling PIC16C558-20I/SO extends operation to -40 C for factory-floor environments.
Recommended
Simple Toy and Hobby Electronics
The PIC16C558T-20/SO powers low-cost educational toys, hobby robotics controllers, and RC servo sequencers where its OTP memory and polled architecture keep BOM costs minimal. The 35-instruction RISC core is straightforward for beginners learning embedded programming in assembly or PIC BASIC, while 13 I/O pins drive hobby servos, read sensors, and control motor H-bridges. The 20MHz speed provides responsive servo pulse generation (50Hz refresh with 1us resolution) and the 18-SOIC through-hole-friendly footprint simplifies breadboard and perfboard prototyping for hobbyist designs.
Recommended
Automotive Aftermarket Accessory Module
The PIC16C558T-20/SO (or its industrial-grade sibling PIC16C558-20I/SO) drives aftermarket automotive accessories such as alarm systems, remote start modules, and interior light controllers. The 13 I/O pins read door-switch inputs, drive siren and relay outputs, and interface with RF receivers, while the 3.5KB OTP stores custom alarm logic and timing sequences. The industrial temperature variant tolerates -40 C to +85 C cabin and under-hood environments, and the 3.0-5.5V supply operates from 12V vehicle rails after regulation. The wide voltage tolerance handles automotive load-dump and cold-crank transients within regulation limits.
Recommended
Recommended Products Summary
Engineering reference data for PIC16C558T-20/SO — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | PIC16C558-20/SO | PIC16C558-20I/SO | PIC16C558T-20E/SO | PIC16C558T-20I/SO | PIC16C554T-20/SO |
|---|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 18-SOIC | 18-SOIC - same | 18-SOIC - same | 18-SOIC - same | 18-SOIC - same | 18-SOIC - same |
| Program Memory | 3.5KB OTP (2K x 14) | 3.5KB OTP (2K x 14) | 3.5KB OTP (2K x 14) | 3.5KB OTP (2K x 14) | 3.5KB OTP (2K x 14) | 0.875KB OTP (-75%) |
| Maximum CPU Frequency | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz | 20 MHz |
| RAM Size | 128 x 8 bytes | 128 x 8 bytes | 128 x 8 bytes | 128 x 8 bytes | 128 x 8 bytes | 128 x 8 bytes |
| Number of I/O Pins | 13 | 13 | 13 | 13 | 13 | 13 |
| Operating Temperature Range | 0 C to +70 C (Commercial) | 0 C to +70 C (Commercial) | -40 C to +85 C (Industrial) | -40 C to +125 C (Extended) | -40 C to +85 C (Industrial) | 0 C to +70 C (Commercial) |
| Shipping Format | Tape and Reel | Tube | Tube | Tape and Reel | Tape and Reel | Tape and Reel |
| Lifecycle Status | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete | Obsolete |
Key Differentiators
- Industrial temperature grade with identical pinout (vs PIC16C558-20I/SO)
- Extended temperature grade for harsh environments (vs PIC16C558T-20E/SO)
- Reduced program memory for cost-optimized designs (vs PIC16C554T-20/SO)
Design Notes
The PIC16C558T-20/SO lacks interrupts and uses only a 2-level hardware stack - firmware written for mid-range PIC16F parts that rely on interrupt-driven ISRs and deep call stacks will fail on this baseline device. Designers migrating code must convert interrupt handlers to polled flag-checking main loops and inline deep subroutines. The 12-bit program counter cannot address more than 2K instructions, so the 3.5KB OTP should be treated as 2K x 14 words rather than bytes when estimating code capacity.
The 18-SOIC pin 1 is identified by a molded dot or notch on the package top; orient the IC so pin 1 is at the top-left when the dot is at upper-left per JEDEC MS-013. The /MCLR pin (pin 4) must be pulled up to VDD through a 10-50 kohm resistor per Microchip baseline PIC reference designs; leaving /MCLR floating causes erratic resets. Place the 0.1 uF VDD decoupling capacitor within 5 mm of pin 16, and keep the OSC1/OSC2 traces short when using a crystal oscillator configuration.
The PIC16C558T-20/SO operates from 3.0V to 5.5V across the commercial 0-70 C temperature range. Brown-out detection is not available on baseline PIC16C5xx devices, so external voltage supervisory circuits (such as the MCP100 or TPS3839) are required if unpredictable VDD dropouts could cause code execution errors. Power-On Reset (POR) is built in but only triggers below approximately 1.5V; intermediate voltage brown-outs between 1.5V and 3.0V may corrupt program flow without triggering a reset.
The PIC16C558T-20/SO is a low-power CMOS device that typically draws 2-5 mA active at 20MHz and 5V, dissipating well under 25 mW even at maximum clock rate. The 18-SOIC package has a theta_JA of approximately 85 C/W, supporting operation up to the commercial 70 C ambient without thermal management. Estimated: at 5V VDD and 5 mA active current, power dissipation is 25 mW, giving a junction temperature rise of only 2.1 C above ambient - thermal design is not a constraint for this part.
Compliance Information
RoHS and lead-free status not directly available in the verified data; engineers should request the latest Microchip material declaration document for the PIC16C558 family. Not AEC-Q100 qualified - automotive designs should use automotive-grade PIC16F variants instead.
